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Plum (Prunus spp.) is an economically and nutritionally important stone fruit that is grown worldwide. Gummosis disease (GD) is one of the most common limiting factors that adversely affects the yield and quality of stone fruits such as plum. Elucidating plum fruit metabolomics responses is essential to develop sustainable agricultural practices to combat GD in the future. Herein, an ultra-high-performance liquid chromatography coupled to mass-spectrometry (UHPLC-MS) pseudo-targeted metabolomic profiling was first performed to elucidate the overall metabolic alterations in Asian plum (Prunus salicina Lindl.) fruit in response to GD. The most pivotal differential metabolites, including certain amino acids and proanthocyanidins, in GD and control groups were identified by combining multivariate data analysis with strict statistical criteria. Metabolic pathway enrichment analysis showed that GD induced a series of coordinated defence responses and reprogramming of various metabolic pathways, including glucosinolate biosynthesis, 2-oxocarboxylic acid metabolism, valine, leucine and isoleucine degradation, and isoquinoline alkaloid biosynthesis pathways. Using UHPLC-MS-based pseudo-targeted metabolomic profiling, we systematically evaluated overall metabolic modifications in Asian plum fruits in response to GD for the first time. The identified metabolic pathway alterations helped to better understand the internal relationships and related metabolic networks.

Soil in most areas of the world is selenium (Se) deficient, which results a low Se content in agricultural products. To improve the fruit tree Se accumulation, the effects of different Artemisia argyi water extract concentrations (0, 100, 200, 300, and 400-fold dilutions) on the growth and Se accumulation of peach seedlings were studied by a pot experiment. A 300- and 400-fold dilution of A. argyi water extract increased the root and shoot biomass (dry weight), leaf chlorophyll a content, superoxide dismutase (SOD) activity, and peroxidase (POD) activity of peach seedlings, but decreased the leaf chlorophyll a/b. Different A. argyi water extract concentrations had no significant effects on peach leaf chlorophyll a content of peach seedlings, but increased the leaf carotenoid content, catalase (CAT) activity, and soluble protein content. Different A. argyi water extract concentrations increased the total Se, inorganic Se, and organic contents in roots and shoots of peach seedlings to some extent. Furthermore, A. argyi water extract concentration exhibited a linear relationship with the root and shoot total Se contents. Compared with the control, the 100-, 200-, 300-, and 400-fold dilutions of A. argyi water extract increased the shoot total Se content by 18.95%, 31.31%, 39.32%, and 51.59%, respectively. Different A. argyi water extract concentrations also increased the leaf Se metabolism-related enzyme activities of peach seedlings, including the activities of adenosine triphosphate sulfurase (ATPS), adenosine 5’-phosphosulfate reductase (APR), and serine acetyltransferase (SAT), as well as selenocysteine methyltransferase (SMT) to some extent. Moreover, correlation and grey relational analyses revealed the root total Se content, CAT activity, and ATPS activity to be closely associated with the total shoot Se content. Therefore, applying A. argyi water extract can thus promote the growth and Se uptake of peach seedlings, and the future study should focus on the application effects of Se uptake in peach fruits.

The selenium (Se) deficiency is threatening the human health, and the increase of Se content in food can prevent the Se deficiency of human body. To increase the Se content in fruit trees and alleviate the Se stress to fruit trees, the effects of gibberellic acid (GA) on the growth and Se accumulation in Cyphomandra betacea under Se stress were studied. Although GA increased the biomass of C. betacea, it did not significantly affect the root/shoot ratio. The root and shoot biomass had a quadratic polynomial regression relationship with the GA concentration. Furthermore, GA increased the photosynthetic pigment content, photosynthetic parameters, and antioxidant enzyme activity of C. betacea. GA also increased the Se content in C. betacea, peaking at 300 mg/L GA. For instance, GA (300 mg/L) increased the Se contents in roots and shoots of C. betacea by 70.31 and 22.02%, respectively, compared with the control. Moreover, the root Se and shoot Se contents had a quadratic polynomial regression relationship with the GA concentration. Correlation and gray relational analyses showed that the carotenoid, chlorophyll a, and chlorophyll b contents were closely related to the Se uptake in C. betacea under the GA application. These results show that GA (300 mg/L) can promote the growth and Se uptake of C. betacea under Se stress.

Cadmium (Cd) contamination of paddy soil affects safe crop production. This study aimed to evaluate the effects of plant biostimulant amino acid fertilizer on the phytoremediation capability of an emergent accumulator plant

Herein, we prepared a pot experiment to explore the potential effects of cadmium (Cd) hyperaccumulator Solanum photeinocarpum and its post grafting generations straw on Cd accumulation in loquat se...

