Genetic control of enation leaf curl virus disease tolerance in cultivated species of okra

Abstract

ABSTRACTOkra enation leaf curl virus (ELCV) disease is an emerging threat to okra (Abelmoschus esculentus L. Moench.) cultivation in the tropics. Identifying and utilizing tolerant germplasm, and understanding the genetic control of ELCV disease tolerance, is necessary to develop an effective breeding strategy. Six generations of the crosses: Tolerant × Tolerant and Tolerant × Susceptible, were utilized to study the genetic basis of ELCV disease tolerance. The pattern of segregation of 2 tolerant parents indicated a single dominant gene, along with some minor factors, governed ELCV disease susceptibility in tolerant parents. The segregation pattern for ELCV disease in the F2 generation of 2 Tolerant × Susceptible crosses indicated existence of 2 genes with duplicate recessive epistasis. Non-additive gene action and duplicate epistasis were the most predominant types of gene effects controlling days to 1st appearance of ELCV disease and percent disease index of ELCV traits. For improvement of these traits, selection should be in later segregating generations, and intermating among selected segregates be followed by 1 or 2 generations of selfing to break the undesirable linkage and allow accumulation of favorable alleles.