جستجوی مقالات مرتبط با کلیدواژه « generation mean analysis » در نشریات گروه « بیوتکنولوژی و ژنتیک گیاهی »

Drought stress is one of the factors that reduces yield in the world. Considering that wheat is grown mostly in semi-arid areas, much attention has been paid to develop drought tolerant varieties. This experiment was conducted during 2013-2014 in Tabriz University research farm, Iran. In this investigation the inheritance of some agronomic and physiological traits was studied in the field condition through generations mean analysis. The generations were produced from the cross of Arg (tolerant to drought) and Moghan3 (sensitive to drought) varieties. The experiment was a split plot design based on randomized complete blocks with two replications. The irrigation conditions were arranged in the main plots and generations in the subplots. In the stress condition, irrigation was withheld after pollination. Based on the analysis of variance, significant difference were observed among different generations in terms of plant height, peduncle length, flag leaf length, flag leaf width, number of fertile tillers, leaf chlorophyll content, leaf temperature, days to maturity, spike weight, straw weight, biomass, grain yield and harvest index. The interaction between generations and irrigation conditions was significant only for grain yield. The generation mean analysis in both normal and drought stress conditions showed that chi-square of three parameter model was significant for all of the studied characteristics, indicating the presence of non-allelic interactions in the inheritance of these traits. The broad sense and narrow sense heritabilities for the traits under study were estimated as 0.502-0.946 and 0.244-0.429 in the normal condition and 0.653-0.951 and 0.221-0.377 in the water stress condition, respectively. The average degree of dominance for all of the characters in both normal and water stress conditions was greater than one which indicated the existence of over-dominance gene action in controlling these traits. At both conditions, the dominance genetic variance was higher than the additive genetic variance for all of the traits. The results indicate the necessity of selection in advanced generation or exploiting dominance gene action in the breeding programs, if hybrid varieties are produced in the wheat plant.

This experiment was conducted during 2013-2014 in Tabriz University research farm, Iran. In this research, the inheritance of some agronomic and physiological traits in different generations of Bam (tolerant to drought) and Artha (sensitive to drought) cross was studied in field conditions by generation mean analysis. The experiment was a split plot design using randomized complete blocks with two replications with the irrigation conditions in the main plots and generations in the sub-plots. The interaction between generations and irrigation conditions was significant only for grain yield. Based on the result of generation means analysis for the spike length and straw weight, the threeparameter model was found fitting the analysis. For the thousand-seed weight in the water stress condition and for the plant weight in the irrigation condition, a non-significant chi-square suggesting that the six-parameter model for these traits is suitable. For the other traits, the chi-square was significant in both conditions. For spike length and leaf area, the degree of dominance was greater than one (2.3 and 1.53, respectively) which showed the existence of over-dominance gene action in controlling these traits. Straw weight in normal condition, leaf area and thousand seed weight in the stress condition had a high broad-sense heritability. The narrow-sense heritability for all other traits was low, suggesting the need for exploiting dominance gene action in the breeding programs if hybrid varieties are produced in the bread wheat.

In order to evaluate heritability and gene action for some of the important quantitative traits in oriental tobacco, two genotypes, Basma 16-10 and SPT406 were crossed with Basma S. 31 cultivar, separately in 2009-2010. Parents with F1, F2, BC1 and BC2 generations were planted in a randomized complete block design with three replications. Traits such as plant height, leaf length, leaf width, leaf number, internnode number, stem diameter and yield per plant were recorded. The results obtained from analysis of variance indicated that generations mean squares were statistically significant for all traits expect for stem diameter. Therefore, generation mean analysis was performed for significant triats to estimate gene actions using Chi-square and scaling tests. The Chi-square of simple three-parametric model (additive-dominance model) was significant for studied crosses, indicating the presence of non allelic-interactions in the inheritance of these traits in oriental tobacco. Both additive and dominance genetic effects were significant for plant height, leaf length, leaf width, leaf number and internnode number. In addition, presence of high amount of dominance effect and dominance × dominance interactions suggests the importance of non-additive genetic effects for these traits in oriental tobacco. Therefore, selection for these traits in early generations can not be successful. However, additive genetic effects play an important role in the inheritance of yield, and then selection for this trait is hopeful in early generations during tobacco breeding process.

