Search

The purpose of this study was to explore the effects of different factors on the compressive mechanical properties of corn kernels. Explore the relationship between endosperm hardness and compressive mechanical properties of corn kernels by polynomial regression analysis. The results showed that the variety and kernel orientation had a significant effect on the compressive mechanical properties of corn kernels. Flint corn had a stronger ability to resist damage than floury corn. As the loading rate increased from 5 to 25 mm/min, the rupture force and rupture energy of corn kernels changed accordingly. The hardness of horny endosperm was significantly higher than that of floury endosperm. The dense starch‐protein network structure of horny endosperm leads to higher hardness. According to the fitting results, the compressive mechanical properties of corn kernels could be predicted using the hardness of the horny endosperm within a certain range. Practical applications: As a widely planted food crop in the world, corn is not only an important food crop, but also a high‐quality feed for livestock and poultry. The compressive mechanical properties (elastic modulus, compressive failure force, failure energy, etc.) of corn kernels were explored, and the relationship between endosperm hardness and its mechanical properties was analyzed. It can provide technical parameters for mechanical processing equipment, reduce the loss of corn grain in the processing process, and improve its economic value. [ABSTRACT FROM AUTHOR]

The floury endosperm mutants of rice can not only be used to uncover the molecular mechanisms involved in regulating starch synthesis and grain development but are also suitable for dry milling to produce rice flour of good quality. In this study, we identified and characterized a rice floury endosperm mutant, M10, from a mutant pool induced by EMS. The total starch content in the M10 seeds significantly decreased, while the soluble sugar content demonstrably increased. The grain hardness of M10 was lower than that of the wild type because of the spherical and loosely packed starch granules. The modified MutMap analysis demonstrated that AGPL2 on chromosome 1 is most likely to be the candidate gene causing a floury endosperm. The genome sequences of AGPL2 in M10 carried a single nucleotide substitution of guanine (G) to adenine (A) in the seventh exon, leading to a missense mutation from glycine (Gly) to glutamic acid (Glu) at the 251st amino acid. Allele test confirmed that AGPL2 is the gene responsible for the M10 phenotype. Both transcriptional and protein levels of AGPL2 in M10 were obviously higher than those in the developing endosperm of wild type, indicating a positive feedback regulation is caused by AGPL2 mutation. Together, our results suggest that AGPL2 plays a critical role in starch synthesis and that the modified MutMap method is feasible for identifying floury endosperm mutant genes in rice. [ABSTRACT FROM AUTHOR]

Rice cultivars with floury endosperm provide a useful raw material for producing dry-milled rice flour, helping to enhance the processed rice food industry. To expand the genetic resources for breeding floury endosperm rice cultivars, we developed Samkwang(SA)-flo3 (SK-flo3), a floury endosperm mutant line derived from the chemical mutagenesis of Samkwang, an elite Korean japonica rice cultivar. Compared with Samkwang, SK-flo3 showed significantly lower grain hardness, which is suitable for producing dry-milled flour without the soaking and drying processes required in regular wet rice milling. The dry-milled flour of SK-flo3 exhibited excellent physicochemical properties with less damaged starch and finer flour particles relative to Samkwang. Genetic analyses revealed a G-to-A point mutation in exon 7 of cyOsPPDKB, substituting glycine with aspartic acid as a causative mutation for the floury endosperm of SK-flo3. We named this allele flo4-6 and developed a molecular marker to efficiently transfer it to commercial rice cultivars. Our results provide useful genetic resources and information for developing specialty rice cultivars for high-quality rice flour production with reduced milling costs. [ABSTRACT FROM AUTHOR]

BACKGROUND: Andean purple maize (APM) is an ancient crop widely used as a natural coloring in traditional Peruvian cuisine. However, it has been little explored within the food industry. The present study assessed how APM impacts on techno‐functional properties and sensory acceptance of breakfast cereals. Extruded samples formulated with 100, 75, 50, and 25% APM, and complemented with yellow corn grits (YCG), were analyzed for their techno‐functional and sensory properties. RESULTS: Increases in bulk density, as well as reduction in the expantion and porosity were observated for extrudates containing ≥ 50% APM, accompanied by an increase in purple color intensity. Increase in milk absorption index, reduction in milk solubility index and decrease in cereal hardness with increase in APM were also observed. Despite this, APM extented the cereal bowl‐life. High sensory scores of overall liking (6) and color (7) were obtained for extruded formulations containing ≥ 50% APM and low values for extrudates with 25% APM. Aroma, flavor, and texture scores did not present significant differences. CONCLUSION: APM is an ingredient with the potential to be used to produce breakfast cereals since it improves their techno‐functional characteristics and sensory acceptance, at the same time, it leads to the production of healthy, nutritious, and sustainable food. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Starch and proteins are main storage product to determine the appearance, cooking, texture, and nutritional quality of rice (Oryza sativa L.). OsNAC20 and OsNAC26, as pivotal transcription factors, redundantly regulate the expression of genes responsible for starch and protein synthesis in the rice endosperm. Any knockout of OsNAC20 or OsNAC26 did not result in visible endosperm defects. In this study, we had isolated and characterized a mutant named as floury endosperm25 (flo25). The caryopsis of the flo25 mutant exhibits a floury endosperm, accompanied by reductions in both the 1000-grain weight and grain length, as well as diminished levels of total starch and protein. Through map-based cloning, it was determined that FLO25 encodes a NAM, ATAF, and CUC (NAC) transcription factors, namely OsNAC26, with a lysine to asparagine substitution at position 98 in the flo25 mutant. Remarkably, lysine 98 is conserved across plants species, and this mutation does not alter the subcellular localization of OsNAC26 but significantly attenuates its transcriptional activity and its ability to activate downstream target genes. Furthermore, the mutant protein encoded by OsNAC26 -flo25 could interact with OsNAC20, disrupting the native interaction between OsNAC20 proteins. Additionally, when lysine 98 is substituted with asparagine in OsNAC20, the resulting mutant protein, OsNAC20(K98N), similarly disrupts the interaction between OsNAC26 proteins. Collectively, these findings underscore the pivotal role of Lysine 98 (K) in modulating the transcriptional activity of NAC20/NAC26 within the rice endosperm. • The flo25 mutant showed floury endosperm along with reduced protein and starch content. • The cytosine-to-adenine at position 294 in OsNAC26 caused floury endosperm phenotype in flo25. • Lysine at position 98 is crucial for the transcriptional activation of OsNAC26 and OsNAC20. [ABSTRACT FROM AUTHOR]

“Baromi2” is an improved resistant early maturing rice variety with floury endosperm, and is suitable for dry milling. This variety was developed in 2019 by crossing “Suweon542,” which is ideal for dry milling, and “Jopyeong” by the rice breeding team at the National Institute of Crop Science, Rural Development Administration. The heading date of “Baromi2” was July 27 in the Honam Plains, 17 d earlier than that of “Seolgaeng.” The culm length of “Baromi2” was 76 cm, which was almost the same as its check variety “Seolgaeng”; additionally, its panicle length, panicle number, and 1,000 grain-weight of brown rice were 23 cm, 11, and 18.4 g, respectively. “Baromi2” showed strong resistance against rice blast, bacterial blight, and stripe virus disease, but was susceptible to dwarf and brown and small brown planthoppers. The milled rice yield of “Baromi2” was approximately 475 kg/10a in the local adaptability test for 3 years in the late planting culture. The grain hardness of “Baromi2” with a floury endosperm was 2 and 3 times lower than that of “Seolgaeng” with opaque endosperm and “Jopyeong” with transparent endosperm, respectively. The rice flour of “Baromi2” exhibited superior physicochemical characteristics with respect to granule size and damaged starch content compared with any other check varieties. These results inferred that “Baromi2” was suitable for dry milling and for the processed rice industry, owing to its lower milling costs and eco-friendly milling methods (Registration No. 9052). [ABSTRACT FROM AUTHOR]

