Growth curve and biochemical analyses of callus of ipê-branco (Tabebuia roseo alba (Ridl.) Sand.)

Abstract

The understanding of biochemical changes that occur during the callus growth and development can provide support to the in vitro cultivation process. In addition, the substances present in these structures such as secondary metabolites can also be determined. With these premises in mind, the objective of this work was to determine the growth curve of callus of ipê-branco and to biochemically analyze them through the determination of the contents of total soluble sugars, reducing sugars, total soluble proteins and amino acids. Leaf segments of ipê-branco were inoculated onto MS medium supplemented with sucrose (30 g L-1), agar (6 g L-1) and 1 mg L-1 2,4-D associated to 2 mg L-1 kinetin. The material was kept in the dark for 90 days. Each 15 days the material was taken out to be analyzed. The growth curve of the fresh material of the callus formed from leaf explants of ipê-branco presents sigmoid growth, with five distinct phases. The transfer of the calli to a new culture medium should be done between 60th and 75th days of cultivation. Maximum contents of total soluble sugars and reducing sugars were observed on the 45th day of cultivation. The contents of total soluble proteins were higher on the inoculation day, showing a decrease on the following days. Maximum contents of amino acids were observed on the 15th day of cultivation.