The study was conducted to investigate the genetic basis of kenaf fiber yield and quality In two sets of generations derived from 1X51 x Ghana07 and Gregg x Ghana07 crosses. Analysis of generation meansusing weighted least squares procedure was performed on stalk dry weight, bast percentage, days to flowering, plant height, and basal stalk diameter. Analysis of generation means revealed that bast percentage was mainly controlled by dominance effects whereas stalk dry weight was mainly controlled by additive effects. Estimates of heterosis based on midparental values were generally high and ranged from 10 to 55% for stalk dry weight and bast percentage. Estimates of inbreeding depression, calculated from F1 and F2 generation means, were 55% for stalk dry weight in Population 1 and 43% in Population 2. Estimates of inbreeding depression for bast percentage were 5% in Population 1 and 15% in Population 2. The results of this study indicated that the portion of phenotypicvariations, which is controlled by additive gene effects, was generally high for stalk dry weight. Thus, selectingthe segregating generations would lead to significant improvement of fiber yield.

This research was conducted to study the resistance inheritance of common bean to BCMNV virus. The Cross used in the experiment was between cultivars Goli (the resistant parent) and Derakhshan (the sensitive parent). Six generation seed obtain from Khomain bean national station and as randomized complete block design with four replications, planting and inoculate in plastic pot. Evaluation of plants performed with Elisa test and IC-RT-PCR 21 day after planting, and by observation at 45 day after planting. Resistance inheritance study with use of generation mean analysis, indicate that additive and dominant component have important role in control of infection rate. And simple model of additive – dominant can explain for genetic changes. Also determined that, for all traits under study, traits reduce genes are dominant and also this traits controlling genes with according to symptom and largeness are at different place. Means of broad-sense and narrow-sense heritability account 74 and 54 percent respectively. Thus selection for highest resistance can be effective. Accounting of effective factors number (genes) indicate that a great effect gene have role to genetic resistance control (probably I gene) and seem one or some small effect gene assistant to I gene for resistance induction.

Septoria tritici Blotch (STB) was enumerated as the most important disease in which is responsible for abundant losses in wheat product. In this study, three spring wheat varieties and a resistant line of International Center Agriculture Research in Dry Area (ICARDA) were evaluated in a genetic design of the generation mean analysis, in order to study the existence of resistance to STB disease and genetic analysis of resistance at seedling stage in greenhouse. Therefore Six basis generations included parental varieties, F1, F2 and Backcrosses (BC1 & BC2) were planted in Completely Randomized Design (CRD) at the greenhouse. Result of generation mean analysis in resistant line×tajan cross indicated manifest roles of additative effects in controlling the necrose and necrose Area Under Disease Progress Curve (nAUDPC) traits. Also in this cross For picnid and picnid Area Under Disease Progress Curve (pAUDPC) traits the roles of dominance effects were more pronounced. In the crosses of the resistant line×Moghan and Morvarid×Moghan roles of dominance effects is much more than additive effect and noallelic interaction dominance×dominance was contributed significantly in all traits. High estimate of dominance and epistatic effects emphasized on hybrid seed production as trait breeding strategy, also indicated that selection should be delayed after several generations of selection such as single seed descent until a high level of gene fixation is attained. effective factors controlling resistance to STB disease was varied between 1 and 3 in various cross.

In this study, an F2:3 population derived from the cross between Hiberna and Pfyner was used to analyze the inheritance of yield and its components in barley by generation mean analysis and to map the corresponding QTLs (quantitative trait loci) by microsatellite markers. Generation mean analysis suggested that both additive and dominance effects were important for most of the traits evaluated, but dominance and non-allelic interaction had a more pronounced effect for days to maturity, number of grains per spike, spike length and plant height. The highest heritability was obtained for number of tillers, indicating that this trait is controlled by additive effects. The additive effects played major role in the inheritance of grain yield per plant, since heritability of this trait was low. The linkage map constructed by 159 microsatellite markers covered a total length of about 1030.5 cM. Using the method of composite interval mapping 2, 4, 2, 4, 1, 4 and 7 QTLs were detected for days to maturity, number of tillers, 1000-grain weight, plant height, spike length, number of grains per spike and grain yield, respectively. Ten QTLs had corresponding occurrences with the QTLs reported earlier, indicating that these QTLs are stable across genetic backgrounds. The results of this study also showed that, grain yield per plant controls with several minor genes.