Fhb1 gene providing resistance to Fusarium graminearum in wheat cloned!!
Fusarium graminearum is a serious fungal pathogen of several important crop plants such as, wheat, barley, maize, oats, and rye. It causes millions of dollar losses annually worldwide, not only due to reduction in crop yields, but also severely affecting the grain quality because of the associated mycotoxins. Deoxynivalenol (DON), which is a major toxin produced in wheat and barley grains by F. graminearum, makes the grain unsuitable for human consumption at levels as low as 1ppm. In wheat the disease caused by F. graminearum is known as Fusarium Head Blight (FHB), or wheat scab. Use of resistant cultivars is one of the most sustainable and promising strategies for minimizing losses due to FHB in wheat. Resistance to F. graminearum is not very common and is found only in a few Chinese landraces, from where it has been deployed worldwide in breeding programs to tackle FHB. Nevertheless, nothing is known about the gene, named as ‘Fhb1’, that provides this resistance. The investigators have identified the gene that confers resistance to the spread of F. graminearum in wheat spikes. It is a novel kind of resistance gene, and provides a broad-spectrum resistance against Fusarium species. Most of the plant resistance genes, also known as NBS-LRR kind of resistance genes, are race-specific and are effective against limited strains of the pathogen, because of their unique signatures which are compatible with the pathogen. However, Fhb1 lacks this type of gene-for-gene match with the pathogen, making it effective against a wide array of Fusarium species. Fhb1 encodes a chimeric lectin protein having two agglutinin domains and a pore-forming toxin-like domain, which arrests the fungal growth. The findings of the group have been recently published in highly esteemed journal ‘Nature Genetics’. Work was led by Dr. Nidhi Rawat who has recently joined University of Maryland as an assistant professor to work on this disease. The majority of research work was done in the Laboratory of Dr. Bikram Gill, at Kansas State University and included collaborators: Dr. Jim Anderson from University of Minnesota, Dr. Mike Pumphrey from Washington State University, Dr. Eduard Akhunov, Dr. Vijay Tiwari from University of Maryland, and Dr. Harold Trick from Kansas State University. This discovery is just a beginning; as further research is being conducted by the investigator to explore how this gene actually functions in plants to control the fungus from spreading. This understanding will be highly applicable to transfer the resistance to other crop systems, as F. graminearum species complex has a very broad host-range and infects many different crop plants.