Assessment phenotypic diversity of rice (Oryza sativa L.) genotypes by multivariate analysis

An efficient way to achieve superior productivity is to determine the genetic variation of the various rice genotypes. This research was aimed at estimating potential variations between rice genotypes and identifying each trait contribution in total variation and classifying superior genotypes. The experiment was performed at the Rice Research and Training Centre, Sakha, Kafr El-Sheik, Egypt. Twenty-two genotypes of rice were analyzed using seven agronomic traits. Multivariate approaches were utilized including principal components and cluster analysis. Results showed that PC1 and PC2 represented 66.1% of the variation between studied genotypes, mainly 48% because of grain yield per plant variation in PC1 followed by the characteristics of its components i.e., number of panicles per plant, number of filled grains per panicle, and 1000-grain weight. The three Egyptian rice genotypes Giza 181, Giza 178, and Giza 177 were the best genotypes for grain yield. Cluster results revealed that the majority of genotypes originated from one source (except for Indian variety IET1444) or belonged to one classification were clustered together. Multivariate analytical approaches are ideal instruments for providing information on agronomic character variations. Consequently, the results of the current study should be taken into account when developing new rice varieties.  &nbsp

Multi-environmental evaluation of wheat tetraploid genotypes for agronomic traits under rainfed conditions in Syria

This study was conducted at Homs, Al-Swaida and Tartous, General Commission for Scientific Agricultural Research, Syria during 2016/2017 season. Seven wheat genotypes were planted under rainfed conditions in randomized complete block design with three replications. Studied traits were days to maturity, plant height, number of grain per spike, grain weight per spike, 1000 kernal weight and grain yield per plant to evaluate variance between genotypes and locations. Results showed existence of high variance between studied genotypes in all traits especially plant height. It resulted that genotype W45193 was significantly superior in grain yield per plant with an increasing rate of 69.62% comparing to control Sham 5. Also, it was significantly superior in spike numbers with an increasing rate of 53.53%, 57.24% compared to both controls Sham 3 and Sham 5, respectively. Genotype W45064 was significantly superior in grain weight per spike and 1000 kernal weight compare to both controls Sham 3 and Sham 5. W 45194 was significantly superior in 1000 kernal weight comparing to control Sham 5 (36.34, 31.16 g), respectively. Furthermore, all studied traits (except spike number per plant) were more significant in Tartous compare to both Homs and Al-Swaida

GWAS revealed effect of genotype × environment interactions for grain yield of Nebraska winter wheat

Background: Improving grain yield in cereals especially in wheat is a main objective for plant breeders. One of the main constrains for improving this trait is the G × E interaction (GEI) which affects the performance of wheat genotypes in different environments. Selecting high yielding genotypes that can be used for a target set of environments is needed. Phenotypic selection can be misleading due to the environmental conditions. Incorporating information from phenotypic and genomic analyses can be useful in selecting the higher yielding genotypes for a group of environments. Results: A set of 270 F3:6 wheat genotypes in the Nebraska winter wheat breeding program was tested for grain yield in nine environments. High genetic variation for grain yield was found among the genotypes. G × E interaction was also highly significant. The highest yielding genotype differed in each environment. The correlation for grain yield among the nine environments was low (0 to 0.43). Genome-wide association study revealed 70 marker traits association (MTAs) associated with increased grain yield. The analysis of linkage disequilibrium revealed 16 genomic regions with a highly significant linkage disequilibrium (LD). The candidate parents’ genotypes for improving grain yield in a group of environments were selected based on three criteria; number of alleles associated with increased grain yield in each selected genotype, genetic distance among the selected genotypes, and number of different alleles between each two selected parents. Conclusion: Although G × E interaction was present, the advances in DNA technology provided very useful tools and analyzes. Such features helped to genetically select the highest yielding genotypes that can be used to cross grain production in a group of environments

Allelic state at the microsatellite locus Xgwm261 marking the dwarfing gene Rht8 in Egyptian bread wheat (Triticum aestivum L.) genotypes released from 1947 to 2004

Rht8 is widely used in dry environments such as Mediterranean regions where it increases plant adaptability. Variation at the Gatersleben wheat microsatellite Xgwm261 locus, whose 192-bp allele closely linked to the dwarfing gene Rht8, on chromosome 2D within 0.6 cM, was used to screen thirty Egyptian bread wheat genotypes released from (1947-2004) to assess the variation at this locus. There were three microsatellite allelic variants based on size. Screening of this wheat collection showed that the three alleles Xgwm261-165, Xgwm261-174 and Xgwm261-192 bp were the most frequent. The highest allele frequency was observed for a Xgwm261-165 bp fragment (65.52%) followed by a Xgwm261-174 bp fragment (24.14%). However, the allele frequency of a Xgwm261-192 bp fragment among these wheat genotypes was 10.34%. The percentage distribution of dwarfing alleles for the microsatellite locus Xgwm261 in the Egyptian wheat breeding programs was 30, 20, 20 and 30% for the wheat breeding program Giza, Sakha, Gemmiza and Sids, respectively. PIC for Xgwm261 was 0.527. Genetic heritage of Egyptian genotypes at the microsatellite locus Xgwm261 is consequence of new parental components usage, carriers short plant and early maturity attributes and consequent selection progeny with these traits in breeding programs. The present study will be helpful in characterization Egyptian wheat genotypes, as well as in accurate selection of parents for wheat breeding program in Egypt