SUSCEPTIBILITY TO BACTERIAL LEAF STREAK MEDIATED BY A PUTATIVE SULFATE TRANSPORTER IN RICE: MECHANISM AND INTERVENTION

The long-term goals served by this project are mechanistic understanding of plant disease and development of effective and durable control measures. The project seeks to structurally and functionally characterize a pathogen-activated host gene that plays a critical role in disease in a major crop species, and to ascertain the potential of strategies to interfere with activation or function of the gene to prevent disease development. The disease, bacterial leaf streak of rice, is caused by the bacterium Xanthomonas oryzae pv. oryzicola (Xoc), and the host gene, OsSULTR3;6, is predicted to encode a sulfate transporter. OsSULTR3;6 is activated by direct binding of a pathogen-injected transcription activator-like effector (TALE) protein. Each of several Xoc strains examined to date has this effector and activates OsSULTR3;6. The activity of OsSULTR3;6 as a disease susceptibility gene is antagonized by expression of the closely related OsSULTR3;2 gene. The specific objectives of the project are to:Structurally and functionally characterize OsSULTR3;6 toward mechanistic understanding of its role in susceptibility. Determine how many of 50 additional Xoc strains activate OsSULTR3;6, any candidate alternate S genes, and whether perturbations related to apoplastic sulfate, sugar, amino acids, or water can substitute for or counteract OsSULTR3;6 activation.Determine how OsSULTR3;2 antagonizes the S gene function of OsSULTR3;6.Assess three OsSULTR3;6-centered strategies for improving control of bacterial leaf streak in rice: a) targeted mutation of the Tal2g binding site in the OsSULTR3;6 promoter, b) amendment of the OsSULTR3;2 promoter with one or more other Xoc TALE binding sites, and c) TALE inducible transgenic expression of OsSULTR3;6-specific nanobodies (small, single chain anitbodies)To broaden impact, a) provide research experience and mentoring for junior scientists, undergraduates, and high school students b) contribute mini-courses in plant biology for local K-12 students, and c) provide online access to project information and deliverables