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1.
Plant height determines plant biomass yield, harvest index and economic yield. We analyzed quantitative trait loci (QTL) and gene action controlling plant height. We generated the maternal and paternal testcrossing (TC/M and TC/P) populations based on a recombinant inbred line population. Data for plant height at t1, t2, t3, t4 or t5 stages were collected over 2 years from 3 TC/M field trials and 2 TC/P field trials. At single-locus level, 32 QTLs at five stages and 24 conditional QTLs at four intervals were detected, and 14 QTLs shared in different years or populations or stages. Plant height displayed dynamic characteristics through expression of QTLs. A total of 21 novel QTLs were detected and 11 QTLs validated the previous results. And 19 QTLs explained over 10% of phenotypic variation, such as qPH-Chr9-2, qPH-Chr19-4 and qPH-Chr22-4. The region of NAU5330-NAU1269 on chromosome 19 may be a desired target for genetic improvement of plant height in Upland cotton. In addition, five and eight heterotic loci were identified in TC/M and TC/P populations, respectively. Additive, partial dominance and overdominance effects were observed in both TC populations. We also identified 43 epistatic QTLs and QTLs by environment interactions by inclusive composite interval mapping method. Taken together, additive, partial dominance and overdominance effects together with epistasis explained the genetic basis of plant height in Upland cotton.  相似文献   

2.
Gossypium barbadense L. cotton has significantly better fiber quality than Upland cotton (G. hirsutum L.); however, yield and environmental adaptation of G. barbadense is not as wide as Upland. Most cotton in the world is planted to Upland cultivars. Many attempts have been made, over a considerable number of years, to introgress fiber quality alleles from G. barbadense into Upland. However, introgression barriers, primarily in the form of interspecific incompatibility, have limited these traditional approaches. The use of chromosome substitution lines (CSL) as a bridge should provide a more efficient way to introgress alleles from G. barbadense into Upland. We crossed 18 G. barbadense CSL to three cultivars and developed a random mated population. After five cycles of random mating followed by one generation of self-pollination to increase the seed supply, we grew the random mated population and used 139 G. barbadense chromosome specific SSR markers to assess a random sample of 96 plants for introgression. We recovered 121 of 139 marker loci among the 96 plants. The distribution of the G. barbadense alleles ranged from 10 to 28 alleles in each plant. Among the 96 plants we found individual plants with marker loci from 6 to 14 chromosomes or chromosome arms. Identity by descent showed little relatedness among plants and no population structure was indicated by a heat map. Using CSL we were able to develop a mostly Upland random mated population with considerable introgression of G. barbadense alleles which should be useful for breeding.  相似文献   

3.
Soybean is a primary source of plant oil and protein and has a high nutritional value. Plant height (PH) and flowering time (FT) are two important agronomic traits in breeding programs for soybean. In this study, we mapped QTLs associated with PH and FT in three environments using a population with determinate growth including 236 recombinant inbred lines (NJZY-RIL) derived from a cross between two summer planting varieties, ZXD and NN1138-2. A high-density genetic map with 3255 SLAF-markers was constructed that spanned 2144.85 cM of the soybean genome with an average marker distance of 0.66 cM. Altogether, six QTLs controlling PH and eleven QTLs controlling FT were mapped using mixed-model-based composite interval mapping and composite interval mapping methods. qPH-1-1 and qFT-15-2 were two novel main effect QTLs identified in this study; qFT-6-2, qFT-15-2, qFT-16-1, qPH-1-1, qPH-15-1 and qPH-16-1 were consistently detected across environments and by the two mapping methods. Two pairs of QTLs, qFT-15-2 and qPH-15-1 as well as qFT-16-1 and qPH-16-1, which were located in the same marker interval on chromosomes 15 and 16, respectively, were found to have close linkage or pleiotropy. These results may increase our understanding of the genetic control of PH and FT in soybean and provide support for implementing marker-assisted selection in developing soybean cultivars with high yield and early maturity in summer planting regions.  相似文献   

