Evolution of diverse symbiotic phenotypes among native soil bacteria following spread of a genomic island from a rhizobial inoculant. The quality of legume protein depends on symbiotic nitrogen fixation by root nodule bacteria (RNB). Sustainable legume production in Australian agriculture depends on legume inoculation with effective strains of these bacteria. Unfortunately inoculant strains transfer DNA to other soil bacteria resulting in soil populations of RNB that compete for nodulation but a ....Evolution of diverse symbiotic phenotypes among native soil bacteria following spread of a genomic island from a rhizobial inoculant. The quality of legume protein depends on symbiotic nitrogen fixation by root nodule bacteria (RNB). Sustainable legume production in Australian agriculture depends on legume inoculation with effective strains of these bacteria. Unfortunately inoculant strains transfer DNA to other soil bacteria resulting in soil populations of RNB that compete for nodulation but are less effective in nitrogen fixation. This transfer of DNA threatens a $2 billion asset in Australian agriculture. We will use molecular microbial ecology to investigate the mechanisms of genetic transfer of symbiotic DNA in RNB, and use this knowledge to prevent it.Read moreRead less
Race status, resistance mechanisms, and new sources of resistance to Phytophthora clandestina, a major threat to subterranean clover production. Devastating outbreaks of disease caused by Phytophthora clandestina (Phytophthora root rot) since the late 1970s demonstrated the capacity of this disease to impact severely on clover pasture production across southern Australia, particularly as new races of Phytophthora have rapidly emerged to overcome the resistance of all commercial cultivars. The p ....Race status, resistance mechanisms, and new sources of resistance to Phytophthora clandestina, a major threat to subterranean clover production. Devastating outbreaks of disease caused by Phytophthora clandestina (Phytophthora root rot) since the late 1970s demonstrated the capacity of this disease to impact severely on clover pasture production across southern Australia, particularly as new races of Phytophthora have rapidly emerged to overcome the resistance of all commercial cultivars. The proposed research seeks to delineate new races of the pathogen, to identify the histological and biochemical mechanisms by which resistance to Phytophthora root rot is expressed, and to identify new sources of host resistance. This proposed research will enable breeders, for the first time, to incorporate multiple types of resistance and against different races into new host varieties.Read moreRead less