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[学术文献 ] Genome-wide identification of the B3 gene family in soybean and the response to melatonin under cold stress 进入全文
Front Plant Sci
Introduction: Melatonin is a multipotent molecule that exists widely in animals and plants and plays an active regulatory role in abiotic stresses. The B3 superfamily is a ubiquitous transcription factor with a B3 functional domain in plants, which can respond temporally to abiotic stresses by activating defense compounds and plant hormones. Despite the fact that the B3 genes have been studied in a variety of plants, their role in soybean is still unknown. Methods: The regulation of melatonin on cold resistance of soybean and the response of B3 genes to cold stress were investigated by measuring biochemical indexes of soybean. Meanwhile, the genome-wide identification of B3 gene family was conducted in soybean, and B3 genes were analyzed based on phylogeny, motifs, gene structure, collinearity, and cis-regulatory elements analysis. Results: We found that cold stress-induced oxidative stress in soybean by producing excessive reactive oxygen species. However, exogenous melatonin treatment could increase the content of endogenous melatonin and other hormones, including IAA and ABA, and enhance the antioxidative system, such as POD activity, CAT activity, and GSH/GSSG, to scavenge ROS. Furthermore, the present study first revealed that melatonin could alleviate the response of soybean to cold stress by inducing the expression of B3 genes. In addition, we first identified 145 B3 genes in soybean that were unevenly distributed on 20 chromosomes. The B3 gene family was divided into 4 subgroups based on the phylogeny tree constructed with protein sequence and a variety of plant hormones and stress response cis-elements were discovered in the promoter region of the B3 genes, indicating that the B3 genes were involved in several aspects of the soybean stress response. Transcriptome analysis and results of qRT-PCR revealed that most GmB3 genes could be induced by cold, the expression of which was also regulated by melatonin. We also found that B3 genes responded to cold stress in plants by interacting with other transcription factors. Discussion: We found that melatonin regulates the response of soybean to cold stress by regulating the expression of the transcription factor B3 gene, and we identified 145 B3 genes in soybean. These findings further elucidate the potential role of the B3 gene family in soybean to resist low-temperature stress and provide valuable information for soybean functional genomics study.
[学术文献 ] Selenium seed priming enhanced the growth of salt-stressed Brassica rapa L. through improving plant nutrition and the antioxidant system 进入全文
Front Plant Sci
Various abiotic stresses may affect the germination, growth, and yield of direct-seeded vegetable crops. Seed priming with effective antioxidant mediators may alleviate these environmental stresses by maintaining uniformity in seed germination and improving the subsequent health of developing seedlings. Salt-induced stress has become a limiting factor for the successful cultivation of Brassica rapa L., especially in Southeast Asian countries. The present study was performed to elucidate the efficacy of seed priming using selenium (Se) in mitigating salt-induced oxidative stress in turnip crops by reducing the uptake of Na+. In this study, we administered three different levels of Se (Se-1, 75 μmol L−1; Se-2, 100 μmol L−1; and Se-3, 125 μmol L−1) alone or in combination with NaCl (200 mM). Conspicuously, salinity and Se-2 modulated the expression levels of the antioxidant genes, including catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), and ascorbate peroxidase (APX). The upregulated expression of stress-responsive genes alleviated salt stress by scavenging the higher reactive oxygen species (ROS) level. The stress ameliorative potential of Se (Se-2 = 100 μmol L−1) enhanced the final seed germination percentage, photosynthetic content, and seedling biomass production up to 48%, 56%, and 51%, respectively, under stress. The advantageous effects of Se were attributed to the alleviation of salinity stress through the reduction of the levels of malondialdehyde (MDA), proline, and H2O2. Generally, treatment with Se-2 (100 μmo L−1) was more effective in enhancing the growth attributes of B. rapa compared to Se-1 (75 μmo L−1) and Se-3 (125 μmo L−1) under salt-stressed and non-stressed conditions. The findings of the current study advocate the application of the Se seed priming technique as an economical and eco-friendly approach for salt stress mitigation in crops grown under saline conditions.
[学术文献 ] Transcriptomic comparison of seeds and silique walls from two rapeseed genotypes with contrasting seed oil content 进入全文
Front Plant Sci
Silique walls play pivotal roles in contributing photoassimilates and nutrients to fuel seed growth. However, the interaction between seeds and silique walls impacting oil biosynthesis is not clear during silique development. Changes in sugar, fatty acid and gene expression during Brassica napus silique development of L192 with high oil content and A260 with low oil content were investigated to identify key factors affecting difference of their seed oil content. During the silique development, silique walls contained more hexose and less sucrose than seeds, and glucose and fructose contents in seeds and silique walls of L192 were higher than that of A260 at 15 DAF, and sucrose content in the silique walls of L192 were lower than that of A260 at three time points. Genes related to fatty acid biosynthesis were activated over time, and differences on fatty acid content between the two genotypes occurred after 25 DAF. Genes related to photosynthesis expressed more highly in silique walls than in contemporaneous seeds, and were inhibited over time. Gene set enrichment analysis suggested photosynthesis were activated in L192 at 25 and 35 DAF in silique walls and at both 15 and 35 DAF in the seed. Expressions of sugar transporter genes in L192 was higher than that in A260, especially at 35 DAF. Expressions of genes related to fatty acid biosynthesis, such as BCCP2s, bZIP67 and LEC1s were higher in L192 than in A260, especially at 35 DAF. Meanwhile, genes related to oil body proteins were expressed at much lower levels in L192 than in A260. According to the WGCNA results, hub modules, such as ME.turquoise relative to photosynthesis, ME.green relative to embryo development and ME.yellow relative to lipid biosynthesis, were identified and synergistically regulated seed development and oil accumulation. Our results are helpful for understanding the mechanism of oil accumulation of seeds in oilseed rape for seed oil content improvement.
