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1.
Temperature and photoperiod fluctuate rapidly in different seasons of the year, and analyzing their effects on rice yield components is crucial for adaptation of rice under various climatic conditions. To study the effects of seasonal changes on yield components, 168 recombinant inbred lines derived from a cross between two Oryza sativa L. indica varieties, Zhenshan 97 and Zhongzao 18 were grown for phenotype collection, in three different seasons, within a year. The results implied that temperatures across the three seasons played a crucial role in determining the trait effects. Spikelets per panicle (SPP), panicle length (PL) and plant height (PH) traits increased with high temperatures in middle season. Genetic analysis detected major quantitative trait loci (QTLs) qSPP10, qPL10 and qPH10 for SPP, PL and PH in the interval between markers RM1375 and RM3229 on chromosome 10, in all the three seasons. Two-way ANOVA showed that genotype by environment and QTL by environment interactions for these traits were highly significant (P < 0.0001). The region with a cluster of QTLs detected in all three seasons could be the preferred target to breeders in developing rice varieties that can be accustomed to different seasonal changes.  相似文献   

2.
A quantitative trait loci (QTL) analysis of grain yield and yield-related traits was performed on 93 durum wheat recombinant inbred lines derived from the cross UC1113 × Kofa. The mapping population and parental lines were analyzed considering 19 traits assessed in different Argentine environments, namely grain yield, heading date, flowering time, plant height, biomass per plant, and spikelet number per ear, among others. A total of 224 QTL with logarithm of odds ratio (LOD) ≥ 3 and 47 additional QTL with LOD > 2.0 were detected. These QTL were clustered in 35 regions with overlapping QTL, and 12 genomic regions were associated with only one phenotypic trait. The regions with the highest number of multi-trait and stable QTL were 3BS.1, 3BS.2, 2BS.1, 1BL.1, 3AL.1, 1AS, and 4AL.3. The effects of epistatic QTL and QTL × environment interactions were also analyzed. QTL putatively located at major gene loci (Rht, Vrn, Eps, and Ppd) as well as additional major/minor QTL involved in the complex genetic basis of yield-related traits expressed in Argentine environments were identified. Interestingly, the 3AL.1 region was found to increase yield without altering grain quality or crop phenology.  相似文献   

3.
The rice FRIZZY PANICLE (FZP) locus on chromosome 7, in which an ERF and acidic domain are present, is concerned with the regulation of spikelet meristem identity and the determination of panicle architecture. Many fzp mutants drastically alter panicle morphology with higher-order rachis-branches developing successively instead of the development of floral organs in these mutants. A new mutant showing the same fzp phenotype was induced by γ-ray irradiation of seeds of a rice cultivar “Gimbozu”. Examination of this fzp-like mutant for its allelism to a known allele of fzp-1, nucleotide sequence, and panicle and agronomic characteristics clearly indicated that the allele of this fzp-like mutant is located in FZP. Because there is a previously identified allele called fzp-9, we designated this new allele as fzp-10. fzp-10 has a single nucleotide (cytosine) deletion between the ERF domain and the acidic domain, which results in a frameshift mutation and a premature stop codon, thereby altering the C-terminus of the encoded protein. The degree of higher-order branching in the panicles was significantly reduced in the fzp-10 mutant compared with that of fzp-1. Moreover, the fzp-10 mutant showed highly depressed culm and panicle lengths and panicle number, as well as delayed heading dates compared with its wild type and also with fzp-1. fzp-10 has several new characteristics, its altered nucleotide position and severity of phenotype alteration, and, therefore, could be a new gene resource to examine the function of FZP and the determination of rice panicle architecture.  相似文献   

