Cloning and expression pattern analyses of tobacco DELLA gene family

In order to clarify the transcription regulation function of DELLA gene family in tobacco under adversity stress, three members (NtDELLA1, NtDELLA2, NtDELLA3) of DELLA gene family were cloned by tobacco EST sequence alignment, and their gene structures and expression patterns were analyzed. The results of bioinformatics analysis showed that the full length of tobacco DELLA genes were around 1 700 bp, and the proteins encoded by those genes contained DELLA protein feature structures, DELLA motif and VHYNP motif, and were highly homologous to GAI protein of Arabidopsis DELLA protein family. Thus, it was assumed that the functions of tobacco DELLA proteins were similar to those of Arabidopsis. qRT-PCR analysis further confirmed that the three genes had similar expression patterns in different tissues at key development stages, and their expression levels in tobacco stalk were the highest. The results of analysis on stress responses indicated that tobacco responded to drought, low temperature, TMV infection and exogenous hormones at varying degrees, and drought, GA and ABA inhibited the expression of tobacco DELLA gene family, while low temperature induced up-regulated expression of NtDELLA1, TMV induced the abundant expression of NtDELLA1 and NtDELLA2.