Dongsheng Gao

Expression of ABA Metabolism-Related Genes Suggests Similarities and Differences Between Seed Dormancy and Bud Dormancy of Peach (Prunus persica)

Dormancy inhibits seed and bud growth of perennial plants until the environmental conditions are optimal for survival. Previous studies indicated that certain co-regulation pathways exist in seed and bud dormancy. In our study, we found that seed and bud dormancy are similar to some extent but show different reactions to chemical treatments that induce breaking of dormancy. Whether the abscisic acid (ABA) regulatory networks are similar in dormant peach seeds and buds is not well known; however, ABA is generally believed to play a critical role in seed and bud dormancy. In peach, some genes putatively involved in ABA synthesis and catabolism were identified and their expression patterns were studied to learn more about ABA homeostasis and the possible crosstalk between bud dormancy and seed dormancy mechanisms. The analysis demonstrated that two 9-cis-epoxycarotenoid dioxygenase-encoding genes seem to be key in regulating ABA biosynthesis to induce seed and bud dormancy. Three CYP707As play an overlapping role in controlling ABA inactivation, resulting in dormancy-release. In addition, Transcript analysis of ABA metabolism-related genes was much similar demonstrated that ABA pathways was similar in the regulation of vegetative and flower bud dormancy, whereas, expression patterns of ABA metabolism-related genes were different in seed dormancy showed that ABA pathway maybe different in regulating seed dormancy in peach.

Genome-wide identification of WRKY family genes in peach and analysis of WRKY expression during bud dormancy

Bud dormancy in deciduous fruit trees is an important adaptive mechanism for their survival in cold climates. The WRKY genes participate in several developmental and physiological processes, including dormancy. However, the dormancy mechanisms of WRKY genes have not been studied in detail. We conducted a genome-wide analysis and identified 58 WRKY genes in peach. These putative genes were located on all eight chromosomes. In bioinformatics analyses, we compared the sequences of WRKY genes from peach, rice, and Arabidopsis. In a cluster analysis, the gene sequences formed three groups, of which group II was further divided into five subgroups. Gene structure was highly conserved within each group, especially in groups IId and III. Gene expression analyses by qRT-PCR showed that WRKY genes showed different expression patterns in peach buds during dormancy. The mean expression levels of six WRKY genes (Prupe.6G286000, Prupe.1G393000, Prupe.1G114800, Prupe.1G071400, Prupe.2G185100, and Prupe.2G307400) increased during endodormancy and decreased during ecodormancy, indicating that these six WRKY genes may play a role in dormancy in a perennial fruit tree. This information will be useful for selecting fruit trees with desirable dormancy characteristics or for manipulating dormancy in genetic engineering programs.

GOLDEN 2-LIKE Transcription Factors of Plants

Golden2-like (GLK) transcription factors are members of the GARP family of Myb transcription factors with an established relationship to chloroplast development in the plant kingdom. In the last century, Golden2 was proposed as a second golden producing factor and identified as controlling cellular differentiation in maize leaves. Then, GLKs were also found to play roles in disease defense and their function is conserved in regulating chloroplast development. Recently, research on GLKs has rapidly increased and shown that GLKs control chloroplast development in green and non-green tissues. Moreover, links between phytohormones and GLKs were verified. In this mini-review, we summarize the history, conservation, function, potential targets and degradation of GLKs.

Analysis of basic leucine zipper genes and their expression during bud dormancy in peach (Prunus persica).

Dormancy is a biological characteristic developed to resist the cold conditions in winter. The bZIP transcription factors are present exclusively in eukaryotes and have been identified and classified in many species. bZIP proteins are known to regulate numerous biological processes, however, the role of bZIP in bud dodormancy has not been studied extensively. In total, 50 PpbZIP transcription factor-encoding genes were identified and categorized them into 10 groups (A-I and S). Similar intron/exon structures, additional conserved motifs, and DNA-binding site specificity supported our classification scheme. Additionally, chromosomal distribution and collinearity analyses suggested that expansion of the PpbZIP transcription factor family was due to segment/chromosomal duplications. We also predicted the dimerization properties based on characteristic features of the leucine zipper and classified PpbZIP proteins into 23 subfamilies. Furthermore, qRT-PCR results indicated that PpbZIPs genes may be involved in regulating dormancy. The same gene of different species might participate in different regulating networks through interactions with specific partners. Our expression profiling results complemented the microarray data, suggesting that co-expression patterns of bZIP transcription factors during dormancy differed among deciduous fruit trees. Our findings further clarify the molecular characteristics of the PpbZIP transcription factor family, including potential gene functions during dormancy. This information may facilitate further research on the evolutionary history and biological functions of bZIP proteins in peach and other rosaceae plants.