4.
Fine mapping of a quantitative trait locus, qFLL6.2, controlling flag leaf length (FLL) and yield traits in rice was conducted using four sets of near isogenic lines (NILs) that were developed from a common residual heterozygote at F7 generation of the indica rice cross Zhenshan 97/Milyang 46. Each of the NIL sets consisted of 40 lines that are S1 progenies of ten maternal homozygotes, ten paternal homozygotes, and 20 heterozygotes differing in a portion of the 1.19-Mb interval RM3414–RM6917 on the short arm of rice chromosome 6. Analysis of phenotypic differences among the three genotypic groups in each NIL set delimited qFLL6.2 to a 62.1-kb region flanked by simple sequence repeat marker RM3414 and sequence-tagged site marker Si2944. This QTL explained 52.73% of the phenotypic variance, and the Zhenshan 97 allele increased FLL by 2.40 cm. Based on data collected from homozygous lines of three of the NIL sets, qFLL6.2 was shown to have major effects on all the three yield traits analyzed, including the number of spikelets per panicle, the number of filled grains per panicle, and grain weight per panicle. A comparison of the different groups revealed that the effect of qFLL6.2 was highly consistent across different genetic backgrounds and environments, providing a good candidate for map-based cloning and investigating the source–sink relationship in rice.  相似文献   

5.
A recombinant inbred line (RIL) population with 305 lines derived from a cross of Hanxuan 10 × Lumai 14 was used to identify the dynamic quantitative trait loci (QTL) for plant height (PH) in wheat (Triticum aestivum L.). Plant heights of RILs were measured at five stages in three environments. Total of seven genomic regions covering PH QTL clusters on different chromosomes identified from a DH population derived from the same cross as the RIL were used as the candidate QTLs and extensively analyzed. Five additive QTLs and eight pairs of epistatic QTLs significantly affecting plant height development were detected by unconditional QTL mapping method. Six additive QTLs and four pairs of epistatic QTLs were identified using conditional mapping approach. Among them, three additive QTLs (QPh.cgb-1B.3, QPh.cgb-4D.1, QPh.cgb-5B.2) and three pairs of epistatic QTLs (QPh.cgb-1B.1–QPh.cgb-1B.3, QPh.cgb-2A.1–QPh.cgb-2D.1, QPh.cgb-2D.1–QPh.cgb-5B.2) were common QTLs detected by both methods. Three QTLs (QPh.cgb-4D.1, QPh.cgb-5B.3, QPh.cgb-5B.4) were expressed under both drought and well-water conditions. The present data are useful for wheat genetic manipulations through molecular marker-assisted selection (MAS), and provides new insights into understanding the genetic mechanism and regulation network underlying the development of plant height in crops. Our result in this study indicated that combining unconditional and conditional mapping methods could make it possible to reveal not only the stable/conserved QTLs for the developmental traits such as plant height but also the dynamic expression feature of the QTLs.  相似文献   

6.
Quantitative trait loci for yield, yield components and seed protein content were investigated on the basis of experiments performed with two populations of pea (Pisum sativum L.) lines derived from linked crosses between lines Wt11238, Wt3557 and Wt10245 with contrasting characteristics. The yield-related traits were defined as components giving the grain yield in a multiplicative way. The aim was to clarify the genetic architecture of the relation between seed yield, its components and protein content, with a possible inclusion of the role of epistasis in this explanation. To take full advantage of the availability of the two populations, additive QTL effects and both types of epistasis were analysed: the QTL by genetic background interaction and the first-order QTL–QTL interaction. The two hybrid populations differed with respect to the prevailing gene action, which in the Wt11238 × Wt3557 progeny was mainly additive, while in the Wt10245 × Wt11238 progeny mainly epistatic. Some loci with previously reported, large, repeatable, but contradictory effects on yield and protein content were confirmed. New loci with alleles coming from the protein-rich Wt11238 line, positive for yield components, were identified. It was found that the first order QTL–QTL interaction events were more frequent for the loci showing the QTL by genetic background interaction.  相似文献   

