Abstract
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.
Highlights
Bamboo is one of the most important non-timber forestry products which is characterized by fast growth with a long vegetative period and high yield, and its forest production has been estimated at about USD 2.5 billion per year on average [1]
Similar to Arabidopsis thaliana, rice, poplar and other plants, the EXPA subfamily composed the largest clade with 45 members, followed by 29 expansin-like B (EXLB), 7 EXPB and 1 expansin-like A (EXLA) member(s) (Table 1)
With regard to abiotic stress response elements, we found an MYB binding site involved in drought inducibility (MBS) and low-temperature response elements (LTR) in the promoter regions of 31 and 23 PeEXs, respectively
Summary
Bamboo is one of the most important non-timber forestry products which is characterized by fast growth with a long vegetative period and high yield, and its forest production has been estimated at about USD 2.5 billion per year on average [1]. Drought reduces the decomposition process, leading to the accumulation of organic matter on the forest floor, thereby increasing the frequency or intensity of fires or reducing nutrient cycling [4]. This will cause great harm to yield and ecological environment
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