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Powdery mildew (PM) poses an extreme threat to wheat yields and quality. In this study, 262 recombinant inbred lines (RILs) of Doumai and Shi 4185 cross were used to map PM resistance genes across four environments. High-density genetic linkage map of the Doumai/Shi 4185 RIL population was constructed using the wheat Illumina iSelect 90K single-nucleotide polymorphism (SNP) array. In total, four stable quantitative trait loci (QTLs) for PM resistance, QPm.caas-2AS, QPm.caas-4AS, QPm.caas-4BL, and QPm.caas-6BS, were detected and explained 5.6%–15.6% of the phenotypic variances. Doumai contributed all the resistance alleles of QPm.caas-2AS, QPm.caas-4AS, QPm.caas-4BL, and QPm.caas-6BS. Among these, QPm.caas-4AS and QPm.caas-6BS overlapped with the previously reported loci, whereas QPm.caas-2AS and QPm.caas-4BL are potentially novel. In addition, six high-confidence genes encoding the NBS-LRR-like resistance protein, disease resistance protein family, and calcium/calmodulin-dependent serine/threonine-kinase were selected as the candidate genes for PM resistance. Three kompetitive allele-specific PCR (KASP) markers, Kasp_PMR_2AS for QPm.caas-2AS, Kasp_PMR_4BL for QPm.caas-4BL, and Kasp_PMR_6BS for QPm.caas-6BS, were developed, and their genetic effects were validated in a natural population including 100 cultivars. These findings will offer valuable QTLs and available KASP markers to enhance wheat marker-assisted breeding for PM resistance.

Autophagy is a highly conserved process in eukaryotes that is used to recycle the cellular components from the cytoplasm. It plays a crucial function in responding to both biotic and abiotic stress, as well as in the growth and development of plants. Autophagy-related genes (ATG) and their functions have been identified in numerous crop species. However, their specific tasks in potatoes (Solanum tuberosum L.), are still not well understood. This work is the first to identify and characterize the potato StATG18 subfamily gene at the whole-genome level, resulting in a total of 6 potential StATG18 subfamily genes. We analyzed the phylogenetic relationships, chromosome distribution and gene replication, conserved motifs and gene structure, interspecific collinearity relationship, and cis-regulatory elements of the ATG18 subfamily members using bioinformatics approaches. Furthermore, the quantitative real-time polymerase chain reaction (qRT-PCR) analysis suggested that StATG18 subfamily genes exhibit differential expression in various tissues and organs of potato plants. When exposed to heat stress, their expression pattern was observed in the root, stem, and leaf. Based on a higher expression profile, the StATG18a gene was further analyzed under heat stress in potatoes. The subcellular localization analysis of StATG18a revealed its presence in both the cytoplasm and nucleus. In addition, StATG18a altered the growth indicators, physiological characteristics, and photosynthesis of potato plants under heat stresses. In conclusion, this work offers a thorough assessment of StATG18 subfamily genes and provides essential recommendations for additional functional investigation of autophagy-associated genes in potato plants. Moreover, these results also contribute to our understanding of the potential mechanism and functional validation of the StATG18a gene’s persistent tolerance to heat stress in potato plants.

BackgroundsAs a conserved signaling pathway, mitogen-activated protein kinase (MAPK) cascade regulates cellular signaling in response to abiotic stress. High temperature may contribute to a significant decrease in economic yield. However, research into the expression patterns of StMAPKK family genes under high temperature is limited and lacks experimental validation regarding their role in supporting potato plant growth.MethodsTo trigger heat stress responses, potato plants were grown at 35°C. qRT-PCR was conducted to analyze the expression pattern of StMAPKK family genes in potato plants. Plant with StMAPKK5 loss-of-function and gain-of-function were developed. Potato growth and morphological features were assessed through measures of plant height, dry weight, and fresh weight. The antioxidant ability of StMAPKK5 was indicated by antioxidant enzyme activity and H2O2 content. Cell membrane integrity and permeability were suggested by relative electrical conductivity (REC), and contents of MDA and proline. Photosynthetic capacity was next determined. Further, mRNA expression of heat stress-responsive genes and antioxidant enzyme genes was examined.ResultsIn reaction to heat stress, the expression profiles of StMAPKK family genes were changed. The StMAPKK5 protein is located to the nucleus, cytoplasm and cytomembrane, playing a role in controlling the height and weight of potato plants under heat stress conditions. StMAPKK5 over-expression promoted photosynthesis and maintained cell membrane integrity, while inhibited transpiration and stomatal conductance under heat stress. Overexpression of StMAPKK5 triggered biochemical defenses in potato plant against heat stress, modulating the levels of H2O2, MDA and proline, as well as the antioxidant activities of CAT, SOD and POD. Overexpression of StMAPKK5 elicited genetic responses in potato plants to heat stress, affecting heat stress-responsive genes and genes encoding antioxidant enzymes.ConclusionStMAPKK5 can improve the resilience of potato plants to heat stress-induced damage, offering a promising approach for engineering potatoes with enhanced adaptability to challenging heat stress conditions.

