Studies on Phytohormone Requirements for Regeneration from Potato Explants

Abstract

In the present thesis work, attempts have been made to study and adopt different regeneration protocols for indigenous potato cultivars. Different phytohormones employed for the purpose include auxins like IAA (Indole acetic acid) and NAA ( naphthalene acetic acid), cytokinins like BAP (Benzyl amino purine) and zeatin, and gibberellic acid (GA3). The potato cultivars chosen for regeneration studies were Kufri chipsona- 1 (CS-1), Kufri chipsona-2 (CS-2), Kufri jyoti (KJ), Kufri chandramukhi (KCM). These varieties are well adapted to the agroclimatic conditions of our country. The internodal stem segments of potato cultivars were chosen as explants because of their lesser sensitivity towards injuries while manipulation during regeneration studies. Initially, the media employed for regeneration consists of phytohormones like NAA, BAP and GA3. But the response amongst the cultivars was not promising. The possible chances of occurrence of somaclonal variation because of the longer period of incubation of intervening callus phase made the indirect mode of regeneration an undesirable process. The promising results of using zeatin as a cytokinin in the regeneration media as cited in previous studies prompted us to incorporate zeatin in regeneration media for our indigenous potato cultivars. Media composition with different concentration of zeatin in combination with IAA and GA3 were designed in this study. The introduction of zeatin in regeneration media resulted in minimum callus phase and accelerated shoot bud formation. Although the presence of zeatin in the media resulted in development of highly organogenic microcalli but the response was not same in all the cultivars. Out of all the cultivars studied, Kufri Chipsona (CS-1) showed best results. So, attempts need to be made further to modify the media for relatively rapid and efficient regeneration.