جستجوی مقالات مرتبط با کلیدواژه "recombinant inbred lines" در نشریات گروه "زراعت"

Rice is one of the important and staple food crops in Iran, and its grain yield improvement has always been the most important objective in rice breeding programs. One of the important breeding methods in rice is crossing between selected varieties to develop recombinant inbred lines (RILs), and then identifying promising lines. This experiment was carried out with the aim of identifying high-yielding superior lines. One hundred forty one recombinant inbrd lines together with their parental cultivars were evaluated using randomized complete block design with three replications in research field of faculty of agricultural sciences, University of Guilan, Rasht, Iran, in 2018. Important agronomic traits were measured and recorded for all RILs. Analysis of variance showed that there was significant differences among RILs for all studied traits, indicating significant genetic variation among them. Estimated coefficients of phenotypic and genetic variations as well as variance components also showed that there was considerable variation among RILs population, particularly for number of filled and unfilled grains panicle-1, number of panicles plant-1 and grain yield. The narrow-sense heritability varied from about 20% for panicle length to 43% for grain width, days to maturity, and 1000-grain weight. Factor analysis showed that three main and independent factors explained about 96% of the total observed variance among RILs, and were the main reasons for significant relationships between traits. These three factors were deignated as yield and its components, grain appearance quality and phenological factors. Cluster analysis by UPGMA method classified the 141 studied RILs into three clusters. Cv. Sepidrood and cv. Gharib (parental cultivars) were grouped in the first and second clusters, respectively. Evaluation of the cluster values for different traits showed that the first cluster had the highest values for grain yield and its components and the third cluster for grain dimensions and appearance quality. In conclusion, the results of this experiment showed that there was significant genetic variation among the studied RIls. Therefore, successful improvement of important agronomic traits, particularly grain yield and its components, is feasible. The superior high-yielding lines with desirable appearance quality were also identified.

To detect main and epistatic QTLs and their environmental interactions for rice important agronomic traits, 242 recombinant inbred lines (RIL) from two F6 rice populations derived from crosses between Alikazemi / IR67017-180-2-1-2 (IRA population) and Ali Kakami / Saleh (SA) cultivars were evaluated in two locations. Results of the present experiment showed that the linkage map of the two populations using 87 polymorph microsatellite markers (SSR) covered 1356.0 cM of rice genome with an average distance of 15.58 cM between two markers. A total of 20 main QTLs (M-QTLs) and 33 epistatic QTLs (E-QTLs) were identified with positive and negative effects. Five M-QTLs and five E-QTLs had a significant interaction with the environment. Eight M-QTLs and ten E-QTLs with significant effect on agronomic traits were stable and did not have any significant interaction with the environment. These QTLs include two M-QTLs and two E-QTLs for reducing plant height, three M-QTLs and three E-QTLs for decreasing heading date, an M-QTL and an E-QTL for increasing panicle length and two M-QTLs and four E-QTLs to increase grain yield. These main QTLs explained 11.12% (qHD6) and 24.5% (qGY1) phenotypic variation, respectively. Therefore, such useful QTLs can be used for gene pyramiding programs to improve rice agronomical traits. Furthermore, six linked SSR markers (RM421, RM178, RM3441, RM5101, RM7551 and RM5302) were identified with less than 5 cM distance from important QTLs, suggesting that such SSR markers can be used in marker-assisted selection to select rice lines with desirable traits in segregation generations.

To estimate heritability and association between traits traits, 148 recombinant inbred lines and their parents (Yecora Rojo and No. 49) were evaluated in Alfa lattice design with two replications under normal and water deficit conditions during two cropping season (2013-15). Results showed that there were significant differences between genotypes for all studied traits. The estimated heritabilities for spikes per square meter, stem weight, biomass, spike length, peduncle length, peduncle weight, shoot length, number of grains per spike and spike weight were in the range of 15.04 to 22.41 and for grain yield, 1000- kernel weight and harvest index were in the range of 25.93 to 26.92, respectively. Under water deficit conditions, estimated heritabilities for spike length, spike weight, shoot length, spike per square meter, biomass, peduncle weight, peduncle length and stem weight were between 13.64 to 19.35 percent and for number of grains per spike, harvest index, thousand kernel weight and grain yield were in the range of 22 to 25.61 percent. The highest genetic gain in both conditions belongs to peduncle weight and harvest index, respectively. Finally based on regression and path analysis traits of number of grains per spike and 1000- kernel weights were identified as the most effective traits on grain yield in both conditions. Therefore, use of harvest index, grain yield, number of grains per spike and grain weight as indicators of selection, probably can provides access to high-yielding lines.

