Micropropagation and in vitro fructan production by Chresta exsucca DC. (Asteraceae)

Abstract

Chresta exsucca DC. (Asteraceae) is a species native to Cerrado that stores inulin-type fructans in its underground organs. These water-soluble polysaccharides are valuable in the pharmaceutical and food industries and are crucial in plant responses to abiotic stress. Although several Asteraceae species have been micropropagated, few have been studied for in vitro fructan production. This study aimed to establish the micropropagation protocol of C. exsucca and examine fructan production in the organs of plants cultivated in vitro. Cypselae of C. exsucca, collected from field-grown plants, were disinfested for in vitro germination. The seedlings provided nodal segments that were inoculated in Murashige and Skoog (MS) medium with varying concentrations of 6-benzylaminopurine (BAP) for shoot induction, followed by indole-3-acetic acid (IAA) for rooting. Fructans were analyzed in the organs of micropropagated plants. All cypselae of C. exsucca successfully germinated in vitro after the disinfestation treatment with 1.25% active chlorine followed by inoculation in MS medium without or with 100% of macronutrients. The highest shoot proliferation occurred on MS containing 4.44 µM BAP. Root elongation was most pronounced in the absence of IAA or at the lower concentration tested (0.57 and 2.86 µM), whereas higher IAA levels inhibited root extension. Plants acclimatized in a 1:1 mixture of commercial substrate and soil from C. exsucca’s natural habitat achieved a 73.3% survival rate. Inulin-type fructans were produced in vitro in roots and calluses but not in other organs. The micropropagation techniques applied were effective in obtaining fructan-producing clones of C. exsucca.