جستجوی مقالات مرتبط با کلیدواژه "ترکیب پذیری" در نشریات گروه "بیوتکنولوژی و ژنتیک گیاهی"

Increasing grain yield and improving the quality of bread are among the most important goals of wheat breeding programs in Iran. Understanding the genetic control of traits and finding molecular or morphological markers associated with them are also prerequisites for any genetic engineering program. In this study, 100 progenies of a 10 × 10 diallel cross were used to analyse the genetics of grain yield and bakery values using STS markers associated with HMWG subunits. This research was carried out during 2018 and 2019 cropping season at Gorgan University of Agricultural Sciences and Natural Resources experimental fields. In the first year, 10 wheat cultivars, including Gonbad, Morvarid, Kalate, Ehsan, Sirvan, Baharan, Chamran2, Shush, Mehrgan and Brat collected from different geographical regions of Iran were planted and crossed in the field. In the second year, the parents and crosses were planted in the form of a randomized complete block design with three replications. The grain yield, number of spikes per plant, number of seeds per spike, seed weight, days to emergence and plant height were recorded. The results of this study indicated significant genetic differences between the parents. Narrow-sense heritability analysis revealed that the crossing of cultivars is the best breeding method to enhance seed yield, number of spikes per plant and days to emergence. Also, to improve the number of seeds per spike, seed weight and plant height, classical breeding methods may offer higher efficiency. Marvarid and Gonbad were ranked 1st and 2nd, respectively with respect to general combining abilities for grain yield, attributed to their positive and significant general combining ability effects. The highest specific combining ability was observed for Ehsan×Gonbad, Marvarid×Chamran 2 and Shush×Sirvan crosses. The results of molecular markers analysis showed that the STS markers were able to identify the difference in the baking value of cultivars. The quality score of the cultivars ranged 6 and 10 and to this end, Kalate and Brat were the top cultivars. Therefore, due to superiority in terms of both quantity and quality for yield, these cultivars can be used as parents with desirable genes for future breeding programs. Overall, the STS markers employed in this study proved to be valuable markers for enhancing the genetic background of bread wheat, particularly when employing marker-assisted selection for bakery value.

In breeding programs determination of gene effects and general and specific combining ability for screening of test crosses is necessary. In order to estimate the genetic variance components and the general and specific combining ability of sweet corn lines, an experiment was conducted using 8 sweet corn S6 inbred lines (including 4 maternal and 4 paternal lines) by line × tester mating design in 2019, at the Agricultural and Natural Resources Research and Education Center of Khorasan Razavi Province, Mashhad, Iran. The obtained test cross hybrids were evaluated in a randomized complete block design with 3 replications in 2020. The results of line, tester and line × tester analysis for most of measured traits showed significant differences (p < 0.05). The σ2gca/σ2sca ratio for grain yield was equal to 0.1, showed that while both additive and dominance effects play a role in controlling this trait, but dominance effect was higher. The results for general combining ability of L3 and T1 lines showed positive and significant GCA effect for grain yield. Also, the specific combining ability of grain yield showed that T4 × L2, T1 × L3 and T3 × L1 had the highest SCA rate. In this study, in terms of grain yield, T1 × L3, T4 × L2 and T1 × L4 with 33.96, 30.47 and 27.85 tons per hectare had the highest green ear yield, respectively. These combinations can be as the hybrids with high yield potential in advanced breeding programs for release of new sweet corn varieties.

In order to determine the heritability and genetic parameters of some agronomic traits in barely (Hordeum vulgare L.) cultivars, a seven-parent half diallel (F1 crosses + parents) was conducted in the non-stress and salt stress (8 and 12 ds m-1) conditions in a randomized complete block design with three replications. Genetic analysis was performed by Hayman’s method and Griffing’s fixed model, method 2. The slope of linear regression of Wr on Vr were significantly higher than 0 and had not significant difference with 1 indicating the additive-dominant model was satisfied in all cases. The narrow-sense heritability of traits was medium to high (0.4-0.8) but their broad-sense heritability was estimated relatively high (0.7-0.9). Results of regression graphs showed that Afzal parent had the most dominant allele. The significance of “a” component in most of the studied traits indicated the presence of the additive effects in controlling of traits. The significance of “b” component in most of the studied traits indicated the presence of the dominance effects in controlling of traits. The proportion of positive and negative genes was lower than 0.25 in all of the traits (except for grain weight per spike in 12 ds m-1 salinity), indicating the presence of asymmetry in the distribution of the positive and negative alleles in the parents. Based on general combining ability effects, it was concluded that under salinity, cultivar “Kavir” had favorable alleles in plant height, grain weight per spike and 100 grain weight traits and can be used as a general parent in breeding programs. Estimates of high broad-sense heritability and narrow-sense heritability in most traits indicated that these genetic materials were promising for breeding under normal and salinity stress conditions.

Drought is one of the environmental factors which damages tobacco production in many countries as well as in Iran. Therefore, breeding for tolerance to drought stress has taken a major attention in Iran. In the present investigation, combining ability, gene action and genetic analysis of four characteristics including nicotine and sugar contents and nitrogen and K2O percent were studied in five Virginia varieties of tobacco and their ten F2 populations. The materials were evaluated in two different experiments using a Randomized Completely Block Design (RCBD) with three replications at two drought stress and normal irrigation conditions in 2006 at the Rasht Tobacco Research Center. Analysis of variance revealed significant differences among genotypes for all of the traits. Diallel cross analysis was conducted using model II of method II of Griffing. General combiningability (GCA) and the specific combining ability (SCA) effects were highly significant for all the traits in both conditions. The results showed that the non-additive genetic variance had an important role in controlling nicotine and sugar content in both conditions, while, for K2O percent in non-stress condition and nitrogen percent in stress condition, the additive variance was more important than dominance variance. K394 variety innon- drought stress condition and Coker254 in stress condition were introduced as the best parents to reduce nicotine content. Coker347 in both drought stress and non-drought stress conditions was found as the best cultivar to increase sugar content. The best hybrid for decreasing nicotine content was known in both drought stress and non-drought stress conditions of Coker347
Coker254. The best hybrid for increasing sugar content in non-drought stress condition belonged to Coker347
VE1, while, no hybrids was identified with high sugar content in drought stress condition. Hayman method was also used for graphical and genetical analysis of nicotine content and K2O percent in both conditions. Graphical analysis results showed that the over dominance genetic effects were existed for nicotine in both conditions.

Persian walnut (Juglans regia L.), a native plant of central Asia, is one of the most important tree species in the world. Walnut has many economic values which covers fruits and wood production. Genetic improvement of walnut could help better production and use of its fruit and wood. This research was performed on Full-sib progenies in Chaharmahal and Bakhtiari province in order to investigate the effects of controled pollination on several growth characteristics. At the first step parental trees of the species were selected with different characteristics and controled pollination were performed. After fruit harvesting, several characteristics were recorded on the hybrid seeds and seedlings. GCA and SCA were estimated on Full-sib seedlings. Results showed that general combining ability of female number 12 for germination percentage and seedlings establishment, and male number 6 for seedlings height were higher than others. According to special combining ability, female number 11 and male number 1 for plant height and collar diameter and female number 12 and male number 6 for germination percentage were shown to be the best crossed female and male trees.