7.
Tef is a staple cereal of Ethiopia in high demand by consumers. In order to cope up with this high consumer demand, productivity per unit of land must increase through the development and use of high-yielding varieties. To this effect, the National Tef Research Project has long been striving towards the development of high yielding varieties through direct selection from germplasm and concentrating favourable alleles through hybridization and selection, despite the tedious crossing technique. The objective of this study was to assess the degree of genetic variation in F2 populations of tef as a basis for improving grain yield. F2 populations from 12 crosses and their parents were grown at the Debre Zeit Agricultural Research Center, Ethiopia, and assessment was made on eight traits on individual plant basis. Eleven of the 12 crosses showed substantial genetic variation for grain yield and its components, indicating the potential for improvement through selection. Moreover, grain yield, plant weight and yield related traits showed moderate to high heritability values (17–80%). In all the crosses, tiller number, panicle weight, yield per panicle and panicle length showed significant (P ≤ 0.05) and positive association with grain yield. Considering the degree of genetic variation and heritability values, emphasis should be given to selected crosses in an effort to developing high-yielding tef varieties.  相似文献   

8.
Increasing seed oil content is an important breeding goal for Brassica napus L. (B. napus). The identification of quantitative trait loci (QTL) for seed oil content and related traits is important for efficient selection of B. napus cultivars with high seed oil content. To get better knowledge on these traits, a molecular marker linkage map for B. napus was constructed with a recombinant inbred lines (RIL) population. The length of the map was 1,589 cM with 451 markers distributed over 25 linkage groups. QTL for seed oil content, seed hull content and seed coat color in three environments were detected by composite interval mapping (CIM) tests. Eleven QTL accounted for 5.19–13.57% of the variation for seed oil content. Twelve QTL associated with seed hull content were identified with contribution ranging from 5.80 to 22.71% and four QTL for seed coat color accounted for 5.23–15.99% of the variation. It is very interesting to found that co-localization between QTL for the three traits were found on N8. These results indicated the possibility to combine favorable alleles at different QTL to increase seed oil content, as well as to combine information about the relationship between seed oil content and other traits.  相似文献   

9.
Pseudomonas syringae is the main pathogen responsible for bacterial blight disease in pea and can cause yield losses of 70%. P. syringae pv. pisi is prevalent in most countries but the importance of P. syringae pv. syringae (Psy) is increasing. Several sources of resistance to Psy have been identified but genetics of the resistance is unknown. In this study the inheritance of resistance to Psy was studied in the pea recombinant inbred line population P665 × ‘Messire’. Results suggest a polygenic control of the resistance and two quantitative trait loci (QTL) associated with resistance, Psy1 and Psy2, were identified. The QTL explained individually 22.2 and 8.6% of the phenotypic variation, respectively. In addition 21 SSR markers were included in the P665 × ‘Messire’ map, of which six had not been mapped on the pea genome in previous studies.  相似文献   

10.
Grain samples from a combined intermediate and advanced stage barley breeding trial series, grown at two sites in two consecutive years were assessed for detailed grain quality and ruminant feed quality. The results indicated that there were significant genetic and environmental effects for “feed” traits as measured using grain hardness, acid detergent fibre (ADF), starch and in-sacco dry matter digestibility (ISDMD) assays. In addition, there was strong genotypic discrimination for the regressed feed performance traits, namely Net Energy (NE) and Average Daily Gain (ADG). There was considerable variation in genetic correlations for all traits based on variance from the cultivars used, sites or laboratory processing effects. There was a high level of heritability ranging from 89% to 88% for retention, 60% to 80% for protein and 56% to 68% for ADF. However, there were only low to moderate levels of heritability for the feed traits, with starch 30–39%, ISDMD 55–63%, ADF 56–68%, particle size 47–73%, 31–48% NE and ADG 44–51%. These results suggest that there were real differences in the feed performance of barleys and that selection for cattle feed quality is potentially a viable option for breeding programs.  相似文献   

