Mapping of QTLs for frost tolerance and heading time using SSR markers in bread wheat

Selection for complex genetic traits, such as frost tolerance, can be simplified in plant breeding programs when linked markers were detected. The use of microsatellite markers for tagging and mapping important genes or QTLs is a goal in wheat genetic projects. In this study, 200 microsatellite markers were studied and after parental assay, 41 polymorphic SSR markers were used for genotyping of 280 F2 individual plants derived from F1 generation of wheat cross (Norstar× Zagros). The progeny of individual F2 plants were used as F2:3 families for the assessment of LT50 and heading time. Single marker analysis revealed that seven markers with total of 27% of phenotypic variance determination linked to LT50 and five markers linked to the heading time. Two markers that were located on 2B and 5A chromosomes affected both LT50 and heading time significantly. It was assumed, therefore, that someclosely linked QTLs or QTLs with pleiotropic effects govern both traits simultaneously, as the LT50 of F2:3 families were significantly correlated with the heading time of F2:3 families, Thus, it is concluded that later heading time is associated with the higher level of frost tolerance in wheat

Relationship between salt tolerance related physiological traits and protein markers in soybean cultivars (Glycine max L.)

This study was conducted to evaluate the salinity tolerance in seedling stage of soybean (Glycine max L.). Factorial experiment was done based on randomized complete block design with three replicates. 17 soybean genotypes were used in three salinity stress levels (consisting of control, 75 mM and 150 mM NaCl stress). The experiment was carried out in a greenhouse condition and proline, sodium, potassium, and chlorophyll a, chlorophyll b, chlorophyll a/b and total chlorophyll content were examined. To create salinity stress, NaCl was used in the experiment. The results revealed that different salinity stress had significant effects on all traits except for chlorophyll b and chlorophyll a/b. The cluster analysis in the control and at 75 and 150 mM salinity levels classified genotypes into two, two and three groups respectively. In each condition, the dpx and clean genotypes were placed in a group which the average traits were higher than the other genotypes. This can be generalized to the conditions of control as well as 75 and 150 mM salinity stress. Regression analysis showed possible informative loci encoding protein markers that was probable potential for selection strategies for salt weather proved by complementary tests

Changes in fruit yield and photosynthesis parameters in different olive cultivars (Olea europaea L.) under contrasting water regimes

The evergreen tree olive (Olea europaea L.) is the only species of the genus Olea that produces edible fruits with high ecological and economic value. This tree species has developed a series of physiochemical mechanisms to tolerate drought stress and grow under adverse climatic environments. One of these mechanisms is photosynthesis activities, so that as yet little information achieved about the relations between olive production and photosynthetic parameters under drought conditions. An experiment was carried out during two consecutive years (2015–2017) to study the response of 20 different olive tree cultivars (Olea europaea L.) to drought stress. Several parameters like net photosynthetic rate (PN), stomatal conductance (GS), transpiration rate (TE), photosynthetic pigments (total chlorophyll, chlorophyll a, b and carotenoid) and fruit yield were measured. The results of combined analysis of variance for fruit yield and other measured traits showed that year, drought treatment, cultivar main effects and their interactions were highly significant. The results indicated that drought stress reduced all traits, however GS (42.80%), PN (37.21%) and TE (37.17%) significantly affected by drought. Lower reduction in photosynthetic performance (PN, GS and TE) in the cultivar T7 compared to other olive cultivars allowed them to maintain better fruit yield. Principal component analysis (PCA) identified two PCs that accounted for 82.04 and 83.27% of the total variation in photosynthetic parameters under optimal and drought stress conditions, respectively. Taken together, mean comparison, relative changes due to drought and biplot analysis revealed that cultivars ‘T7’, ‘Roghani’, ‘Koroneiki’, ‘Korfolia’ and ‘Abou-satl’ displayed better response against drought stress. According to our results, one olive cultivar namely ‘T7’, could be used in olive breeding programs to improve new high yielding cultivars with drought tolerance for use in the drought-prone environments