4.
Pseudostems of bunching onion (Allium fistulosum L.) show wide variation in morphological traits and skin color. However, despite being one of the most important agronomic traits, molecular studies of bunching onion pseudostems remain limited. In this study, six morphological traits (plant height, leaf length, pseudostem length, leaf width, pseudostem width and number of leaf sheaths) along with pseudostem pigmentation indices were evaluated in two field trials using an F2:3 population derived from a single F1 cross between a white single pseudostem (non-tillering) and a red tillering bunching onion. Plant height was highly correlated with both leaf length and pseudostem length, but not the number of leaf sheaths. In contrast, the number of leaf sheaths was significantly negatively correlated with both leaf width and pseudostem width. A total of 27 QTLs for the six morphological traits were detected in 16 regions of 11 linkage groups, with a major QTL for the number of leaf sheaths repeatedly detected on Chr. 8. Meanwhile, two QTLs associated with pseudostem pigmentation were repeatedly detected on linkage groups Chr. 4a and Chr. 5a-2. The latter (qPig5a-2) was considered a major QTL, and its location estimated by marker genotyping of the F2 population around the qPig5a-2 region as being within a 7.6 cM interval.  相似文献   

5.
Kernel size and weight are important agronomic traits, as well as crucial traits that influence grain yield in maize. In the present study, 150 F7 recombinant inbred lines derived from a cross 178×K12 were evaluated for kernel length (KL), kernel width (KW), kernel thickness (KT), and 100-kernel weight (HKW) across seven environments. Natural variations in KL, KW, KT, and HKW were observed in the population. A set of quantitative trait loci (QTLs) for the kernel-related traits were identified by inclusive composite interval mapping method. For the four kernel traits from seven environments and the best linear unbiased prediction data, a total of 52 QTLs were detected, which distributed on all chromosomes except chromosome 6. The LOD values ranged from 2.52 to 8.91, the additive effect from ??2.22 to 1.37, and the range of individually explaining phenotypic variation was from 5.8 to 23.49%. Amongst these QTLs, most were detected only in one or two environments. Three stable QTLs, qKL4-1 at bin 4.07/4.08, qKW4-2 at bin 4.06 and qKT2-1 at bin 2.02/2.03, were identified across at least three environments. Besides, several overlapping QTLs associated with multiple traits were identified. For example, qKW3-1 for KW and qHKW3-1 for HKW were located in the same marker interval at Bin 3.01/3.02. These stable QTLs and overlapping QTLs found in this study will contribute to the understanding of genetic components of grain yield and provide the foundation for molecular marker-assisted breeding in maize.  相似文献   

6.
Both low-temperature germinability (LTG) and cold tolerance at the seedling stage (CTS) are important traits for rice. In this study, a rice population of recombinant inbred lines (RILs), derived from the backcross population of a cross between Dongnong422 and Kongyu131, was developed to detect quantitative trait loci (QTL) affecting LTG and CTS by using seed of different storage times. Correlation analysis indicated that there was no significant relationship between LTG and CTS, suggesting that cold tolerance might be genetic differences for LTG and CTS. In total, Twelve and twenty-three major QTLs were detected for LTG and CTS, respectively, which could explain greater than 10% of the phenotypical variation. Eight (qCG12-1, qGI12-1, qGV9-1, qMLIT12-1, qPV6-1, qMDG12-1, qLDWcold10-1, qLFWcold10-1) significant QTLs were mapped for different storage time, it concluded that such QTLs were not affected by environment (storage time) and were closely related QTLs to cold tolerance. One or more QTLs were identified for each trait with some of these QTLs co-locating, qMLIT7-1, qCG7-1, and qGI7-1 for LTG, qLFWcold10-1, and qLDWcold10-1 for CTS with contributions over 15% were mapped common marker interval, respectively, co-location of QTLs for different traits can be an indication that a locus has pleiotropic effects on multiple traits due to a common mechanistic basis. Two lines, RIL128 and RIL73, might be valuable to improve the LTG and CTS through a combination of crosses. The identified QTLs might be applicable to improve the rice cold tolerance by the marker-assisted selection approach.  相似文献   

