Inheritance of Urdbean Leaf Crinkle Virus Disease in Blackgram [Vigna mungo (L.) Hepper]

Abstract

Background: Blackgram or Urdbean [Vigna mungo (L.) Hepper] is an important food legume crop of Indian sub-continent. Urdbean Leaf Crinkle Virus (ULCV) disease is an emerging major yield limiting factor. The yield loss due to ULCV disease ranges from 62 - 100%. So far, no information is available on the genetics of this disease. Hence, the present investigation was carried out to study the nature of inheritance of ULCV disease in blackgram. Methods: The present investigation was conducted at the National Pulses Research Center, Vamban, Tamil Nadu, India. Seven crosses were made between ULCV susceptible [VBN (Bg] 4, VBN 6 and VBN 8) and resistant (Mash 114, Mash 1008 and VBG 11053) genotypes during Nov-Dec 2016 season. All F2 populations were artificially screened during July-Aug, 2017 for their resistance against ULCV disease through sap transmission technique. Individual plants in F2 generation were scored as resistant and susceptible based on the symptom appearance. Disease reaction was recorded on 60 days after sap transmission. Ratio for ULCV disease (resistance: susceptible) in the segregating population was tested through Chi-square test. Result: Among crosses viz., VBN 6 x Mash 114, VBN 6 x Mash 1008, VBN 8 x Mash 114, VBN 8 x Mash 1008 and VBN 8 x VBG 11053 had digeneic inhibitory gene action (13R:3S). The cross VBN (Bg) 4 x Mash 1008 had trigeneic inhibitory gene action (49R:15S). The cross VBN (Bg) 4 x Mash 114 did not fit into any genetic ratio. Differences in number of genes involved for ULCV might be due to the presence of similar allelic pattern for a gene among male and female parents. Gene symbols were assigned for six genotypes viz., S1S1S2S2ii [VBN (Bg) 4], S1S1s2s2ii (VBN 6 and VBN 8) and s1s1s2s2ii (Mash 114, Mash 1008 and VBG 11053). Hence, delayed selection in recombination breeding was suggested to enhance the ULCV disease resistance in black gram.