Nuclear recessive and oligogenic inheritance of resistance to Pepper yellow leaf curl Indonesia virus in Capsicum (Capsicum annuum L.)

The Pepper yellow leaf curl Indonesia Virus (PepYLCIV) significantly restricts pepper production in Indonesia. The aim of this study sought to (1) clarify the inheritance pattern of pepper resistance to PepYLCIV, (2) determine the number of resistance genes based on phenotypic segregation in F2 and backcross genotypes. The selected resistant and susceptible parental lines, BISI HP 17627 and BISI HP 17628 respectively, were utilized to generate F1, F1 reciprocal, F2, and Backcross plants (BC1 and BC2 plants). Each plant was artificially infected with 10 Bemisia tabaci carrying the PepYLCIV single virus. Severity and RAUDPC were assessed in each plant. The results indicated that F1 plants were susceptible, reflecting recessive gene controlled the resistance trait. The F2 population exhibited a non-normal distribution of RAUDPC values. Chi-square analysis of categorized resistant vs susceptible plants indicated the best fit to a 10:54 segregation ratio, aligning with a model that incorporates three recessive genes demonstrating duplicate recessive epistasis. This discovery is corroborated by the backcross ratio and the estimated number of genes regulated by two genes. The findings indicate that resistance to PepYLCIV in pepper is governed by a recessive oligogenic mechanism, wherein resistance manifests only when a minimum of two out of three loci are homozygous recessive. Molecular validation using the CAPS marker S05_14208507 target for pepy-1 gene and viral load quantification confirmed this inheritance model. This information suggests the use of two or more resistant genes in breeding procedures to generate stable hybrid cultivars with enduring PepYLCIV resistance. These findings offer promising prospects for developing hybrid cultivars with durable resistance to PepYLCIV.