Research Projects

Over the past three decades, tremendous progress has been made in understanding how beneficial bacteria interact with plants in standard terrestrial environments and how these interactions affect host health, productivity, and ecological fitness. In contrast, nothing is known about beneficial plant-bacterial interactions in brackish environments, an interface between marine, and terrestrial ecosystems that is important for a wide range of plants including crops. With a particular interest in how native salt-tolerant rice crops and their beneficial microbial symbionts interact in brackish environments. The PI’s lab discovered a unique symbiosis between a novel marine phytobeneficial rhizobacteria, named Pokkaliibacter plantistimulans gen. nov. sp. nov., and its host, a brackish-grown native salt-tolerant pokkali rice (Krishnan et al 2018). In this mutualistic relationship, P. plantistimulans promotes pokkali rice growth and provides protection against higher salinity, and in turn, the host provides suitable habitat and nutrients for its bacterial partner. Further investigation has established that P. plantistimulans is an integral part of the pokkali rice root microbiota and exerts its beneficial effects including salinity tolerance through an unknown mechanism. Of special significance, the brackish condition was identified as the key environmental factor that determines the symbiotic relationship between P. plantistimulans and pokkali rice. These findings indicate an intimate ecological relationship exists between P. plantistimulans and pokkali rice, which largely depends on their growth environment, especially brackish conditions. This warrants further investigation. Currently, the underlying molecular and genetic mechanisms through which P. plantistimulans interact with its host, pokkali rice, in the presence of the brackish condition, are largely unknown and uncharacterized. Here, in this proposal, using P. plantistimulans and its natural host, pokkali rice as a research system, we would like to identify novel genetic traits of P. plantistimulans colonization and their functional role in pokkali rice symbiosis under brackish conditions for the first time. To address this research question, we will adopt advanced molecular and genetic tools including large-scale random transposon mutagenesis, RNA transcriptome, site-directed mutagenesis, and gene fusions with functional in planta assays. The work will contribute significant new knowledge on a highly unusual mutualistic relationship between P. plantistimulans and pokkali rice under brackish conditions. Further, this study will broadly impact the understanding of how changing global climatic conditions in particular rising seawater, will impact specific plant-beneficial bacteria interactions critical for enhancing crop performance in coastal agriculture.