Rice blast, caused by the fungal pathogen Magnaporthe oryzae (Magnaporthe grisea), is the most devastating disease of rice and severely threatens global food production and agricultural sustainability, which also affects wheat worldwide. Particularly in China, all rice growth regions suffer from the disease. The most profitable and environmental-friendly strategy to control diseases is to develop varieties with durable and broad-spectrum resistance. Although many resistance (R) genes have been identified, very few R genes have been adopted for broad-spectrum and durable disease resistance in long-term crop breeding programs due to either resistance breakdown or defense cost (yield penalty) if R genes are pyramided. Therefore, discovery and application of such genes are critical to rice breeding and production.
Prof. Zuhua HE
and his colleagues from Shanghai Institute of Plant Physiology and Ecology (SIPPE), Chinese Academy of Sciences (CAS), with collaboration with other groups, identified a rice blast resistance locus called Pigm
from the indigenous Chinese rice variety GM4. The Pigm
locus, which contains several nucleotide-binding leucine-rich repeat (NLR) receptors, confers durable and broad-spectrum blast resistance without yield penalty. They found that within the Pigm
cluster, one NLR receptor PigmR provides broad-spectrum resistance but causes yield decrease through reducing grain size. Interestingly, they revealed that the yield cost by PigmR-
mediated resistance could be counteracted by another NLR receptor named PigmS within the same locus. The expression of PigmS
is spatially regulated due to epigenetic regulation: it is silenced in the vegetative organs but highly expressed in the reproductive organs. As a result, PigmS only suppresses the PigmR-mediated grain size reduction without interfering with PigmR-mediated resistance in leaves. Overall, this study reveals a novel mechanism of balancing broad-spectrum resistance and yield through epigenetic regulation of a pair of antagonistic NLRs, providing a practical tool to develop elite rice variety with both high disease resistance and yield potential.
The study entitled “Epigenetic regulation of antagonistic receptors confers rice blast resistance with yield balance” has been published online in Science on Feb. 2, 2017.
The study was supported by Chinese Academy of Sciences, the Ministry of Agriculture, and Natural Science Foundation of China.
Field resistance test of the new elite hybrid rice Longliangyou3189 harboring Pigm at seedling stage in blast nusery
A proposed model for Pigm function and evolution
Yiwen Deng, Ph.D.
National Key Laboratory of Plant Molecular Genetics
Shanghai Institute of Plant Physiology and Ecology
Chinese Academy of Sciences
300 Fenglin Road