Genetic Diversity in Castor Bean

Abstract

Castor bean is an important nonedible oilseed crop that has many industrial uses. Genetic diversity in a germplasm is the fundamental requirement for crop improvement programs. There are several genetic markers available for assessment of genetic diversity among the genotypes and accessions. Though castor bean is a monotypic, it exhibits wide phenotypic diversity. In castor bean, genetic markers such as agro-morphological characters, biochemical and cytological markers were widely used in characterization of genetic variation in the germplasm from India, Nigeria, Turkey, China, Brazil, Iran, and Ethiopia which indicated a low-to-high-level diversity in the castor bean germplasm depending on the markers and the genotypes studied. Genetic diversity in castor bean was assessed by using both dominant and codominant molecular markers (random amplified polymorphic DNA, RAPD), inter-simple sequence repeats (ISSR), start codon targeted (SCoT), amplified fragment length polymorphism (AFLP), simple sequence repeat (SSR), expressed sequence tag-simple sequence repeats (EST-SSR), and random microsatellite amplified polymorphic DNA (RMAPD), and also advanced molecular markers, such as single nucleotide polymorphism (SNP), sequence-related amplification polymorphism (SRAP), target region amplification polymorphism (TRAP), and methylation-sensitive amplification polymorphism (MSAP). Molecular marker utilization in the characterization of genetic diversity in germplasm from countries including India, China, Brazil, Mexico, and worldwide collection revealed a low-modest genetic diversity in castor bean. The availability of castor bean genome has accelerated the molecular marker development of easy, fast, and reliable DNA markers for the assessment of genetic variation in the castor bean and further these would serve as a major tool in the characterization of genetic diversity and assist marker-assisted breeding programs for crop improvement.