11.
Based on studies of the distribution of alleles at the important Rht and Ppd loci on wheat chromosomes 4B, 4D and 2D, different groups of winter wheat cultivars registered in the Czech and Slovak Republics during the period 1976–2007 were examined for a range of agronomic traits using official data from multi-location trials. Significant variation for all traits was detected among and between genotype groups. The frequent introduction of ‘Rht-D1b’ cultivars from the UK and Western Europe to the Czech Republic since 1995 has positively influenced lodging resistance and undoubtedly also yielding ability, but negatively affected winter-hardiness and bread making quality. An improved opportunity for earlier flowering cultivars with high winter-hardiness levels, in combination with high bread-making quality, can be obtained with genotypes carrying the Xgwm261 allele 192-bp that is probably indicative of the presence of Rht8. While GA insensitive Rht genes caused approximately a 10 cm reduction of plant height, the 192-bp allele at Xgwm261 was not associated, in these conditions, with a significant reduction in plant height when compared to Xgwm261 alleles 165- and 174-bp. Likewise, the photoperiod insensitive allele Ppd-D1a did not have a significant effect on plant height and it had not adversely affected other characters. Later heading genotypes carrying Xgwm261 alleles174- and 165-bp, often in combination with Ppd-D1b, could probably guarantee broader adaptability, which is highly desirable for changeable weather conditions. While the presence of the 192-bp allele was clearly associated with suitability for cultivation in the warmer maize growing regions, this was not so obvious for Ppd-D1a, particularly when combined with the 174-bp allele. GA responsive genes did not, apparently, influence adaptability to the different growing conditions. These studies reveal that there were both shortcomings and benefits attributable to the use of germplasm from different origins when introducing Rht and Ppd alleles. These results should be helpful to breeders in optimizing the choice of parents for crossing, and selection strategy in these target environments.  相似文献   

12.
Nicotiana wuttkei Clarkson and Symon discovered in the 1990s in Australia may be of potential interest to breeders as it carries resistance to Peronospora hyoscyami de Bary. The crossability between N. wuttkei (2n = 4x = 32) and three N. tabacum (2n = 4x = 48) cultivars (‘Puławski 66’, ‘Wiślica’ and ‘TN 90’) and the morphology and cytology of their amphihaploid hybrids (2n = 4x = 40) were studied. Seeds were produced only when N. wuttkei was used as the maternal parent, but under normal germination all seedlings died. Viable F1 hybrids of N. wuttkei × N. tabacum cv. ‘Puławski’ and N. wuttkei × N. tabacum cv. ‘Wiślica’ were obtained only by in vitro cotyledon culture. The amphihaploid plants were intermediate between the parents for most morphological traits. In 46.4% of the PMC’s, only univalents were present. The remainder of the cells had 1–5 bivalents and 1–2 trivalents. In spite of a detectable frequency of monads (2.6%), dyads (2.6%) and triads (4.5%), the hybrids were self and cross sterile.  相似文献   

13.
Powdery mildew is one of the most important melon pathogens all over the world. So far, many genes conferring resistance to powdery mildew of melon have been described, but few of these have been finely mapped or cloned. Two F2 populations derived from Ano2 × Hami413 and Ano2 × Queen were used to map the powdery mildew resistance gene by methods of Bulked Segregation Analysis (BSA), comparative genomics and Resistance Gene Analogues (RGA) mapping. It was found that the resistance to powdery mildew in Ano2 was conferred by a dominant gene, and the gene was named Pm-AN. The genetic analysis revealed that Pm-AN located between two codominant markers RPW and MRGH63B in linkage groupV. The genetic distances between Pm-AN and these two markers were 1.4–1.8 and 1.6–2 cM. No recombination was found between Pm-AN and markers ME/E1, SRAP23. Pm-AN was located in a RGA-rich region and cosegregated with the RGA marker MRGH5 and the resistance gene Vat. Synteny analysis showed that markers in this region were collinear between melon and cucumber. Segregation distortion was found in this region using both Ano2 × Hami413 and Ano2 × Queen F2 populations, and the distortion was more distinct in Ano2 × Hami413 F2 population. The center of segregation distortion was located in the RGA rich region harboring Pm-AN.  相似文献   