The effects of living plants and straws of four hyperaccumulator plant species (Siegesbeckia orientalisL., Crassocephalum crepidioides, Galinsoga parviflora and Solanum nigrumL.) on the growth and ...

This study was conducted to investigate the visual appearance and physicochemical changes of postharvest jujube fruits (Ziziphus jujuba Mill. cv. Shucuizao) stored under 0 °C for 15 days. The fruits were dipped in 0 (control), 50, 100, 200 and 400 µM melatonin solutions after harvest. The results showed that treatment with a suitable melatonin concentration improved the rate of crisp fine fruits, delayed weight loss and firmness decline, and suppressed changes in total soluble solids (TSS) and titratable acidity (TA) contents of jujube fruits compared with the control. In addition, jujube fruits soaked with melatonin showed improved antioxidant capacity through increased ascorbic acid (AsA) content, enhanced superoxide dismutase (SOD) activity, and decreased malonaldehyde (MDA) content. As a result, 50 µM melatonin showed the greatest improvement of visual appearance and quality maintenance, and could be used as an effective treatment to preserve postharvest jujube fruit.

The selenium (Se) deficiency is threatening the human health, and the increase of Se content in food can prevent the Se deficiency of human body. To increase the Se content in fruit trees and alleviate the Se stress to fruit trees, the effects of gibberellic acid (GA) on the growth and Se accumulation in

The newly released Donghong kiwifruit is a promising commercial cultivar. The dynamic changes of major phenolic compounds (flavonols, flavanols, phenolic acids, and anthocyanins) during the representative stages of fruit development and ripening of the Donghong kiwifruit were determined by high-performance liquid chromatography. The corresponding time-course transcriptional changes were evaluated using the combined analysis of RNA-Seq and qRT-PCR. The most predominant phenolic compound in the Donghong kiwifruit was epicatechin. Cyanidin 3-O-[2-O-(β-xylosyl)-β-galactoside] and cyanidin 3-O-β-galactoside were two essential anthocyanins detected. Candidate genes and pathways involved in phenolic compounds biosynthesis were highlighted. The structural genes (AcLDOX2, Ac5GGT1, and Ac5AT2) and the transcription factor (bHLH74-2) were strongly associated with anthocyanin biosynthesis. AcMYB4-1 may be a novel transcription factor that reduces anthocyanin accumulation. Results from the study may be a very useful supplement to current knowledge of molecular mechanisms to elucidate coloration in the red-fleshed kiwifruit and could help breeders modify the kiwifruit germplasm.

Farmland and mining ecotypes of the potential cadmium (Cd)-hyperaccumulator Solanum photeinocarpum were collected to study the effects of reciprocal grafting on the growth of, and Cd accumulation i...

To determine whether grafting increases cadmium (Cd) accumulation in the post-grafting generation of hyperaccumulator plants, the effects of grafting on Cd accumulation characteristics of post-grafting generations of a potential Cd-hyperaccumulator Solanum photeinocarpum were evaluated in pot and field experiments. The following four grafting combinations were examined: ungrafted (UG), self-rooted grafting involving one S. photeinocarpum seedling (SG), self-rooted grafting involving two S. photeinocarpum seedling developmental stages (DG), and grafting on wild potato rootstock (PG). Grafting did not induce genetic changes in S. photeinocarpum, and increased the shoot biomass and the amount of Cd extracted by the shoots of the first, second, and third generations of S. photeinocarpum (PG > DG > SG > UG). Additionally, enhanced superoxide dismutase, peroxidase, and catalase activities and increased soluble protein contents of the first post-grafting generation were observed for the DG and PG, whereas only enhanced superoxide dismutase and peroxidase activities were observed for the SG. Grafting increased the DNA methylation levels by inducing hypermethylation in the first post-grafting generation (PG > DG > SG > UG). Therefore, grafting can enhance the Cd accumulation (phytoremediation) ability of post-grafting generations of S. photeinocarpum by enhancing DNA methylation levels, especially when wild potato rootstock is used.

We studied the genetic diversity of 34 fig varieties (Ficus carica L.) to provide a reference for analyzing the phylogenetic relationships and variety identification of figs. A total of 34 fig materials were amplified by inter-simple sequence repeat (ISSR) molecular marker technique. The products were detected by agarose gel electrophoresis and analyzed by using POPGENE 1.32 and NTSYS 2.10. Nine polymorphic primers were screened from 100 ISSR primers, and 107 loci were amplified, 74 were polymorphic loci, and the polymorphic loci ratio was 69.16%. The number of alleles was observed. The Na average was 1.6729, and the effective allele number (Ne) was 1.4022. The Nei’s gene diversity index (He) was 0.2316. The Shannon information index (I) was 0.3447, and the genetic similarity coefficient (GS) was between 0.6262 and 0.9720 the average values. UPGMA method was used to construct the clustering map. With GS 0.824 as the threshold, 34 fig varieties were divided into eight groups, thus indicating that ISSR molecular markers can be effectively applied to the genetic diversity analysis of different fig varieties.

