OPTIMIZATION OF REGENERATION PROTOCOL AND MOLECULAR ASSESSMENT OF SOMACLONAL VARIATIONS IN PEANUT (Arachis hypogaea L.)

Abstract

This investigation was carried over three successive generations. Seeds of eight peanut cultivars, i.e., Giza-5, Giza-6, Ismailia-1, Sohag-104, Sohag-110, R-92, Virginia and Gregory were irradiated with five gamma ray doses i.e. 0, 50, 100, 200 and 300 Gy and sown at Ismailia Research station. At the same time, regeneration protocol for peanut was established. The plantlets were transferred to the greenhouse for acclimatization process and obtain R1 and R2 regenerates. Evaluation of M2 and M3 generations were done at Ismailia Research station in the next two seasons under natural infection with studied pests, i.e., Two-spotted spider mite (Tetranychus urticae), Ahphids (Aphis craccivora Koch) and Cotton leaf worm (Spodoptera littoralis) under field conditions. M2 and M3 generations and R1 and R2 regenerates were evaluated under artificially infestation conditions with the studied pests. All cultivars ranged from resistant to moderately susceptible against the studied economic pests. Meanwhile, three genotypes appeared; one of them, developed via irradiation with gamma ray doses (CMPM-4), and two were developed through combination between somaclonal variation and irradiation with gamma ray doses; CMPM-2 and CMPM-8, they were resistant to the studied pests. Ten RAPD primers and seven ISSRs primers across the eight peanut cultivars and the three newly developed resistant mutants were used to genetically characterize the eleven genotypes and find out molecular markers associated with pests resistance in peanut. Several molecular markers either positive or negative related to pests resistance in some peanut mutants were obtained.

Key words: Peanut, Tissue culture, Gamma ray, pest resistance, two- spotted spider mite, aphid, cotton leaf worm, RAPD, ISSRs.