Development and characterization of interspecific hybrids of Trifolium alexandrinum×T. apertum using embryo rescue

Abstract

AbstractThis is the first report on the development of interspecific hybrids between Trifolium alexandrinum and T. apertum using embryo rescue and characterization of F1 plants. T. apertum was used as the male parent and T. alexandrinum as the female parent. Development of interspecific hybrids under natural conditions is not successful and so embryo rescue was attempted. Of the several combinations tried, pollination 2 days after emasculation and embryos rescued 11 days after pollination was found to be the best. For embryo culture, EC3 medium consisting of MS basal supplemented with 2.3 μM kinetin and 3% sucrose was used. Germinated embryos were transferred to LSP3 medium 25 days after inoculation wherein most of the cultures showed multiple shoots that were split and subcultured on RL1 medium for rooting. After hardening, about 75% of hybrids were successfully transferred to the field. The hybrids, in general, showed morphological traits intermediate between the two parents; however, a few hybrids showed better growth than either parent. Some F1 plants were almost 3 weeks later in flowering than the female parent. Pollen fertility among these plants ranged from 78 to approximately 100%. Chromosomal associations at diakinesis and isozyme banding patterns for acid phosphatase (ACP), superoxide dismutase (SOD) and peroxidase also confirmed the hybrid nature of the plants.