BackgroundsPotato is sensitive to heat stress particularly during plant seedling growth. However, limited studies have characterized the expression pattern of the StGATA family genes under heat stress and lacked validation of its function in potato plants.MethodsPotato plants were cultivated at 30°C and 35°C to induce heat stress responses. qRT-PCR was carried out to characterize the expression pattern of StGATA family genes in potato plants subjected to heat stress. StGATA2 loss-of-function and gain-of-function plants were established. Morphological phenotypes and growth were indicated by plant height and mass. Photosynthesis and transpiration were suggested by stomatal aperture, net photosynthetic rate, transpiration rate, and stomatal conductance. Biochemical and genetic responses were indicated by enzyme activity and mRNA expression of genes encoding CAT, SOD, and POD, and contents of H2O2, MDA, and proline.ResultsThe expression patterns of StGATA family genes were altered in response to heat stress. StGATA2 protein located in the nucleus. StGATA2 is implicated in regulating plant height and weight of potato plants in response to heat stresses, especially acute heat stress. StGATA2 over-expression promoted photosynthesis while inhibited transpiration under heat stress. StGATA2 overexpression induced biochemical responses of potato plant against heat stress by regulating the contents of H2O2, MDA and proline and the activity of CAT, SOD and POD. StGATA2 overexpression caused genetic responses (CAT, SOD and POD) of potato plant against heat stress.ConclusionOur data indicated that StGATA2 could enhance the ability of potato plants to resist heat stress-induced damages, which may provide an effective strategy to engineer potato plants for better adaptability to adverse heat stress conditions.

Background and aimsMitogen-activated protein kinases (MAPKs) have been reported to respond to various stimuli including heat stress. This research aimed to investigate whether StMAPK1 is implicated in the transduction of the heat stress signal to adapt heat stress as a thermos-tolerant gene.Materials and methodsPotato plants were cultivated under mild (30°C) and acute (35°C) heat stress conditions to analyze mRNA expression of StMAPKs and physiological indicators. StMAPK1 was up-regulated and down-regulated by transfection. Subcellular localization of StMAPK1 protein was observed by fluorescence microscope. The transgenic potato plants were assayed for physiological indexes, photosynthesis, cellular membrane integrity, and heat stress response gene expression.ResultsHeat stress altered the expression prolife of StMAPKs. StMAPK1 overexpression changed the physiological characteristics and phenotypes of potato plants under heat stresses. StMAPK1 mediates photosynthesis and maintains membrane integrity of potato plants in response to heat stress. Stress response genes (StP5CS, StCAT, StSOD, and StPOD) in potato plants were altered by StMAPK1 dysregulation. mRNA expression of heat stress genes (StHSP90, StHSP70, StHSP20, and StHSFA3) was affected by StMAPK1.ConclusionsStMAPK1 overexpression increases the heat-tolerant capacity of potato plants at the morphological, physiological, molecular, and genetic levels.

Soybean seed protein content (PC) and oil content (OC) have important economic value. Detecting the loci/gene related to PC and OC is important for the marker-assisted selection (MAS) breeding of soybean. To detect the stable and new loci for PC and OC, a total of 320 soybean accessions collected from the major soybean-growing countries were used to conduct a genome-wide association study (GWAS) by resequencing. The PC ranged from 37.8% to 46.5% with an average of 41.1% and the OC ranged from 16.7% to 22.6% with an average of 21.0%. In total, 23 and 29 loci were identified, explaining 3.4%–15.4% and 5.1%–16.3% of the phenotypic variations for PC and OC, respectively. Of these, eight and five loci for PC and OC, respectively, overlapped previously reported loci and the other 15 and 24 loci were newly identified. In addition, nine candidate genes were identified, which are known to be involved in protein and oil biosynthesis/metabolism, including lipid transport and metabolism, signal transduction, and plant development pathway. These results uncover the genetic basis of soybean protein and oil biosynthesis and could be used to accelerate the progress in enhancing soybean PC and OC.