Rice flour is useful as a substitute for wheat flour, however, to obtain fine flour, millers need special milling facilities, which increase the cost of milling. To reduce the milling cost, we developed a floury mutant line by irradiating gamma-rays to dry seeds of the japonica cultivar 'Hoshinoyume'. The line was registered as a new cultivar, 'Hoshinoko'. Genetical analysis of the floury trait was conducted using an F2 population derived from a cross between 'Hoshinoko' and 'Corbetti' (a japonica rice cultivar with normal endosperm), which indicated the involvement of a single recessive gene located near the RM163 marker on the long arm of rice chromosome 5, flanking flo4 identified by Kang et al. (2005). Sequence analysis of flo4 showed a two-bp (CA) insertion in the eighth exon of in 'Hoshinoko' compared to that of 'Hoshinoyume', which led to a frameshift mutation. The CAPS-based genotype of flo4 gene completely correlated to the phenotype of endosperm in two populations. This CAPS marker could be helpful for rice breeders to develop new cultivars harboring floury endosperm of the flo4-303 gene. [ABSTRACT FROM AUTHOR]

The improvement of the cooking and eating quality (CEQ) of rice is one of the major objectives of current rice-breeding programs. A few major genes such as Waxy (Wx) and starch synthase IIa (SSIIa) have been successfully applied in molecular breeding. However, their interactive effects on CEQ have not been fully understood. In this study, a recombinant inbred line (RIL) population was constructed by crossing the white-core mutant GM645 with the transparent phenotype of the japonica rice variety Tainung 67 (TN67). GM645 and TN67 contain different alleles of FLOURY ENDOSPERM2 (FLO2), Wx, and SSIIa. The effects of different allele combinations of FLO2, Wx, and SSIIa on the CEQ of rice were investigated. The inbred lines with the mutation allele flo2 had a significantly lower apparent amylose content (AAC), viscosity characteristics except for setback (SB), and gel texture properties compared to those lines with the FLO2 allele. The allelic combination of FLO2 and Wx significantly affected the AAC, breakdown (BD), and gel textural properties, which could explain most of the variations in those rice quality traits that were correlated with AAC. The allelic combination of FLO2 and SSIIa significantly affected the hot paste viscosity (HPV) and pasting temperature (PT). The Wx × SSIIa interaction had a significant effect on the PT. The interaction of FLO2, Wx and SSIIa significantly affected the AAC, cold paste viscosity (CPV), PT, and consistency viscosity (CS). These results highlight the important roles of these quality-related genes in regulating the CEQ of rice and provide new clues for rice-quality improvement by marker-assisted selection. [ABSTRACT FROM AUTHOR]

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Endosperm as the storage organ of starch and protein in cereal crops largely determines grain yield and quality. Despite the fact that several pentatricopeptide repeat (PPR) proteins required for endosperm development have been identified in rice, the molecular mechanisms of many P-type PPR proteins in endosperm development remains unclear. Here, we isolated a rice floury endosperm mutant ppr5 that developed small starch grains and an abnormal aleurone layer, accompanied by decreased starch, protein, and amylose contents. Map-based cloning combined with a complementation test demonstrated that PPR5 encodes a P-type PPR protein that is localized to the mitochondria. The mutation in PPR5 caused reduced splicing efficiency of mitochondrial NADH dehydrogenase 4 (nad4) gene intron 3 and reduced complex I assembly and activity. Loss of PPR5 function greatly up-regulated expression of alternative oxidases (AOXs), reduced ATP production, and affected mitochondrial morphology. We demonstrate that PPR5, as a P-type PPR protein, is required for mitochondrial function and endosperm development by controlling the cis-splicing of mitochondrial nad4 intron 3.

Endosperm, the major storage organ in cereal grains, determines the grain yield and quality. Mitochondria provide the energy for dry matter accumulation, in the endosperm development. Although mitochondrial single-stranded DNA-binding proteins (mtSSBs) play a canonical role in the maintenance of single-stranded mitochondrial DNA, their molecular functions in RNA processing and endosperm development remain obscure. Here, we report a defective rice endosperm mutant, floury endosperm26 (flo26), which develops abnormal starch grains in the endosperm. Map-based cloning and complementation experiments showed that FLO26 allele encodes a mitochondrial single-stranded DNA-binding protein, named as mtSSB1.1. Loss of function of mtSSB1.1 affects the transcriptional level of many mitochondrially-encoded genes and RNA splicing of nad1 , a core component of respiratory chain complex I in mitochondria. As a result, dysfunctional mature nad1 led to dramatically decreased complex I activity, thereby reducing ATP production. Our results reveal that mtSSB1.1 plays an important role in the maintenance of mitochondrial function and endosperm development by stabilizing the splicing of mitochondrial RNA in rice. • flo26 displays opaque endosperm. • FLO26 encodes a mitochondrial single-stranded DNA binding protein (OsmtSSB1.1). • OsmtSSB1.1 affects the transcriptional levels of mitochondrion-encoding genes and RNA splicing of nad1. • OsmtSSB1.1 plays an important role in the maintenance of mitochondrial function and endosperm development. [ABSTRACT FROM AUTHOR]

Rice cultivars with floury endosperm provide a useful raw material for producing dry-milled rice flour, helping to enhance the processed rice food industry. To expand the genetic resources for breeding floury endosperm rice cultivars, we developed Samkwang(SA)-flo3 (SK-flo3), a floury endosperm mutant line derived from the chemical mutagenesis of Samkwang, an elite Korean japonica rice cultivar. Compared with Samkwang, SK-flo3 showed significantly lower grain hardness, which is suitable for producing dry-milled flour without the soaking and drying processes required in regular wet rice milling. The dry-milled flour of SK-flo3 exhibited excellent physicochemical properties with less damaged starch and finer flour particles relative to Samkwang. Genetic analyses revealed a G-to-A point mutation in exon 7 of cyOsPPDKB, substituting glycine with aspartic acid as a causative mutation for the floury endosperm of SK-flo3. We named this allele flo4-6 and developed a molecular marker to efficiently transfer it to commercial rice cultivars. Our results provide useful genetic resources and information for developing specialty rice cultivars for high-quality rice flour production with reduced milling costs.

The floury endosperm mutants of rice can not only be used to uncover the molecular mechanisms involved in regulating starch synthesis and grain development but are also suitable for dry milling to produce rice flour of good quality. In this study, we identified and characterized a rice floury endosperm mutant, M10, from a mutant pool induced by EMS. The total starch content in the M10 seeds significantly decreased, while the soluble sugar content demonstrably increased. The grain hardness of M10 was lower than that of the wild type because of the spherical and loosely packed starch granules. The modified MutMap analysis demonstrated that AGPL2 on chromosome 1 is most likely to be the candidate gene causing a floury endosperm. The genome sequences of AGPL2 in M10 carried a single nucleotide substitution of guanine (G) to adenine (A) in the seventh exon, leading to a missense mutation from glycine (Gly) to glutamic acid (Glu) at the 251st amino acid. Allele test confirmed that AGPL2 is the gene responsible for the M10 phenotype. Both transcriptional and protein levels of AGPL2 in M10 were obviously higher than those in the developing endosperm of wild type, indicating a positive feedback regulation is caused by AGPL2 mutation. Together, our results suggest that AGPL2 plays a critical role in starch synthesis and that the modified MutMap method is feasible for identifying floury endosperm mutant genes in rice.

