Breeding plant broad-spectrum resistance without yield penalties

A central goal of crop improvement is to breed varieties with broad-spectrum resistance (BSR) to pathogens, but most of the major resistance (R) genes identified to date confer race-specific resistance to their adapted pathogens. Although these R genes are effective for a specific pathogen, their durability in the field is typically short due to mutations in the pathogen population that overcome the resistance. An alternative strategy of incorporating multiple R genes against different pathogens into elite cultivars is time-consuming and technically challenging, and usually results in a yield penalty as the crop diverts energy to implementing disease resistance (1). Many pathogens infect rice ( Oryza sativa ), the staple food crop of over half of the world’s population. Among them, the fungal pathogen Magnaporthe oryzae and the bacterial pathogen Xanthomonas oryzae pv oryzae ( Xoo ) are two of the most destructive and can cause devastating yield losses in most rice-growing countries (2). Over the past two decades, many rice R genes have been identified, but none confers resistance to both pathogens. Although manipulating the expression of several defense-responsive genes, or genes in defense signaling pathways, has led to BSR (3, 4), few such genes have been successfully deployed in rice production for disease control. In PNAS, Zhou et al. (5) report the identification of the broad-spectrum resistance Kitaake-1 ( Bsr-k1 ) gene, which negatively regulates BSR, and the bsr-k1 allele, which confers nonspecific BSR to both M. oryzae and Xoo without a yield penalty. The resistant bsr-k1 mutant was identified from an ethylmethane sulfonate-treated mutant population of the japonica cultivar Kitaake that had been inoculated with seven Kitaake-compatible M. oryzae … [↵][1]1To whom correspondence should be addressed. Email: wang.620{at}osu.edu. [1]: #xref-corresp-1-1