تنوع ژنتيكي و اپي ژنتيكي تحمل شوري در گندم، ايژيلوپس سيلندريكا و لاين هاي حاصل از تلاقي برگشتي آنها

Salinity has emerged as a major abiotic stressor in modern agriculture, significantly limiting production in crop plants including wheat. The development of modern wheat cultivars has been hindered by genetic bottlenecks, including limited genetic variation an‎d the ongoing erosion of genetic diversity. Leveraging the genetic diversity available in wild relative species is therefore essential for enhancing genetic variation in wheat, particularly for adaptation to biotic an‎d abiotic stress. This study assessed the phenotypic an‎d epigenetic variation of 156 introgressed wheat lines (BC4F2) derived from hybridization between wheat cultivars ‘Chinese Spring’ (CS) an‎d ‘Roshan’ (R) an‎d Aegilops cylindrical (AC). These two groups of genetic background lines, along with their recurrent parents (totally 158), were eva‎luated under field normal an‎d saline conditions using the following traits: plant height, spike length, number of spikes per plant, number of grains per spike, grain weight, grain yield. Then, selec‎ted BC4F2 lines along with their parents (AC, CS, an‎d R) grown under control an‎d salt stress conditions subjected to physiological, DNA cytosine methylation, an‎d expression analysis of HKT1;5, NHX1, an‎d SOS1 genes. The results demonstrated significant impacts of salinity stress on the agro-physiological variables including yield an‎d related traits. Thereby, grain yield under normal an‎d salt stress conditions along with stress tolerance indices were used to selec‎t the most tolerant an‎d most sensitive lines. Agro-physiological, epigenetic, an‎d gene expression analyses showed the significant effects of salt stress an‎d genetic background, as well as, differential response of the extreme lines to salt stress. A significant difference between the osmolyte content of sensitive an‎d tolerant lines under salinity was observed only for the total soluble sugars )TSS( content of the CS group. The disparity in leaf an‎d root K, Na, an‎d K/Na content, an‎d Chla, Chlb, Car, an‎d MDA levels, unlike DPPH radical levels, between salt-tolerant an‎d salt-sensitive lines in both genetic backgrounds of wheat under saline conditions indicated a clear distinction in salinity tolerance. Quantitative Real-Time PCR indicated a greater increase in expression levels of NHX1 an‎d SOS1 genes in the leaf an‎d root tissues of tolerant lines compared to those of sensitive lines. While the expression patterns of the HKT1;5 gene in both wheat groups were higher only in the leaf tissue of tolerant lines than in that of sensitive lines. Global leaf an‎d root DNA methylation analysis revealed the significant effects of salinity on the methylation modifications an‎d confirmed successful introgression of salt-tolerance epigenome from Ae. cylindrica into wheat. Exploiting the genetic diversity of wild wheat relatives is a crucial goal for increasing genetic an‎d epigenetic variation to enhance plant adaptation to salt stress.

احمد ارزاني , قدرت اله سعيدي

فابريزيو آرانيتي

محمدرضا سبزعليان دستجردي , بدرالدين ابراهيم سيدطباطبايي , بهروز شيران