The endosperm of corn kernel consists of two components, a horny endosperm, and a floury endosperm. In the experiment, a kind of floury endosperm corn was identified. The result of phenotypic trait analysis and determination of amino acid content showed that the floury endosperm filled with the small, loose, and scattered irregular spherical shape starch granules and contained higher content of amino acid. The starch biochemical properties are similar between floury corns and regular flint corn. By using dynamically comparative transcriptome analysis of endosperm at 20, 25, and 30 DAP, a total of 113.42 million raw reads and 50.508 thousand genes were obtained. By using the weighted gene co-expression network analysis, 806 genes and six modules were identified. And the turquoise module with 459 genes was proved to be the key module closely related to the floury endosperm formation. Nine zein genes in turquoise module, including two zein-alpha A20 (Zm00001d019155 and Zm00001d019156), two zein-alpha A30 (Zm00001d048849 and Zm00001d048850), one 50 kDa gamma-zein (Zm00001d020591), one 22 kDa alpha-zein 14 (Zm00001d048817), one zein-alpha 19D1 (Zm00001d030855), one zein-alpha 19B1 (Zm00001d048848), and one FLOURY 2 (Zm00001d048808) were identified closely related the floury endosperm formation. Both zein-alpha 19B1 (Zm00001d048848) and zein-alpha A30 (Zm00001d048850) function as source genes with the highest expression level in floury endosperm. These results may provide the supplementary molecular mechanism of structure and nutrient formation for the floury endosperm of maize. [ABSTRACT FROM AUTHOR]

Composition and structure of endosperm starch are major determinant factors for rice quality. Glycosylinositol phosphorylceramides (GIPC) is a kind of sphingolipid and it accounts for ~ 25% of total plasma membrane lipids in plants. The relationship between synthesis of GIPC and development of endosperm starch, however, remains unclear. We here identified a mutant with a floury and opaque endosperm, named floury and shrunken endosperm 6 (fse6). The mutant seeds displayed a shrunken grain appearance. Physicochemical analysis showed that both total starch and amylose contents were decreased, while lipid and protein contents were increased in the mature mutant seeds, compared to their counterparts in the wild type. Further observation of semi-thin sections indicated the development of mutant amyloplasts was defective. The mutant seeds germinated normally but failed to survive in a later stage of seedling growth. Map-based cloning and genetic complementation revealed that FSE6 encodes a glycosyltransferase and is homologous to Arabidopsis GLUCOSAMINE INOSITOLPHOSPHORYLCERAMIDE TRANSFERASE1 (GINT1), an enzyme vital for GIPC synthesis. We further found that cellulose content and starch biosynthesis in the mutant were altered. This study connects a gap between a rice GINT1 and starch synthesis, which will be helpful for rice quality improvement. [ABSTRACT FROM AUTHOR]

The endosperm of corn kernel consists of two components, a horny endosperm, and a floury endosperm. In the experiment, a kind of floury endosperm corn was identified. The result of phenotypic trait analysis and determination of amino acid content showed that the floury endosperm filled with the small, loose, and scattered irregular spherical shape starch granules and contained higher content of amino acid. The starch biochemical properties are similar between floury corns and regular flint corn. By using dynamically comparative transcriptome analysis of endosperm at 20, 25, and 30 DAP, a total of 113.42 million raw reads and 50.508 thousand genes were obtained. By using the weighted gene co-expression network analysis, 806 genes and six modules were identified. And the turquoise module with 459 genes was proved to be the key module closely related to the floury endosperm formation. Nine zein genes in turquoise module, including two zein-alpha A20 (Zm00001d019155 and Zm00001d019156), two zein-alpha A30 (Zm00001d048849 and Zm00001d048850), one 50 kDa gamma-zein (Zm00001d020591), one 22 kDa alpha-zein 14 (Zm00001d048817), one zein-alpha 19D1 (Zm00001d030855), one zein-alpha 19B1 (Zm00001d048848), and one FLOURY 2 (Zm00001d048808) were identified closely related the floury endosperm formation. Both zein-alpha 19B1 (Zm00001d048848) and zein-alpha A30 (Zm00001d048850) function as source genes with the highest expression level in floury endosperm. These results may provide the supplementary molecular mechanism of structure and nutrient formation for the floury endosperm of maize.

Our objective was to evaluate the relative effects of endosperm type and conservation method of corn grain on ruminal kinetics, site of nutrient digestion, and flow of nitrogen fractions to the duodenum in lactating dairy cows. Seven ruminally and duodenally cannulated Holstein cows (73 ± 39 d in milk; mean ± SD) were used in a duplicated 4 × 4 Latin square design with 21-d periods. A 2 × 2 factorial arrangement of treatments was used, with main effects of corn grain endosperm type (floury or vitreous) and conserved as dry ground corn (DGC) or high-moisture corn (HMC). Rations were formulated to contain 27.0% starch, 26.6% neutral detergent fiber (NDF), 19.1% forage NDF, and 16.5% crude protein. Corn grain treatments supplied 86.6% of dietary starch, and alfalfa silage was the sole forage. True ruminal starch digestibility was increased by HMC compared with DGC (87.2 vs. 64.3%) and by floury compared with vitreous corn grain (83.7 vs. 67.7%). The increase for HMC compared with DGC was because of an increase in the degradation rate (33.8 vs. 23.1%/h) and a decrease in passage rate of starch (7.6 vs. 15.2%/h). The increase for floury compared with vitreous corn grain was because of an increase in the degradation rate (31.5 vs. 25.4%/h) and a decrease in rate of starch passage from the rumen (7.9 vs. 14.9%/h). Apparent total-tract starch digestibility was increased by HMC compared with DGC and by floury compared with vitreous corn, but the increase for floury corn was greater for the DGC treatment. Dry ground corn compared with HMC tended to increase nonammonia N flow to the duodenum (466 vs. 431 g/d) by increasing flow of nonammonia nonmicrobial N (211 vs. 111 g/d) despite a decrease in microbial N flow (255 vs. 320 g/d). Vitreous corn increased nonammonia nonmicrobial N flow to the duodenum (187 vs. 135 g/d) compared with floury corn, but microbial N flow to the duodenum was not affected by endosperm type. Efficiency of microbial N production was not affected by treatment. Endosperm type and conservation method of corn grain greatly affect digestion kinetics and ruminal digestibility of starch as well as flow of N fractions to the duodenum and should be considered during diet formulation for lactating cows. [ABSTRACT FROM AUTHOR]