[学术文献 ] Analysis of Structure Variations and Expression Characteristics of DMP8 and DMP9 Genes in Brassicaceae 进入全文
Horticulturae
Doubled haploid (DH) technology based on in vivo haploid induction (HI), which is used to obtain true-breeding lines within a single generation, is a technique that significantly increases modern crop-breeding efficiency. Recently, dicot Arabidopsis thaliana lines containing mutations in DMP8/9 were used as haploid inducer lines, but the use of this new HI mechanism is limited in Brassicaceae species, which include many important vegetable, oil, and fodder crops. Here, we investigated the phylogenetic distribution of the DMP8 and DMP9 homologous genes from 26 sequenced Brassicaceae species. We found that DMP8 only exists in the tribe Arabideae, while multiple copies of the DMP9 gene are presenting in all the investigated Brassicaceae species. The syntenic DMP9 genes were divided into two groups derived from the S genomic block and R genomic block, respectively. We further investigated the duplication, structure variations, and expression of the DMP9 genes in Brassica species that had undergone an extra whole-genome triplication. Our results revealed that DMP9 was lost in the most fractionated (MF2) subgenome, and the retained DMP9s in the least fractionated (LF) subgenome and medium fractionated (MF1) subgenome showed diversified expression patterns, indicating their functional diversification. Our results will be useful for obtaining the target DMP genes for the establishing of HI lines in Brassicaceae crops.
[学术文献 ] Fine mapping and cloning of a novel BrSCC1 gene for seed coat color in Brassica rapa L 进入全文
Theoretical and Applied Genetics
Yellow seed is a valuable breeding trait that can be potentiality applied for improving seed quality and oil produc-tivity in oilseed Brassica crops. However, only few genes for yellow seed have been identified in B. rapa. We previously identified a minor quantitative trait locus (QTL), qSC3.1, for seed coat color on chromosome A03 in B. rapa. In order to isolate the seed coat color gene, a brown-seeded chromosome segment substitution line, CSSL-38, harboring the qSC3.1, was selected and crossed with the yellow-seeded recurrent parent, a rapid cycling inbred line of B. rapa (RcBr), to construct the secondary F2 population. Metabolite identification suggested that seed coat coloration in CSSL-38 was independent of proanthocyanidins (PAs) accumulation. Genetic analysis revealed that yellow seed was controlled by a single recessive gene, Seed Coat Color 1 (BrSCC1). Utilizing bulked segregant analysis (BSA)-seq and secondary F2 and F2:3 recombinants analysis, BrSCC1 was fine mapped within a 41.1-kb interval. By integrating gene expression profiling, genome sequence comparison, metabolite analysis, and functional validation through ectopic expression in Arabidopsis, the BraA03g040800.3C gene was confirmed to be BrSCC1, which positively correlated with the seed coat coloration. Our study provides a novel gene resource for the genetic improvement of yellow seeds in oilseed B. rapa.
[学术文献 ] BrACOS5 mutations induced male sterility via impeding pollen exine formation in Chinese cabbage (Brassica rapa L. ssp. pekinensis) 进入全文
Theoretical and Applied Genetics
Chinese cabbage (Brassica rapa L. ssp. pekinensis) is one of the major vegetable crops in East Asia, and the utiliza-tion of male-sterile line is an important measure for its hybrid seed production. Herein, we isolated three allelic male-sterile mutants, msm1-1, msm1-2 and msm1-3, from an ethyl methane sulfonate (EMS) mutagenized population of Chinese cabbage double-haploid (DH) line ‘FT’, whose microspores were completely aborted with severely absent exine, and tapetums were abnormally developed. Genetic analyses indicated that the three male-sterile mutants belonged to allelic mutation and were triggered by the same recessive nuclear gene. MutMap-based gene mapping and kompetitive allele-specific PCR (KASP) analysis demonstrated that three different single-nucleotide polymorphisms (SNPs) of BraA09g012710.3C were response-ble for the male sterility of msm1-1/2/3, respectively. BraA09g012710.3C is orthologous of Arabidopsis thaliana ACOS5 (AT1G62940), encoding an acyl-CoA synthetase in sporopollenin biosynthesis, and specifically expressed in anther, so we named BraA09g012710.3C as BrACOS5. BrACOS5 localizes to the endoplasmic reticulum (ER). Mutations of BrACOS5 resulted in decreased enzyme activities and altered fatty acid contents in msm1 anthers. As well as the transcript accumula-tions of putative orthologs involved in sporopollenin biosynthesis were significantly down-regulated excluding BrPKSA. These results provide strong evidence for the integral role of BrACOS5 in conserved sporopollenin biosynthesis pathway and also contribute to uncovering exine development pattern and underlying male sterility mechanism in Chinese cabbage.