To identify whether the auxin treatment could promote the growth and reduce the cadmium (Cd) of fruit trees, the effects of different concentrations of indole acetic acid (IAA, one of the auxin) on...

Carotenoids are the pigment substances of yellow-fleshed kiwifruit, and among them β-cryptoxanthin has only been detected in the brighter yellow-fleshed variety ‘Jinshi 1’. β-Carotene hydroxylase (BCH) catalyzes the formation of β-cryptoxanthin and zeaxanthin, but its molecular characteristics and functions have not been fully explained. Here we isolated two β-carotene hydroxylase genes, AcBCH1 and AcBCH2 from kiwifruit (Actinidia chinensis), and their relative expression levels exhibited a close correlation with the content of β-cryptoxanthin. AcBCH1 catalyzed the formation of β-cryptoxanthin when transformed into β-carotene-accumulating yeast cells. Moreover, silenced expression of AcBCH1 in kiwifruit caused decreases in the contents of zeaxanthin, lutein, and β-cryptoxanthin, and an increase in β-carotene content. The content of β-carotene decreased significantly after the AcBCH1/2 genes were overexpressed in tomato. The content of zeaxanthin increased and β-carotene decreased in transgenic kiwifruit seedlings. The results will enrich our knowledge of the molecular mechanisms of carotenoid biosynthesis in kiwifruit.

Gamma amino butyric acid (GABA), an important free amino acid in plant tissues, plays an essential role in all stages of plant growth and development. In this study, we aimed to explore the effects of GABA on the nutrient absorption of loquat [Eriobotrya japonica (Thunb.) Lindl.] seedlings. The effects of applying exogenous GABA in different concentrations (0.0, 0.5, 1.0, 1.5, and 2 g L−1) on the nutrient uptake of loquat seedlings were studied. GABA increased the biomass (dry weight) and contents of photosynthetic pigments in loquat seedlings to a certain extent. GABA concentration exhibited a quadratic polynomial regression relationship with the biomass. Exogenous GABA in different concentrations increased the total nitrogen (N) and phosphorus (P) contents in loquat seedlings, whereas only 0.5 and 1.0 g L−1 of GABA increased the potassium (K) content. Similarly, GABA concentration also had a polynomial regression relationship with the total N, P, and K contents. Compared to the control, 0.5, 1.0, 1.5, and 2.0 g L−1 of GABA increased the shoot total N content by 27.30, 32.99, 15.41, and 12.93%, respectively, and also increased the shoot total P content by 26.12, 37.52, 21.99, and 9.61%, respectively. Furthermore, correlation and grey relational analyses showed that the carotenoid content, root biomass, and soil alkali-hydrolyzable N concentration were the indicators most closely associated with the uptakes of N, P, and K in shoots. This study shows that exogenous GABA can promote the growth and nutrient uptake of loquat seedlings at an optimum concentration of 1.0 g L−1.

Loquats have drawn much attention due to their essential nutrients and unusual phenology, which fills a market gap in early spring. Fruit firmness (FF) is one of the most important quality attributes. Dynamic changes in FF, cell wall (CW) polysaccharides, CW hydrolase activity, and expression of CW metabolism-related genes during the fruit development and ripening stages of two contrasting loquat cultivars were compared. Although the two cultivars possessed similar FF at the initial fruitlet stage, Dawuxing was significantly firmer than Ninghaibai at all subsequent time points. FF was positively correlated with the contents of covalent-soluble pectin and hemicellulose, activity of peroxidase, and gene expressions of PME, EG, CAD6, and POD; and negatively correlated with the contents of water-soluble pectin, activities of polygalacturonase, endo-glucanase, cellobiohydrolase, and xylanase, and gene expressions of PG, EG2, PAL1, PAL3, and CAD5. Identifying molecular mechanisms underlying the differences in FF is useful for fundamental research and crop improvement in future.

