接种不同致病力黄萎病菌的F1代棉花的基因型抗性研究

 在乌兹别克斯坦，棉黄萎病对棉花造成严重损失。为了选育能抗强致病力菌系的棉花品种，需确定棉花对不同地域的强致病力菌系的基因型抗性和F₁代的抗性遗传度。研究发现，品种Omad和品系L-44，L-408，L-155，L-1708对所选菌系的抗性最好。当受到侵染时，它们表现出超敏感性，但不表现黄萎病症状。F₁代的黄萎病抗性为超显性和显性遗传，且与鉴定方法无关。同时，存在中间性遗传。遗传优势度取决于其亲本的配合力、F₁代受侵染时的基因反应型和不同地域菌系的致病力。其中，Omad，С-5621，L-44，L-1708的表型抗性高；在F₁代中，组合L-155×С-5621和L1708×С-5621的表型抗性较高，在50％～80％。黄萎病抗性遗传控制的特点是趋向于最好或最差亲本的负或正的超显性、显性遗传以及中间型遗传。对所选菌系，杂交组合L-155×С-5621 和 L-155×L-44的综合抗性最好。

Genotypic Resistance of F1 Cotton Hybrids by Inoculation with Different Viru-lent Isolates of the Fungus Verticillium Dahliae Kiebahn

The plant pathogen Verticillium dahliae causes severe cotton loss in Uzbekistan. To create cotton varieties that are resistant to the more virulent races of V. dahliae, we wanted to determine genotypic resistance of varieties and lines of cotton to more virulent isolates of different geographic populations of the fungus V. dahliae isolated from different cotton varieties in Uzbekistan, and deter-mine the inheritance of wilt resistance with hybrids of the first generation to various isolates of V. dahliae. We found that the highest wilt resistance was observed in the variety Oread and lines L-44, L-408, L155 and L-1708 to the isolates 28, 30, 32, 36, 40 and 44. They exhibited hypersensitivity when the pathogen was inoculated into the plant, but they did not display external symptoms of wilt. Wilt resistance of hybrids of the first generation as determined by inoculation with the isolates of V. dahliae was inherited according to the type of super dominance and dominance toward the resistant or susceptible parent independent from the method used to determine the disease index. Also intermedi-ate inheritance was observed. The degree of dominance depended on the combinational ability of par-ents and genotype reaction of F1 hybrids when pathogens were introduced into the plant, and also on the virulence of the isolates found in different varieties of cotton from different soil-climatic regions. The varieties with the highest phenotypic wilt resistance (i. e., tolerance) were Oread, C-5621 and lines L-44 and L-1708. Among hybrids, the hybrid combinations L-155 X C-5621 and L1708 X C-5621 had the highest phenotypic wilt resistance. The degree of tolerant resistance to wilt varied from 50% Sponsor: USDA, Agricultural Research Service - Former Soviet Union Scientific Cooperation Program, Project(P-105).to 80 %. Genetic control of resistance to V. dahliae isolates and F1 hybrids was characterized by nega-tive and positive super dominance, dominance toward the best or the worst parent and intermediate in-heritance. The hybrid combinations L-155 X C-5621 and L-155 X L-44 had the best combinational wilt resistance toward the V. dahliae isolates studied, as compared to other hybrid combinations with the maternal forms Omad, C-8284 and L-408.