| Fructan, as an important metabolic component bridged between sources andsinks in wheat, can not only reduce plant injury in adverse environments by itsintrinsic osmotic regulation, but act as vital carbon sources for grain filling. Wheatfructan stored in vegetative organs, particularly when water is limiting during thepost-anthesis period, is always favorable for compensation of yield loss induced bydrought stress to some extent, in which fructan can be effectively transported fromvegetative organs to spikes. Deeply mining the expression pattern of fructan contentand its genes of the key enzyme induced by drought would be of greatly importancein ensuring the drought-resistant genetic improvement and breeding in wheat.Therefore, two cultivars with different drought tolerances, Longjian19(drought-resistant) and Q9086(drought-sensitive), were performed as materials under differentwater conditions, to make insight into the relationship of the fructan content and keygenes after flowering in different water stress conditions. The detailed results wereobtained as follows:1. The growth stage, water condition and organ were as main factors tosignificantly influence the variation of fructan content in wheat. Their rates ofcontribution reached to30.79%,21.05%and11.14%, respectively. During grainfilling, the variation trend in fructan content of different growth stages was of a risefirst and then fall. The fructan content of different organs was significantly regulatedby water conditions, showed its higher content in moderate drought stress, but lowerin drought stress. Significant existing differences were also found in different organs,indicating corresponding content from higher to lower as internode, sheath,leaf/glume. In moderate drought stress condition, the fructan content was increased,comparing with well watered condition. But it would dropped significantly with thedegree of drought stress strengthening.2. The mRNA relative expressions of the6-SFT and FEH gene of differentorgans during the grain filling were significantly (P≤0.05) or greatly significantly (P≤0.01) influenced by genotype, water, stage, organ and their significantly interactionswith each other. The main variation factors of the relative expression in the6-SFTgene were influenced by growth stage, water, stage and organ interactive, organ. Their rates of contribution reached to36.07%,17.21%,14.42%and11.48%. The mainvariation factors of the relative expression in FEH gene were influenced by growthstage, organ and water and stage interaction, organ. The contribution reached to37.73%,19.44%and15.60%, respectively. Other factors and their interactive effectshad less influenced to the relative expressions of the6-SFT and FEH genes.3. The peak value of relative expression in the6-SFT gene was the biggestduring the grain filling stage in the moderate drought stress, comparing to other twowater conditions. But, there were big differences among different organs. Whendrought stress was strengthening, the peak value of relative expression of target genesin Longjian19was more closed to Q9086. But its duration of the high expression wassignificantly less than that in the well-watered condition. It suggested that moderatedrought stress improved the fructan content during the grain filling. If the degree ortime of drought stress was too strengthened or long, the relative expression of6-SFTwould be significantly lowered.4. The peak value of relative expression in the FEH gene of different organsshowed higher in well watered, but lower in drought stress during the grain filling.Thepeak would process earlier with progressive drought stress. It was also influenced bythe fructan concentration. If the fructan content was higher before anthesis, therelative expression of the FEH gene would be larger. As fructan concentration wascontrolled by6-SFT, the relative expression of the FEH gene was also controlled bythe relative expression of the6-SFT. |
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