The flavor and nutritional characteristic of four strawberry varieties cultured in soilless system

Abstract Strawberry fruits (cv. Benihoppe, Tochiotome, Sachinoka, and Guimeiren) were harvested and evaluated the flavor and nutritional parameters. By principal component analysis and hierarchical clustering analysis, differences were observed based on the volatile compounds composition, sugar and acid concentration, sweetness, and total soluble sugars/total organic acids of the four varieties. A total of 37, 48, 65, and 74 volatile compounds were identified and determined in cv. Benihoppe, Tochiotome, Sachinoka, and Guimeiren strawberry fruits extracted by head‐space solid‐phase microextraction (HS‐SPME), respectively. Esters significantly dominated the chemical composition of the four varieties. Furaneol was detected in cultivars of Sachinoka and Guimeiren, but mesifuran was only found in cv. Tochiotome. Tochiotome and Sachinoka showed higher content of linalool and (E)‐nerolidol. Sachinoka showed the highest content of total sugars and total acids. Guimeiren showed higher sweetness index than the other three cultivars. Firmness of Tochiotome was highest among all the varieties. The highest total soluble solids TSS value was found in cv. Sachinoka, followed by the Guimeiren and Tochiotome varieties. Sachinoka had the highest titratable acidity TA value. The content of ascorbic acid (AsA) of cv. Tochiotome was higher than the others, but there was no significant difference in cultivars of Benihoppe, Tochiotome, and Sachinoka. Fructose and glucose were the major sugars in all cultivars. Citric acid was the major organic acid in cv. Tochiotome, cv. Sachinoka, and cv. Guimeiren. Tochiotome had higher ratios of TSS/TA and total sugars/total organic acids than others, arising from its lower acid content. The order of the comprehensive evaluation score was Sachinoka>Guimeiren>Tochiotome>Benihoppe.

Identification and characterization of Prunus persica miRNAs in response to UVB radiation in greenhouse through high-throughput sequencing

BackgroundMicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression of target mRNAs involved in plant growth, development, and abiotic stress. As one of the most important model plants, peach (Prunus persica) has high agricultural significance and nutritional values. It is well adapted to be cultivated in greenhouse in which some auxiliary conditions like temperature, humidity, and UVB etc. are needed to ensure the fruit quality. However, little is known about the genomic information of P. persica under UVB supplement. Transcriptome and expression profiling data for this species are therefore important resources to better understand the biological mechanism of seed development, formation and plant adaptation to environmental change. Using a high-throughput miRNA sequencing, followed by qRT-PCR tests and physiological properties determination, we identified the responsive-miRNAs under low-dose UVB treatment and described the expression pattern and putative function of related miRNAs and target genes in chlorophyll and carbohydrate metabolism.ResultsA total of 164 known peach miRNAs belonging to 59 miRNA families and 109 putative novel miRNAs were identified. Some of these miRNAs were highly conserved in at least four other plant species. In total, 1794 and 1983 target genes for known and novel miRNAs were predicted, respectively. The differential expression profiles of miRNAs between the control and UVB-supplement group showed that UVB-responsive miRNAs were mainly involved in carbohydrate metabolism and signal transduction. UVB supplement stimulated peach to synthesize more chlorophyll and sugars, which was verified by qRT-PCR tests of related target genes and metabolites’ content measurement.ConclusionThe high-throughput sequencing data provided the most comprehensive miRNAs resource available for peach study. Our results identified a series of differentially expressed miRNAs/target genes that were predicted to be low-dose UVB-responsive. The correlation between transcriptional profiles and metabolites contents in UVB supplement groups gave novel clues for the regulatory mechanism of miRNAs in Prunus. Low-dose UVB supplement could increase the chlorophyll and sugar (sorbitol) contents via miRNA-target genes and therefore improve the fruit quality in protected cultivation of peaches.