Carotenoids are the pigment substances of yellow-fleshed kiwifruit, and among them β-cryptoxanthin has only been detected in the brighter yellow-fleshed variety 'Jinshi 1'. β-Carotene hydroxylase (BCH) catalyzes the formation of β-cryptoxanthin and zeaxanthin, but its molecular characteristics and functions have not been fully explained. Here we isolated two β-carotene hydroxylase genes

The "Manicure Finger" grape is notable for its fingerlike berries with a bright red top and yellow base; however, the mechanism underlying this color difference remains unknown. This study showed that the anthocyanin concentration and the expression levels of anthocyanin-related genes in the top skin were notably higher than those in the basal skin. The expression levels of

Plums are widely consumed, contain high levels of phenolic compounds, and have strong antioxidant activity. In this study, the main Sichuan cultivars ‘Qiangcuili’ and ‘Cuihongli’ were used to study the changes in the appearance, internal quality, phenolic compounds, and antioxidant activities during fruit development and the expression of phenolic-compound-related structural genes. The results showed that, during development of the two plums, the total soluble solid and soluble sugar contents were highest at the mature stage. The phenolic contents (total phenol content (TPC), total flavonoid content (TFC), and total flavanol content (TFAC)) trended gradually downward as the fruits of the two cultivars matured, while the total anthocyanin content gradually increased in ‘Cuihongli’. The main phenolic components were neochlorogenic acid, chlorogenic acid, ferulic acid, benzoic acid, rutin, and proanthocyanidin B1. The changes in the DPPH and FRAP scavenging activities decreased with fruit ripening. The antioxidant capacity was positively correlated with the TPC, TFC, and TFAC. In the two cultivars, the total phenols, phenolic components, and antioxidant capacity were higher in the peel than in the pulp. CHS, PAL3, and HCT1 may be the regulatory genes related to the accumulation of phenolic substances in the pericarp and pulp of ‘Qiangcuili’ and ‘Cuihongli’. HCT1 may be an important regulator involved in the accumulation of chlorogenic acid in plums. The changes in the quality of the phenols, phenolic components, and antioxidant activity were elucidated during the development of the main plum cultivars in Sichuan, particularly the changes that provided a theoretical basis for the development of bioactive substances in local plum cultivars.

Cadmium (Cd) contamination of orchard soils is a global problem that has been increasing. To decrease the Cd accumulation in fruits, intercropping the orchard crops with hyperaccumulator plants has been used for soil remediation. A pot and a field experiment were conducted to study the effects of intercropping the potential Cd-hyperaccumulator Intercropping the potential Cd-hyperaccumulator

In this study, farmland and mining ecotypes of Solanum photeinocarpum (a potential cadmium (Cd) hyperaccumulator plant) were reciprocally hybridized each other, and the Cd accumulation characteristics of the F1 hybrids were studied. In pot experiments, higher biomasses and Cd extraction abilities were found for two S. photeinocarpum F1 hybrids than for the parents, but the Cd contents in various organs were lower in the hybrids than the parents. However, the differences between the Cd contents in the two hybrids were not significant. The antioxidant enzyme (superoxide dismutase and peroxidase) activities were higher for the S. photeinocarpum F1 hybrids than the parents. Less DNA methylation was found in the hybrids than the parents because more demethylation occurred in the hybrids than the parents. The biomass, Cd content, and Cd extraction ability effects in field experiments were similar to the effects in the pot experiments. It was concluded that reciprocally hybridizing different S. photeinocarpum ecotypes improved the ability of S. photeinocarpum to be used to phytoremediate contaminated land.

A pot experiment was conducted to study the effects of different rootstocks on the cadmium (Cd) accumulation characteristics of the post-grafting generations of Cd-hyperaccumulator Galinsoga parvif...

Grapevine (Vitis vinifera L.) intercropping with floricultural cadmium (Cd) accumulator plants (Helianthus annuus L., Cosmos sulphureus Cav., Cosmos bipinnata Cav., and Impatiens balsamina L.) in Cd-contaminated soils (5 mg/kg) was conducted in pot experiment to screen the floricultural Cd-accumulator plants that can effectively reduce Cd uptake in grapevine. Intercropping with H. annuus, C. sulphureus, and I. balsamina decreased the biomass of grape plants compared with that of the grape monoculture, whereas intercropping with C. bipinnata did not show differences in grape plant biomass both as compared to monoculture in Cd-contaminated soils and to control plants, grown in the same soil without Cd spiking. The superoxide dismutase and catalase activities, as well as soluble protein content, were increased by intercropping with C. bipinnata compared with the grape monoculture, but were decreased by the other intercropping treatments. In general, intercropping with the four floricultural Cd-accumulator plants decreased the Cd content in grape plants compared with the monoculture, and the Cd content in grapevine for the different treatments was as follows: monoculture > intercropped with I. balsamina > intercropped with C. bipinnata > intercropped with H. annuus > intercropped with C. sulphureus. As for the amount of Cd accumulated by shoots of the floricultural plants, the ranking was as follows: I. balsamina > C. sulphureus > H. annuus > C. bipinnata. Therefore, intercropping with floricultural Cd-accumulator plants could effectively decrease Cd accumulation in grape plants, and intercropping with C. sulphureus gave the best results in this study.

