ASSESSMENT OF THE MOLECULAR BASIS OF SALT TOLERANCE IN BREAD WHEAT Triticum aestivum L.

Abstract

This study was carried out in the laboratories of the Genetics Dept., Fac. of Agric., Ain Shams Univ. and Ain Shams Center for Genetic Engineering and Biotechnology (ACGEB) during the period from 2016 to 2021. Bread wheat is the most important, cultivated and consumed cereals crop in most countries worldwide, including Egypt. However, salinity is one of the major problems in wheat production which severely limits and threatens its production. Therefore, salt tolerance is an important feature that must be improved in wheat genotypes. This study aimed at screening and evaluation of some wheat RILs for salinity tolerance, select promising lines for future breeding experiments, understand the response generated at the morphological, biochemical and molecular level following stress treatment, and validate microsatellite markers for salt tolerance. This study was conducted to assess the effect of salinity on some bread wheat (Triticum aestivum L.) RILs and determine the salt tolerant and sensitive lines by using NaCl to simulate salinity with concentration of 102 mM and tap water as a control which equivalent 10 mM. The experiment was carried out in a growth chamber following a completely randomized design (CRD) with three replications for each treatment. Treatments included wheat cultivars Shandaweel-1 (a local salt tolerant cultivar) and Giza-168 (salt sensitive cultivar) as parents for 12 RILs that were produced via single seed descent (SSD), all genotypes were grown under two levels of salinity (10, 102 mM). The 12 RILs and their parents were grown in normal conditions (10 mM) for 25 days, then treated with NaCl salt for 30 days. We measured salt injury index (SII) for the two parents and their RILs after growing under salt stress (102 mM) for 30 days and under control conditions (10mM), in order to confine the proportional damage for NaCl. Three phenotypic traits were measured under the control and salt stress conditions namely; plant height (cm), number of tillers/plant, and number of leaves/plant. Proline content was estimated for the two parents and the studied RILs under control and salt stress conditions. The genomic DNA of the 12 RILs and their parents were extracted. To evaluate salt tolerance of the 12 studied RILs at the molecular level, 12 SSRs primers pairs, associated with salt tolerance, were tested. The twelve SSRs primers were used first to assess the two contrasting parents, and then the polymorphic markers were used to screen the studied RILs.