Our objective was to evaluate effects of corn grain endosperm type and fineness of grind on feed intake, feeding behavior, ruminal fermentation, and productive performance of lactating cows. Eight ruminally and duodenally cannulated Holstein cows in mid lactation (130 ± 42 d in milk; mean ± standard deviation) were used in a duplicated 4 × 4 Latin square design with 21-d periods. A 2 × 2 factorial arrangement of treatments was used with main effects of corn grain endosperm type (floury or vitreous) and fineness of grind of corn grain (fine or medium). Rations were formulated to contain 29% starch, 27% neutral detergent fiber, 18.2% forage neutral detergent fiber, and 18% crude protein. Corn grain treatments supplied 86.2% of dietary starch. Endosperm was 25% vitreous for floury corn and 66% vitreous for vitreous corn. Fineness of grind did not affect dry matter intake (DMI), but floury corn tended to reduce DMI (23.8 vs. 25.1 kg/d) compared with vitreous corn. Floury corn increased meal frequency more for fine grind size (9.57 vs. 9.41 meals/d) than medium grind size (9.78 vs. 9.75 meals/d). However, there were no effects of treatment on any other measure of feeding behavior. Endosperm type did not affect yields of milk or milk components or milk composition except that vitreous corn tended to decrease milk lactose concentration compared with floury corn. Finely ground corn decreased yields of milk (31.1 vs. 33.1 kg/d), 3.5% fat-corrected milk (33.1 vs. 35.1 kg/d), milk fat (1.22 vs. 1.32 kg/d), milk lactose (1.48 vs. 1.59 kg/d), and solids not fat (2.46 vs. 2.63 kg/d) compared with medium grind size. However, fineness of grind did not affect milk composition. Treatments had no effect on change in body weight or body condition score or efficiency of milk production (kg of 3.5% fat-corrected milk/kg of DMI). Mean ruminal pH was not affected by treatment, but pH variance was decreased by vitreous compared with floury corn. Total volatile fatty acids and propionate concentrations in the rumen were increased by floury compared with vitreous corn but were not affected by fineness of grind. Effects of fineness of grind on yield of milk and milk components were greater than the effects of corn grain vitreousness. [ABSTRACT FROM AUTHOR]

Our objective was to evaluate the effects of corn grain varying in endosperm type and conserved as high-moisture or dry ground corn on dry matter intake (DMI), feeding behavior, ruminal fermentation, and yields of milk and milk components of cows in early to mid-lactation. Seven ruminally and duodenally cannulated Holstein cows (73 ± 39 d in milk; mean ± SD) were used in a duplicated 4 × 4 Latin square design with 21-d periods. A 2 × 2 factorial arrangement of treatments was used with main effects of corn grain endosperm type (floury or vitreous) conserved as high-moisture corn (HMC) or dry ground corn (DGC). Rations were formulated to contain 27.0% starch, 26.6% neutral detergent fiber (NDF), 19.1% forage NDF, and 16.5% crude protein. Corn grain treatments supplied 86.6% of dietary starch and contained alfalfa silage as the sole forage. Dry matter intake was increased 1.3 kg/d by DGC compared with HMC. The increase in DMI by DGC was related to a shorter intermeal interval (104.4 vs. 118.2 min/d), and meal size was not affected by treatment. Dry ground corn decreased rumination bout length and number of chews per bout compared with HMC. No differences were detected between endosperm treatments for DMI, yields of milk, 3.5% fat-corrected milk (FCM), milk fat, protein, lactose, or solids-not-fat (SNF). Mean yield of 3.5% FCM across treatments was 47.5 kg/d. However, a tendency for an interaction was observed for feed efficiency; floury endosperm increased efficiency 0.05 kg 3.5% FCM per kg of DMI for DGC but decreased it by 0.14 kg 3.5% FCM per kg of DMI for HMC relative to vitreous endosperm. Vitreous compared with floury corn tended to increase true protein concentration in milk when conserved as DGC (2.68% vs. 2.62%) but not as HMC. Concentration of SNF was increased by DGC compared with HMC (8.45 vs. 8.37%) due, in part, to the effect of treatment on milk protein concentration. Body weight was not affected by treatment, but vitreous endosperm tended to increase loss of body condition compared with floury endosperm. Corn endosperm type and conservation method had little effect on productive performance of high-producing cows. [ABSTRACT FROM AUTHOR]

Mechanical damage of maize kernel caused by external forces during processing is closely related to its internal mechanical properties. In this research, three main tissues’ (horny endosperm, floury endosperm and germ) mechanical properties of three maize varieties (Jinyu818, Zhengdan958 and Dafeng30) and five stages of moisture contents (11.78–34.73% w.b.) were evaluated using puncture test. Results showed that there was no (p > .05) or weak significant (0.01 0.80) with each other. This study can be considered as a contribution towards further studying and minimizing the mechanical damage of the maize kernel when applying external force during and post harvesting.

The improvement of the cooking and eating quality (CEQ) of rice is one of the major objectives of current rice-breeding programs. A few major genes such as Waxy (Wx) and starch synthase IIa (SSIIa) have been successfully applied in molecular breeding. However, their interactive effects on CEQ have not been fully understood. In this study, a recombinant inbred line (RIL) population was constructed by crossing the white-core mutant GM645 with the transparent phenotype of the japonica rice variety Tainung 67 (TN67). GM645 and TN67 contain different alleles of FLOURY ENDOSPERM2 (FLO2), Wx, and SSIIa. The effects of different allele combinations of FLO2, Wx, and SSIIa on the CEQ of rice were investigated. The inbred lines with the mutation allele flo2 had a significantly lower apparent amylose content (AAC), viscosity characteristics except for setback (SB), and gel texture properties compared to those lines with the FLO2 allele. The allelic combination of FLO2 and Wx significantly affected the AAC, breakdown (BD), and gel textural properties, which could explain most of the variations in those rice quality traits that were correlated with AAC. The allelic combination of FLO2 and SSIIa significantly affected the hot paste viscosity (HPV) and pasting temperature (PT). The Wx × SSIIa interaction had a significant effect on the PT. The interaction of FLO2, Wx and SSIIa significantly affected the AAC, cold paste viscosity (CPV), PT, and consistency viscosity (CS). These results highlight the important roles of these quality-related genes in regulating the CEQ of rice and provide new clues for rice-quality improvement by marker-assisted selection.

As a staple food for more than half of the world's population, the importance of rice is self-evident. Compared with ordinary rice, rice cultivars with superior eating quality and appearance quality are more popular with consumers due to their unique taste and ornamental value, even if their price is much higher. Appearance quality and CEQ (cooking and eating quality) are two very important aspects in the evaluation of rice quality. Here, we performed a genome-wide association study on floury endosperm in a diverse panel of 533 cultivated rice accessions. We identified a batch of potential floury genes and prioritize one (LOC_Os03g48060) for functional analyses. Two floury outer endosperm mutants (flo19-1 and flo19-2) were generated through editing LOC_Os03g48060 (named as FLO19 in this study), which encodes a class I glutamine amidotransferase. The different performances of the two mutants in various storage substances directly led to completely different changes in CEQ. The mutation of FLO19 gene caused the damage of carbon and nitrogen metabolism in rice, which affected the normal growth and development of rice, including decreased plant height and yield loss by decreased grain filling rate. Through haplotype analysis, we identified a haplotype of FLO19 that can improve both CEQ and appearance quality of rice, Hap2, which provides a selection target for rice quality improvement, especially for high-yield indica rice varieties. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effects of drying temperature (30, 50, 70, and 90 °C) and genotype (yellow floury corn, white floury corn, and yellow flint corn) on the morphology and technological and thermal properties of corn starch. The white and yellow genotypes with floury endosperm (soft) had spherical starch granules, while the granules of the yellow flint genotype were polyhedral. White floury corn showed higher extraction yield, higher resistance during granules' swelling before the physical collapse, as it was not affected by the increase in drying temperature, and at 90 °C it presented higher breakdown and energy necessary for gelatinization. There were peak viscosity and gelatinization enthalpy reduction on starch from yellow floury corn and yellow flint corn according to the increase in drying temperature. Drying temperatures below 50 °C are indicated for all genotypes studied. White floury corn is indicated due to the higher extraction yield presented. Yellow floury corn is indicated for application in chilled and frozen products due to lower starch retrogradation. The yellow flint corn is indicated for application as a thickening agent due to higher gel hardness. • Drying temperature of different corn genotype was studied. • White floury corn showed higher extraction yield. • Pre-gelatinization of starch granules occurred during drying. • Yellow floury corn showed lower retrogradation. • Yellow flint corn showed higher gel hardness. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the effects of drying methods (tempering–10 min, tempering–30 min, fixed-bed, and infrared radiation) and drying air temperature (70 °C and 90 °C) on proteins, thermal, and pasting properties of white floury corn. When proteins were extracted with sodium dodecyl sulfate (SDS) only, the grains dried at 90 °C in the tempering–10 min and tempering–30 min methods showed higher absorbance on β-glutelin fraction. Regardless of the drying method, increasing the drying temperature from 70 °C to 90 °C reduced soluble protein, peak viscosity, breakdown, final viscosity, and setback. In both temperatures, a higher gelatinization enthalpy (∆H) of corn flour was observed in the tempering–10 min. The fixed-bed drying method (70 °C and 90 °C) resulted in higher soluble protein, lipase activity, peak viscosity, and breakdown, and lower acidity compared to other methods. [ABSTRACT FROM AUTHOR]