Photosynthetic activities, C3 and C4 indicative enzymes and the role of photoperiod in dormancy induction in ‘Chunjie’ peach

Our study examined the relationship between photosynthetic performance and activities of key photosynthetic enzymes to understand the photosynthetic variation and reasons for the variation during dormancy induction under different photoperiods in peach (Prunus persica L. cv. Chunjie). Furthermore, the study explained the changes in the key enzymes from the viewpoint of differential proteomics. The results showed that the leaf net photosynthetic rate (PN) and stomatal conductance tended to decrease, while the intercellular CO2 concentration rose, which indicated that the reduced PN resulted from nonstomatal limitation. During the dormancy induction period, the activities of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and phosphoenolpyruvate carboxylase (PEPC) declined, which was the main reason for the reduced PN. Two-dimensional electrophoresis maps and differential protein identification demonstrated that the decrease in activity of the photosynthetic enzymes was mainly due to enzymatic degradation. The enzyme degradation by a long-day treatment occurred later and to a lesser degree than that of the short-day treatment. In the long-day treatment, the carboxylation activity of Rubisco was higher than that of the control treatment, and the PEPC activity and the ratio of the PEPC/Rubisco activity were lower than the corresponding activities during the control treatment. These differences under long-day conditions were significant but did not occur in the short-day treatment, suggesting that the C4 pathway might be more active under short-day conditions.

Sugar metabolism changes in response to the ultraviolet B irradiation of peach (Prunus persica L.)

The protected cultivation of peach (Prunuspersica L.) trees is more economical and efficient than traditional cultivation, resulting in increased farmers’ incomes, but the peach sugar contents are lower than in open planting. In the greenhouse, a high-sugar variety of peach ‘Lumi 1’ was irradiated with 1.44 KJ·m−2.d−1 intensity ultraviolet B radiation. The soluble sugar contents in fruit, peel and leaf were quantified using liquid chromatography. Overall, sucrose and sorbitol increased before the second fruit-expansion period. To further understand the mechanisms regulating sucrose and sorbitol accumulation in peach fruit, expression profiles of genes involved in sugar metabolism and transport were measured. The activity and translocation protein contents of these enzymes were measured by enzyme-linked immunosorbent assay. The increased sucrose synthase activity and sucrose transporter level in the pericarp promoted the synthesis of sucrose and intake of sucrose into fruit. Sorbitol transport into fruit was promoted by the increased sorbitol transporter protein levels in leaves. In summary, greenhouse the sucrose and sorbitol contents were increased when supplemented with 1.44 kJ·m−2·d−1 ultraviolet B radiation before the second fruit-expansion period of peach.

Effect of exogenously applied molybdenum on its absorption and nitrate metabolism in strawberry seedlings

Molybdenum (Mo)-an essential element of plants-is involved in nitrogen (N) metabolism. Plants tend to accumulate more nitrate and show lower nitrogen use efficiency (NUE) under Mo-deficient conditions. Improving NUE in fruits reduces the negative effect of large applications of chemical fertilizer, but the mechanisms underlying how Mo enhances NUE remain unclear. We cultivated strawberry seedlings sprayed with 0, 67.5, 135, 168.75, or 202.5xa0g Mo·ha-1 in a non-soil culture system. The Mo concentration in every plant tissue analyzed increased gradually as Mo application level rose. Mo application affected iron, copper, and selenium adsorption in roots. Seedlings sprayed with 135xa0g Mo·ha-1 had a higher [15N] shoot:root (S:R) ratio, and 15NUE, and produced higher molybdate transporter type 1 (MOT1) expression levels in the roots and leaves. Seedlings sprayed with 135xa0g Mo·ha-1 also had relatively high nitrogen metabolic enzyme activities and up-regulated transcript levels of nitrate uptake genes (NRT1.1; NRT2.1) and nitrate-responsive genes. Furthermore, there was a significantly lower NO3- concentration in the leaves and roots, a higher NH4+ concentration in leaves, and a higher glutamine/glutamate (Gln/Glu) concentration at 135xa0g Mo·ha-1. Seedlings sprayed with 202.5xa0g Mo·ha-1 showed the opposite trend. Taken together, these results suggest that a 135xa0g Mo·ha-1 application was optimal because it enhanced NO3- transport from the roots to the shoots and increased NUE by mediating nitrogen metabolic enzyme activities, nitrate transport, and nitrate assimilation gene activities.

Additional file 4: Table S4. of Identification and characterization of Prunus persica miRNAs in response to UVB radiation in greenhouse through high-throughput sequencing

Details of targets genes and their annotation, GO classification, and KEGG pathway for the known miRNAs. (PDF 2823Âxa0kb)