Genome-Wide Identification of the MAPK and MAPKK Gene Families in Response to Cold Stress in Prunus mume .

Protein kinases of the MAPK cascade family (MAPKKK-MAPKK-MAPK) play an essential role in plant stress response and hormone signal transduction. However, their role in the cold hardiness of (Mei), a class of ornamental woody plant, remains unclear. In this study, we use bioinformatic approaches to assess and analyze two related protein kinase families, namely, MAP kinases (MPKs) and MAPK kinases (MKKs), in wild and its variety var. . We identify 11 and 7 genes in the former species and 12 and 7 genes in the latter species, and we investigate whether and how these gene families contribute to cold stress responses. Members of the and gene families located on seven and four chromosomes of both species are free of tandem duplication. Four, three, and one segment duplication events are exhibited in , and , respectively, suggesting that segment duplications play an essential role in the expansion and evolution of and its gene variety. Moreover, synteny analysis suggests that most and genes have similar origins and involved similar evolutionary processes in and its variety. A cis-acting regulatory element analysis shows that and genes may function in and its variety's development, modulating processes such as light response, anaerobic induction, and abscisic acid response as well as responses to a variety of stresses, such as low temperature and drought. Most and exhibited tissue-specifific expression patterns, as well as time-specific expression patterns that protect them through cold. In a low-temperature treatment experiment with the cold-tolerant cultivar 'Songchun' and the cold-sensitive cultivar 'Lve', we find that almost all and genes, especially and , dramatically respond to cold stress as treatment duration increases. This study introduces the possibility that these family members contribute to 's cold stress response. Further investigation is warranted to understand the mechanistic functions of MAPK and MAPKK proteins in development and response to cold stress.