A RelA/SpoT homolog, HpRSH, was identified in Haematococcus pluvialis. HpRSH was found to catalyze Mg2+-dependent guanosine tetraphosphate (ppGpp) synthesis and Mn2+-dependent ppGpp hydrolysis, respectively. The transcription of HpRSH was significantly upregulated by environmental stresses, such as darkness, high light, nitrogen limitation, and salinity stress. The intracellular ppGpp level was also increased when exposed to these stresses. In addition, the classical initiator of stringent response, serine hydroxamate (SHX), was found to upregulate the transcription of HpRSH and increase the level of ppGpp. Moreover, stringent response induced by SHX or environmental stresses was proven to induce the accumulation of astaxanthin. These results indicated that stringent response regulatory system involved in the regulation of astaxanthin biosynthesis in H. pluvialis. Furthermore, stringent response was unable to induce astaxanthin accumulation under dark condition. This result implied that stringent response may regulate astaxanthin biosynthesis in a light-dependent manner.

Background and aims: Mitogen-activated protein kinases (MAPKs) have been reported to respond to various stimuli including heat stress. This research aimed to investigate whether StMAPK1 is implicated in the transduction of the heat stress signal to adapt heat stress as a thermos-tolerant gene. Materials and methods: Potato plants were cultivated under mild (30°C) and acute (35°C) heat stress conditions to analyze mRNA expression of StMAPKs and physiological indicators. StMAPK1 was up-regulated and down-regulated by transfection. Subcellular localization of StMAPK1 protein was observed by fluorescence microscope. The transgenic potato plants were assayed for physiological indexes, photosynthesis, cellular membrane integrity, and heat stress response gene expression. Results: Heat stress altered the expression prolife of StMAPKs. StMAPK1 overexpression changed the physiological characteristics and phenotypes of potato plants under heat stresses. StMAPK1 mediates photosynthesis and maintains membrane integrity of potato plants in response to heat stress. Stress response genes (StP5CS, StCAT, StSOD, and StPOD) in potato plants were altered by StMAPK1 dysregulation. mRNA expression of heat stress genes (StHSP90, StHSP70, StHSP20, and StHSFA3) was affected by StMAPK1. Conclusions: StMAPK1 overexpression increases the heat-tolerant capacity of potato plants at the morphological, physiological, molecular, and genetic levels. [ABSTRACT FROM AUTHOR]

A high-density consensus map is a powerful tool for gene mapping, cloning and molecular marker-assisted selection in wheat breeding. The objective of this study was to construct a high-density, single nucleotide polymorphism (SNP)-based consensus map of common wheat (Triticum aestivum L.) by integrating genetic maps from four recombinant inbred line populations. The populations were each genotyped using the wheat 90K Infinium iSelect SNP assay. A total of 29,692 SNP markers were mapped on 21 linkage groups corresponding to 21 hexaploid wheat chromosomes, covering 2,906.86 cM, with an overall marker density of 10.21 markers/cM. Compared with the previous maps based on the wheat 90K SNP chip detected 22,736 (76.6%) of the SNPs with consistent chromosomal locations, whereas 1,974 (6.7%) showed different chromosomal locations, and 4,982 (16.8%) were newly mapped. Alignment of the present consensus map and the wheat expressed sequence tags (ESTs) Chromosome Bin Map enabled assignment of 1,221 SNP markers to specific chromosome bins and 819 ESTs were integrated into the consensus map. The marker orders of the consensus map were validated based on physical positions on the wheat genome with Spearman rank correlation coefficients ranging from 0.69 (4D) to 0.97 (1A, 4B, 5B, and 6A), and were also confirmed by comparison with genetic position on the previously 40K SNP consensus map with Spearman rank correlation coefficients ranging from 0.84 (6D) to 0.99 (6A). Chromosomal rearrangements reported previously were confirmed in the present consensus map and new putative rearrangements were identified. In addition, an integrated consensus map was developed through the combination of five published maps with ours, containing 52,607 molecular markers. The consensus map described here provided a high-density SNP marker map and a reliable order of SNPs, representing a step forward in mapping and validation of chromosomal locations of SNPs on the wheat 90K array. Moreover, it can be used as a reference for quantitative trait loci (QTL) mapping to facilitate exploitation of genes and QTL in wheat breeding.

