Variable level of genetic dominance controls important agronomic traits in rice populations under water deficit condition

Abstract

Plant hybridization is an important breeding technique essential for producing a genotype (hybrid) with favorable traits (e.g., stress tolerance, pest resistance, high yield potential etc.) to increase agronomic, economic and commercial values. Studying of genetic dominance among the population helps to determine gene action, heritability and candidate gene selection for plant breeding program. Therefore, this investigation was aimed to evaluate gene action, heritability, genetic advance and heterosis of rice root, agronomic, and yield component traits under water deficit conditions. In this study, crossing was performed among the four different water-deficit tolerant rice genotypes to produce better hybrid (F1), segregating (F2) and back-cross (BC1 and BC2) populations. The Giza 178, WAB56-204, and Sakha104 × WAB56-104 populations showed the better physiological and agronomical performances, which provided better adaptability of the populations to water deficit condition. Additionally, the estimation of heterosis and heterobeltiosis of some quantitative traits in rice populations were also studied. The inheritance of all studied traits was influenced by additive gene actions. Dominance gene actions played a major role in controlling the genetic variance among studied traits in both crossed populations under well-watered and drought conditions. The additive × additive type of gene interactions was essential for the inheritance of root length, root/shoot ratio, 1,000-grain weight, and sterility % of two crossed populations under both conditions. On the contrary, the additive × dominance type of gene interactions was effective in the inheritance of all studied traits, except duration in Giza178 × Sakha106, and plant height in Sakha104 × WAB56-104 under water deficit condition. In both crosses, the dominance × dominance type of gene interactions was effective in the inheritance of root volume, root/shoot ratio, number of panicles/plant and 1,000-grain weight under both conditions. Moreover, dominance × dominance type of gene interaction played a major role in the inheritance of root length, number of roots/plant, plant height, panicle length, number of filled grain/panicle and grain yield/plant in Giza178 × Sakha106 under both conditions. The studied traits in both crossed populations indicated better genetic advance as they showed advanced qualitative and quantitative characters in rice populations under water deficit condition. Overall, our findings open a new avenue of future phenotypic and genotypic association studies in rice. These insights might be useful to the plant breeders and farmers for developing water deficit tolerant rice cultivars.

Studies on Combining Ability and Heterosis for Some Traits of Root and Yield Characters of Some Rice Genotypes Under Normal and Water Deficit Conditions

“…Significant and highly significant mean square estimates were recorded for genotypes, parents, crosses and the interaction among them for all these traits under both water deficit and normal conditions, except root/shoot ratio under both conditions for all sources of variance, chlorophyll content and relative water content under water deficit and 1000-grain weight under normal condition for parents vs. crosses which were insignificant. These results agree with those obtained by Saleem et al, (2010), El-Hity et al, (2015, Daher (2018), Abdelaty et al, (2022) and Hassan et al, (2023). Estimates of both general (GCA) and specific combining ability (SCA) variances were found to be highly significant for all root traits, yield and its components and some physiological traits under both water deficit and normal irrigation conditions, except root/shoot ratio under both conditions and root length for testers under water deficit condition which were insignificant, indicating the importance of additive and non-additive genetic variances in determining the inheritance of these studied traits.…”

“…About one-third of total cultivated area is exposed to water shortage annually in Egypt (Abdallah et al 2016). Hence, irrigation water is the most limiting factor for expanding rice cultivation area in Egypt Hassan et al, (2023) and Shehab et al, (2023).…”

Determining the Gene Action Type for Grain Yield and its Components using Generation Mean Analysis in Rice (Oryza sativa L.)

“…These results refer to five parameters model is effective to illustrate the type of gene action for these significant characteristics. The comparable outcomes were found by Hassan (2012) and Hassan et al, (2023) displayed one as a minimum of calculated parameters (C and D) were significant for the traits studied. This finding suggests that allelic interaction is necessary for the genetic regulation of these traits.…”

Genome-wide association studies of salinity tolerance in local aman rice

“…Because only three MTA were rediscovered within the range of functional genes, these three SNP will need to be studied further to determine their role in regulating salinity stress in rice. There are many reports regarding the effect of salinity on the biology, physiology and biochemical of different plants (37)(38)(39)(40) that the effect of genome and genes on these mechanisms can be investigated.…”