Pataky J K, Bohn M O, Lutz J D, Richter P M
University of Illinois, Department of Crop Sciences, Urbana, IL 61801, USA.
Phytopathology. 2008 Apr;98(4):469-74. doi: 10.1094/PHYTO-98-4-0469.
The objectives of this research were to identify quantitative trait loci (QTL) for Stewart's wilt resistance from a mapping population derived from a sweet corn hybrid that is highly resistant to Pantoea stewartii and to determine if marker-based selection for those QTL could substantially improve Stewart's wilt resistance in a population derived from a cross of resistant lines and a highly susceptible sweet corn inbred. Three significant QTL for Stewart's wilt resistance on chromosomes 2 (bin 2.03), 5 (bin 5.03), and 6 (bin 6.06/6.07) explained 31% of the genetic variance in a population of 110 F(3:4) families derived from the sweet corn hybrid Bonus. The three QTL appeared to be additive in their effects on Stewart's wilt ratings. Based on means of families that were either homozygous or heterozygous for marker alleles associated with the resistance QTL, the QTL on chromosomes 2 and 6 appeared to have dominant or partially dominant gene action, while the QTL on chromosome 5 appeared to be recessive. A population of 422 BC(2)S(2) families was derived from crosses of a sweet corn inbred highly susceptible to Stewart's wilt, Green Giant Code 88 (GG88), and plants from two F(3:4) families (12465 and 12467) from the Bonus mapping population that were homozygous for marker alleles associated with Stewart's wilt resistance at the three QTL. Mean Stewart's wilt ratings for BC(2)S(2) families were significantly (P < 0.05) lower for families that were homozygous for the bnlg1902 marker allele (bin 5.03) from resistant lines 12465 or 12467 than for families that were heterozygous at this marker locus or homozygous for the bnlg1902 marker allele from GG88. Resistance associated with this QTL was expressed only if F(3:5) or BC(2)S(2) families were homozygous for marker alleles associated with the resistant inbred parent (P(1)). Marker alleles identified in the F(3:5) mapping population that were in proximity to the resistance QTL on chromosomes 2 and 6 were not polymorphic in crosses of GG88 with 12465 and 12467. Selection for other polymorphic marker loci adjacent to these two regions did not improve Stewart's wilt resistance of BC(2)S(2) families.
本研究的目标是从一个对斯图尔特氏萎蔫病具有高度抗性的甜玉米杂交种衍生的作图群体中鉴定出与斯图尔特氏萎蔫病抗性相关的数量性状位点（QTL），并确定基于这些QTL的标记辅助选择是否能显著提高一个由抗性品系与一个高度感病的甜玉米自交系杂交产生的群体对斯图尔特氏萎蔫病的抗性。在2号染色体（2.03区间）、5号染色体（5.03区间）和6号染色体（6.06/6.07区间）上发现了3个与斯图尔特氏萎蔫病抗性相关的显著QTL，它们在一个由甜玉米杂交种“博尼斯”衍生的110个F(3:4)家系群体中解释了31%的遗传变异。这3个QTL对斯图尔特氏萎蔫病评级的影响似乎是累加的。基于与抗性QTL相关的标记等位基因纯合或杂合的家系均值，2号和6号染色体上的QTL似乎具有显性或部分显性基因作用，而5号染色体上的QTL似乎是隐性的。一个由422个BC(2)S(2)家系组成的群体来自一个对斯图尔特氏萎蔫病高度感病的甜玉米自交系“绿巨人88号”（GG88）与来自“博尼斯”作图群体的两个F(3:4)家系（12465和12467）的杂交，这两个家系在3个QTL上与斯图尔特氏萎蔫病抗性相关的标记等位基因是纯合的。对于来自抗性品系12465或12467且对bnlg1902标记等位基因（5.03区间）纯合的BC(2)S(2)家系，其斯图尔特氏萎蔫病评级均值显著（P < 0.05）低于在该标记位点杂合或对来自GG88的bnlg1902标记等位基因纯合的家系。只有当F(3:5)或BC(2)S(2)家系对与抗性自交亲本（P(1)）相关的标记等位基因纯合时，与该QTL相关的抗性才会表达。在F(3:5)作图群体中鉴定出的与2号和6号染色体上的抗性QTL相邻的标记等位基因在GG88与12465和12467的杂交中没有多态性。对这两个区域相邻的其他多态性标记位点进行选择并没有提高BC(2)S(2)家系对斯图尔特氏萎蔫病的抗性。
