Generation mean analysis of resistance to downy mildew in adult muskmelon plants

• Published in: Euphytica Vol. 173; no. 1; pp. 121 - 127
• Main Authors: Shashikumar, K. T, Pitchaimuthu, M, Rawal, R. D
• Format: Journal Article
• Language: English
• Published: Dordrecht Dordrecht : Springer Netherlands 01.05.2010; Springer Netherlands; Springer; Springer Nature B.V
• Subjects: additive gene effects; Agronomy. Soil science and plant productions; Airborne microorganisms; alleles; Biological and medical sciences; Biomedical and Life Sciences; Biotechnology; Cucumis melo; disease resistance; dominance (genetics); downy mildew; Experiments; field experimentation; Field tests; fruit crops; Fundamental and applied biological sciences. Psychology; Fungi; genetic resistance; Genetics; Genetics and breeding of economic plants; germplasm screening; greenhouse experimentation; heritability; heterosis; Inbreeding; inheritance (genetics); Life Sciences; mature plants; muskmelons; Pest resistance; plant age; Plant diseases; Plant Genetics and Genomics; plant pathogenic fungi; Plant pathogens; Plant Pathology; Plant Physiology; Plant Sciences; Pseudoperonospora cubensis; Varietal selection. Specialized plant breeding, plant breeding aims; India; Quantitative resistance; Dominance; Downy mildew; Generation mean analysis; Stramenopila; Plant pathogen; Cucurbitaceae; Oomycota; Fungus resistance; Fruit crop; Dicotyledones; Angiospermae; Genetic improvement; Adult plant; Spermatophyta; Nonspecific resistance; Cucumis melo; Pseudoperonospora cubensis
• ISSN: 0014-2336; 1573-5060
• DOI: 10.1007/s10681-010-0132-0

Downy mildew (Pseudoperonospora cubensis) is the most devastating disease in muskmelon (Cucumis melo). A generation mean analysis study was designed to determine the types of gene action and estimate the heritability for resistance to downy mildew in four selected crosses of muskmelon. Generation mean analysis revealed that genetic dominance may be of greater importance for expression of resistance to downy mildew in both greenhouse and field experiments and in all the crosses. The F₁ mean was significantly lesser than the mid-parent value and skewed towards resistant parent in all the crosses. Negative sign associated with gene effects indicated, in those crosses, that disease level could be decreased in relation to midparent. All the crosses expressed significant and positive additive (d) gene effects. Dominance (h) and dominance × dominance (l) gene effects had opposite sign in all crosses and both experiments, which implied duplicate type of gene action. High mid-parent heterosis in all the crosses indicated strong dominance effects (as combination of parental alleles) for resistance to downy mildew. In all the crosses, both resistant and susceptible parent contributed one or more dominant/partially dominant factors for resistance. Estimates of broad-sense heritability were high and relatively consistent in both experiments. The two different screening experiments showed that fixable gene effects (d + i) were lower than the non-fixable gene effects (h + l) in all the crosses indicating greater role of non-additive effects in the inheritance of resistance to downy mildew. Resistance to downy appeared to be controlled mainly by dominance effects, therefore the inbred lines IIHR 121 and IIHR 122 could be used strategically to exploit heterotic effects.