A histological tool to assess the progress of somatic embryogenesis in cotton (Gossypium hirsutum L.)

Abstract

A study was conducted on local elite cultivars of American cotton (Gossypium hirsutum L.) viz., MCU7 and TCH 1569 in order to assess their callusing as well as regeneration potential. Although six different media compositions were tested for the callusing, results revealed that the medium MS salts + 0.4 mg/I thiamine HG1 + 2.0mg/lNAA+ 1.0 mg/1 kinetin+30 g/1 glucose + 0.8% agar exhibited successful and faster induction of calli. After the induction of calli, they were placed on different sub-culture media for inducing embryogenic calli. However, significant differentiation for the formation of embryogenic calli was not observed with the media compositions attempted in the study. As the cotton crop is reported to be recalcitrant for regeneration through somatic embryogenesis, to know the progress of tissue culture or development of embryogenic calli, histological studies were carried out using microtomy. The results of the microtome study clearly revealed the clumping and organisation of large number of cells into a definite structure irrespective of the genotypes ancl explants. Therefore, further manipulation or alteration of hormonal/vitamin combinations of media may induce friable embryogenic calli resulting in mature somatic embryos, which will give raise to a plantlet. This histological tool experienced as an efficient tool to save the time in tissue culture by knowing the progress of somatic embryogenesis on the other hand is also guiding the scientist to switchover to newer media composition in case of nonembryogenesis.