The Effect of Mono- and Mixed Phytoplasma and Bacterial Infections on Galega orientalis L. Plants

In recent years, in regions of intensive agriculture, due to unfavorable agro-ecological conditions, mixed infections have become a serious threat to the production of high-quality crop products, in particular, Galega orientalis L. Objective. To investigate the effect of mono- and mixed phytoplasma and bacterial infection on Galega orientalis L. plants. Methods. Plants of Galega orientalis L. were inoculated with phytoplasma strains: A. laidlawii var. granulum 118 ‒ the causative agent of pale green dwarfism of wheat; A. laidlawii 101 and A. laidlawii 178 ‒ pathogens of tomato trunk, and Pseudomonas syringae pv. atrofaciens D13 ‒ the causative agent of wheat basal bacteriosis. Different schemes of inoculation of Galega orientalis L. plants were used in the experiments, which were applied both in mono- and mixed phytoplasma and phytoplasma-bacterial infection. Symptoms were recorded by visual examination starting from the 14th day. Uninfected plants of this crop served as a control. Results. Under both mono- and mixed phytoplasma-infection, both typical (anthocyanin coloration of stems and formation of additional shoots from the base of internodes ("witch's brooms") and atypical (small leaves and shortened internode spacing, which are characteristic of pale green dwarfism of wheat (PGD) symptoms of phytoplasmosis, were established on plants of Galega orientalis L. Under the conditions of phytoplasma-bacterial infection in plants, a noticeable thickening of the stem and stunted growth were observed, i.e., the symptoms that are characteristic of the development of phytoplasmosis, and were recorded, but their manifestation was atypical for legumes. Thus, in the case of phytoplasma-bacterial infection, the vast majority of symptoms characteristic of phytoplasmosis (namely, pale green dwarfism of wheat) were recorded such as dwarfism, small leaves, shortened distances between internodes, which are atypical for legumes. Conclusions. Typical and atypical symptoms of phytoplasmosis and bacteriosis for Galega orientalis L. under mono- and mixed infection have been established. Mono- and especially mixed infections with phytoplasmas and phytopathogenic bacteria significantly affect the development of Galega orientalis L. plants. The increase in the infectious load on Galega orientalis L. plants, as well as the priority of the pathogen's penetration into plant tissues, leads to a significant inhibition of the development of infected plants of this crop. The obtained data can be useful for diagnostics of Galega orientalis L. crops affected by phytoplasmosis or bacteriosis.