IMPROVING DROUGHT TOLERANCE POTENTIAL IN WHEAT (TRITICUM AESTIVUM L.) THROUGH EXOGENOUS SILICON SUPPLY

摘要

A hydroponic experiment was conducted to study the effects of exogenous salicylic acid (SA) on root length, relativealuminum content in the apical cell wall, acid phosphatase (APA) and pectin methyl esterase (PME) activity, root pectin,hemicellulose 1(HC1), and hemicellulose 2 (HC2) contents of Anguo Trichosanthes kirilowii (Al-tolerant genotype) andPujiang T. kirilowii (Al-sensitive genotype) under 800 μmol/L of aluminum stress. The results showed that the growth of AltolerantAnguo T. kirilowii and Al-sensitive Pujiang T. kirilowii was inhibited when exposed to 800 μmol/L of aluminumsolution. APA and PME activities were also enhanced for both genotypes. The contents of relative aluminum, pectin, HC1,and HC2, as well as Al accumulation in the root tips were increased under aluminum toxicity. Pujiang T. kirilowii showedhigher enzyme activity and cell wall polysaccharide contents than Anguo T. kirilowii. In addition, the root cell wall pectin,HC1, and HC2 contents of Pujiang T. kirilowii were increased by a large margin, showing its greater sensitivity to aluminumtoxicity. Root length is an important indicator of aluminum toxicity, and has an important relationship with cell wallpolysaccharide content. Aluminum toxicity led to the accumulation of pectin and high PME activity, and also increased thenumber of free carboxyl groups, which have more aluminum binding sites. Membrane skim increased extensively with theincrease in APA activity, damaging membrane structure and function. Different SA concentrations can decrease enzymeactivity and cell wall polysaccharide content to some extent. With the addition of different SA concentrations, the rootrelative aluminum content, cell wall polysaccharide content, APA and PME activities decreased. Aluminum toxicity to bothgenotypes of T. kirilowii was relieved in different degrees as exogenous SA concentration increased. Inter-simple sequencerepeat (ISSR) marker was used to examine the genetic distance, genetic identity, and phylogenetic relationships. A certaincorrelation was found between the differences in Al tolerance, genetic distance, genetic identity, and phylogeneticrelationship of T. kirilowii genotypes.