On the morning of April 10th, the High-Level Lecture on Crop Science and the 120th Anniversary series of academic activities of the Plant Science and Technology College were held in the 103 reporting-hall of Molecular Building. Prof. Godelive Gheysen from Belgium introduced the research progress of the molecular mechanism of the interaction between root-knot elegans and rice using the theme of "Rice Root-Knot Elegans Interactions in Susceptible and Resistant Cultivars".
At the meeting, Prof. G. Gheysen explained to us the three reasons why rice was selected as the research object: rice is an important food crop; rice is a model plant and can be used as a model system for the interaction of plants and nematodes; rice is facing serious nematode damage, particularly in dry rice. Prof. G. Gheysen elicited the research content of this report with the question of "How does rice root-knot elegans invade and colonize?".
Firstly, Prof. G. Gheysen introduced two defense mechanisms of rice containing plant cell walls and immune-induced defense and described how root-knot elegans break through these two defenses. She mentioned that the plant cell wall is a structural obstacle when pathogens including nematodes invade plants. Nematodes can secrete various types of cell wall-modified protein to hydrolyze plant cell walls, breaking through the physical barriers of plant cell walls. These cell wall-modified proteins are synthesized in two sub-epidermal cells of the nematodes and are secreted into the plant by the nematode's stylus. Studies have found that cell wall-modified proteins secreted by nematodes are obtained from bacteria and fungi through horizontal gene transfer, such as cellulase and pectin lyase.
Another barrier is the plant's immune-induced defense. Plant immune defense system has two different levels of resistance, the first one is based on immunity, that is PAMP-triggered immunity (PTI); the second is resistant gene-mediated disease resistance, also known as Effector-Triggered Immunity (ETI). Although a highly effective plant immune defense system confers disease resistance on most pathogens to plants, root-knot elegans can inhibit PTI and ETI of plant hosts by secreting various kinds of effectors, thereby assisting root-knot elegans to infect and colonize host plants. At present, Professor Gheysen's team has studied and found that the rice hormones ABA, JA, SA, and ET play an important biological role in the resistance response of rice to paragonum nematophila. Besides,there are interactions among these hormones.
Subsequently, Prof. G. Gheysen introduced us to the research team's research on the resistant genes of rice paragonum nematophila. The team found that the Asian rice varieties LD24 and KPM were resistant to rice paragonum nematophila disease, and disease resistance was most pronounced at the early stage of nematode infestation. At the same time, the major disease-resistance genes of LD24 and KPM were located in the same region of chromosome 11. Professor G. Gheysen also expressed the need for further analysis of rice disease resistance. "Is the resistance site in LD24 specific for resistance to rice paragonum nematophila?" "Is this resistance site equally resistant to other root-knot elegans?" "Is this resistance given by a single gene, can we locate and clone the gene?” and a series of questions are waiting to be solved.
Finally, G. Gheysen introduced her next research plan. She said that her and her team will further analyze the disease resistance of rice varieties KPM and LD24, use target map cloning technology to clone target disease resistance genes, and carry out functional studies of target disease resistance genes.