Genome-wide identification, characterization and expression analysis of the expansin gene family under drought stress in tea (Camellia sinensis L.)

During several developmental processes, expansins contribute to cell enlargement by promoting cell wall loosening. To explore the biological roles of expansins during drought stress response and to characterize different expansins in tea, we performed a detailed analysis of the expansin gene family covering phylogeny, gene structure, profiling of gene expression and co-expression network analysis. We identified a total of 40 expansin genes in the tea genome belonging to 3 subfamilies, out of which 29 tea expansins belong to EXPA, 9 to EXLA and 2 to EXPB subfamilies. A minimum of 3 and a maximum of 13 exons are present in the gene structure of expansins. Presence of drought stress responsive cis-acting elements in the upstream of promoter regions of 40% of the identified expansins shows that the putative expansins may have been involved in tea plant’s response to drought stress. At least 15 out of the 40 expansin genes are found to be differentially expressed in response to drought in each of the drought stress related public datasets analysed in-silico. TEA022767 belonging to EXPA subfamily is seen to be upregulated during drought stress, as revealed from the analysis of all three publicly available bio-projects. Co-expression network analysis shows that TEA022767 and TEA032954 form a connecting link between two expression correlation groups that further signifies their role in drought stress response in tea. This study helps to interpret and to understand the biological roles of diverse expansin genes in tea plants under drought stress conditions.

Growth of tobacco hairy roots with constitutive expression of the NtEXPA5 expansin gene

Tobacco hairy roots with constitutive expression of the NtEXPA5 expansin gene were obtained and analyzed, which were characterized by higher growth rates and increased productivity under normal conditions, as well as the action of stress factors.

Genome-Wide Identification of the Expansin Gene Family and Its Potential Association with Drought Stress in Moso Bamboo

Expansins, a group of cell wall-loosening proteins, are involved in cell-wall loosening and cell enlargement in a pH-dependent manner. According to previous study, they were involved in plant growth and abiotic stress responses. However, information on the biological function of the expansin gene in moso bamboo is still limited. In this study, we identified a total of 82 expansin genes in moso bamboo, clustered into four subfamilies (α-expansin (EXPA), β-expansin (EXPB), expansin-like A (EXLA) and expansin-like B (EXPB)). Subsequently, the molecular structure, chromosomal location and phylogenetic relationship of the expansin genes of Phyllostachys edulis (PeEXs) were further characterized. A total of 14 pairs of tandem duplication genes and 31 pairs of segmented duplication genes were also identified, which may promote the expansion of the expansin gene family. Promoter analysis found many cis-acting elements related to growth and development and stress response, especially abscisic acid response element (ABRE). Expression pattern revealed that most PeEXs have tissue expression specificity. Meanwhile, the expression of some selected PeEXs was significantly upregulated mostly under abscisic acid (ABA) and polyethylene glycol (PEG) treatment, which implied that these genes actively respond to expression under abiotic stress. This study provided new insights into the structure, evolution and function prediction of the expansin gene family in moso bamboo.