Grain characteristics, particularly grain weight, grain morphology, and grain protein content (GPC), are important components of grain yield and quality in wheat. A set of 98 bread wheat landraces from different geographic regions of Iran were used across 2013-2014 and 2014-2015 to determine the phenotypic diversity and relations between thousand grain weight (TGW), grain morphology and grain quality. A high-throughput method was used to capture grain size and shape. The genotypes were significantly different (P < 0.001) for all traits which reflects the high levels of diversity. A moderate to high broad sense heritability was found for all traits and ranged between 0.68 and 0.95 for grain yield and factor from density (FFD), respectively. Significant positive correlations were observed between TGW and grain size (or shape) exception of aspect ratio (AR) and roundness. However, grain quality traits, especially GPC had significant negative correlation with TGW. Based on stepwise regression analysis by taking TGW as dependent variable, grain volume, FFD, width, perimeter and Hardness Index (HI) were recognized as the most important traits and explained more than 99.3% of total variation of TGW. The path analysis revealed that FFD has maximum direct effect on TGW followed by volume, whereas perimeter and width had relatively less direct effect on TGW. According to cluster analysis, landraces separated into 5 clusters, and cluster III and IV had the maximum and minimum average for the most traits, respectively. Our study provides new knowledge on the relations between TGW, grain morphology and grain quality in bread wheat, which may aid the improvement of wheat grain weight trait in further research.

The present study was conducted to understand the genetic diversity of bread wheat's that grown in Iran, and to evaluate polymorphism information content (PIC) of some wheat SSR primers. Experiment was done in the genomics Laboratory in Islamic Azad University, Khorramabad branch, Iran in 2012. Ninety-two bread wheat varieties were assayed to study the genetic diversity and polymorphism based on forty whole-genome SSR markers. Eighty alleles were identified and 2 alleles per locus were detected. The majority of SSR markers showed a high level of polymorphism. PIC values ranged from 0.12 (XBARC 148) to 0.80 (XBARC 54), with an average of 0.59 per primer, which indicates that markers were highly informative. According to similarity matrix, genetic similarity value ranged from 0.17 to 0.88. The lowest and highest genetic similarity were observed between 'Mihan' and 'Star' (No 31 and 57), 'Azadi' and 'Mahdavi' (No 4 and 6), respectively. Cluster analysis using the UPGMA method based on Jaccard coefficients was performed. Based on cluster analysis, 92 wheat cultivars were grouped in six clusters. Results indicated that Iranian grown wheat cultivars had high genetic diversity which could be exploited in wheat breeding programs.

Grain characteristics, particularly grain weight, grain morphology, and grain protein content (GPC), are important components of grain yield and quality in wheat. A set of 98 bread wheat landraces from different geographic regions of Iran were used across 2013-2014 and 2014-2015 to determine the phenotypic diversity and relations between thousand grain weight (TGW), grain morphology and grain quality. A high-throughput method was used to capture grain size and shape. The genotypes were significantly different (P < 0.001) for all traits which reflects the high levels of diversity. A moderate to high broad sense heritability was found for all traits and ranged between 0.68 and 0.95 for grain yield and factor from density (FFD), respectively. Significant positive correlations were observed between TGW and grain size (or shape) exception of aspect ratio (AR) and roundness. However, grain quality traits, especially GPC had significant negative correlation with TGW. Based on stepwise regression analysis by taking TGW as dependent variable, grain volume, FFD, width, perimeter and Hardness Index (HI) were recognized as the most important traits and explained more than 99.3% of total variation of TGW. The path analysis revealed that FFD has maximum direct effect on TGW followed by volume, whereas perimeter and width had relatively less direct effect on TGW. According to cluster analysis, landraces separated into 5 clusters, and cluster III and IV had the maximum and minimum average for the most traits, respectively. Our study provides new knowledge on the relations between TGW, grain morphology and grain quality in bread wheat, which may aid the improvement of wheat grain weight trait in further research.

No abstract

Stripe rust caused by the fungus Puccinia striiformis f. sp. tritici (Pst) may decrease wheat yield significantly in severe outbreaks. The most cost-effective and environmentally friendly approach to reduce yield losses due to rust diseases is deployment of effective resistant genes in wheat cultivars. The causal agents evolve and may break existing resistant sources as well. Therefore, long-term conventional breeding strategies and the ongoing evolution of pathogen populations in the region would put the success of breeding programmes at risk so that there is always a need for speeding up the process of germplasm enhancement through production of doubled-haploid breeding materials. In this study, we aimed at introgression of stripe rust resistance trait from three genotypes (Flanders, Martonvasar-17 (MV17) and Bersee) into a widely adapted cultivar "Ghods". Positively selected F2BC 2 progenies of three backcrossing schemas, i.e. (i) Flanders/3 * Ghods; (ii) Ghods * 3/MV17; and (iii) Hybride-de-bersee/3 * Ghods, were used to produce three small-size doubled-haploid populations via wheat × Maize pollination methodology. The doubled-haploid populations were examined against two predominantly isolates of P. striiformis f. sp. tritici (Pst) i.e. 6E134A + and 6E2A + Yr27 + and the screening revealed that 44 and 52 of the progenies are resistant to the above-mentioned isolates, respectively. Field data have shown that the stripe rust resistance doubled-haploid germplasm are comparable to local check cultivars in yield and earliness.