Identification of Quantitative Trait Loci Associated with Cold Tolerance in Maize (Zea Mays L.) PDF Download
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Author: Choosak Jompuk
Publisher:
ISBN:
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Languages : en
Pages : 100
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Author: Choosak Jompuk
Publisher:
ISBN:
Category :
Languages : en
Pages : 100
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Author: Robert A. Guse
Publisher:
ISBN:
Category :
Languages : en
Pages : 168
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Author: Rkia Moutiq
Publisher:
ISBN:
Category :
Languages : en
Pages : 280
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In general, maize, especially germplasm from the tropics and subtropics, is sensitive to photoperiod. This sensitivity hindered the exchange of germplasm between latitudes. To identify quantitative trait loci (QTL) associated with the response to photoperiod, a population of 236 F3 lines produced from a cross between a photoperiod-sensitive line CML9 and insensitive inbred A632Ht was used. These F3 lines were evaluated in three long and three short-day environments, in adjacent fields using artificial light, and in fields located in different latitudes, Mexico and Iowa. Days from sowing to anthesis (DTA), final leaf number (FLN) and plant height (PH) were measured. For each of these traits, photoperiod response (PPR) was estimated as the difference between the trait in long- and short-days divided by the trait in short-days. Composite interval mapping was used to detect QTL for each trait and comparison of locations of QTL detected in different daylengths for the same trait and for different traits were examined. A unique set of QTL was detected for each photoperiod and for each trait. One QTL for DTA, three QTL for FLN and four QTL for PH were detected in the same genetic regions in both daylengths. Five QTL for DTA, four QTL for FLN and three QTL for PH were detected only in long-day environments. Nine QTL for DTA, five QTL for FLN and three QTL for PH were detected only in short-day environments. QTL for photoperiod response were detected on four chromosomes for PPR[Subscript DTA], on three chromosomes for PPR[Subscript FLN] and on three chromosomes for PPR[Subscript PH]. Chromosomes 2, 3, 4, 5, 6, 8, 9, and 10 had a cluster of QTL for different traits. This might suggest a common initial mechanism with subsequent specific pathways that regulate different traits.
Author: Matthew David Krakowsky
Publisher:
ISBN:
Category :
Languages : en
Pages : 338
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Composite interval mapping (CIM) was used to detect QTL for each trait, and the relationships between the QTL detected for the same traits in different generations and among different traits in the same generation were examined. Seven and fourteen QTL for stalk tunneling were observed in the mean environments for the F3 and RI lines of B73 x De811, four and twelve of which, respectively, are linked to QTL for CWCs. The previously reported genetic correlations for ECB stalk tunneling with CWCs in the F3 lines (r[Subscript g] = -0.11 to -0.33) indicate that a genetic association may exist between the two traits. However, the genetic correlations for the RIL were -0.03 to 0.08, raising the possibility that the correlations observed in the F3 lines were either due to environmental factors or the result of linkage disequilibrium. Factors other than concentrations of CWCs appear to be associated with the expression of resistance to stalk tunneling in this population.
Author: Jesse Abner Poland
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Category :
Languages : en
Pages : 0
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Several large scale quantitative genetic studies were conducted to better understand the genetic basis for quantitative disease resistance (QDR) in plants. The focus of these studies was the economically important disease of maize (Zea mays L. ssp. mays), northern leaf blight (NLB, caused by Setosphaeria turcica L. anamorph Exserohilum turcicum). The maize nested association mapping (NAM) population, a reference design population consisting of 4,630 recombinant inbred lines, was evaluated over three environments for quantitative resistance to NLB, giving highly heritable resistance phenotypes. Over 200 resistance alleles at 30 different quantitative trait loci (QTL) for disease resistance were identified. Genome-wide nested association mapping for NLB resistance identified genes at six of the QTL that have been associated with disease resistance including three receptor-like kinases, two ethylene response factors, and one Mlo-like gene. Further insight on QDR, with a focus on multiple disease resistance (MDR), was gained by jointly analyzing independent data on NAM for resistance to southern leaf blight (SLB), gray leaf spot (GLS) and NLB. To examine the possibility of MDR genes, the estimated allele effects from each founder inbred were compared at loci were QTL for two or more diseases co-localized. At seven loci, positively correlated allele effects provided evidence for MDR genes. Analysis of the NAM population suggested that resistance to the three diseases studied here is largely due to the accumulation of disease-specific genes and, to a limited extent, pleiotropic genes that condition MDR. A final study was conducted to determine the effect of variability in visual disease rating on mapping disease QTL by assessing the effects of scorer variability and rating scales on mapping QTL for NLB in a single recombinant inbred line population from NAM. Stepwise general linear model selection (GLM) and inclusive composite interval mapping (ICIM) were used for QTL mapping. For both GLM and ICIM the same QTL were largely found across scorers, though some QTL were only identified by some scorers. Strikingly, the magnitudes of estimated allele effects from different scorers at identified QRL were drastically different, sometime by as much as three fold. The studies conducted here advance the understanding of QDR in plants and lay groundwork for identifying the genes responsible for resistance to NLB in maize. A greater understanding of QDR will assist in the development of durable resistant crop cultivars, improving food security and safety.
Author: Ruth Petzold Koester
Publisher:
ISBN:
Category :
Languages : en
Pages : 312
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Author: Yingfang Zhu
Publisher: Frontiers Media SA
ISBN: 2832507182
Category : Science
Languages : en
Pages : 210
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Category :
Languages : en
Pages :
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Identification of QTL can aide in future breeding objectives by allowing breeders either to improve a line through targeted introgressions or assist in forward breeding strategies. Such analyses may be particularly helpful in integrating exotic germplasm into a breeding program. The percentage of tropical maize germplasm grown in U.S. farmers' fields is almost nonexistent. Tropical germplasm in maize (Zea mays L.) is a valuable resource to decrease the dependence upon a limited genetic base currently used to produce commercial hybrids, extend selection limits for grain yield, and to provide an insurance function against emerging biotic and abiotic stresses. Results of research presented in this dissertation support these recommendations. Experiments were conducted to evaluate 143 S4:5 recombinant inbred lines (RILs) resulting from a cross between NC300, an all-tropical, temperate adapted line, and B104, a stiff stalk line. The 143 RILs were topcrossed to the Lancaster tester FR615xFR697 and randomly subdivided into two sets. The two sets were evaluated for resistance to GLS disease and yielding ability in three and eight North Carolina environments, respectively. Spatial trends were examined in the GLS trials. Significant (P d".01) trend effects were fitted in five of the six set-by-environment combinations, which led to improved analyses within and across environments for both sets. Ninety-three and eighty-two percent of the RILs in topcrosses (RILT) were significantly (P = 0.05) more resistant to GLS when compared to the mean of the commercial checks for set 1 and 2, respectively. Twenty-one RILs from both sets did not differ significantly (P = 0.05) for grain yield when compared to the mean of the commercial checks. RIL 2070 yielded significantly (P = 0.05) higher when compared to one commercial check, HC33. TR7322. RIL 1991 was rated the most resistant entry in set 1 and also did not differ from the mean of the commercial checks for grain yield. The RILs we.
Author: Noor E Mujjassim
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Author: Michael Richard Kerns
Publisher:
ISBN:
Category :
Languages : en
Pages : 168
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