A comprehensive review on role of recessive alleles in the genetic improvement of plantation crops

Abstract

Recessive alleles play a significant role in the genetic improvement of plantation crops such as examples: oilseed (coconut, oil palm), beverage (coffee, tea, cocoa), nut (arecanut), etc. These alleles contribute to agronomically important including disease resistance, stress tolerance, yield enhancement and quality improvement. Unlike dominant alleles, recessive traits require a homozygous state for expression, making their deployment in breeding programs more challenging, yet often rewarding due to their unique genetic advantages. Recent advancements in marker-assisted selection (MAS), genomic sequencing and genome editing (CRISPR-Cas9) have facilitated the identification and application of beneficial recessive alleles in crop breeding. Examples include low-caffeine coffee, coconut varieties enriched in lauric acid and high-yield oil palms. Additionally, recessive mutations contribute to pathogen resistance (e.g., lethal yellowing in coconut, leaf rust in coffee and Phytophthora resistance in cocoa). Despite their benefits, challenges such as low allele frequency, inbreeding depression and linkage with undesirable traits require strategic breeding approaches. Advances in genomics and biotechnological tools are accelerating the deployment of recessive alleles in commercial cultivars, ensuring sustainable and climate-resilient crop production. This review underscores the pivotal role of recessive alleles in plantation crop breeding and emphasizes the transformative potential of modern genomics and biotechnology to harness these traits for sustainable agriculture.