Genome-wide identification, molecular evolution and expression analysis of the B-box gene family in mung bean (Vigna radiata L.).

BACKGROUND: Mung bean (Vigna radiata L.) is an important warm-season grain legume. Adaptation to extreme environmental conditions, supported by evolution, makes mung bean a rich gene pool for stress tolerance traits. The exploration of resistance genes will provide important genetic resources and a theoretical basis for strengthening mung bean breeding. B-box (BBX) proteins play a major role in developmental processes and stress responses. However, the identification and analysis of the mung bean BBX gene family are still lacking. RESULTS: In this study, 23 VrBBX genes were identified through comprehensive bioinformatics analysis and named based on their physical locations on chromosomes. All the VrBBXs were divided into five groups based on their phylogenetic relationships, the number of B-box they contained and whether there was an additional CONSTANS, CO-like and TOC1 (CCT) domain. Homology and collinearity analysis indicated that the BBX genes in mung bean and other species had undergone a relatively conservative evolution. Gene duplication analysis showed that only chromosomal segmental duplication contributed to the expansion of VrBBX genes and that most of the duplicated gene pairs experienced purifying selection pressure during evolution. Gene structure and motif analysis revealed that VrBBX genes clustered in the same group shared similar structural characteristics. An analysis of cis-acting elements indicated that elements related to stress and hormone responses were prevalent in the promoters of most VrBBXs. The RNA-seq data analysis and qRT-PCR of nine VrBBX genes demonstrated that VrBBX genes may play a role in response to environmental stress. Moreover, VrBBX5, VrBBX10 and VrBBX12 are important candidate genes for plant stress response. CONCLUSIONS: In this study, we systematically analyzed the genomic characteristics and expression patterns of the BBX gene family under ABA, PEG and NaCl treatments. The results will help us better understand the complexity of the BBX gene family and provide valuable information for future functional characteristics of specific genes in this family.

Genome-wide analysis of OSCA gene family members in Vigna radiata and their involvement in the osmotic response.

BACKGROUND: Mung bean (Vigna radiata) is a warm-season legume crop and belongs to the papilionoid subfamily of the Fabaceae family. China is the leading producer of mung bean in the world. Mung bean has significant economic and health benefits and is a promising species with broad adaptation ability and high tolerance to environmental stresses. OSCA (hyperosmolality-gated calcium-permeable channel) gene family members play an important role in the modulation of hypertonic stress, such as drought and salinity. However, genome-wide analysis of the OSCA gene family has not been conducted in mung bean. RESULTS: We identified a total of 13 OSCA genes in the mung bean genome and named them according to their homology with AtOSCAs. All the OSCAs were phylogenetically split into four clades. Phylogenetic relationship and synteny analyses showed that the VrOSCAs in mung bean and soybean shared a relatively conserved evolutionary history. In addition, three duplicated VrOSCA gene pairs were identified, and the duplicated VrOSCAs gene pairs mainly underwent purifying selection pressure during evolution. Protein domain, motif and transmembrane analyses indicated that most of the VrOSCAs shared similar structures with their homologs. The expression pattern showed that except for VrOSCA2.1, the other 12 VrOSCAs were upregulated under treatment with ABA, PEG and NaCl, among which VrOSCA1.4 showed the largest increased expression levels. The duplicated genes VrOSCA2.1/VrOSCA2.2 showed divergent expression, which might have resulted in functionalization during subsequent evolution. The expression profiles under ABA, PEG and NaCl stress revealed a functional divergence of VrOSCA genes, which agreed with the analysis of cis-acting regulatory elements in the promoter regions of VrOSCA genes. CONCLUSIONS: Collectively, the study provided a systematic analysis of the VrOSCA gene family in mung bean. Our results establish an important foundation for functional and evolutionary analysis of VrOSCAs and identify genes for further investigation of their ability to confer abiotic stress tolerance in mung bean.

Characterization of the genetic and regulatory networks associated with sugar and acid metabolism in apples via an integrated strategy.

Although sugars and acids have a substantial influence on the taste of apple fruits, the genetic and regulatory networks underlying their metabolism in fruit remain insufficiently determined. To fully decipher the genetic basis of the accumulation of sugars and acids in apple fruits, we adopted an integrated strategy that included time-course RNA-seq, QTL mapping, and whole-genome sequencing to examine two typical cultivars ('HanFu' and 'Huahong') characterized by distinctive flavors. Whole-genome sequencing revealed substantial genetic variation between the two cultivars, thereby providing an indication of the genetic basis of the distinct phenotypes. Constructed co-expression networks yielded information regarding the intra-relationships among the accumulation of different types of metabolites, and also revealed key regulatory nodes associated with the accumulation of sugars and acids, including the genes MdEF2, MdPILS5, and MdGUN8. Additionally, on the basis of QTL mapping using a high-density genetic map, we identified a series of QTLs and functional genes underlying vital traits, including sugar and acid contents. Collectively, our methodology and observations will provide an important reference for further studies focusing on the flavor of apples.

The interaction of ABA and ROS in plant growth and stress resistances.

The plant hormone ABA (abscisic acid) plays an extremely important role in plant growth and adaptive stress, including but are not limited to seed germination, stomatal closure, pathogen infection, drought and cold stresses. Reactive oxygen species (ROS) are response molecules widely produced by plant cells under biotic and abiotic stress conditions. The production of apoplast ROS is induced and regulated by ABA, and participates in the ABA signaling pathway and its regulated plant immune system. In this review, we summarize ABA and ROS in apoplast ROS production, plant response to biotic and abiotic stresses, plant growth regulation, ABA signal transduction, and the regulatory relationship between ABA and other plant hormones. In addition, we also discuss the effects of protein post-translational modifications on ABA and ROS related factors.