Instabilidade fenotípica na variedade RB872552 de cana- de-açúcar: marcadores ISSR e enzimas do sistema antioxidativo

Abstract

The sugarcane culture has great importance in the socio-economic development of Brazil, being one of the earliest economic activities in the country's history. The proliferation of commercial varieties of sugarcane has been successfully accomplished by applying techniques of tissue culture, as an example the system of temporary immersion bioreactor (TIB). In this system the plant material is immersed in liquid medium for controlled intervals of time, which favors the absorption of nutrients from the culture medium by stimulating the production of seedlings. During the in vitro culture the plant material is submitted to unusual environmental conditions that can cause physiological morphological, biochemical and molecular imbalances. Such imbalances can lead to large losses in the production of biofactories, as well as in research institutions. Therefore, the evaluation both biochemical and molecular in vitro plants has great importance for the production of seedlings genetically faithful to matrix plant. In order to assess the causes of physiological disorder observed in sugarcane RB872552 variety which caused the uncontrolled growth of small buds, forming a cluster of shoots known a "green mass" were performed biochemical and molecular analysis. The "masses" green "and the plants were collected by the TIB and subcultured in flasks containing MS liquid medium supplemented or not with 1.5 mg L-1 6-benzylaminopurine (BAP), following the conventional micropropagation of sugarcane. The activity of catalase and peroxidase was higher in samples of "green mass” cultured on TIB. The ascorbate peroxidase activity was higher in the "green masses cultured in the presence of BAP in the two micropropagation systems. The ascorbate peroxidase activity was higher in the "green masses” grow in the presence of BAP in the two micropropagation systems. The DNA fragments obtained after amplification of the whole plant material analyzed showed monomorphism, suggesting genetic fidelity of cloned material. The profile of enzymatic antioxidative system associated with the molecular analysis showed that the physiological disorder that resulted in the emergence of "green masses" was not caused by genetic variation but a result of stress conditions to which the material was submitted during cultivation in vitro.