Regulation Of Sulphur Nutrition To The Expression Of The Wheat Sulphate Transporter Gene Under Drought Condition

Drought is one of the severe constraints on farming. One of the important pathway in the resolution to drought is to increasing the drought tolerance of crops. Sulfur is an essential element in crops nutrition, which plays a vital role in crop growth and metabolism. It has been reported that Sulfur nutrition regulates the functions of some channel proteins and has a crucial role in the trans-membrane transport of water and inorganic nutrient elements. Whereas on the whole regulation of sulfur assimilation, sulfate transporter, the first key protein, plays a central role. Therefore, to study the expression of sulphate transporter under different water and sulfur condition would provided a preliminary research of the function of sulfur in helping crops fighting against drought on a molecular level. Total RNA was extracted from the roots of a type of high-sensitive-to-drought wheat and RT-PCR was proceeded for cloning a piece of sulphate transporter gene. Sequencing was done after it linked to cloning vector pGEM-Teasy. Sequence alignments showed that this partial piece belongs to wheat sulphate transporter gene StA1.1a. After random labeling with DIG, RNA dot blot was proceed to test the expression of this gene under different growth condition. Results showed that the expression of this gene was positive regulated by sulphate starvation, and a weak inhibition was found when drought condition was involved at the same time. A straightforward semi-quantitative RT-PCR method was developed to study the expression of the same sulphate transporter gene piece, using a cross-intron α-Tubulin partial sequence to be the inner control. A stable two-step reverse transcription of a specific transcript within total RNA was involved and product amount determination by densitometric analysis of ethidium bromide fluorescence upon gel electrophoresis. Results also showed that the expression of this piece was positively regulated by sulphate starvation; Minor variance was also detected between samples with different water growth condition under sufficient sulphate supply, but this effect was far less than the effect of sulphate starvation. All these results provided a preliminary discussion of the function of sulfur in helping crops fighting against drought on a molecular level, and the stable two-step RT-PCR system of the cross-intron RT-PCR product of housekeeping gene α-Tubulin could also provided a good method to test the reverse process of wheat mRNAs.