Prevalence of seed-borne bacterial diseases poses a severe threat to rice production due to a drastic rise of toxin-producing Burkholderia pathogens, which lead to destructive damage to yield, quality and even resilience of paddy ecosystem. Manipulating disease resistance of the host plant is deemed to be a promising alternative and a more environmentally friendly approach in modern agricultural practices. However, is disease resistance related to the microbiota of the host plant? Is it hereditary? These questions remain largely obscure.
Recently, the role of bacterial seed endophytes in disease resistance in rice was unveiled by the research team led by Dr. WANG Mengcen from Zhejiang University and the team led by Dr. Tomislav Cernava from Graz University of Technology, and these findings were published as a featured cover article in Nature Plants.
Researchers observed that rice plants of the same cultivar can be differentiated into disease-resistant and susceptible phenotypes under the same pathogen pressure. The disease-resistant phenotype was characterized by the predominantly occurring Sphingomonas members in the seed endosphere. In the follow-up analyses, it was observed that Sphingomonas melonis, accumulated and transmitted across generations in disease-resistant rice plants, confers resistance to disease-susceptible phenotypes by producing anthranilic acid. Without affecting cell growth, anthranilic acid interferes with the sigma factor RpoS of the seed-borne pathogen Burkholderia plantarii, probably leading to the impairment of upstream cascades that are required for virulence factor biosynthesis.
In the phytopathology paradigm of ‘disease triangles’ that encompasses the plant, pathogens and environmental conditions, the hidden role of seed endophytes is highlighted as “extended immune system” in this study. Besides, “Insight into the disease resistance associated with seed endophytic microbiome, not only opens up a novel way for the exploitation of disease resistance resources and the management of disease resistance loss, but also of important significance for designing microbiome-based biopesticides,” says Haruna Matsumoto.
More information: Haruna Matsumoto et al. Bacterial seed endophyte shapes disease resistance in rice, Nature Plants (2021). DOI: 10.1038/s41477-020-00826-5
Photo: Dr. WANG Mengcen