Production of interspecific hybrids between Sesamum alatum Thonn and Sesamum indicum L. through ovule culture and screening for phyllody disease resistance

Abstract

Sesame (Sesamum indicum L.) is an important oilseed crop grown in the tropical and subtropical regions of the world. Despite the nutritional value and cultural importance, the biotechnological research on sesame is very limited. In this study, we have optimized a simple and efficient protocol for producing an interspecific hybrid between Sesamum alatum and S. indicum through ovule culture. In the cross S. alatum×S. indicum, capsule retention without embryo abortion was extended up to 7days after pollination by spraying the growth regulator mixture containing 289µM gibberellic acid (GA3), 80.6µM α-naphthalene acetic acid (NAA) and 23.3µM kinetin. Direct organogenesis was successfully achieved when the ovules, excised from 7-day-old capsules, were cultured on MS medium containing 8.8µM benzylaminopurine (BAP), 2.8µM indole acetic acid (IAA) and 1712.3µM glutamine. The regenerants produced roots on half strength MS medium supplemented with 0.27µM NAA. Phenotypically, the S. alatum×S. indicum hybrid plants were intermediate to those of parents for majority of the traits. Cytological studies revealed normal meiosis in the hybrid without any chromosomal abnormalities. Peroxidase and esterase isozymes were demonstrated to be useful in the identification of hybrid plants. Screening against phyllody disease under greenhouse conditions revealed that the hybrids were moderately resistant.