Characterization Of Smallheat Shock Proteins Associated With Maize Tolerance To Combined Drought And Heat Stress

To investigate the mechanisms of small heat sock protein (sHSPs) regulating maize responds to the combination of drought and heat stress, leaf protein patterns were monitored using a proteomic approach in maize plants exposed to combined drought and heat stress. Two-dimensional electrophoresis (2-DE) was used to identify combined drought and heat-responsive protein spots in maize leaves. After coomassie brilliant blue (CBB) staining, approximately 450 protein spots were reproducibly detected on each gel, wherein 7 protein spots were only expressed under heat and combined drought and heat stress, almost undetected under control and drought. Using MALDI-TOF MS, a total of 7 proteins were identified, including cytochrome b6-f complexiron-sulfur subunit, sHSP17.4, sHSP17.2, sHSP26, guanine nucleotide-binding protein beta subunit-like protein, Putative uncharacterized protein and Granule bound starch synthase IIa. Moreover, the gene expression of three HSPs were analyzed at the transcriptional level, which indicated that three sHSPs all expressed under several treatments though their expression levels were enhanced by heat and combined drought and heat stress obviously more than by control and drought. Besides, in order to investigate the effect of abscisic acid (ABA) on three sHSPs, pretreatment with ABA enhanced substantially three sHSPs expression in protein level, but slightly in mRNA level. These results show that transcription levels is not completely concomitant with translation and suggest that ABA induces the post-transcriptional regulation of sHSP17.2, sHSP17.4, sHSP26 expression, which can lead to a better understanding of the mechanisms of plant response to the combination of drought and heat.