Comprehensive identification and systematical characterization of BRX gene family and the functional of GhBRXL5A in response to salt stress.

BACKGROUND: BRVIS RADIX (BRX) family is a small gene family with the highly conserved plant-specific BRX domains, which plays important roles in plant development and response to abiotic stress. Although BRX protein has been studied in other plants, the biological function of cotton BRX-like (BRXL) gene family is still elusive. RESULT: In this study, a total of 36 BRXL genes were identified in four cotton species. Whole genome or segmental duplications played the main role in the expansion of GhBRXL gene family during evolutionary process in cotton. These BRXL genes were clustered into 2 groups, α and ß, in which structural and functional conservation within same groups but divergence among different groups were found. Promoter analysis indicated that cis-elements were associated with the phytohormone regulatory networks and the response to abiotic stress. Transcriptomic analysis indicated that GhBRXL2A/2D and GhBRXL5A/5D were up/down-regulated in response to the different stress. Silencing of GhBRXL5A gene via virus-induced gene silencing (VIGS) improved salt tolerance in cotton plants. Furthermore, yeast two hybrid analysis suggested homotypic and heterotypic interactions between GhBRXL1A and GhBRXL5D. CONCLUSIONS: Overall, these results provide useful and valuable information for understanding the evolution of cotton GhBRXL genes and their functions in salt stress.

Systematical Characterization of the Cotton Di19 Gene Family and the Role of GhDi19-3 and GhDi19-4 as Two Negative Regulators in Response to Salt Stress.

Drought-induced 19 (Di19) protein is a Cys2/His2 (C2H2) type zinc-finger protein, which plays a crucial role in plant development and in response to abiotic stress. This study systematically investigated the characteristics of the GhDi19 gene family, including the member number, gene structure, chromosomal distribution, promoter cis-elements, and expression profiles. Transcriptomic analysis indicated that some GhDi19s were up-regulated under heat and salt stress. Particularly, two nuclear localized proteins, GhDi19-3 and GhDi19-4, were identified as being in potential salt stress responsive roles. GhDi19-3 and GhDi19-4 decreased sensitivity under salt stress through virus-induced gene silencing (VIGS), and showed significantly lower levels of H2O2, malondialdehyde (MDA), and peroxidase (POD) as well as significantly increased superoxide dismutase (SOD) activity. This suggested that their abilities were improved to effectively reduce the reactive oxygen species (ROS) damage. Furthermore, certain calcium signaling and abscisic acid (ABA)-responsive gene expression levels showed up- and down-regulation changes in target gene-silenced plants, suggesting that GhDi19-3 and GhDi19-4 were involved in calcium signaling and ABA signaling pathways in response to salt stress. In conclusion, GhDi19-3 and GhDi19-4, two negative transcription factors, were found to be responsive to salt stress through calcium signaling and ABA signaling pathways.

Cotton DMP gene family: characterization, evolution, and expression profiles during development and stress.

Members of DOMAIN OF UNKNOWN FUNCTION 679 membrane protein (DMP) gene family, a type of plant-specific membrane proteins, have been proposed to function in various physiological processes such as reproductive development and senescence in plants. Here, a total of 174 DMP genes were identified and analyzed in 16 plant species (including 58 DMPs in four cotton species). Phylogenetic analysis showed that these DMPs could be clustered into five subfamilies (I-V). 137 duplicated cotton gene pairs were identified and most duplicate events were formed by whole-genome duplication (WGD)/segmental duplications. Expression analysis revealed that most of cotton DMPs were mainly expressed in the reproductive organs (the sepal, petal, pistil and anther) and the fiber of secondary cell wall stage. GhDMPs promoter regions containing the different cis-elements also showed different responses to abiotic stress. In addition, gene interaction networks showed that DMPs, as an endomembrane system, were involved in plant senescence process and flower reproductive development. We speculated GhDMP8-A/-D, GbDMP8-A/-D could be used as some candidate gene for inducing cotton haploid. This genome-wide study provides a systematic analysis of the cotton DMP gene family, and further insights towards understanding the potential functions of candidate genes.