Biochimical Resistance Mechanism Study of Jatropha Curcas (Euphorbiaceae) Against Lasiodiplodia Theobramae, a Leaf Blight and Necrosis Agent

This study was initiated in order to understand the biochemical mechanisms involved in the resistance of J. curcas to Lasiodiplodia theobromae. Artificial inoculations were done on young seedlings leaves of 8 J. curcas local accessions from Burkina Faso including 4 resistant and 4 susceptible. Two extractions were made for the evaluation of each biochemical parameter: one on the 1st day before and the second on the 7th day after inoculation. The study revealed that the response of J curcas to L. threobromae infection is depending to the resistance or the susceptibility of accessions. It showed an increase in the content of biomolecules synthesis such as phenolic, flavonoids, proteins, photosynthetic pigments, salicylic acid and also an increase of catalase and trypsin inhibition activities. In susceptible accessions, the study revealed a decrease in the photosynthetic pigments and an increase in MDA content comparatively to resistant accessions. The ACP performed on the basis of the evaluated biochemical parameters showed that the axis F1 allows the separation of the resistant and the susceptible accessions, and indicated that the resistance of accessions result in the activation of biomolecules synthesis such as phenolic, flavonoids, proteins, photosynthetic pigments, salicylic acid and stimulation of catalase and trypsin inhibition activities. The F2 axis is associated with sugars content and, chymotrypsin inhibition and SOD activities. In susceptible accessions, an increase in MDA content and SOD activity were observed. This study represents an important step in combating leaf fungal diseases by opting to the green technology and by breeding for genotypes with inducing natural defense compounds.