Rice varieties with suitable flour-making qualities are required to promote the rice processed-food industry and to boost rice consumption. A rice mutation, Namil(SA)-flo1, produces grains with floury endosperm. Overall, grains with low grain hardness, low starch damage, and fine particle size are more suitable for use in flour processing grains with waxy, dull endosperm with normal grain hardness and a high amylose content. In this study, fine mapping found a C to T single nucleotide polymorphism (SNP) in exon 2 of the gene encoding cytosolic pyruvate phosphate dikinase (cyOsPPDK). The SNP resulted in a change of serine to phenylalanine acid at amino acid position 101. The gene was named FLOURY ENDOSPERM 4-5 (FLO4-5). Co-segregation analysis with the developed cleaved amplified polymorphic sequence (CAPS) markers revealed co-segregation between the floury phenotype and the flo4-5. This CAPS marker could be applied directly for marker-assisted selection. Real-time RT-PCR experiments revealed that PPDK was expressed at considerably higher levels in the flo4-5 mutant than in the wild type during the grain filling stage. Plastid ADP-glucose pyrophosphorylase small subunit (AGPS2a and AGPS2b) and soluble starch synthase (SSIIb and SSIIc) also exhibited enhanced expression in the flo4-5 mutant. [ABSTRACT FROM AUTHOR]

Summary: Pyrophosphate‐fructose 6‐phosphate 1‐phosphotransferase (PFP1) reversibly converts fructose 6‐phosphate and pyrophosphate to fructose 1, 6‐bisphosphate and orthophosphate during glycolysis, and has diverse functions in plants. However, mechanisms underlying the regulation of starch metabolism by PFP1 remain elusive. This study addressed the function of PFP1 in rice floury endosperm and defective grain filling. Compared with the wild type, pfp1‐3 exhibited remarkably low grain weight and starch content, significantly increased protein and lipid content, and altered starch physicochemical properties and changes in embryo development. Map‐based cloning revealed that pfp1‐3 is a novel allele and encodes the regulatory β‐subunit of PFP1 (PFP1β). Measurement of nicotinamide adenine dinucleotide (NAD+) showed that mutation of PFP1β markedly decreased its enzyme activity. PFP1β and three of four putative catalytic α‐subunits of PFP1, PFP1α1, PFP1α2, and PFP1α4, interacted with each other to form a heterotetramer. Additionally, PFP1β, PFP1α1 and PFP1α2 also formed homodimers. Furthermore, transcriptome analysis revealed that mutation of PFP1β significantly altered expression of many essential enzymes in starch biosynthesis pathways. Concentrations of multiple lipid and glycolytic intermediates and trehalose metabolites were elevated in pfp1‐3 endosperm, indicating that PFP1 modulates endosperm metabolism, potentially through reversible adjustments to metabolic fluxes. Taken together, these findings provide new insights into seed endosperm development and starch biosynthesis and will help in the breeding of rice cultivars with higher grain yield and quality. [ABSTRACT FROM AUTHOR]

Abstract Background The Flo2 gene is a member of a conserved gene family in plants. This gene has been found to be related to thousand grain weight (TGW) in rice. Its orthologs in hexaploid wheat were cloned, and the haplotype variation in TaFlo2-A1 was tested for association with TGW. Results The cloned sequences of TaFlo2-A1, TaFlo2-B1 and TaFlo2-D1 contained 23, 23 and 24 exons, respectively. The deduced proteins of TaFlo2-A1 (1734 aa), TaFlo2-B1 (1698 aa) and TaFlo2-D1 (1682 aa) were highly similar (>94%) and exhibited >77% similarity with the rice FLO2 protein. Like the rice FLO2 protein, four tetratricopeptide repeat (TPR) motifs were observed in the deduced TaFLO2 protein. An 8-bp InDel (−10 to −17 bp) in the promoter region and five SNPs in first intron of TaFlo2-A1 together formed two haplotypes, TaFlo2-A1a and TaFlo2-A1b, in bread wheat. TaFlo2 was located on homeologous group 2 chromosomes. TaFlo2-A1 was inferred to be located on deletion bin ‘2AL1–0.85-1.00’. The TaFlo2-A1 haplotypes were characterized in the Chinese Micro Core Collection (MCC) and Pakistani wheat collection using the molecular marker TaFlo2-Indel8. TaFlo2-A1 was found to be associated with TGW but not with grain number per spike (GpS) in both the MCC and Pakistani wheat collections. The frequency of TaFlo2-A1b (positive haplotype) was low in commercial wheat cultivars; thus this haplotype can be selected to improve grain weight without negatively affecting GpS. The expression level of TaFlo2-A1 in developing grains at 5 DAF (days after flowering) was positively correlated with TGW in cultivars carrying the positive haplotype. Conclusion This study will likely lead to additional investigations to understand the regulatory mechanism of the Flo2 gene in hexaploid wheat. Furthermore, the newly developed molecular marker ‘TaFlo2-InDel8’ could be incorporated into the kit of wheat breeders for use in marker-assisted selection.