14.
The inheritance of two flowering traits of chrysanthemum, initial blooming time and the duration of flowering, was investigated using segregation within an F 1 population derived from a cross between the autumn-flowering ‘Yuhualuoying’ and the summer-flowering ‘Aoyunhanxiao’ cultivars. The analysis, based on a single segregating generation and the major gene plus polygene mixed inheritance model, showed that the inheritance of both traits was compatible with the presence of two pairs of major genes displaying additivity–dominance–epistasis, with additivity predominating. As the heritability of both pairs of major genes was high (initial blooming time ~65%, duration of flowering ~72%), it should be possible to select for both traits in early breeding generations. A marker-trait association analysis based on sequence-related amplified polymorphism (SRAP) genotyping uncovered 10 (initial blooming time) and 12 (duration of flowering) markers significantly associated with phenotype, cumulatively explaining, respectively, 46 and 54% of the variation. Some potentially useful markers were identified.  相似文献   

15.
To better understand the underlying mechanisms of agronomic traits related to drought resistance and discover candidate genes or chromosome segments for drought-tolerant rice breeding, a fundamental introgression population, BC3, derived from the backcross of local upland rice cv. Haogelao (donor parent) and super yield lowland rice cv. Shennong265 (recurrent parent) had been constructed before 2006. Previous quantitative trait locus (QTL) mapping results using 180 and 94 BC3F6,7 rice introgression lines (ILs) with 187 and 130 simple sequence repeat (SSR) markers for agronomy and physiology traits under drought in the field have been reported in 2009 and 2012, respectively. In this report, we conducted further QTL mapping for grain yield component traits under water-stressed (WS) and well-watered (WW) field conditions during 3 years (2012, 2013 and 2014). We used 62 SSR markers, 41 of which were newly screened, and 492 BC4F2,4 core lines derived from the fourth backcross between D123, an elite drought-tolerant IL (BC3F7), and Shennong265. Under WS conditions, a total of 19 QTLs were detected, all of which were associated with the new SSRs. Each QTL was only identified in 1 year and one site except for qPL-12-1 and qPL-5, which additively increased panicle length under drought stress. qPL-12-1 was detected in 2013 between new marker RM1337 and old marker RM3455 (34.39 cM) and was a major QTL with high reliability and 15.36% phenotypic variance. qPL-5 was a minor QTL detected in 2013 and 2014 between new marker RM5693 and old marker RM3476. Two QTLs for plant height (qPHL-3-1 and qPHP-12) were detected under both WS and WW conditions in 1 year and one site. qPHL-3-1, a major QTL from Shennong265 for decreasing plant height of leaf located on chromosome 3 between two new markers, explained 22.57% of phenotypic variation with high reliability under WS conditions. On the contrary, qPHP-12 was a minor QTL for increasing plant height of panicle from Haogelao on chromosome 12. Except for these two QTLs, all other 17 QTLs mapped under WS conditions were not mapped under WW conditions; thus, they were all related to drought tolerance. Thirteen QTLs mapped from Haogelao under WS conditions showed improved drought tolerance. However, a major QTL for delayed heading date from Shennong265, qDHD-12, enhanced drought tolerance, was located on chromosome 12 between new marker RM1337 and old marker RM3455 (11.11 cM), explained 21.84% of phenotypic variance and showed a negative additive effect (shortening delay days under WS compared with WW). Importantly, chromosome 12 was enriched with seven QTLs, five of which, including major qDHD-12, congregated near new marker RM1337. In addition, four of the seven QTLs improved drought resistance and were located between RM1337 and RM3455, including three minor QTLs from Haogelao for thousand kernel weight, tiller number and panicle length, respectively, and the major QTL qDHD-12 from Shennong265. These results strongly suggested that the newly screened RM1337 marker may be used for marker-assisted selection (MAS) in drought-tolerant rice breeding and that there is a pleiotropic gene or cluster of genes linked to drought tolerance. Another major QTL (qTKW-1-2) for increasing thousand kernel weight from Haogelao was also identified under WW conditions. These results are helpful for MAS in rice breeding and drought-resistant gene cloning.  相似文献   

