Cloning of heat shock transcription factor（Hsf）gene family from mulberry and analysis of MnHsfA1 gene expression pattern

【Objective】This paper cloned the heat shock transcription factor(Hsf) gene family members in mulberry, analyzed expression pattern of the MnHsfA1 genes to provide theoretical reference for in-depth research on the regulatory mechanism of this family in mulberry heat stress response and mulberry breeding.【Method】Using seedlings of Morus notabilis as experimental materials, the MnHsfs genes were cloned. And the physicochemical properties, conserved domains, signal peptides, transmembrane domains, subcellular localization, and promoter cis acting elements of MnHsfs proteins were predicted by multiple sequence alignment, phylogenetic tree construction, and MEME conserved motif.The expression pattern of MnHsfA1 genes under high temperature and drought stress were analyzed using real-time fluorescence quantitative PCR.【Result】Fourteen full-length coding sequences of MnHsfs genes were cloned from mulberry trees, including MnHsfA4a, MnHsfA4b, MnHsfA2, MnHsfA5, MnHsfA6b-1, MnHsfA6b-2, MnHsfB4-2, MnHsfA8, MnHsfB3, MnHsfB2b, MnHsfC1, MnHsfB2a, MnHsfB4-1 and MnHsfA1. Their open reading frame lengths were 1239, 1278, 1404, 1431, 1101, 1140, 1185, 1197, 711, 996, 1029, 936, 900 and 1437 bp and encoded 412, 425, 467, 476, 366, 379, 394, 398, 236, 331, 342, 312, 299 and 478 amino acids residues respectively. And most of MnHsfs proteins were hydrophilic and unstable acidic proteins. MnHsfs protein included domains such as function domain(DBD), oligomerization function domain(OD), AHA, and KLFGV, and were divided into class A, class B, and class C. The similarity between MnHsfA1 and HsfA1 of apple, spinach, and Arabidopsis were the highest. Compared with the control, the expression of MnHsfA1 gene and mRNA transcription level were significantly up regulated under high temperature and drought stress treatments(P<0.05).【Conclusion】MnHsfs genes have relatively high genetic conservatism, and the expression level of MnHsfA1 gene is up regulated under high temperature and drought stress. The cis acting element of MnHsfA1 gene promoter contains hormone responsive elements such as abscisic acid, methyl jasmonate, gibberellin, as well as transcription factors related to various abiotic stresses. It is speculated that it may regulate multiple abiotic stresses simultaneously.