Melatonin is involved in regulating plant growth and responding to multiple environmental stresses. The underlying mechanism by which melatonin mediates drought tolerance in some plant species remains unknown. We investigated the effects of melatonin with different doses (50, 100, and 200 μM) on growth and photosynthesis in kiwifruit (A. chinensis var. deliciosa cv. Qinmei) seedlings under drought stress. Drought stress strongly suppressed biomass accumulation, damaged cellular membranes, and inhibited photosynthesis in the seedlings. However, irrigation with melatonin mitigated the drought-induced impairment in a dose-dependent manner, with the greatest efficiency provided by 100 μM. Melatonin promoted the development of the root system architecture, reduced lipid peroxidation and pigment degradation, alleviated injuries to cell membranes, promoted the accumulation of osmotica, and inhibited the degradation of or facilitated synthesis of certain proteins. In addition, melatonin improved photosynthesis by inhibiting stomatal closure, enhancing light energy absorption, and promoting electron transport in PSII. Moreover, transcription of 11 genes for enzymes involved in CO2 fixation (Rubisco, PGK, GAPA, FBA, FBP, TIM, TKT, RPK, SEBP, RPI, and RPE) was upregulated in response to melatonin. These results demonstrate that supplemental melatonin could effectively ameliorate the repression of biomass accumulation and photosynthesis caused by drought and thus enhance the seedlings adaptability to drought stress.

Jujube is a characteristic light-demanding fruit tree, but fruit quality is frequently degraded because of the weak light in protected cultivation facilities in south China. In this study, a black shade net was used to set three light intensities artificially: no shading (0%, control, NS), moderate shading (45%, MS), and severe shading (76%, SS) to investigate the effect of low light on sugar metabolism of jujube. Compared with NS, chlorophyll and carotenoid contents in shaded leaves were increased, while specific leaf weight was decreased. A decrease in sucrose content, rather than fructose and glucose, was the main factor affecting sugar content in shaded leaves and fruits. Low expression of ZjSS2 and ZjSS3 inhibited sugar synthesis in shaded leaves, thereby reducing sucrose content by 23.7% in SS leaf than that in NS. Compared with NS, sucrose content in SS fruit was decreased by 58.1%, which was mainly caused by the down-regulated expression of ZjSS2 and ZjSPS1. In conclusion, sugar accumulation in leaf and fruit with shading treatment was suppressed, which was associated with differential transcription levels of related metabolic genes. The study provides new insights into sugar metabolism in leaf and fruit of phototropic plants under low light environments, such as jujube.

The whole-genome molecular mechanisms of melatonin (MT)-mediated enhancement of thermotolerance in plants has rarely been studied. In this study, the genome-wide gene expression profiles of kiwifruit seedlings primed with MT and non-MT at 45°C were analyzed by RNA-Seq. A total of 3299 differentially expressed genes (DEGs) were screened between MT and non-MT treatment, in which carotenoid biosynthesis was one of the high-enrichment pathways revealed by Kyoto Encyclopedia of Genes and Genomes analysis. Further, qRT-PCR verified that MT significantly induced the upregulated expression of the carotenoid biosynthesis gene, which was consistent with the increase of carotenoid content. In addition, 10 heat shock proteins (HSPs) were identified to have a highly upregulated expression by MT. These findings provide a set of informative and fundamental data on the role of MT in heat resistance.

Cadmium (Cd) contamination of orchard soils is a global problem that has been increasing. To decrease the Cd accumulation in fruits, intercropping the orchard crops with hyperaccumulator plants has been used for soil remediation. A pot and a field experiment were conducted to study the effects of intercropping the potential Cd-hyperaccumulator Solanum photeinocarpum and its post-grafting generations with loquat (Eriobotrya japonica) on the growth and Cd uptake of these two plant species. In the pot experiment, intercropping improved the biomass, Cd content, Cd extraction, and root-to-shoot Cd translocation in both species. Intercropping increased the DNA methylation levels, antioxidant enzyme activity, and soluble protein content of loquat seedlings. These results indicate that intercropping could improve the phytoremediation of S. photeinocarpum and its post-grafting generations and increase the Cd uptake in loquat seedlings. In the field experiment, intercropping increased the Cd contents in the old branches, while it decreased that in the young branches and fruits of loquat. These findings indicate that intercropping could increase the Cd uptake in old tissues but reduce the Cd uptake in young tissues and fruits of loquat. So, intercropping loquat with S. photeinocarpum and its post-grafting generations could be used in Cd-contaminated orchards. Intercropping the potential Cd-hyperaccumulator Solanum photeinocarpum and its post-grafting generations with loquat mutually promoted the growth of two plant species, and also promoted the cadmium uptakes in S. photeinocarpum and old branches of loquat, while inhibited the Cd uptake in the loquat young tissues (young branches and fruits). These results are the new findings of the intercropping.

