Vol. 12, Special Issue 10 (2023)

Author(s):
Shivani Indrajeet Yadav, Kuldeep Pandey, Sanjay Pathak and Jagveer Singh

Abstract:
Fruit crops have traditionally been improved through conventional breeding methods that involve selecting plants with desirable traits over many generations to achieve incremental improvements. This approach aims to enhance various phenotypic traits, such as fruit size, yield, nutritional properties, and aroma/taste. The introduction of new traits, such as disease resistance, requires crossing an elite line with a disease-resistant variety, followed by repeated backcrossing with the elite parent to preserve as much of the genetic material from the elite variety as possible while introducing the new resistance allele. This process takes many generations and can take several decades in species with a long juvenile phase for the selectable phenotype to emerge in each generation. The outcrossing nature of many fruit- bearing crops makes it impossible to recover the original genotype and phenotype, which makes the chance selection of a desirable phenotype in an elite cultivar highly valuable. The development of resistance to apple scab is a good example of the difficulties of conventional breeding, as crosses between a wild type and an elite line of apple initiated in the 1950s have not yet resulted in derivative cultivars with desired fruit quality traits. Marker-assisted selection, which involves selecting molecular markers linked to the desired trait at an earlier developmental stage, has been developed to some extent, but it still requires generations of backcrossing to achieve successful introgression.