Evaluation of an Indian collection of black gram germplasm and identification of resistance sources to Mungbean yellow mosaic virus.

Abstract

Yellow mosaic disease (YMD) of black gram is an important production constraint in India. Black gram germplasm, consisting of 344 accessions, originally collected from different geographic regions of India and conserved in National Gene Bank at National Bureau of Plant Genetic Resources, India, were evaluated for their response against YMD. None of the accessions tested was found to be immune, however, considerable variation in disease response was observed among them. Of the 344 accessions, 32 showed resistance in the field during the rainy season (JuneeSeptember) 2010 as assessed by coefficient of infection (CI) and area under disease progress curve (AUDPC). These accessions were re-evaluated during rainy season (JuneeSeptember) 2011 and 2012 for their disease resistance along with yield-associated characters. Eight accessions that exhibited consistently highly resistant (HR) or resistant (R) reaction (CI 9) along with lower AUDPC value ( 650), were further evaluated following inoculation with whiteflies or via agroinoculation. Along with the resistant trait, these eight accessions were also found either similar or even better in their yield potential as compared to check. After artificial inoculation using viruliferous whiteflies under glasshouse, of the eight field-resistant accessions, response of two (IC144901 and IC001572) were categorized as HR as <10% plants exhibited minute yellow specks after 17 e22 dpi. Two accessions viz. IC011613 and IC485638 showed <20% incidence with bright yellow specks or spots after 15e20 dpi and were grouped into R category. The resistance of these four accessions was further confirmed through agroinoculation of the infectious cloned viral DNA under controlled conditions. In resistant accessions low accumulation of viral DNA was observed over a period of time. These four accessions could be used in future breeding programmes to develop black gram cultivars resistant to YMD or could be used directly as varieties to manage YMD after adaption to various agro-climatic regions.