Genome-Wide Identification and Expression Analysis of the Metacaspase Gene Family in Species.

Metacaspases (MCs) are cysteine proteases that are important for programmed cell death (PCD) in plants. In this study, we identified 89 genes in the genomes of four species (, , , and ), and classified them as type-I or type-II genes. All of the type-I and type-II genes contain a sequence encoding the peptidase C14 domain. During developmentally regulated PCD, type-II genes may play an important role related to fiber elongation, while type-I genes may affect the thickening of the secondary wall. Additionally, 13 genes were observed to be differentially expressed between two cotton lines with differing fiber strengths, and four genes (, , , and ) were predominantly expressed in cotton fibers at 5-30 days post-anthesis (DPA). During environmentally induced PCD, the expression levels of four genes were affected in the root, stem, and leaf tissues within 6 h of an abiotic stress treatment. In general, the MC gene family affects the development of cotton fibers, including fiber elongation and fiber thickening while four prominent fiber- expressed genes were identified. The effects of the abiotic stress and hormone treatments imply that the cotton gene family may be important for fiber development. The data presented herein may form the foundation for future investigations of the gene family in species.