16.
7–7365AB is a recessive genic male sterile (RGMS) two-type line, which can be applied in a three-line system with the interim-maintainer, 7–7365C. Fertility of this system is controlled by two duplicate dominant epistatic genes (Bn;Ms3 and Bn;Ms4) and one recessive epistatic inhibitor gene (Bn;rf). Therefore an individual with the genotype of Bn;ms3ms3ms4ms4Rf_ exhibits male sterility, whereas, plant with Bn;ms3ms3ms4ms4rfrf shows fertility because homozygosity at the Bn;rf locus (Bn;rfrf) can inhibit the expression of two recessive male sterile genes in homozygous Bn;ms3ms3ms4ms4 plant. A cross of 7–7365A (Bn;ms3ms3ms4ms4RfRf) and 7–7365C (Bn;ms3ms3ms4ms4rfrf) can generate a complete male sterile population served as a mother line with restorer in alternative strips for the multiplication of hybrid seeds. In the present study, molecular mapping of the Bn;Rf gene was performed in a BC1 population from the cross between 7–7365A and 7–7365C. Bulked segregant analysis (BSA) and amplified fragment length polymorphism (AFLP) technique was used to identify molecular markers linked to the gene of interest. From a survey of 768 primer combinations, seven AFLP markers were identified. The closest marker, XM5, was co-segregated with the Bn;Rf locus and successfully converted into a sequence characterized amplified region (SCAR) marker, designated as XSC5. Two flanking markers, XM3 and XM2, were 0.6 cM and 2.6 cM away from the target gene, respectively. XM1 was subsequently mapped on linkage group N7 using a doubled-haploid (DH) mapping population derived from the cross Tapidor × Ningyou7, available at IMSORB, UK. To further confirm the location of the Bn;Rf gene, additional simple sequence repeat (SSR) markers in linkage group N7 from the reference maps were screened in the BC1 population. Two SSR markers, CB10594 and BRMS018, showed polymorphisms in our mapping population. The molecular markers found in the present study will facilitate the selection of interim-maintainer.  相似文献   

17.
Two cucumber recombinant inbred lines (RILs) differing in plant habit were crossed and progeny self-pollinated to produce F3 individuals upon which phenotypic selection was practiced to identify a base population which in turn underwent either two cycles of MAS or random mating without selection (RAN). MAS and RAN were practiced to produce F4 and F5 progeny sets. RIL, crossing parents, and F3–F5 progeny sets were then evaluated under replicated field conditions for fruit yield and quality (L:D and E:T) to evaluate gain from selection (ΔG). The broad-sense heritability (h 2 B) over cycles (C) of selection ranged 0.22–0.45, 0.09–0.20, and 0.11–0.15 for yield, L:D, and E:T, respectively. Although one cycle of PHE selection followed by MAS was effective in conserving the performance of the traits examined during inbreeding, progeny performance during RAN fluctuated (F4–F5 generation; C2). Lack of ΔG during advanced generations (F4–F5) of MAS was likely due to allelic fixation and/or optimized epistatic complementation.  相似文献   

