Bacillus thuringiensis - Mediated Priming Induces Jasmonate/Ethylene and Salicylic Acid-Dependent Defense Pathways Genes in Tomato Plants

Bacillus thuringiensis Berliner as a biological control agent can play a crucial role in the integrated management of a wide range of plant pests and diseases. B. thuringiensis is expected to elicit plant defensive response through plant recognition of microbe-associated molecular patterns (MAMPs), however, there is little information on the molecular base of induced systemic resistance priming of tomatoes. Using q-RT-PCR technique, the transcription rate of the genes responsive to salicylic acid, SA (Chi9, Chi3, PR1), jasmonic acid, JA (Pin2), and of the signaling regulatory genes of jasmonate/ ethylene, JA/ ET hormones (WRKY33, ERF1, MYC2) were studied at the time of 6, 12, 24, 48, 72, and 96 hours after inoculation of tomato plants with B. thuringiensis strain IBRC-M 11096 as the promoting plant growth factor. The bacterial strain could prime tomato cultivar of Early Urbana through induction of all three hormonal signaling pathways (SA, JA, and ET) involved in the resistance to a broad range of necrotrophic as well as biotrophic pathogens. However, further transcription of WRKY33, ERF1, MYC2, and Pin2 genes in the inoculated plants, indicated that the observed priming effect was mainly based on JA/ ET signaling pathway. These promising results indicate high potential of superior isolates of B. thuringiensis in the field management of the crops.

Keywords:

Beneficial soil microbes , Hormone signaling pathway , Induced systemic resistance , Systemic acquired resistance