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Epigenetic regulation of antagonistic receptors confers rice blast resistance with yield balance

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Science  03 Mar 2017:
Vol. 355, Issue 6328, pp. 962-965
DOI: 10.1126/science.aai8898

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Widespread resistance, localized relief

Rice blast fungus can devastate a rice harvest. Genes that provide resistance to the fungus usually depress rice yield. Deng et al. analyzed the molecular underpinnings of a rice variant that is resistant to rice blast but still high-yielding (see the Perspective by Wang and Valent). The key locus encodes several R (resistance) genes. One gene confers resistance and is expressed throughout the plant. Another gene fails to confer resistance and is expressed only in pollen and panicles (the rice-producing flower clusters). Because the R proteins function as dimers, heterodimerization in pollen and panicles disables resistance. The plants thus produce smaller but more numerous rice grains, which sustains yield, while the body of the plant resists fungal infection.

Science, this issue p. 962; see also p. 906

Abstract

Crop breeding aims to balance disease resistance with yield; however, single resistance (R) genes can lead to resistance breakdown, and R gene pyramiding may affect growth fitness. Here we report that the rice Pigm locus contains a cluster of genes encoding nucleotide-binding leucine-rich repeat (NLR) receptors that confer durable resistance to the fungus Magnaporthe oryzae without yield penalty. Among these NLR receptors, PigmR confers broad-spectrum resistance, whereas PigmS competitively attenuates PigmR homodimerization to suppress resistance. PigmS expression, and thus PigmR-mediated resistance, are subjected to tight epigenetic regulation. PigmS increases seed production to counteract the yield cost induced by PigmR. Therefore, our study reveals a mechanism balancing high disease resistance and yield through epigenetic regulation of paired antagonistic NLR receptors, providing a tool to develop elite crop varieties.

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