Background: Actinidia latifolia is an exceptional source with extremely high ascorbic acid (AsA) content. However, its transcriptome atlas is lacking and how AsA accumulates during fruit development and ripening of this special kiwifruit and its associated molecular mechanisms are still poorly understood.Results: Herein, the dynamic changes of AsA content of six stages of A. latifolia fruit development and ripening determined by HPLC demonstrated a rapid increasing profile during the initial expansion stage with a peak around 60 days after flowering (1194.21±69.25 mg 100g-1 FW), followed by a progressive, albeit not significant decrease tendency and reached the minimum levels (1028.76±31.19 mg 100g-1 FW) at maturity. A high-quality full-length (FL) transcriptome of A. latifolia was successfully constructed by third-generation sequencing for the first time, comprising 326,926 FL non-chimeric reads, 15,505 coding sequences, 2882 transcription factors, 18,797 simple sequence repeats, 3328 long noncoding RNAs, and 231 alternative splicing events. Illumina RNA-seq in combination with weighted gene co-expression network analysis revealed a network module highly correlated (r=0.5, p=0.03) with AsA content. Gene co-expression in this network module was explained by its roles in protein processing in endoplasmic reticulum (ko04141), glycolysis/gluconeogenesis (ko00010), and carbon metabolism (ko01200). Moreover, the expression patterns of genes involved in AsA biosynthesis and metabolism validated by qRT-PCR exhibited a similar trend with AsA accumulation.Conclusions: Overall, the dynamic changes of AsA content and associated key genes and enriched metabolic pathways were deciphered, which paves the way for genetic improvement that aims for development of kiwifruit with super-high AsA content.

Background: Tree tomato (Cyphomandra betacea (Cav.) Sendtn.) is a neglected, fast-growing, promising small fruit crop which provides a rich source of nutrition for human consumption. However, the transcriptome atlas of this important species is still lacking.Results: In this study, RNA samples from a broad diversity of tissues (roots, leaves, stems, flowers and fruits) of tree tomato were sequenced using Pacific Biosciences’ long-read single-molecule real-time sequencing technology. A total of 308699 full-length non-chimeric sequences with a mean length of 1005 bp and an N50 length of 1974 bp were obtained from our multi-tissue normalized cDNA libraries. A total of 140327, 104294, 135138, 78300, 53520, 152310 and 53520 transcripts were functionally annotated using Nr, Swiss-Prot, KEGG, KOG, GO, Nt and Pfam databases, respectively. Gene structural characteristics of the full-length transcriptome of tree tomato was subsequently investigated, including the predication of coding sequence and the identification of transcription factor families, long non-coding RNA and simple sequence repeat (SSR) marker. Thirty primers were randomly selected to evaluate the application of SSR markers, 23 of which obtained successfully amplification.Conclusions: This is the first confident characterization of FL transcriptome profiling of tree tomato. The large-scale and high-quality transcriptome atlas and SSR molecular markers provided in the present study will facilitate further genetic studies of this important species.

Farmland and mining ecotypes of the potential cadmium (Cd)-hyperaccumulator

Methyl jasmonate (MeJA) is an airborne signaling phytohormone that can induce changes in endogenous jasmonates (JAs) and cause photosynthetic responses. However, the response of these two aspects of citrus plants at different MeJA concentrations is still unclear. Four MeJA concentrations were used in two citrus varieties, Huangguogan (C. reticulata × C. sinensis) and Shiranuhi [C. reticulata × (C. reticulata × C. sinensis)], to investigate the effects of MeJA dose on the endogenous JAs pathway and photosynthetic capacity. We observed that MeJA acted in a dose-dependent manner, and its stimulation in citrus leaves showed a bidirectional character at different concentrations. This work demonstrates that MeJA at only a concentration of 2.2 mM or less contributed to the activation of magnesium protoporphyrin IX methyltransferase (ChlM, EC 2.1.1.11) and protochlorophyllide oxidoreductase (POR, EC 1.3.1.11) and the simultaneous accumulation of Chl a and Chl b, which in turn contributed to an improved photosynthetic capacity and PSII photochemistry efficiency of citrus. Meanwhile, the inhibition of endogenous JAs synthesis by exogenous MeJA was observed. This was achieved by reducing the ratio of monogalactosyl diacylglycerol (MGDG) to diagalactosyl diacylglycerol (DGDG) and inhibiting the activities of key enzymes in JAs synthesis, especially 12-oxo-phytodienoic acid reductase (OPR, EC 1.3.1.42). Another noteworthy finding is that there may exist a JA-independent pathway that could regulate 12-oxo-phytodienoic acid (OPDA) synthesis. This study jointly analyzed the internal hormone regulation mechanism and the external physiological response, as well as revealed the effects of exogenous MeJA on promoting the photosynthesis and inhibiting the endogenous JAs synthesis.