In order to identify genomic regions with main, epistatic, and QTL×environment interaction effects for some of the phenological and morphological traits in bread wheat, an experiment with 167 recombinant inbred lines and their parents (‘SeriM82’ and ‘Babax’) was conducted at Research Farm of the Agricultural Research Station of Sistan in 2015-16 cropping season. The experiment was carried out using two alpha lattice designs with two replications under non-stress and terminal heat stress conditions. Seven traits including days to maturity (DM), grain filling duration (GFD), maximum quantum efficiency of photosystemII (Fv/Fm), cytoplasmic membrane stability (CMS), grains per spike (GPS), grain yield (GY) and thousand grain weight (TGW) were measured. There were significant differences among the genotypes for all studied traits and maximum correlation was observed between GY and Fm/Fv (r = 0.86**). QTL analysis was conducted by Mixed-Model based composite interval mapping (MCIM) method. A total of 33 main-effect QTLs for studied traits were detected. Phenotypic variances explained by these QTLs varied from 7.04% for GFD to 19.41% for TGW. The major Qtgw7D (R2 = 19/41) was identified near the marker of acc/cat-10 and after validation can be used in marker-assisted selection (MAS) in order to produce heat tolerant wheat varieties.

Salinity is one of the most important abiotic stresses that has a negative effect on the growth and productivity of plants cultivated around the world by reducing soil fertility. Unfortunately, due to inefficient irrigation management of agricultural fields, high exploitation of agricultural soil and rising ground-water levels, the area affected by soil salinity is increasing every year. For utility of lands affected by salinity or using salty water resources, identification and selection of salt tolerant genotypes are important. Sunflower botanically is a dicotyledonous, annual, monoicous plant from North America. The plant is often cultivated for its edible oil. Different criteria are proposed for selecting genotypes on the basis of their appearance in stress or non-stress environments. In general, a criterion is considered as the best index for determining drought tolerance genotypes when it is highly correlated with plant performance in both normal and stress conditions. In such a case this index is able to identify genotypes with high performance in both environments. Since for calculating tolerance indices need to evaluate genotypes in both normal and stress conditions; by identifying molecular markers associated with tolerance indices, it will be possible to select tolerant genotypes in normal conditions at seedling stage. The aim of this research is to identify molecular markers associated with salt tolerance indices in order to use them in sunflowers salt tolerance breeding programs.
In this study, 59 recombinant inbred lines (F9) of sunflower coming from the cross between PAC2 (maternal) × RHA266 (paternal) accompanied with their parental lines were evaluated in both normal and salt stress conditions. The factorial experiment was conducted in completely randomized design with three replications in Urmia University. Several tolerance indices including mean productivity (MP), geometric mean productivity (GMP), harmonic mean (HM), stress tolerance index (STI), yield stability index (YSI) and tolerance index (TOL) were calculated based on yield performance under normal and salt stress conditions. In order to identify molecular markers associated with salt tolerance indices, a genetic linkage map including 210 SSR and 11 SNP markers on 17 linkages groups with average distance of 7.44 CM between marker pairs were used. Identification of QTLs linked to tolerance indices was performed by QGene software via composite interval mapping method (CIM).
Considering simple correlation results, high correlation was observed between yield under normal and salinity conditions with mean productivity, geometric mean productivity and harmonic mean. So, these indices are introduced as the most appropriate measures to identify sunflower lines tolerant to salinity stress. Based on three dimensional plots constructed by yield in normal and salt stress conditions and each one of appropriate indicators (GMP, MP and HM), lines such as C86, C61, C142, C134a, C62, C70a, LR1, C153, C108, C6, C106, C98b and C148 are considered as salt tolerant lines. In QTL analysis, totally 5 QTLs was identified significantly associated with salt tolerance indices. The results indicate co-localization of the identified QTLs for GMP, MP and HM in linkage group 14 with QTL identified for grain yield under salt stress conditions.
The results support the phenotypic correlations observed between grain yield and salt tolerance indices. After validation and fine mapping of genomic regions associated with salt tolerance indices, they can be used for MAS (marker-assisted selection) in sunflower breeding programs. This leads to increase the efficiency of traditional breeding methods.

To identify the genomic regionswith main, epistatic, and QTL×environment (Q×E) interaction effects for some of the physiological and biochemical traits of wheat, an experiment was conductedat Research Farm of Agricultural and Natural Resources Research Center of Sistan, Iran, in 2015-16 growing season. The experiment was carried outusing two alpha lattice designs with two replications under non-stress and terminal heat stress conditions.Plant materials were 167 recombinant inbred lines andtheir parents (‘SeriM82’and ‘Babax’) andsix traits including grain yield (GY), proline content(PRO), water soluble carbohydrates (WSC), maximum efficiency of photosystem II (Fv/Fm), cytoplasmic membrane stability (CMS) and chlorophyll content (CHL) were measured. QTL analysis was conducted by Mixed-Model basedcomposite interval mapping (MCIM) method. There were significant differences among the genotypes for all studied traits and transgressive segregations in both directions were also observed. Using mixed linear model,a total of 23 main-effect QTLs were detected. The Q×E interaction was significant in five main-effect QTLs and two epistatic QTLs were also detectedfor studied traits. The most of mapped QTLsappear to be quite stable. Therefore, can be used in marker-assisted selection (MAS) in order to produce high-performance and heat tolerant wheat genotypes.