Pentatricopeptide repeat (PPR) proteins constitute one of the largest protein families in land plants. Recent studies revealed the functions of PPR proteins in organellar RNA metabolism and plant development, but the functions of most PPR proteins, especially PPRs localized in the nucleus, remain largely unknown. Here, we report the isolation and characterization of a rice mutant named floury and growth retardation1 (fgr1). fgr1 showed floury endosperm with loosely arranged starch grains, decreased starch and amylose contents, and retarded seedling growth. Map-based cloning showed that the mutant phenotype was caused by a single nucleotide substitution in the coding region of Os08g0290000. This gene encodes a nuclear-localized PPR protein, which we named OsNPPR1, that affected mitochondrial function. In vitro SELEX and RNA-EMSAs showed that OsNPPR1 was an RNA protein that bound to the CUCAC motif. Moreover, a number of retained intron (RI) events were detected in fgr1. Thus, OsNPPR1 was involved in regulation of mitochondrial development and/or functions that are important for endosperm development. Our results provide novel insights into coordinated interaction between nuclear-localized PPR proteins and mitochondrial function. [ABSTRACT FROM AUTHOR]

Highlights • Starch from vitreous endosperm (VS) was larger than that from floury endosperm (FS). • VS had higher amylose and damaged starch contents than FS. • VS had lower relative crystallinity and lamellar peak intensity than FS. • Native FS was more resistant to gelatinization and enzyme hydrolysis than VS. • Gelatinized and retrograded VS and FS had similar digestion properties. Abstract Starches were isolated from vitreous and floury endosperms from the same kernels, and their physicochemical properties were investigated to reveal their differences. Starch from vitreous endosperm had more surface indentations, larger granule size, and higher contents of protein, amylose and damaged starch than that from floury endosperm. Both starches from vitreous and floury endosperms exhibited A-type crystalline structure, but starch from vitreous endosperm had lower relative crystallinity and lamellar peak intensity than that from floury endosperm. Starch from floury endosperm had higher gelatinization temperature and enthalpy but lower gelatinization temperature range and percentage of retrogradation than that from vitreous endosperm. Native starch from floury endosperm was more resistant to enzyme hydrolysis than that from vitreous endosperm. Gelatinized and retrograded starches had similar digestion properties between starches from vitreous and floury endosperms. Principal component analysis indicated that starches from vitreous and floury endosperms had significant differences in their physicochemical properties. [ABSTRACT FROM AUTHOR]

Three maize cultivars with different endosperm types (flint, semiflint, and dent maize cultivars) were studied to characterize vitreous endosperm flour properties compared with those of floury endosperm flour from the same maize kernels. Vitreous endosperm flour had higher amylose and protein contents, and lower starch content, higher percentage of large starch granule, bigger mean diameter of starch granule, higher iodine capacity, higher trough viscosity and final viscosity and setback, lower swelling power, lower peak viscosity and breakdown, and higher peak time and pasting temperature than the counterpart floury endosperm flour. X‐ray diffraction analysis indicated typical A‐pattern for starches of vitreous and floury endosperm flours. Floury endosperm flour showed the presence of greater crystallinity and higher enthalpy change (∆Hgel) than vitreous endosperm flour for three cultivars. Retrogradation enthalpy (∆Hret) and retrogradation percentage (R) of vitreous and floury endosperm flours ranged from 6.23 to 7.92 J/g and 52.72% to 73.62%, and from 5.46 to 6.45 J/g and 45.70% to 56.58%, respectively. In conclusion, vitreous and floury endosperm flours had significantly different physicochemical properties. Results of this study provide a foundation for better and valid utilization of different endosperm section during grain processing. [ABSTRACT FROM AUTHOR]

Mechanization of postharvest handling and conditioning inflicts damage on the physical, physiological, and sanitary qualities of corn (Zea mays) seeds, resulting in significant economic loss. The mechanical damage is related to the compression strength and strain, and therefore to the moisture content (MC) and endosperm type. This study was conducted from 2012 to 2014 at the Montecillo and Chapingo agricultural institutes in Mexico, where physical properties such as volumetric weight; apparent density; rupture compression strength, strain, and energy; and endosperm type were evaluated for five corn seed cultivars (floury, semi-floury, floury-flint, semi-flint, and flint) at seven MC levels (8%, 12%, 16%, 20%, 24%, 28%, and 32% w.b.). The aim of this study was to develop moisture-strength, moisture-strain, and moisture-energy regression models for postharvest handling of corn to prevent quality loss due to mechanization. For three model groups, the relationship (1) between MC and rupture strain was linear and directly proportional for the five studied cultivars; (2) between MC and rupture strength was linear and directly proportional for the floury cultivar, inverse for the semi-flint and flint cultivars, and quadratic for the semi-floury and floury-flint cultivars; and (3) between MC and rupture energy was linear and directly proportional for the floury cultivar and quadratic for the semi-floury, floury-flint, semi-flint, and flint cultivars. The models obtained in this study might be used as a reference for better handling of corn seeds, as none of the five studied varieties had a uniformly superior rupture strength, strain, or energy at the studied MC levels. Floury endosperm types might be handled at high MC and flint endosperm types might be handled at low MC to avoid mechanical damage produced by static loads; both types of endosperm support greater energy loads, e.g., impact, at higher MC. [ABSTRACT FROM AUTHOR]

The vitreous and floury endosperms have regional distributions in maize kernels, and influence their qualities and applications. In this study, the whole transverse and longitudinal sections of maize mature dent, flint, and pop kernels were observed to reveal and compare the morphological characteristics of cell, starch, and protein in different regions of endosperm. The shape and size of cells had significant differences in different regions of dent and flint maize endosperms, but had no relationship with vitreous and floury texture. Popcorn had homogeneously polygonal cells in whole endosperm. The vitreous endosperm in middle and central regions of kernel had polygonal starch granules with large size and that close to aleurone cells had spherical granules with small size, but the floury endosperm had only spherical granules with different sizes. The shape and size of starch granules did not directly determine the texture of vitreous and floury endosperm. The storage protein was distributed regionally in endosperm, and its content and spatial distribution was related with vitreous endosperm. The above results not only enriched our knowledge of vitreous and floury endosperms of maize, but also provided some information for quality breeding and applications of maize kernels with different vitreousness. • The whole sections were prepared in maize mature dent, flint and pop kernels. • Cell, starch and protein in different regions of endosperm were viewed and compared. • The shape and size of cells had no relationship with vitreous and floury endosperm. • Starch granules did not determine the texture of vitreous and floury endosperm. • The content and spatial distribution of protein was related with vitreous endosperm. [ABSTRACT FROM AUTHOR]

Starch is a major storage substance in cereal grains, and starch biosynthesis is a complex process. In order to elucidate regulation of the starch biosynthesis pathway, we screened a series of rice (Oryza sativa L.) endosperm mutants. In this study, we identified a floury white-core endosperm mutant named floury endosperm12 (flo12). The flo12 mutant exhibited loosely packed starch granules and a lower thousand kernel weight compared to wild type. Semithin sections revealed that compound starch grains (SG) in flo12 interior endosperm cells were developed abnormally. Furthermore, amylose content was decreased, while total protein content was significantly increased in flo12 grains. Map-based cloning showed that FLO12 encodes rice alanine aminotransferase 1 (OsAlaAT1). OsAlaAT1 is highly expressed in developing endosperm. Subcellular localization showed that OsAlaAT1 is localized in the cytosol. Moreover, the expression of most starch synthesis-related genes was decreased, while most of the storage protein coding genes had elevated expression levels in the flo12 mutant. In addition, overexpression of the OsAlaAT1 gene increased grain weight. In brief, we demonstrated that OsAlaAT1 regulates carbon and nitrogen metabolism, which provides a new insight for the improvement of rice quality and yield. [ABSTRACT FROM AUTHOR]

