Introgression of yellow vein mosaic virus resistance from Abelmoschus caillei (A.Cher) steveis into A. escuientus (L.) Moench.

Abstract

The present investigation on “Introgression of Yellow Vein Mosaic Virus resistance from A.caillei (A. Cher.) Steveis into A.esculentus (L.) Moench” was conducted at the Department of Olericulture, College of Horticulture, KAU, Vellanikkara, Thrissur during 2003 to 2004. The major objective of this study was to transfer YVMV resistance from A.caillei variety Susthira to popular but highly susceptible variety Salkeerthi (A.esculentus).

The study was aimed at finding the chromosome affinity between two species involved in interspecific hybridisation. Biochemical characterization based on activity of peroxidase, polyphenol oxidase and protein content, protein banding pattern in parental species and its derivatives. A.caillei variety Susthira and A.esculentus variety Salkeerthi were crossed reciprocally and crossability index between the species was worked out. It was found that crossing between the species was more successful when A.caillei was used as female parent. The interspecific F1 seeds obtained were used to raise the F2 generation. The parental species, interspecific F1 hybrids and F2 generation were subjected to detailed testing programmes for reaction to YVMV. A.caillei and F2 generation were highly resistant to YVMV. Whereas A.esculentus and F1 generation plants were susceptible to YVMV. The F2 generation plants were morphologically more similar to semi wild parent A.caillei. However, three F2 selections viz.,F2-2, F2-4, F2-6 having more fruit length and desirable number of ridges per fruit could be selected. These selections showed considerably good amount of pollen fertility and seed set. So these selections can be further advanced and stabilized with desirable agronomic traits like fruit characters can be selected in future.

The cytological study showed that the chromosome number of A.esculentus and A.caillei as 2n = 130 and 2n =184 respectively. In the interspecific F1 hybrid (A.caillei x A.essculentus) mostly 65 bivalents could be observed suggesting a good amount of affinity between the genome of two species.

Biochemical analysis on activity of peroxidase, polyphenol oxidase and protein estimation, protein banding pattern in relation to YVMV resistance in the parental species, F1 hybrids and F2 generation was carried out. The genotype A.esculentus showed maximum YVMV infection of (C.I. 70.7) in the field screening studies, in which low peroxidase activity (58.94 units/g/min.) and polyphenol oxidase (14.1 units/g/min.) supporting with low protein content of 9.8 mg/g of seed. A.esculentus showed only one protein band of Rm = 0.788 which was common for all genotypes studied. It implies that the resistant factor acquired in A.caillei as well as F2 has no place in the susceptible species A.esculentus.

A.caillei with high peroxidase, polyphenol oxidase and high protein content (15 mg/g of seed), additional protein band (Rm value = 0.211) influenced on resistance to YVMV. The disease incidence in F1 plants showed symptom at 35 days after sowing the symptom of YVMV disappeared at the stage of maturity in F1 which was clearly indicated by one additional protein band (Rm value = 0.322). This protein band (Rm value = 0.322) which may be performing the function of the resistance/ tolerance of the resistant species and F2 plants in which the protein banding was expressed (Rm value = 0.211). The disease infection in the early stage may be due to the cumulative action of low peroxidase, low polyphenol oxidase and low protein (11.8 mg/g of seed) which was lower than resistant parents.F2 generation plants were free from symptom of YVMV infection which may be influenced by high peroxidase, high polyphenol oxidase and high protein content, additional protein band (Rm value = 0.211). Which was similar to that of resistant parent A. caillei and indicated that semi-wild parental resistant character was expressed in the F2 generation.