18.
Jethobudho is an aromatic rice landrace of the Pokhara valley in middle hills of Nepal. Although local consumers are willing to pay a high price for its purchase, the landrace has a problem with quality variation. Decentralized participatory population improvement for specific market-identified traits was conducted on “Jethobudho” populations collected from farmers’ fields in seven geographic regions of the valley in Nepal. The preferred post harvest quality traits, field tolerance to blast and lodging, and superior post harvest quality traits of Jethobudho were established by a consumer market survey. These traits were used for screening the materials. 338 sub-populations of Jethobudho were evaluated for yield, disease, lodging resistance, and post harvest quality traits. Significant variation was found for culm strength, neck blast tolerance, awn characteristics, panicle length, number of grains per panicle, test grain weight and post harvest quality traits, whereas no significant variation was found in grain yield, plant height, tiller number, maturity period and leaf blast. Based on these identified traits and micro-milling evaluations, 183 populations were screened in on-farm and on-station nurseries, and in succeeding years populations were further screened by plant breeders and expert farmers in research trials, resulting in the selection of 46 populations for post harvest quality traits. Six accessions with similar agronomic traits, field tolerance to blast and lodging, and superior post harvest quality traits, were bulked and evaluated on-farm using participatory variety selection (PVS). The enhanced Jethobudho accessions were also evaluated for aroma using simple sequence repeat (SSR) and found to have unique aromatic genetic constitution. Community based seed production groups were formed, linked to the Nepal District Self Seed Sufficiency Programme (DISSPRO), and trained to produce basic seeds (truthfully labeled) of Jethobudho. The National Seed Board of Nepal released the enhanced landrace in the name of “Pokhareli Jethobudho” in 2006, as the first bulk variety of traditional high quality aromatic rice improved through participatory plant breeding to be formally released in Nepal for general cultivation under the national seed certification scheme. Landrace improvement is shown as an important option for supporting programmes for in situ conservation of landraces on-farm.  相似文献   

19.
The Wild Abortive (WA) system is the major cytoplasmic male sterility (CMS) source for hybrid rice production in indica rice and its fertility restoration is reported to be controlled by two major loci viz. Rf3 on chromosome 1 and Rf4 on chromosome 10. With the availability of the rice genome sequence, an attempt was made to fine map, develop candidate gene based markers for Rf3 and Rf4 and validate the developed marker system in a set of known restorer lines. Using polymorphic markers developed from microsatellite markers and candidate gene based markers from Rf3 and Rf4 loci, local linkage maps were constructed in two mapping populations of ~1,500 F2 progeny from KRH2 (IR58025A/KMR3R) and DRRH2 (IR68897A/DR714-1-2R) hybrids. QTLs and their interactions for fertility restoration in Rf3 and Rf4 loci were identified. The identified QTL in both mapping populations together explained 66–72 % of the phenotypic variance of the trait suggesting their utility in developing a marker system for identification of fertility restorers for WA-CMS. Sequence comparison of the two candidate genes from the Rf3 and Rf4 regions in male sterile (A) and restorer (R) lines showed 2–3 bp indels and a few substitutions in the Rf3 region and indels of 327 and 106 bp in the Rf4 region respectively. The marker system identified in the present study was validated in 212 restorers and 34 maintainers along with earlier reported markers for fertility restoration of WA-CMS. Together DRCG-RF4-14 and DRCG-RF4-8 for the Rf4 locus and DRRM-RF3-5/DRRM-RF3-10 for the Rf3 locus showed a maximum efficiency of 92 % for identification of restorers.  相似文献   

20.
Root traits are key components of plant adaptation to drought environment. By using a 120 recombined inbred lines (RILs) rice population derived from a cross between IRAT109, a japonica upland rice cultivar and Yuefu, a japonica lowland rice cultivar, a complete genetic linkage map with 201 molecular markers covering 1,833.8 cM was constructed and quantitative trait loci (QTLs) associated with basal root thickness (BRT) were identified. A major QTL, conferring thicker BRT, located on chromosome 4, designated brt4, explained phenotypic variance of 20.6%, was selected as target QTL to study the effects of marker-assisted selection (MAS) using two early segregating populations derived from crosses between IRAT109 and two lowland rice cultivars. The results showed that the flanking markers of brt4 were genetically stable in populations with different genetic backgrounds. In the two populations under upland conditions, the difference between the means of BRT of plants carrying positive and negative favorable alleles at brt4 flanking markers loci was significant. Phenotypic effects of BRT QTL brt4 were 5.05–8.16%. When selected plants for two generations were planted at Beijing and Hainan locations under upland conditions, MAS effects for BRT QTL brt4 were 4.56–18.56% and 15.46–26.52% respectively. The means of BRT for the homozygous plants were greater than that of heterozygous plants. This major QTL might be useful for rice drought tolerance breeding. L. Liu and P. Mu are contributed equally to this work.  相似文献   

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