Mechanical damage of maize kernel caused by external forces during processing is closely related to its internal mechanical properties. In this research, three main tissues' (horny endosperm, floury endosperm and germ) mechanical properties of three maize varieties (Jinyu818, Zhengdan958 and Dafeng30) and five stages of moisture contents (11.78–34.73% w.b.) were evaluated using puncture test. Results showed that there was no (p >.05) or weak significant (0.01 < p <.05) difference between varieties, while significant moisture and tissue material effects were observed. For rupture force (Frp), ultimate strength (σb), toughness (Trp), initial firmness (Finf), average firmness (Favf), modulus of elastic (E), apparent modulus of elastic (AME), bioyeiled force (Fby), bioyeiled strength (σs) and penetration force (Fp), outer layer tissue (horny endosperm) of maize kernel at lower stage of moisture contents were higher than those of inner layer tissues (floury endosperm and germ) at higher moisture contents. While for bioyeiled deformation (Dby) and rupture deformation (Drp) values, results showed that inner layer tissues at with higher moisture content were the highest. Pearson's correlation analysis showed that most of the parameters had a significant correlation (p <.01, r > 0.80) with each other. This study can be considered as a contribution towards further studying and minimizing the mechanical damage of the maize kernel when applying external force during and post harvesting. [ABSTRACT FROM AUTHOR]

The major storage substance in rice endosperm is starch, which accounts for 80% of dry matter weight. In this study, rice mutant flo7, selected from the progeny of Nipponbare's tissue culture, displayed floury and opaque endosperm. Compared with its corresponding wild type (WT) Nipponbare, the mutant flo7 produced longer, narrower, thinner and lighter grains. The levels of glucose, fructose and sucrose in the mutant flo7 endosperm were higher than those in the WT endosperm, whereas the protein content was not affected. With respect to both amylose content and gel consistency, the mutant flo7 was lower than WT, but its alkali value was higher. Scanning electron microscopic examinations showed that the endosperm of the mutant flo7 contained irregular, loosely packed and compound starch granules. Genetic analysis indicated that the mutant phenotype was determined by a single recessive nuclear gene. The flo7 locus was mapped to a region on the long arm of chromosome 12, within a 95.1 kb interval defined by the markers C2-11 and C5-15. There are 13 open reading frames in the mapping interval. Transcription profiling of the developing grains showed that a number of genes involved in starch synthesis were affected differently in the mutant flo7.

Highlights • flo11 display opaque phenotype in the inner core and the periphery of grains. • FLO11 encoded a plastid-localized heat shock protein 70 (OsHsp70cp-2). • OsHsp70cp-2 was associated with Tic complex. • OsHsp70cp-2 is essential for amyloplast development in rice. Abstract Mutations of stromal Hsp70 cause chloroplast developmental abnormalities and knockout mutants of stromal Hsp70 usually exhibit protein import deficiencies. However, their effects have not been studied in amyloplast development. Here, we identified an amyloplast abnormal development mutant, floury endosperm11 (flo11) that exhibited an opaque phenotype in the inner core and the periphery of grains. Semi-thin section revealed defective amyloplast development in the flo11 endosperm. Map-based cloning and subsequent complementation test demonstrated that FLO11 encoded a plastid-localized heat shock protein 70 (OsHsp70cp-2). OsHsp70cp-2 was abundantly expressed in developing endosperm, whereas its paralogous gene OsHsp70cp-1 was mainly expressed in photosynthetic tissues. Ectopic expression of OsHsp70cp-1 under the control of OsHsp70cp-2 promoter rescued the mutant phenotype of flo11. Moreover, simultaneous knockdown of both OsHsp70cp genes resulted in white stripe leaves and opaque endosperm. BiFC and Co-IP assays revealed that OsHsp70cp-2 was associated with Tic complex. Taken together, OsHsp70cp-2 may regulate protein import into amyloplasts, which is essential for amyloplast development in rice. [ABSTRACT FROM AUTHOR]

Pyruvate orthophosphate dikinase (PPDK) is a component of glycolysis to mediate endosperm energy charge by adjusting the ratio of ATP to ADP and AMP that proposed to balance the flow of carbon into starch, protein, fatty acid and amino acid biosynthesis. However, these were inconsistent with the first report of a T-DNA insertional knockout mutant of the rice PPDK gene (flo4) showed that rice with inactivated PPDK gene failed to produce a opaque seeds. Therefore, the PPDK might have multifaceted functions in grain filling stage, which in some ways might depend on the direction of the reversible catalysis. Suweon 542 is a rice (Oryza sativa L.) mutant developed from Oryza sativa ssp. japonica cv. Namil. Suweon 542 has a milky-white floury endosperm suitable for dry filling, with low starch damage, low grain hardness, and fine flour particle size. The mutant locus on chromosome 5 controls the floury endosperm phenotype of Suweon 542. Fine mapping of this locus is required for efficient breeding of rice germplasm suitable for dry milling. In this study, whole genome of Suweon 542 and Milyang 23 were re-sequenced using Illumina HiSeq 2500. Co-segregation analysis of F3:4 family populations derived from Suweon 542/Milyang 23 was performed using eight CAPS markers and phenotypic evaluation of the endosperm. The target region was mapped to a 33 kb region and identified to encode cytosolic pyruvate orthophosphate dikinase protein (cyOsPPDK). A G→A SNP in exon 8 of cyOsPPDK resulting in a missense mutation from Gly to Asp at amino acid position 404 was responsible for the floury endosperm of Suweon 542. qRT-PCR experiments revealed that FLO4-4 was expressed to a considerably higher level in Suweon 542 than in Namil during the grain filling stage. Overall, fine mapping of FLO4-4 and candidate gene analysis provided further insight into the floury endosperm of rice, and reveal a novel SNP in cyOsPPDK gene can affect the floury endosperm phenotype through active PPDK gene during grain filling stage. [ABSTRACT FROM AUTHOR]

[Objectives]Starch is a major component of rice. The content,composition and fine structure of starch are crucial to the rice quality. Therefore,it is of great significance to dissect the molecular mechanisms underlying starch synthesis pathway and its regulation.[Methods]In this study,we obtained a stably inherited floury endosperm mutant flo9 from ‘N22’ mutant library induced by 60Co radiation,with slightly shrunken and homozygous lethal. The morphological characters and the physicochemical properties were analyzed. The endosperm structure was observed by scanning electron microscopy and semi-thin section technology. An F2 population of flo9 mutant and ‘Dianjingyou 1’ were prepared,and the floury individuals were selected for gene-mapping. The expression patterns of starch synthesis genes were analyzed by qRT-PCR.[Results]Compared to the wild type,the 1 000-grain weight,grain length,grain width,grain thickness,amylose content,and lipid content of the flo9 mutant all extremely decreased,while the total starch content had no change. The SBV(setback),CSV(consistance),BDV(breakdown)and the swelling power of starch of flo9 mutant were lower than the wild type. The starch grains in flo9 mutant significantly decreased in section area,were rounder and loosely packed. FLO9 was narrowed down to a 123 kb region on the long-arm of chromosome 9 with 314 recessive individuals. This region contains 13 open reading frames(ORFs). qRT-PCR analysis showed that the expression level of many genes related to starch synthesis and lipid synthesis were changed.[Conclusions]FLO9 was involved in starch and lipid biosynthesis in rice developing endosperm,as well as in amyloplast development. This study lays a foundation for the cloning and functional characterization of FLO9 in rice. [ABSTRACT FROM AUTHOR]