In order to study genetic diversity and identification of QTL controlling seed germination and seedling establishment traits in wheat 148 bread wheat RILs and their parents (RojoYecora and No.49) were studied based on an alpha lattice design with two replications under normal and drought stress conditions in 2016. In this research final germination percentage, germination speed, root and shoot length, root and shoot dry weight and seedling dry weight and vigor index were measured. Analysis of variance showed that between genotypes for all traits, there were significant differences. Under normal moisture conditions the highest heritability was observed for stem length, stem weight and final germination percentage. The highest heritability under drought conditions was found for root length. QTL analysis using composite interval mapping (CIM) for each trait in each environment and mean of two environments were performed. Under normal conditions16 QTL were detected. Phenotypic variance explained by the identified QTLs varied from 11.49 to 21.57 percent. The highest and lowest phenotypic variation belonged to shoot dry weight and root dry weight, respectively. The estimated LODs were in range of 3.15 to 6.76. Under stress conditions 20 QTL were detected. Phenotypic variance explained by these QTLs varied from 11.89 to 24.65 percent. The highest and lowest phenotypic variation were observed fot root dry weight and shoot length respectively. Furthermore LODs were in range of 3.11 to 9.67. Considering the average of two environments, 14 QTL were detected. Phenotypic variance explained by the identified QTLs varied from 11.41 to 23.20 percent, and belonged to root dry weight and shoot dry weight, respectively. The estimated LOD was in range of 3.12 to 7.25. In two different environmental conditions and their average QTL located on chromosome 4B interval markers of Wms121-Sukkula.1300 which control of shoot dry weight and seed vigor and QTL located on chromosome 2D between markers of Gwm349-Wmc445 Which is controlled vigor index was quite stable in all conditions that can be used for marker assisted selection.

The development of high yielding cultivars with wide adaptability is the ultimate aim of plant breeders. However, attaining this goal is made more complicated by genotype-environment interactions. The genotype by environment interaction is a major problem in the study of quantitative traits because it complicates the interpretation of genetic experiments and makes predictions difficult, also it reduces grain yield stability in different environments. Multi-environment trials are often analyzed to assess the yield stability of genotypes. Additive main effects and multiplicative interaction (AMMI) model proved to be a powerful tool in diagnosing genotype × environment interaction patterns. The AMMI statistical model has been widely used to explain complicate G×E interaction, to enhance selection efficiency and to ensure genetic gain from selection. The objective of this study was to investigate the response of the lines in studied locations and to identify lines adapted to the test environments.

Order to investigate response of wheat lines to different environmental conditions and determination of yield stability, this study was conducted by 76 recombinant inbred lines derived the cross between Roshan× Superhead based on randomized complete block design with two replications in five environments. The trials were performed at five locations in Kerman, Jopar, Mahan, Yazd and Ardakan. In order to evaluate the interaction and determine the stable lines, the stability analysis was done using AMMI methods. The data were subjected to statistical analysis using SAS and Excel software.

The results of the combined analysis of variance revealed significant differences of grain yield among lines, environment and also line× environment interaction (P<0.01). Since interaction of line × environment was significant, stability analysis was performed using AMMI analysis in order to more accurate evaluate and status of lines stability. The results of Ammi2 bi-plot showed that the least distance from the center of bi-plot with minimum interaction were identified lines 3, 33, 22, 9, 271, 36, 309, 200, 114, 11, 264, 320, 194, 20, 280, 1, 26, 250, 19, 18, 25, 5, 322, 169, 152, 161 and 32 as stable lines. Lines 258, 218, 176, 48, 82 and 314 for Yazd and line 225 for Ardakan indicated the best response and they had private adaptation to these places.

Overall, based on results of this experiment, among evaluated lines, were introduced lines 9, 3 and 22 based on AMMI1, AMMI2 and AMMI stability value (ASV) parameter as general stable lines. Therefore, the identified promising lines can be recommended to complementary studies for introduce to farmers.

The effects some traits on seed yield of recombinant inbred lines of wheat under water deficit stress was studied. This research was done at the Agricultural Research Stations, Islamic Azad University, Tabriz Branch in 2010- 2011. 28 recombinant inbred lines of wheat bread with two parents (Norstar and Zagros) in split plot experiment based on a randomized complete block design with three replications at two irrigation levels (70 and 140 mm evaporation from pan class A) were studied. Analysis of variance indicated a significant genetic differences in all traits under study among the lines. Lines No. 32, 163 and 182 produced highest yield under both irrigation levels. Number of spikes, grains per spike and harvest index had the highest positive correlation with grain yield. Path analysis based on stepwise regression showed that under the normal irrigation conditions, number spike (0.556), number of grains per spike (0.278), weight of 1000 grain (0.259) and the drought stress number spike (0.430), straw yield (0.276) and peduncle length (0.323) had the most direct and positive effect on yield respectively.