7.
Tiller number per plant (TN) and plant height (PH) are important agronomic traits related to grain yield (GY) in rice (Oryza sativa L.). A total of 30 additive quantitative trait loci (A-QTL) and 9 significant additive × environment interaction QTLs (AE-QTL) were detected, while the phenotypic and QTL correlations confirmed the intrinsic relationship of the three traits. These QTLs were integrated with 986 QTLs from previous studies by metaanalysis. Consensus maps contained 7156 markers for a total map length of 1112.71 cM, onto which 863 QTLs were projected; 78 meta-QTLs (MQTLs) covering 11 of the 30 QTLs were detected from the cross between Dongnong422 and Kongyu131 in this study. A total of 705 predicted genes were distributed over the 21 MQTL intervals with physical length <0.3 Mb; 13 of the 21 MQTLs, and 34 candidate genes related to grain yield and plant development, were screened. Five major QTLs, viz. qGY6-2, qPH7-2, qPH6-3, qTN6-1, and qTN7-1, were not detected in the MQTL intervals and could be used as newly discovered QTLs. Candidate genes within these QTL intervals will play a meaningful role in molecular marker-assisted selection and map-based cloning of rice TN, PH, and GY.  相似文献   

8.
Two recombinant inbred line F10 rice populations (IAPAR-9/Akihikari and IAPAR-9/Liaoyan241) were used to identify quantitative trait loci (QTLs) for ten drought tolerance traits at the budding and early seedling stage under polyethylene glycol-induced drought stress, and two traits of leaf rolling index (LRI) and leaf withering degree (LWD) under field drought stress. The results showed that the drought-tolerance capacity of IAPAR-9 was stronger than that of Akihikari and Liaoyan241. Thirty-four QTLs for 12 drought tolerance traits were detected, and among them, in the IAPAR-9/Akihikari population, qLRI9-1 and qLRI10-1 for LRI were repeatedly detected in RM3600-RM553 on chromosome 9 and in RM6100-RM3773 on chromosome 10, respectively, at two times points of July 31 and August 13 in 2014. The two QTLs are stable against the environmental impact, and qLRI9-1 and qLRI10-1 explained 6.77–13.66% and 5.01–8.32% of the phenotypic variance, respectively, at the two times points. qLWD9-2 for LWD in the IAPAR-9/Liaoyan241 population contributed 8.73% of variation was detected in the same marker interval with the qLRI9-1, and qLRI1-1 for LRI and qLWD1-1 for LWD were located in the same marker interval RM11054-RM5646 on chromosome 1, which contributed 18.82 and 5.78% of phenotype variation respectively. qGV3 for germination vigor and qRGV3 for relative germination vigor at the budding stage were detected in the same marker interval RM426-RM570 on chromosome 3, which explained 14.98 and 16.30% of the observed phenotypic variation respectively, representing major QTLs. The above-mentioned stable or major QTLs regions could be useful for molecular marker assisted selection breeding, fine mapping, and cloning.  相似文献   

9.
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   

10.
The success of breeding for barley leaf rust (BLR) resistance relies on regular discovery, characterization and mapping of new resistance sources. Greenhouse and field studies revealed that the barley cultivars Baronesse, Patty and RAH1995 carry good levels of adult plant resistance (APR) to BLR. Doubled haploid populations [(Baronesse/Stirling (B/S), Patty/Tallon (P/T) and RAH1995/Baudin (R/B)] were investigated in this study to understand inheritance and map resistance to BLR. The seedlings of two populations (B/S and R/B) segregated for leaf rust response that conformed to a single gene ratio (\({\text{X}}_{1:1}^{2}\) = 0.12, P > 0.7 for B/S and \({\text{X}}_{1:1}^{2}\) = 0.34, P > 0.5 for R/B) whereas seedlings of third population (P/T) segregated for two-gene ratio (\({\text{X}}_{1:1}^{2}\) = 0.17, P > 0.6) when tested in greenhouse. It was concluded that the single gene in Baudin and one of the two genes in Tallon is likely Rph12, whereas gene responsible for seedling resistance in Stirling is Rph9.am (allele of Rph12). The second seedling gene in Tallon is uncharacterized. In the field, APR was noted in lines that were susceptible as seedlings. A range of disease responses (CI 5–90) was observed in all three populations. Marker trait association analysis detected three QTLs each in populations B/S (QRph.sun-2H.1, QRph.sun-5H.1 and QRph.sun-6H.1) and R/B (QRph.sun-1H, QRph.sun-2H.2, QRph.sun-3H and QRph.sun-6H.2), and four QTLs in population P/T (QRph.sun-6H.2, QRph.sun-1H.2, QRph.sun-5H.2 and QRph.sun-7H) that significantly contributed to low leaf rust disease coefficients. High frequency of QRph. sun-5H.1, QRph. sun-6H.1, QRph. sun-1H.1, QRph. sun-2H.2, QRph. sun-6H.2, QRph. sun-7H (based on presence of the marker, closely associated to the respective QTLs) was observed in international commercial barley germplasm and hence providing an opportunity for rapid integration into breeding programmes. The identified candidate markers closely linked to these QTLs will assist in selecting and assembling new APR gene combinations; expectantly this will help in achieving good levels of durable resistance for controlling BLR.  相似文献   

