Genome-wide identification of the CsLBD gene family in tea plant and functional characterization of CsAS2 in tea leaf development

Résumé fourni par la source

LATERAL ORGAN BOUNDARIES DOMAIN (LBD) family transcription factors play important roles in plant growth, development, and stress responses. However, their evolutionary characteristics, stress-responsive expression patterns, and molecular functions in tea plants remain poorly understood. Here, 54 LBD genes were identified from Camellia sinensis genome. Genome-wide analyses revealed that CsLBD genes were unevenly distributed across 15 chromosomes and 11 pairs of segmentally duplicated genes were detected, indicating gene duplication contributing to CsLBD family gene expansion. Comparative synteny analyses between tea and Arabidopsis further suggested evolutionary conservation of several LBD members. Expression profiling indicated that CsLBD genes responded to gray blight infection, shading treatment, MeJA treatment, and leafhopper attack, and exhibited differential expression patterns during leaf development. Notably, functional characterization of CsAS2 revealed its involvement in tea leaf morphogenesis. CsAS2 complemented Arabidopsis as2 mutant phenotypes in leaf size, shape, and plant height. CsAS2 and CsAS1a, 1b displayed similar decreasing transcript levels during leaf growth and maturation, and similar co-expression patterns with leaf sizes in tea varieties with diverse leaf types. CsAS2 physically interacted with CsAS1a to form a CsAS2-CsAS1a complex, which can bound to and synergistically repressed CsARF3 promoter trans-activation activity. The conserved CsAS2-CsAS1a-CsARF3 regulatory module regulated tea leaf development in tested tea varieties. This study provides the integrated evolutionary and functional analysis of the tea LBD family, linking genome evolution, stress-responsive regulation, and leaf developmental mechanisms, and offers candidate genes and theoretical support for genetic improvement of tea cultivars.

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