Avaliação do crescimento e da imunidade de plantas de Solanum tuberosum (L.) tratadas com rizobactérias

Abstract

Potatoes (Solanum tuberosum L.) are the third most consumed crop in the world, after rice and wheat. Among the diseases affecting potato, the blackleg and tuber soft rot, caused by phytobacteria Pectobacterium spp., lead to significant losses in the yield crop. Several studies have been exploring the use of plant defense inducers as a strategy to control plant diseases. The use of plant growth-promoting rhizobacteria (PGPR) in agriculture can lead to plant growth and enhancement of plant defense through the promotion of induced systemic resistance (ISR). However, the mechanisms involved in promoting ISR are still poorly understood. This study aimed to screen rhizobacteria of the genus Streptomyces with capacity to promote plant growth and induce Solanum tuberosum innate immunity. To achieve these objectives, we evaluated: i) the ability of Streptomyces isolates to produce auxin (3-indoleacetic acid), ACC deaminase (1-aminocyclopropane-1-carboxylic acid deaminase) and siderophores; ii) their capacity to promote the growth of potato plants; iii) the induction of resistance in potato plants challenged with Pectobacterium carotovorum subsp. brasiliensis and iv) the expression of genes related to defense pathways in S. tuberosum, promoted by Streptomyces and P. carotovorum. Results indicated that the CLV163 isolate presents PGPR features, such as high auxin and siderophores production, and promoted plant defense against P. carotovorum. Although CLV145 showed the highest auxin and siderophores production, it reduced the shoot dry mass and was inefficient in promoting plant defense. Moreover, the ability of Streptomyces in producing ACC deaminase was not critical for promoting plant growth. The CLV163 isolate induced a priming state in potato plants that has occurred through the activation of the AS and ET pathways, and its interaction with S. tuberosum plants did not impair the plant growth.