Physiological mechanism of resistance antibiosis to anthracnose of different Manihot varieties

Abstract

Cassava is one of the main food crops in Africa, particularly in Côte d'Ivoire. However, the cultivated varieties are prone to attack by diseases. The present work focused on the role of phenolic and in particular flavonoid resistance markers in the Manihot esculenta-Colletotrichum gloeosporioides pathosystem. The aim was to elucidate the involvement of flavonoid antibiosis in the natural defense of three cultivars of M. esculenta when confronted with attacks by C. gloeosporioides. The quantitative dosage approach for total phenolics and flavonoids as well as the identification of flavonoid antibiosis have been carried out. The results revealed that the cultivars 9620A, TMS30572 and YACE of M. esculenta have, after the C. gloeosporioides inoculation tests, reacted early 2 days after inoculation (JAI) and accumulated relatively high levels of antibiosis phenolic and flavonoid 9JAI. The three cultivars accumulated constitutive flavonoid antibiosis and 3 neosynthesized antibiosis from 7JAI to 9JAI. The accumulation of flavonoid antibacterials neosynthesized in the stems and in the leaves testify to the expression of a systemic resistance of the cassava plants. The cultivars 9620A and TMS30572 are more tolerant than cultivar YACE. This study approach has made it possible to discriminate between cultivars and can therefore be used as a complementary selection tool to traditional selection tests.

Keywords: Manihot esculenta, anthracnose, flavonoïd antibisis, glyphosate.