Carrizo citrange [Citrus sinensis (L.) Osbeck × Poncirus trifoliata (L.) Raf., CC] is one of the most widely used rootstocks in citriculture worldwide, but its cytogenetic study has been hampered by its inherent small size, morphological similarity to mitotic chromosomes, and lack of accessible cytological landmarks. In our previous study, a spontaneously occurring tetraploid CC seedling was discovered. The main goals of this study were to elucidate the chromosome constitution and construct the karyotypes of diploid CC rootstock and its corresponding spontaneously occurring tetraploid. To accomplish these, the chromosomal characteristics were investigated by sequential multicolor fluorescence in situ hybridization (FISH) with eight properly labeled repetitive DNA sequences, including a centromere-like repeat, four satellite repeats, two rDNAs, and an oligonucleotide of telomeric (TTTAGGG) n repeat. The results nicely demonstrated that these repetitive DNAs are reliable cytogenetic markers that collectively facilitate simultaneous and unequivocal identification of homologous chromosome pairs. Based on chromosome size and morphology together with FISH patterns of repetitive DNAs, an integrated karyotype of CC rootstock was constructed, consisting of 2n = 2x = 12m (1sat) + 6sm with karyotype asymmetry degree being divided into 2B category. Cytogenetically speaking, the variable and asymmetric distribution patterns of these repetitive DNAs were fully confirmed the hybrid nature of CC rootstock. In addition, comparative distribution patterns and chromosomal localizations of these repetitive DNAs convincingly showed that this tetraploid CC material arose from somatic chromosome doubling of diploid CC rootstock. This study revealed, for the first time, the integrated karyotype and chromosomal characteristics of this important citrus rootstock as well as its spontaneously occurring tetraploid plant. Furthermore, this study is a good prospective model for study species with morphologically indistinguishable small chromosomes.

MYB transcription factors (TFs) play an active role in plant responses to abiotic stresses, but they have not been systematically studied in kiwifruit (Actinidia chinensis). In this study, 181 AcMYB TFs were identified from the kiwifruit genome, unevenly distributed on 29 chromosomes. The high proportion (97.53%) of segmental duplication events (Ka/Ks values less than 1) indicated that AcMYB TFs underwent strong purification selection during evolution. According to the conservative structure, 91 AcR2R3-MYB TFs could be divided into 34 subgroups. A combination of transcriptomic data under drought and high temperature from four AcMYB TFs (AcMYB2, AcMYB60, AcMYB61 and AcMYB102) was screened out in response to stress and involvement in the phenylpropanoid pathway. They were highly correlated with the expression of genes related to lignin biosynthesis. qRT-PCR analysis showed that they were highly correlated with the expression of genes related to lignin biosynthesis in different tissues or under stress, which was consistent with the results of lignin fluorescence detection. The above results laid a foundation for further clarifying the role of MYB in stress.

To determine whether the living hyperaccumulator plants and their straws have the same effects on the growth and heavy metal accumulation of common plants, two pot experiments (intercropping experiment and straw mulch experiment) were conducted to study the effects of living hyperaccumulator plants (Solanum photeinocarpum, Tagetes erecta, Galinsoga parviflora and Bidens pilosa) and their straws on the growth and cadmium (Cd) accumulation of common plant Cyphomandra betacea seedlings. Intercropping with T. erecta or B. pilosa promoted the growth of C. betacea seedlings compared with the monoculture, while intercropping with S. photeinocarpum or G. parviflora inhibited that. Intercropping with S. photeinocarpum decreased the Cd contents in the roots and shoots of C. betacea seedlings compared with the monoculture, but intercropping with the other plants did not. In the straw mulch experiment, the straw of S. photeinocarpum or T. erecta promoted the growth of C. betacea seedlings compared with the control, while the straw of G. parviflora or B. pilosa did not. The straw of S. photeinocarpum or T. erecta decreased the Cd contents in the shoots of C. betacea seedlings, and the straw of G. parviflora or B. pilosa increased the shoot Cd contents. Thus, intercropping with S. photeinocarpum and applying S. photeinocarpum or T. erecta straw can reduce the Cd uptake of C. betacea.

