Effect of Micropropagation Conditions on Adventitious Buds Formation and the Circadian Expression of the ACO013229.1 Gene in Ananas Comosus

Abstract

mooth cayenne pineapple cultivar is considered the most suitable variety for the climatic conditions in Egypt, in addition to its distinctive flavor and ability for canning. To meet market demand, large quantities of plant materials are required, which cannot be obtained via traditional breeding methods. As a result, an in vitro technique was designed to increase the multiplication rate, rooting, and acclimatization of this unique pineapple variety. Thidiazuron (TDZ) at 2.0 mg/l proved to be superior for direct organogenesis rate. Half strength Murashige and Skoog (MS) medium containing 1.0 mg/l indole-3-butyric acid (IBA) in combination with 0.5 mg/l naphthalene acetic acid (NAA) improved the number and length of roots. Organogenesis has been accelerated from in vitro derived leaves and developed to healthy plantlets, which were acclimatized in the greenhouse. In order to investigate the effect of micropropagation on circadian rhythm, the circadian expression of Aco013229.1 was compared, which belongs to the MADS-box gene family, between the in vitro propagated plantlets and the in vivo-grown plants. The unaffected expression pattern of Aco013229.1 proposed that in vitro micropropagation did not affect the circadian cycling; hence, the CAM photosynthesis process was not interrupted. Moreover, the circadian expression of Aco013229.1 of the in vitro and in vivo-grown plants showed a similar pattern, strongly pointing at a stable circadian rhythm of the micropropagated plants and thus a well-maintained CAM photosynthesis. This gene family plays a significant role in a number of biological processes especially flowering.