Evaluation of Abnormal Hypocotyl Growth of Mutant Capsicum annuum Plants

Abstract

Horticulture is a dynamically evolving and an ever-changing sector which needs new ideas, plant materials, and cultivating methods to produce more. Involving different mutants in breeding lines may lead to new opportunities to create new cultivating methods. pcx (procumbent plant) and tti (tortuosa internodi) Capsicum annuum mutant plants, which present abnormal stem growth, were investigated in various in vitro experiments. The pcx breeding line presents highly diverse hypocotyl growth even in the early phenophase, such as normally growing plants and the ‘laying’ habit. On the other hand, tti plants only present their elongated slender stem trait in a more mature phase. In our experiment of reorientation, we used one-sided illumination, where each of the phenotypes sensed and reacted to light, and only the pcx plants exhibited a negative gravitropic response. It was also the result that the tti plants sensed gravity, but the weak structure of the hypocotyls made them incapable of following its direction. Since the pcx plants were the only ones with an ‘antigravitropic’ growth, we used them to evaluate the time course they needed to adapt and follow the gravity vector after reorientation. The pcx plants sensing gravity adapted similarly to controls and started bending after 120 min, but those which presented as ‘anti-gravitropic’ did not respond even after 420 min.