Background: The Flo2 gene is a member of a conserved gene family in plants. This gene has been found to be related to thousand grain weight (TGW) in rice. Its orthologs in hexaploid wheat were cloned, and the haplotype variation in TaFlo2-A1 was tested for association with TGW. Results: The cloned sequences of TaFlo2-A1, TaFlo2-B1 and TaFlo2-D1 contained 23, 23 and 24 exons, respectively. The deduced proteins of TaFlo2-A1 (1734 aa), TaFlo2-B1 (1698 aa) and TaFlo2-D1 (1682 aa) were highly similar (>94%) and exhibited >77% similarity with the rice FLO2 protein. Like the rice FLO2 protein, four tetratricopeptide repeat (TPR) motifs were observed in the deduced TaFLO2 protein. An 8-bp InDel (-10 to -17 bp) in the promoter region and five SNPs in first intron of TaFlo2-A1 together formed two haplotypes, TaFlo2-A1a and TaFlo2-A1b, in bread wheat. TaFlo2 was located on homeologous group 2 chromosomes. TaFlo2-A1 was inferred to be located on deletion bin '2AL1-0.85-1.00'. The TaFlo2-A1 haplotypes were characterized in the Chinese Micro Core Collection (MCC) and Pakistani wheat collection using the molecular marker TaFlo2-Indel8. TaFlo2-A1 was found to be associated with TGW but not with grain number per spike (GpS) in both the MCC and Pakistani wheat collections. The frequency of TaFlo2-A1b (positive haplotype) was low in commercial wheat cultivars; thus this haplotype can be selected to improve grain weight without negatively affecting GpS. The expression level of TaFlo2-A1 in developing grains at 5 DAF (days after flowering) was positively correlated with TGW in cultivars carrying the positive haplotype. Conclusion: This study will likely lead to additional investigations to understand the regulatory mechanism of the Flo2 gene in hexaploid wheat. Furthermore, the newly developed molecular marker 'TaFlo2-InDel8' could be incorporated into the kit of wheat breeders for use in marker-assisted selection. [ABSTRACT FROM AUTHOR]

Cereal opaque-kernel mutants are ideal genetic materials for studying the mechanism of starch biosynthesis and amyloplast development. Here we isolated and identified two allelic floury endosperm 8 ( flo8) mutants of rice, named flo8-1 and flo8-2. In the flo8 mutant, the starch content was decreased and the normal physicochemical features of starch were altered. Map-based cloning and subsequent DNA sequencing analysis revealed a single nucleotide substitution and an 8-bp insertion occurred in UDP-glucose pyrophosphorylase 1 ( Ugp1) gene in flo8-1 and flo8-2, respectively. Complementation of the flo8-1 mutant restored normal seed appearance by expressing full length coding sequence of Ugp1. RT-qPCR analysis revealed that Ugp1 was ubiquitously expressed. Mutation caused the decreased UGPase activity and affected the expression of most of genes associated with starch biosynthesis. Meanwhile, western blot and enzyme activity analyses showed the comparability of protein levels and enzyme activity of most tested starch biosynthesis related genes. Our results demonstrate that Ugp1 plays an important role for starch biosynthesis in rice endosperm. [ABSTRACT FROM AUTHOR]

Key message: Decreased PFPase activity in rice perturbs the equilibration of carbon metabolism during grain filling but has no visible phenotypic effects during the vegetative and reproductive growth stages. Abstract: Starch is a primary energy reserve for various metabolic processes in plant. Despite much advance has been achieved in pathways involved in starch biosynthesis, information was still lacked for precise regulation related to carbon metabolism during seed filling in rice ( Oryza sativa). The objective of this study was to identify and characterize new gene associated with carbon metabolism during grain filling. By screening our chemical mutant pool, two allelic mutants exhibiting floury endosperm were isolated. No visible phenotypic defects were observed during both the vegetative and reproductive growth stages, except for the floury-like endosperm of grains with significantly reduced kernel thickness, 1000-grain weight and total starch content. Map-based cloning revealed that the mutant phenotypes were controlled by a gene encoding pyrophosphate: fructose-6-phosphate 1-phosphotransferase (PFP, EC 2.7.1.90) β subunit (PFP), which catalyzes reversible interconversion between fructose-6-phosphate and fructose-1, 6-bisphosphate. The identity of PFP was further confirmed by a genetic complementation test. Subcellular analysis demonstrated that PFPβ was localized in cytoplasm. Quantitative PCR and histochemical staining indicated PFP was ubiquitously expressed in various tissues. Furthermore, we found PFP could express in both the early and late phases of starch accumulation during grain filling and decreased activity of PFP in pfp mutants resulted in compromised carbon metabolism with increased soluble sugar contents and unfavorable starch biosynthesis. Our results highlight PFP functions in modulating carbon metabolism during grain filling stage. [ABSTRACT FROM AUTHOR]

Alteration of storage substances, in particular the major storage form starch, leads to floury endosperm. Because floury mutants have physical attributes for milling processes, identification and characterization of those mutants are valuable. In this study we identified a floury endosperm mutant caused by a T-DNA insertion in O ryza s ativa ala nine- a mino t ransferase 1 ( OsAlaAT1 ). OsAlaAT1 is localized in the cytosol and has aminotransferase enzyme activity. The osalaat1 mutant has less amylose and its amylopectin is structurally altered. OsAlaAT1 is predominantly expressed in developing seeds during active starch synthesis. AlaAT catalyzes the interconversion of pyruvate to alanine, and this pathway is activated under low-oxygen conditions. Consistently, OsAlaAT1 is induced by such conditions. Expression of the starch synthesis genes AGPases , OsSSI , OsSSIIa , and OsPPDKB is decreased in the mutant. Thus, our observations suggest that OsAlaAT1 plays an essential role in starch synthesis in developing seeds that are exposed to low concentrations of oxygen. [ABSTRACT FROM AUTHOR]

Storage lipid is a vital component for maintaining structure of seed storage substances and valuable for rice quality and food texture. However, the knowledge of lipid transporting related genes and their function in seed development have not been well elucidated yet. In this study, we identified OsLTPL36, a homolog of putative lipid transport protein, and showed specific expression in rice developing seed. Transcriptional profiling and in situ hybridization analysis confirmed that OsLTPL36 was exclusively expressed in developing seed coat and endosperm aleurone cells. Down-regulated expression of OsLTPL36 led to decreased seed setting rate and 1000-grain weight in transgenic plants. Further studies showed that suppressed expression of OsLTPL36 caused chalky endosperm and resulted in reduced fat acid content in RNAi lines as compared with wild type (WT). Histological analysis showed that the embryo development was delayed after down regulation of OsLTPL36 . Moreover, impeded seed germination and puny seedling were also observed in the OsLTPL36 RNAi lines. The data demonstrated that OsLTPL36, a lipid transporter, was critical important not only for seed quality but also for seed development and germination in rice. [ABSTRACT FROM AUTHOR]

The major storage substance in rice endosperm is starch, which accounts for 80% of dry matter weight. In this study, rice mutant flo7 , selected from the progeny of Nipponbare's tissue culture, displayed floury and opaque endosperm. Compared with its corresponding wild type (WT) Nipponbare, the mutant flo7 produced longer, narrower, thinner and lighter grains. The levels of glucose, fructose and sucrose in the mutant flo7 endosperm were higher than those in the WT endosperm, whereas the protein content was not affected. With respect to both amylose content and gel consistency, the mutant flo7 was lower than WT, but its alkali value was higher. Scanning electron microscopic examinations showed that the endosperm of the mutant flo7 contained irregular, loosely packed and compound starch granules. Genetic analysis indicated that the mutant phenotype was determined by a single recessive nuclear gene. The flo7 locus was mapped to a region on the long arm of chromosome 12, within a 95.1 kb interval defined by the markers C2-11 and C5-15. There are 13 open reading frames in the mapping interval. Transcription profiling of the developing grains showed that a number of genes involved in starch synthesis were affected differently in the mutant flo7 . [ABSTRACT FROM AUTHOR]