Researchers CHEN Yuhang and ZHOU JIAN-MIN from the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences showed how plants resist clubroot. This primary root disease threatens Brassica crops like rape.
The study was published in the cell. It reveals novel mechanisms that underlie plant immunity and offers a new route for crop breeding.
The most destructive disease to Brassica crops is clubroot, a soil-borne infection. Clubroot affects approximately 3,2-4 million hm 2 of Chinese agricultural land annually. This results in yield losses between 20% and 30%. The resting spores from Plasmodiophora brassicae, the pathogen that causes clubroot, can survive in soils for up to twenty years. This makes soils contaminated and unsuitable for Brassica crop cultivation.
Only two clubroot resistance genes have been cloned to date. Their resistance has now broken down due to newly evolved Pb isolates.
The newly identified resistance gene WTS was found to confer resistance against all Pb isolates, even those that were virulent towards existing resistant rape types. The WTS gene is a wide-spectrum resistant gene that offers excellent potential to breed clubroot disease resistance into crops.
In the absence of a pathogen, WTS does not express. WTS is strongly expressed in the pericycle of the root cells around the stele, but only when Pb is present. The central cylindrical vascular portion of the root contains critical tissues, including the xylem, phloem, and other essential tissues for water and nutrient transport.
Pb colonizes and invades the stele in susceptible plants. This blocks nutrient and moisture transport. WTS expression in the pericycle activates the plant’s defenses and stops Pb from the colonizing stele. WTS is a specific defense mechanism activated precisely at the correct time and place to maintain average plant growth.
WTS also encodes a new protein. Cryo-EM structural analysis revealed that WTS forms a pentameric structure with a central pore, which was previously unknown.
Other studies have shown that the WTS complex also functions as a calcium release channel in the endoplasmic membrane that increases cytosolic calcium, a crucial secondary signal to activate plant defenses.
Researchers have discovered a novel paradigm for plant immunity to soil-borne pathogens. The WTS gene cloned offers new hope in breeding Brassica plants resistant to a devastating but difficult-to-control disease.
