Signalling between plants and microorganisms

Abstract: Plants and microbes can interact in several ways. Plants can be attacked by different types of pathogens like fungi, virus and bacteria, but can also form symbioses with fungi and bacteria. Certain common antimicrobial proteins are produced by the plants regardless of the type of microbial interaction with the plant. In this work, different factors involved in plant-microbe interactions have been analysed and studied. We have used a legume plant called Galega orientalis, which can have symbiosis with bacteria (rhizobia) as well as fungi (mycorrhiza). From roots of this plant, genes were isolated which could have a function in symbiosis or defence. Four chitinases, a legume lectin gene, a LysM domain receptor-like kinase and an extra-large G protein alpha subunit have been isolated and and characterised. In another study, we transformed barley with a class II chitinase in antisense. When antisensed plants were inoculated with a mycorrhizal fungus (Glomus intraradices), an increased number of mycorrhizal vesicles and increased content concentration of fatty acids produced by the mycorrhizal fungus was observed. We suggest the downregulation of this chitinase to be responsible for these effects. From barley infected with Blumeria graminis, three beta-1,3-glucanases were isolated. the nucleotide sequence was determined for two of them. One of the glucanases has more homology to an acidic glucanase from wheat than to any of the earlier described glucanases in barley.