سید محمد تقی طباطبایی

Regulation of ionic homeostasis in plant cells is one of the important aspects in salt tolerance. In this study, the effect of 200 mM salinity stress after 1, 10 and 20 days of stress on some morphological characteristics, elements concentration and expression of some genes involved in salt tolerance of bread wheat genotypes, including lines 7 and 8 (salt-tolerant), line 16 (salt-sensitive) and Sistan cultivar (native tolerant cultivar) were studied factorially in a Completely Randomized Design (CRD) with three replications. The results showed that salinity stress reduced shoot biomass in all tolerant and sensitive lines with the lowest reduction in line 7. Under salt stress conditions, Na+ content had an increasing trend in all lines and K+ content had a decreasing trend. The lowest increase of Na+, and the lowest decrease of K+ and K+/Na+ ratio was observed in line 7. Under salt stress conditions, the highest expression of SOS1, SOS2 and SOS3 genes was observed in line 7 and the lowest expression was observed in lines 16 and 8. The results of this study suggest that line 7 had a higher degree of tolerance and can be considered in breeding programs as well as for additional studies in saline areas.

Bread wheat is one of the grains in the world that provides 20% of the plant-derived protein to the people of the world (Acevedo et al., 2002; Godfray et al., 2010). Drought is an important environmental factor limiting the production of wheat and other crops in the world. Water scarcity has made the production of higher drought-tolerant cultivars an important goal in many breeding programs. One of the goals of wheat cultivation in arid and semi-arid regions is to achieve cultivars that are more tolerant of drought stress at the end of the season in conditions of water restriction and lack of irrigation and have less yield reduction. By achieving such figures, it is possible to increase the efficiency of operations in those conditions and to a large extent prevent the waste of water resources. The aim of this study was to identify agricultural traits associated with changes in wheat grain yield under drought stress and drought-tolerant lines.

In this study, 111 lines along with 3 cultivars of Shahid Narin, Barzegar, and Sistan in the form of repeated experiments (Agent) in 1396 in the research farm of the Research Center located in Yazd city (at 15 degrees and 53 minutes to 40 degrees And 54 minutes east longitude and 46 degrees and 31 minutes to 15 degrees and 32 minutes north latitude and altitude 1200 meters). In order to check the production capacity of the lines, the control was repeated at intervals of every 20 lines. Each line was planted in 2 lines of 2.5 m with a planting distance of 20 cm. In order to investigate the effect of drought stress at the end of the season on the relevant traits in the post-flowering stage, irrigation was stopped. During the growing season, grain yield, yield, and morphological components were evaluated and compared with control cultivars. A simple correlation was used to obtain the relationship between the traits. To identify the main variables that affect grain yield, multi-variable analysis was used by stepwise regression analysis.

The experimental results showed that there is a great variety among the studied lines. Regression tests showed that traits such as 1000-grain weight, number of days to ripening, spike length, plant height, and spike weight had a positive and significant effect on grain yield and explained a significant share of yield changes. The classification of lines is based on cluster analysis by the UPGMA method in 9 groups. Based on the obtained results, 15 genotypes were selected that had more grain yield and some more suitable agricultural characteristics than other genotypes and cultivars.

Although drought stress affects most plant growth traits, this effect depends on the time the plant is exposed to water stress and the lines being tested. The results of this study show that water stress has a different effect on the growth of wheat lines and shows that the ability of bread wheat lines to tolerate drought stress is different. Also, the genetic material in this experiment could be a valuable resource that, in addition to removing new traits, provides a great variety for breeders to improve and produce drought-tolerant wheat cultivars.

In order to identify yield and yield component QTLs under control and salt-stress conditions, a population of 254 recombinant inbred lines (RILs), derived from a cross between two bread wheat cultivars, (Roshan / Sabalan), was assessed. Parents and their 254 recombinant inbred lines (RILs) were evaluated in an alpha-lattice design with two replications in two control and saline environments of Yazd in 2011-2012 cropping season. Yield and yield-related traits were evaluated at harvest time. The genotyping was carried out using SSR and DArT markers. A, B and D genomes were covered by 411.8, 620.4 and 67.5 cM, respectively. Also, a total of 48 QTLs were detected on 11 chromosomes for grain yield, biological yield, harvest index, thousand-kernel weight, grain number per spike, spike weight and spikelet number per spike. Roshan (salt tolerance) alleles were associated with an increase yield under saline conditions. SSR markers including gwm146, gwm577, gwm249 (on chromosomes 2A and 7B) were tightly associated with different QTLs. The major effect QTLs were located on chromosomes 1A and 7B for grain yield, harvest index and spike weight, which were explained 10.2%, 12.98% and 29 % of the total phenotypic variance, respectively. These QTLs and markers could be suitable for marker-assisted selection and gene stacking techniques. Moreover, co-located QTLs were detected on chromosome 2B for evaluated traits.