11.
Verticillium wilt (VW, caused by Verticillium dahliae Kleb) is a destructive fungal soil-borne disease in Upland cotton (Gossypium hirsutum L.). High levels of VW resistance can be transferred into Upland from Pima cotton (G. barbadense L.) through interspecific introgression breeding. In this greenhouse study, VW resistance was evaluated in a multi-parent advanced generation inter-cross (MAGIC) introgressed line (IL) population, derived from a random mated Barbadense Upland population with five generations of intermating (called RMBUP-C4) between three Upland cotton cultivars and 18 CS-B Upland lines each carrying a pair of G. barbadense chromosome or arm in the TM-1 background. The objectives of this study were to, (1) evaluate VW resistance of 530 MAGIC ILs in the greenhouse; and (2) to identify lines with VW resistance in the MAGIC population based on a total of three replicated greenhouse tests. Approximately 8 plants for each line in each replicate were grown and screened for VW resistance using three parameters i.e., disease leaf severity rating, percentage defoliated leaves, and percentage infected plants, with a total of ~?25,190 plants evaluated. A correlation analysis indicated that the three parameters were significantly and positively correlated with one another in each test. The disease leaf severity rating was the best parameter to assess VW resistance due to its relatively low coefficient of variation and its higher resolution to differentiate resistant genotypes from susceptible ones. Of the 530 genotypes, 5 showed resistance to VW, namely, NMIL348, NMIL518, NMIL405, NMIL290, NMIL307 and had higher levels of resistance to VW with mean disease leaf severity ratings, percentage of defoliated leaves, and percentage of infected plants across three tests ranging from 0.58–1.46, 9.46–26.74, and 25–95%, respectively. These lines can be used as parental lines to improve VW resistance in cotton breeding programs.  相似文献   

12.
Upland cotton, Gossypium hirsutum L. is the most widely planted cultivated cotton in the United States and the world. The other cultivated tetraploid species G. barbadense L. is planted on considerable less area; however, it produces extra long, strong, and fine fibers which spins into superior yarn. The wild cotton tetraploid species G. tomentosum Nuttall ex Seemann, native to the Hawaiian Archipelago also exhibits traits, such as drought tolerance, that would also be desirable to transfer to Upland cotton. Long-term breeding efforts using whole genome crosses between Upland and these species have not been successful in transferring very many desirable alleles into Upland cotton. Our chromosome substitution lines (CSL) have one chromosome or chromosome arm from an alien species backcrossed into the Upland cotton line,TM-1, via aneuploid technology. Five Upland cultivars were crossed with CS-B01, CS-T01, CS-B04, CS-T04, CS-B18 and CS-T18 and TM-1 the recurrent parent of the CSLs. This provided an opportunity to determine the effects of chromosomes 01, 04, and 18 from the three species in crosses with the five cultivars. Predicted genotypic mean effects of the parents, F2, and F3 generations for eight agronomic and fiber traits of importance were compared. The predicted hybrid mean effects for the three chromosomes from each species were different for several of the traits across cultivars. There was no single chromosome or species that was superior for all traits in crosses. Parental and hybrid lines often differed in the effect of a particular chromosome among the three species. The predicted genotypic mean effects for F2 and F3, with a few exceptions, generally agree with our previous results for additive and dominance genetic effects of these CSL.  相似文献   

