Introgression of leafhopper resistance from silver leaf sunflower (Helianthus argophyllus G.&T.) to cultivated sunflower.

Abstract

The genetic diversity of the sunflower crop has been significantly reduced during the process of domestication and rigorous breeding. Wild species have always been a source for the novel gene(s) for both biotic and abiotic stress tolerance and therefore seem to be an integral part of the breeding programme for germplasm enhancement. The annual diploid wild species Helianthus argophyllus known as silver leaf sunflower possesses considerable variability for resistance to drought, diseases and parasitic Orobanche and insect resistance which can be utilized for the improvement of cultivated sunflower. Leafhopper, Amrasca biguttula bigittula is a major insect pest during rabi (winter) causing a yield loss of 46% in India. In the present investigation, H. argophyllus was crossed with a maintainer line ARM-243B with an objective of introgressing resistance to leafhopper. A total of 20 interspecific derivatives developed (BC F ) along with two susceptible checks viz., DCMS-2B and Morden were screened in a replicated trial against leafhopper using the infester row method over two years. The mean scale index (MSI) was followed (0-5 scale) to categorise resistant and highly susceptible genotypes. In the first year, seven interspecific derivatives viz., PB-1001, PB-1003, PB-1005, PB-1007, PB-1008, PB-1014 and PB-1019 were found resistant to leafhopper with a MSI of 1.0and leafhopper infestation of 6.8-11.5 nymphs per 3 leaves/plant while the remaining interspecific derivatives exhibited moderately resistance reaction. Susceptible checks, NDCMS-2B and Morden recorded leafhopper populations of 17.8 and 20.2 nymphs per 3 leaves/plant with a MSI of 3.8 and 3.6 (highly susceptible), respectively. The resistant interspecific derivatives and most susceptible checks were assessed for their reaction and the resistance in these lines was confirmed by MSI of 1.0compared to susceptible checks NDCMS-2B (MSI, 4.0) and Morden (MSI, 3.7). Leafhopper infestation in the resistant lines was in the range of 6.8-12.3 leafhopper nymphs/ 3 leaves/plant while susceptible lines NDCMS-2B and Morden harboured 20.0 and 17.3 leafhopper nymphs/3 leaves/plant, respectively. This is the first report from India to introgress resistance to leafhopper using the wild silver leaf sunflower H. argophyllus. The identified resistant lines and tolerant sunflower interspecific derivatives in this study could be further utilized in breeding programmes aimed at incorporation of resistance to leafhoppers.