Paclobutrazol (PP333) can enhance the resistance capabilities of plants to stress conditions. In this study, PP333 were sprayed on the lead (Pb) and zinc (Zn) accumulator plant Pseudostellaria maxi...

In this study, we investigated the effects of melatonin application on berry coloration, sugar accumulation, and nutrient absorption in ‘Summer Black’ grapes. Melatonin spraying at 100 μmol L−1 on grapes during veraison induced skin coloration earlier than that in controls, as well as higher transcript abundance of anthocyanin biosynthesis-related genes and transcription factors MYBA1 and MYBA2. Melatonin treatment increased the soluble sugar content, especially of sucrose, by promoting the activity of sucrose phosphate synthase, and also increased endogenous melatonin content and the concentrations of mineral nutrients N, K, Cu, Fe, and Zn in grape berries. Correlation analysis suggested that high sugar content promoted anthocyanin synthesis. These findings provide a sound theoretical basis for the development of techniques aimed to achieve optimum coloration of grapes in hot and rainy regions.

Carrizo citrange [Citrus sinensis (L.) Osbeck × Poncirus trifoliata (L.) Raf., CC] is one of the most widely used rootstocks in citriculture worldwide, but its cytogenetic study has been hampered by its inherent small size, morphological similarity to mitotic chromosomes, and lack of accessible cytological landmarks. In our previous study, a spontaneously occurring tetraploid CC seedling was discovered. The main goals of this study were to elucidate the chromosome constitution and construct the karyotypes of diploid CC rootstock and its corresponding spontaneously occurring tetraploid. To accomplish these, the chromosomal characteristics were investigated by sequential multicolor fluorescence in situ hybridization (FISH) with eight properly labeled repetitive DNA sequences, including a centromere-like repeat, four satellite repeats, two rDNAs, and an oligonucleotide of telomeric (TTTAGGG)n repeat. The results nicely demonstrated that these repetitive DNAs are reliable cytogenetic markers that collectively facilitate simultaneous and unequivocal identification of homologous chromosome pairs. Based on chromosome size and morphology together with FISH patterns of repetitive DNAs, an integrated karyotype of CC rootstock was constructed, consisting of 2n = 2x = 12m (1sat) + 6sm with karyotype asymmetry degree being divided into 2B category. Cytogenetically speaking, the variable and asymmetric distribution patterns of these repetitive DNAs were fully confirmed the hybrid nature of CC rootstock. In addition, comparative distribution patterns and chromosomal localizations of these repetitive DNAs convincingly showed that this tetraploid CC material arose from somatic chromosome doubling of diploid CC rootstock. This study revealed, for the first time, the integrated karyotype and chromosomal characteristics of this important citrus rootstock as well as its spontaneously occurring tetraploid plant. Furthermore, this study is a good prospective model for study species with morphologically indistinguishable small chromosomes.

A pot experiment was conducted to study the effects of different rootstocks on the cadmium (Cd) accumulation characteristics of the post-grafting generations of Cd-hyperaccumulator

To study the effects of intercropping with accumulator plants on heavy metal accumulation of fruit trees, plants of three Bidens species (Bidens pilosa, Bidens biternata, and Bidens parviflora) were intercropped with Ziziphus acidojujuba seedlings under cadmium (Cd)-contaminated conditions (5 mg kg−1). Intercropping with Bidens species increased the biomass and chlorophyll b content of Z. acidojujuba seedlings compared with monoculture, but decreased their carotenoid content. Intercropping with Bidens species also improved the activity of superoxide dismutase, peroxidase, and catalase in Z. acidojujuba seedlings compared with monoculture. Intercropping with Bidens species decreased the Cd content in the roots of Z. acidojujuba seedlings compared with monoculture. Conversely, when intercropped with B. pilosa, B. biternata, and B. parviflora, the Cd content in the shoots of Z. acidojujuba seedlings increased by 62.18%, 60.10%, and 62.18%, respectively, compared with that of those monocultured. When intercropped with Z. acidojujuba seedlings, the Cd accumulation amount of three Bidens species plants were ranked B. parviflora > B. biternata > B. pilosa. Therefore, intercropping with plants of three Bidens species is not suitable for Cd-contaminated jujube orchards.