13.
Gossypium barbadense L is an important genetic resource to improve fiber quality of Gossypium hirsutum L., but breeders have generally encountered difficulties in introgression following whole genome crosses primarily due to genomic incompatibility, complex genetic basis and low efficiency of phenotypic evaluation and selection on fiber quality. Chromosome segment substitution lines (CSILs) are a powerful tool to dissect and introgress alien alleles while minimizing negative effects from alleles on other chromosome segments of the donor parent. In the present study, using a CSIL+F2 mapping strategy, three QTLs each for fiber length (FL), fiber strength (FS) and micronaire value (MIC) were identified on chromosome 11 and 1, explaining 6.23–10.73 % of the phenotypic variation in the F2:3 population. In addition, through marker-assisted backcrossing, the G. barbadense alleles of these QTLs were incorporated into two elite commerical Upland cotton cultivars, Lumianyan28 (L28) and Shannongmian6 (SNM6). Field evaluation indicated that 80 % of the BC2F3 lines containing the qFL-c11-1 and qFS-c11-1 from Hai7124 had significantly higher FL and FS, while only 14.5 % BC2F3 lines containing the qMIC-c1-1 in SNM6 genetic background showed significant decrease in MIC. Some BC2F3 lines with improved target fiber quality traits and without remarkable deviations in non-target lint yield components were obtained.  相似文献   

14.
Anthocyanins and proanthocyanidins are the primary pigments of red rice and are also important functional nutrients for human health. To identify novel quantitative trait loci (QTLs) underlying anthocyanins and proanthocyanidins (ANC and PAC) in rice, a recombinant inbred line (RIL) derived from a cross of red rice ‘Hong Xiang 1’ (‘HX1’) and white rice ‘Song 98-131’ (‘S98-131’) was cultivated in six environments. A genetic map containing 126 markers covering 1833.4 cM with an average of 14.55 cM between markers was constructed. A total of 21 additive QTLs (A-QTLs) for ANC and PAC were identified from six environments using the IciMapping v3.3 software. Two new QTLs, qANC3 and qPAC12-4, were detected in several environments, and explained significant phenotypic variance. Nine QTLs of ANC and PAC were detected with additive × environmental interaction effects (AE effects) by QTLNetwork 2.1 software, but no epistatic and epistatic × environmental interaction effects (AA and AAE effects) were detected. The information obtained in this study could be useful for fine mapping and molecular marker-assisted selection of ANC and PAC in rice.  相似文献   

15.
Grain weight and grain length are the most stable components of rice yield and important indicators of consumer preference. Considering the potentials of wild rice and to enhance the rice yields to meet the increasing demands, 185 Backcross Inbred Lines (BILs) in the background of O. sativa ssp. indica cv. PR114, including 63 rufi-BILs derived from O. rufipogon IRGC104433 and 122 glumae-BILs from O. glumaepatula IRGC104387 were evaluated for mapping QTLs for yield and yield component traits using Genotyping by Sequencing (GBS). Phenotypic evaluation of BILs in three seasons spanning two locations revealed significant differences compared with recurrent parent. BILs which did not show significant differences for any trait under investigation, or similar based on pedigree, were excluded from GBS. Some glumae-BILs had to be excluded from mapping QTLs due to less sequence information. A custom designed approach for GBS data analysis identified 3322 informative SNPs in 55 rufi-BILs and 3437 informative SNPs in 79 glumae-BILs. QTL mapping identified one QTL for thousand grain weight (qtgw5.1), two for grain width (qgw5.1, qgw5.2) and one for grain length (qgl7.1) in rufi-BILs. In the glumae-BILs, three QTL for thousand grain weight (qtgw2.1, qtgw3.1, qtgw6.1) and two for grain length (qgl3.1, qgl7.1) were identified. Most of the grain weight and width QTL showed positive additive effect contributed by wild species allele, whereas the grain length QTL showed positive additive effect contributed by recurrent parent allele. Based on their physical position, none of the QTLs were found similar to previously cloned QTLs. QTLs for grain traits identified from low yielding wild relatives of rice reveals their significance in improving further the rice yields and widen the genetic base of cultivated rice.  相似文献   

