Efeito de bioestimulantes derivados de macroalgas na atenuação do estresse e propagação in vitro de Comanthera mucugensis (Giul.) L. R. Parra & Giul.

Abstract

Currently, there is a growing debate around the need to intensify agriculture using eco-friendly methods. In this context, seaweed-derived biostimulants emerge as a promising alternative to boost a more sustainable and safe agricultural production. This bioinput can be integrated into in vitro cultivation systems and assist in the conservation of plant genetic resources. The Comantera mucugensis species is endemic to the Chapada Diamantina-BA and is endangered due to extractivism, prolonged droughts and forest fires. The plant tissue culture represents an effective strategy to conserve and propagate the species through organogenesis and somatic embryogenesis protocols. The results of the present thesis demonstrated the potential use of aqueous and polysaccharide extracts of the seaweed Hypnea pseudomusciformis and Agardhiella subulata, and of κ-carrageenan in attenuating heat stress in C. mucugensis seeds exposed to different levels of high temperature. The treatment with κ-carrageenan was also able to attenuate the negative effects of water stress on germination, survival, and root growth of the species, as well as increase the synthesis of polyamines, which may be associated in the induction of shoots via direct organogenesis. Another important finding demonstrated that picloram associated with κ-carrageenan promotes callus formation with embryogenic potential. The biostimulant seems to regulate the metabolism of polyamines that participate in the in vitro morphogenesis processes. In addition, the use of κ-carrageenan as an alternative agent promoted better conditions for plant growth and shoot regeneration via direct and indirect organogenesis compared to agar, resulting in a reduction in the cost of manufacturing the culture medium. The results of the present thesis contribute to the advancement of knowledge on the effects of seaweed-derived biostimulants as attenuators of heat and water stress, and as modulators of in vitro morphogenesis of C. mucugensis. Thus, it was possible to improve in vitro cultivation in a sustainable way and to establish optimized protocols for organogenesis and callogenesis.