Genetics of resistance to Cucumber mosaic virus in Cucumis sativus var. hardwickii R. Alef

Abstract

The genetics of resistance to Cucumber mosaic virus (CMV) in Cucumis sativus var. hardwickii R. Alef, the wild progenitor of cultivated cucumber was assessed by challenge inoculation and by natural infection of CMV. Among the 31 genotypes of C. sativus var. hardwickii collected from 21 locations in India the lowest mean percent disease intensity (PDI) was recorded in IC-277048 (6.33%) while the highest PDI was observed in IC-331631 (75.33%). All the four cultivated varieties (DC-1, DC-2, CHC-1 and CHC-2) showed very high PDI and susceptible disease reaction. Based on mean PDI, 8 genotypes were categorized as resistant, 13 as moderately resistant, 9 as moderately susceptible and one as susceptible. A chi-square test of frequency distribution based on mean PDI in F 2 progenies of six resistant 9 susceptible crosses revealed monogenic recessive Mendelian ratio 1(R):3(S) to be the best fit. This monogenic recessive model was further confirmed by 1(R):1(S) ratio as the best fit for back cross with resistant parent and no fit for either 3:1 or 1:1 in the back cross with the susceptible parent. The results revealed that CMV resistance in C. sativus var. hardwickii was controlled by a single recessive gene. Considering the cross compatibility between C. sativus var. hardwickii and cultivated cucumber, the resistance trait can be easily transferred to cultivated species through simple backcross breeding.

Estimates of Genetic Component of Variances and Genetic Ratios for Earliness and Yield Attributing Traits in Cucumber

“…However, the dominance components were higher than the additive component for most of the traits. These results are in conformity with [7,8,9]. In the present investigation, the predominance of non-additive gene action and low narrow sense heritability for most of the yield attributing characters suggesting the importance of heterosis breeding in cucumber.…”

Genetics of resistance in Luffa cylindrica Roem. against Tomato leaf curl New Delhi virus

“…Data were recorded on 30 plants in the non-segregating generations, namely, P 1 , P 2 and F 1 , 90 plants in the F 2 generation and 45 plants in the B 1 and B 2 generations. To understand the Mendelian genetics of resistance, we classified the individual plants into resistant and susceptible categories (e.g., the plants falling into I, R and MR categories were considered to be resistant, while MS, S and HS plants were considered to be susceptible), as described by Munshi et al (2008). The total number of plants falling into the different reaction classes were counted and subjected to chi-square (v 2 ) analysis for goodness of fit to various classical Mendelian ratios, as suggested by Panse and Sukhatme (1985).…”

Genetic analysis of resistance to watermelon bud necrosis orthotospovirus in watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai]

“…Further, they can tolerate a delayed chemical spray interval and may contribute to significant reduction in chemical inputs. Such a slower disease progress was earlier observed in peanut against GBNV (Kesmala, and Kesmala et al., ) and TSWV (Nascimento et al., ), in cucumber against cucumber mosaic virus (Munshi et al., ) and in okra against okra yellow vein mosaic virus (Seth, Chattopadhyay, Dutta, Hazra, & Singh, ). Further, in the experiment it was also observed that the P1, F 1 , F 2 and BC1 showed a higher plant survival and vine length compared to P2, BC2 and checks for both the crosses.…”

“…TSWV (Nascimento et al, 2006), in cucumber against cucumber mosaic virus (Munshi et al, 2008) and in okra against okra yellow vein mosaic virus (Seth, Chattopadhyay, Dutta, Hazra, & Singh, 2017). Further, in the experiment it was also observed that the P1, F 1 , F 2 and BC1 showed a higher plant survival and vine length compared to P2, BC2 and checks for both the crosses.…”