LAUSR

Agrobacterium tumefaciens is one of the most serious pathogenic bacteria. It is responsible for one of the most devastating crown diseases that account for the maximum yield loss and quality attributes of the ber (Ziziphus mauritiana) fruit plant. Powdery mildew of ber incited by Oidiumerysiphoides f. sp. ziziphi is the most important disease that causes maximum reduction in yield and quality of ber fruits. In the present work, we have carried out the spectroscopic investigations on healthy and bacterial crown gall diseased ber fruits (Ziziphus mauritiana) in order to detect the chemical changes that may take place in the elemental and molecular composition of the ber fruits with the occurrence of crown gall on their surface. Laser-induced breakdown spectroscopy (LIBS) was used for the elemental analysis and FTIR spectroscopy was employed to understand the change in molecular components such as sugar and starch, carbohydrates, fats, lipids, and proteins. LIBS results revealed the decreasing trends of mineral elements calcium (Ca), and increasing trends of magnesium (Mg), potassium (K), silicon (Si), manganese (Mn), and sodium (Na) in diseased samples as compared with healthy samples. Partial least square discriminant analysis (PLS-DA) of the LIBS data has been carried out to find out the differences among the different sample classes. We were able to distinguish healthy fruit samples as compared with diseased ones on the basis of their elemental differences using PLS-DA method. It has been concluded that the chemical changes (elemental and molecular) observed in the ber fruit samples were basically due to the infestation by Agrobacterium tumefaciens, which was further confirmed by the isolation method.