16.
Valsa canker (Valsa ceratosperma (Tode ex Fr.) Maire) is one of the most destructive fungal diseases of apple, especially in Eastern Asia. In this study, the first high density genetic linkage map of Malus asiatica × Malus domestica was constructed by 640 simple sequence repeats (SSRs) and 490 single nucleotide polymorphisms (SNPs), which spanned 1497.5 cM with an average marker interval of 1.33 cM per marker. Quantitative trait loci (QTLs) for apple’s resistance to V. ceratosperma isolates 03-8 and xc56 were identified using the linkage map. Lesion lengths were used as the phenotypic data for the QTL analysis, which were measured on 1-year-old shoots inoculated with conidia of the two isolates. One QTL for resistance to isolate 03-8 was mapped on LG 16, and one QTL for resistance to isolate xc56 was detected on LG 9. Our research not only promoted the further understanding of the genetic basis of apple’s resistance to Valsa canker but also provided two molecular markers that might be used in future marker-assisted selection for resistance in apple breeding programs.  相似文献   

17.
Thorough understanding of the genetic mechanisms governing drought adaptive traits can facilitate drought resistance improvement. This study was conducted to identify chromosome regions harbouring QTLs contributing for water stress resistance in wheat. A RIL mapping population derived from a cross between W7984 (Synthetic) and Opata 85 was phenotyped for root length and root dry weight under water stress and non-stress growing conditions. ANOVA showed highly significant (p ≤ 0.01) variation among the RILs for both traits. Root length and root dry weight showed positive and significant (p ≤ 0.01) phenotypic correlation. Broad sense heritability was 86% for root length under stress and 65% for root dry weight under non-stress conditions. A total of eight root length and five root dry weight QTLs were identified under both water conditions. Root length QTLs Qrln.uwa.1BL, Qrln.uwa.2DS, Qrln.uwa.5AL and Qrln.uwa.6AL combined explained 43% of phenotypic variation under non-stress condition. Opata was the source of favourable alleles for root length QTLs under non-stress condition except for Qrln.uwa.6AL. Four stress specific root length QTLs, Qrls.uwa.1AS, Qrls.uwa.3AL, Qrls.uwa.7BL.1 and Qrls.uwa.7BL.2 jointly explained 47% of phenotypic variation. Synthetic wheat contributed favourable alleles for Qrls.uwa.1AS and Qrls.uwa.3AL. Two stable root dry weight QTLs on chromosomes 4AL and 5AL were consistently found in both water conditions. Three validation populations were developed by crossing cultivars Lang, Yitpi, and Chara with Synthetic W7984 to transfer two of the QTLs identified under stress condition. The F2.3 and F3.4 validation lines were phenotyped under the same level of water stress as RILs to examine the effect of these QTLs. There were 13.5 and 14.5% increases in average root length due to the inheritance of Qrls.uwa.1AS and Qrls.uwa.3AL, respectively. The result indicated that closely linked SSR markers Xbarc148 (Qrls.uwa.1AS) and Xgwm391 (Qrls.uwa.3AL) can be incorporated into MAS for water stress improvement in wheat.  相似文献   