Cyclization of acyclic lycopene by cyclases marks an important regulatory point in carotenoid biosynthesis. Though some algal lycopene epsilon cyclases (LCYEs) have been predicted computationally, very few have been functionally identified. Little is known about the regulation mechanisms of algal LCYEs. Recent comparative genomic analysis suggested that Haematococcus pluvialis contained only the β type cyclase (HpLCYB). However, in this study, carotenoid profiling found trace α-carotene in the salt-treated cells, indicating the in vivo activity of HpLCYE, a missing component for α-branch carotenoids. Thus, genes coding for HpLCYB and HpLCYE were isolated and functionally complemented in Escherichia coli. Substrate specificity assays revealed an exclusive cyclization order of HpLCYE to HpLCYB for the biosynthesis of heterocyclic carotenoids. Expression pattern studies and bioinformatic analysis of promoter regions showed that both cyclases were differentially regulated by the regulatory cis-acting elements in promoters to correlate with primary and secondary carotenoid biosynthesis under environmental stresses. Characterization of the branch components in algal carotenoid biosynthesis revealed a mechanism for control of metabolic flux into α- and β-branch by the competition and cooperation between HpLCYE and HpLCYB; and supplied a promising route for molecular breeding of cyclic carotenoid biosynthesis.

Dough rheological and starch pasting properties play an important role in determining processing quality in bread wheat (Triticum aestivum L.). In the present study, a recombinant inbred line (RIL) population derived from a Gaocheng 8901/Zhoumai 16 cross grown in three environments was used to identify quantitative trait loci (QTLs) for dough rheological and starch pasting properties evaluated by Mixograph, Rapid Visco-Analyzer (RVA) and Mixolab parameters using 90K and 660K single nucleotide polymorphism (SNP) chip assays. A high-density linkage map constructed with 46,961 polymorphic SNP markers from the wheat 90K and 660K SNP assays spanned a total length of 4,121 cM, with an average chromosome length of 196.2 cM and marker density of 0.09 cM/marker; 6,596 new SNP markers were anchored to the bread wheat linkage map, with 1,046 and 5,550 markers from the 90K and 660K SNP assays, respectively. Composite interval mapping identified 119 additive QTLs on 20 chromosomes except 4D; among them, 15 accounted for more than 10% of the phenotypic variation across two or three environments. Twelve QTLs for Mixograph parameters, 17 for RVA parameters and 55 for Mixolab parameters were new. Eleven QTL clusters were identified. The closely linked SNP markers can be used in marker-assisted wheat breeding in combination with the Kompetitive Allele Specific PCR (KASP) technique for improvement of processing quality in bread wheat.

Cyclization of acyclic lycopene by cyclases marks an important regulatory point in carotenoid biosynthesis. Though some algal lycopene epsilon cyclases (LCYEs) have been predicted computationally, very few have been functionally identified. Little is known about the regulation mechanisms of algal LCYEs. Recent comparative genomic analysis suggested that Haematococcus pluvialis contained only the b type cyclase (HpLCYB). However, in this study, carotenoid profiling found trace a-carotene in the salt-treated cells, indicating the in vivo activity of HpLCYE, a missing component for a-branch carotenoids. Thus, genes coding for HpLCYB and HpLCYE were isolated and functionally complemented in Escherichia coli. Substrate specificity assays revealed an exclusive cyclization order of HpLCYE to HpLCYB for the biosynthesis of heterocyclic carotenoids. Expression pattern studies and bioinformatic analysis of promoter regions showed that both cyclases were differentially regulated by the regulatory cis-acting elements in promoters to correlate with primary and secondary carotenoid biosynthesis under environmental stresses. Characterization of the branch components in algal carotenoid biosynthesis revealed a mechanism for control of metabolic flux into a- and b-branch by the competition and cooperation between HpLCYE and HpLCYB; and supplied a promising route for molecular breeding of cyclic carotenoid biosynthesis. [ABSTRACT FROM AUTHOR]