Multi-location preliminary field screening of World Vegetable Center bitter gourd breeding lines for reaction to Tomato leaf curl New Delhi virus in selected hotspots in India
2019
Yadav, K. K. | Hegde, G. | Agarwal, P. | Chawda, V. | Kenyon, L. | Dhillon, N. P. S.
Bitter gourd (Momordica charantia L.) is an economically and nutritionally important vegetable in Asia where approximately 400,000 ha is cultivated annually. Tomato leaf curl New Delhi virus (ToLCNDV) (genus Begomovirus, family Geminiviridae) is a significant biotic constraint to bitter gourd production throughout South Asia. Natural epidemics of ToLCNDV regularly occur on bitter gourd when populations of the vector whitefly (Bemisia tabaci) are abundant. Bitter gourd breeding lines, bred at World Vegetable Center Thailand, were evaluated in three major bitter gourd production areas in India ‒ Guntur (Andhra Pradesh), Jagdalpur (Chhattisgarh) and Bangalore (Karnataka) ‒ where natural epidemics of ToLCNDV regularly occur. Plants were rated 60-days after transplanting for ToLCNDV severity using a 0-2 scale where: 0 = no visible symptoms (= resistant); 1 = mild symptoms (= moderately resistant) and 2 = severe symptoms ( = susceptible). Phylogenetic analysis of the nucleotide sequences of the begomovirus DNA-A components amplified by PCR from infected bitter gourd leaf samples collected from the test fields confirmed infection by strains of ToLCNDV. Breeding line, AVBG1655, remained consistently free of disease symptoms at each location and was considered resistant or highly tolerant, although ToLCNDV DNA-A could be detected in AVBG1655 plants by PCR. Lines AVBG1651, AVBG1652 and AVBG1656 segregated for resistance at each location, and all the other lines were ToLCNDV susceptible. Lines AVBG1651, AVBG1652, AVBG1655 and AVBG1656 are sister lines originating from a landrace population collected in Bangladesh. Line AVBG1655 will be tested further at multiple locations across South Asia, and crosses will be made to understand the genetics of the ToLCNDV resistance.
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