The number of bacteria within the leaves of the plant Arabidopsis, which is due to mutations disrupted some of the ways the immune system against pathogens is reduced. Diversity of this microbiota is also low, and it mainly consists of proteobacteria. These organisms do not give other types of bacteria to grow and cause the reduction of biomass and yellowing of leaves of Arabidopsis. An imbalance of the microbiota resembles dysbiosis of the person. In normal plants there is an immune defense mechanism of proteobacteria, which protects them from dysbiosis, — to such conclusion came the authors of the work published in the journal Nature.
In the above-ground parts of the plant live a diverse community of microorganisms. It’s like the epiphytes — the bacteria that exist on the surface, and the endophytes that penetrate inside the leaves. A well – studied role of microbiota in roots of plant life, and the contribution of communities of bacteria aerial parts remains largely unclear. For example, it is unclear how plants can influence their own microbiota, including its composition. It is known that the structure of the microbiome of the leaf depends on the genotype of the plant, but left open the question of how the health of plants and what are the mechanisms of regulation of the relationship of bacteria and their hosts.
Scientists from China and the United States under the leadership of Ho Shenyang (Sheng Yang He) from the University of Michigan studied the composition of the microbiota and its effect on the health of Arabidopsis, mutant four genes (min7, fs2, efr and cerk1). Such plants impaired immunity, activated molecular structures of pathogens, and one of the ways of transport vesicles. In the previous study, the researchers foundthat these mutants change the composition of the microbiota within the leaves, and the leaves turn yellow.
The composition of the microorganisms was studied using sequencing of genes of bacterial ribosomal RNA (16S rRNA) or in whole leaf, or only within them — for this, the surface sterilized leaves, thus destroying all of epiphytes.
It turned out that the mutant Arabidopsis significantly reduced the number of bacteria within the leaves (p < 0.0001), as well as their diversity. The basis of the community of endophytes steel proteobacteria. Such changes are reminiscent of dysbiosis, which occurs in humans with inflammatory bowel diseases. By analogy, the researchers suggested that changes in the microbiome of plants may be the primary cause of chlorosis (yellowing) of the leaves of mutant Arabidopsis.