Genome-wide identification and characterization of bZIP transcription factors in relation to litchi (Litchi chinensis Sonn.) fruit ripening and postharvest storage

Basic leucine zipper (bZIP) is one of the largest transcription factor families and involved in diverse biological processes in plants. However, information on the functions of bZIP transcription factors in litchi fruit at genomic level is limited. Here, 54 LcbZIPs were identified from litchi genome and divided into 14 subfamilies: A, B, C, D, E, F, G, H, I, K, L, M, O and S. Further analysis on the distribution and collinearity of these LcbZIPs on chromosomes was conducted. Meanwhile, gene structure, promoter sequence as well as possible protein subcellular localizations of these LcbZIPs were characterized. Further, gene expression analysis of LcbZIPs accompanied with cis-element analysis as well as molecular interaction network provided further information on potential biological roles of LcbZIPs in litchi fruit development, senescence and response to fungal infection. Our results suggested that some members from subfamily C and S (LcbZIP7, LcbZIP21, LcbZIP28) as well as LcbZIP1 and LcbZIP4 might be involved in the regulation of litchi fruit senescence during postharvest storage. Additionally, subfamily D of LcbZIPs, especially LcbZIP40/41, might play important roles in the litchi fruit response to pathogen infection. Altogether, this study is beneficial to understand the function and structure of LcbZIP gene in litchi fruit.