18.
The ongoing rise in temperatures caused by global climate change is a critical climatic risk factor for rice production, and enhancing rice heat tolerance is an area of particular research interest. A recombinant inbred line (RIL) mapping population was developed from heat sensitive, rice cultivar IAPAR-9 crossed with heat tolerant, Liaoyan241. RIL and parental lines were exposed to high temperature at the heating and flowering stage in experiments in 2014 and 2015. As indicators of heat tolerance, the seed setting rate under natural (NS) and heat stress (HTS) conditions were measured, and the reduction rate of seed set (RRS) was calculated. Quantitative trait loci (QTL) analysis revealed eleven heat tolerance QTLs located on chromosomes 1, 3, 4, 5, and 6. Single QTL contribution rates were 4.75–13.81% and effect values were ? 5.98 to 5.00. Four major QTLs (qNS1, qNS4, qNS6, and qRRS1) were stable detected in different environments in both years. Thirteen QTLs with epistatic interactions and nine QTLs with environmental interactions were also detected. Major QTLs were all involved in epistatic and environmental interactions. Three QTLs from the SSR marker interval RM471 to RM177 region of chromosome 4 (qNS4, qHTS4, and qRRS4) were all involved in epistatic and environmental interactions and contributed to phenotypic variation, indicating that this region constituted a major QTL hotspot. The major QTL for heat tolerance identified in this study will aid in breeding tolerant cultivars and facilitating investigation of the molecular underpinnings of heat tolerance in rice.  相似文献   

19.
Soil and root samples were collected from major tomato growing areas of Ethiopia during the 2012/2013 growing season to identify root-knot nematode problems. DNA-based and isozyme techniques revealed that Meloidogyne incognita and M. javanica were the predominant Meloidogyne species across the sampled areas. The aggressiveness of different populations of these species was assessed on tomato cultivars Marmande and Moneymaker. The two most aggressive populations of each species were selected and further tested on 33 tomato genotypes. The resistance screening and mechanism of resistance was performed after inoculation with 100 freshly hatched (<24 h) second-stage juveniles (J2). Eight weeks after inoculation the number of egg masses produced on each cultivar was assessed. For the resistance mechanism study, J2 penetration and their subsequent development inside the tomato roots were examined at 1, 2, 4 and 6 weeks after inoculation. On both cultivars Marmande and Moneymaker all M. incognita and M. javanica populations formed a high number of egg masses indicating highly aggressive behaviour. Populations from ‘Jittu’ and ‘Babile’ for M. incognita and ‘Jittu’ and ‘Koka’ for M. javanica were selected as most aggressive. None of the 33 tomato genotypes were immune for these M. incognita and M. javanica populations. However, several tomato genotypes were found to have a significant effect on the number of egg masses produced indicating possible resistance. For M. javanica populations there were more plants from cultivars or breeding lines on which no egg masses were found compared to M. incognita populations. The lowest number of egg masses for both populations of M. incognita was produced on cultivars Bridget40, Galilea, and Irma while for M. javanica it was on Assila, Eden, Galilea, Tisey, CLN-2366A, CLN-2366B and CLN-2366C. Tomato genotypes, time (weeks after inoculation) and their interaction were significant sources of variation for J2 penetration and their subsequent development inside the tomato roots. Differential penetration was found in breeding lines such as CLN-2366A, CLN-2366B and CLN-2366C, but many of the selected tomato genotypes resistance for the tested M. incognita and M. javanica populations were expressed by delayed nematode development. Therefore, developing a simple screening technique to be used by local farmers or extension workers is crucial to facilitate selection of a suitable cultivar.  相似文献   

20.
Flag leaf-related traits (FLRTs) are determinant traits affecting plant architecture and yield potential in wheat (Triticum aestivum L.). In this study, three related recombinant inbred line (RIL) populations with a common female parent were developed to identify quantitative trait loci (QTL) for flag leaf width (FLW), length (FLL), and area (FLA) in four environments. A total of 31 QTL were detected in four environments. Two QTL for FLL on chromosomes 3B and 4A (QFll-3B and QFll-4A) and one for FLW on chromosome 2A (QFlw-2A) were major stable QTL. Ten QTL clusters (C1–C10) simultaneously controlling FLRTs and yield-related traits (YRTs) were identified. To investigate the genetic relationship between FLRTs and YRTs, correlation analysis was conducted. FLRTs were found to be positively correlated with YRTs especially with kernel weight per spike and kernel number per spike in all the three RIL populations and negatively correlated with spike number per plant. Appropriate flag leaf size could benefit the formation of high yield potential. This study laid a genetic foundation for improving yield potential in wheat molecular breeding programs.  相似文献   

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