High-temperature adult-plant (HTAP) resistance expresses when plants grow old and the weather becomes warm. This non-race specific and durable type of resistance has been used successfully in control of wheat stripe r...High-temperature adult-plant (HTAP) resistance expresses when plants grow old and the weather becomes warm. This non-race specific and durable type of resistance has been used successfully in control of wheat stripe rust in the US since early 1960s. This article describes practical procedures for identification and characterization of HTAP resistance and reviews recent studies on discovery of genes conferring HTAP resistance. Recent studies providing insights to the molecular basis for the durability of HTAP resistance will be presented. Strategies for improving levels of HTAP resistance and improving control of stripe rust through combining HTAP resistance with effective all-stage resistance will be discussed.展开更多
Bacterial blight(BB)is a globally devastating rice disease caused by Xanthomonas oryzae pv.oryzae(Xoo).The use of disease resistance(R)genes in rice breeding is an effective and economical strategy for the control of ...Bacterial blight(BB)is a globally devastating rice disease caused by Xanthomonas oryzae pv.oryzae(Xoo).The use of disease resistance(R)genes in rice breeding is an effective and economical strategy for the control of this disease.Nevertheless,a majority of R genes lack durable resistance for long-term use under global warming conditions.Here,we report the isolation of a novel executor R gene,Xa7,that confers extremely durable,broad-spectrum,and heat-tolerant resistance to Xoo.The expression of Xa7 was induced by incompatible Xoo strains that secreted the transcription activator-like effector(TALE)AvrXa7 or PthXo3,which recognized effector binding elements(EBEs)in the Xa7 promoter.Furthermore,Xa7 induction was faster and stronger under high temperatures.Overexpression of Xa7 or co-transformation of Xa7 with avrXa7 triggered a hypersensitive response in plants.Constitutive expression of Xa7 activated a defense response in the absence of Xoo but inhibited the growth of transgenic rice plants.In addition,analysis of over 3000 rice varieties showed that the Xa7 locuswas found primarily in the indica and aus subgroups.A variation consisting of an 11-bp insertion and a base substitution(G to T)was found in EBEAvrXa7 in the tested varieties,resulting in a loss of Xa7 BB resistance.Through a decade of effort,we have identified an important BB resistance gene and characterized its distinctive interaction with Xoo strains;these findings will greatly facilitate research on the molecular mechanism of Xa7-mediated resistance and promote the use of this valuable gene in breeding.展开更多
The rice disease resistance （R） gene Xa3/Xa26 （having also been named Xa3 and Xa26） against Xanthomonas oryzae pv. oryzae （Xoo）, which causes bacterial blight disease, belongs to a multiple gene family clustered...The rice disease resistance （R） gene Xa3/Xa26 （having also been named Xa3 and Xa26） against Xanthomonas oryzae pv. oryzae （Xoo）, which causes bacterial blight disease, belongs to a multiple gene family clustered in chromosome 11 and is from an AA genome rice cultivar （Oryza sativa L.）. This family encodes leucine-rich repeat （LRR） receptor kinase- type proteins, Here, we show that the orthologs （alleles） of Xa3/Xa26, Xa3/Xa26-2, and Xa3/Xa26-3, from wild Oryza spe- cies O. officinalis （CC genome） and O. minuta （BBCC genome）, respectively, were also R genes against Xoo. Xa3/Xa26-2 and Xa3/Xa26-3 conferred resistance to 16 of the 18 Xoo strains examined. Comparative sequence analysis of the Xa3/Xa26 families in the two wild Oryza species showed that Xa3/Xa26-3 appeared to have originated from the CC genome of O. minuta. The predicted proteins encoded by Xa3/Xa26, Xa3/Xa26-2, and Xa3/Xa26-3 share 91-99% sequence identity and 94-99% sequence similarity. Transgenic plants carrying a single copy of Xa3/Xa26, Xa3/Xa26-2, or Xa3PXa26-3, in the same genetic background, showed a similar resistance spectrum to a set of Xoo strains, although plants carrying Xa3/Xa26-2 or Xa3/Xa26-3 showed lower resistance levels than the plants carrying Xa3/Xa26. These results suggest that the Xa3/Xa26 locus predates the speciation of A and C genome, which is approximately 7.5 million years ago. Thus, the resistance spec- ificity of this locus has been conserved for a long time.展开更多
文摘High-temperature adult-plant (HTAP) resistance expresses when plants grow old and the weather becomes warm. This non-race specific and durable type of resistance has been used successfully in control of wheat stripe rust in the US since early 1960s. This article describes practical procedures for identification and characterization of HTAP resistance and reviews recent studies on discovery of genes conferring HTAP resistance. Recent studies providing insights to the molecular basis for the durability of HTAP resistance will be presented. Strategies for improving levels of HTAP resistance and improving control of stripe rust through combining HTAP resistance with effective all-stage resistance will be discussed.
基金supported by the Ministry of Agriculture and Rural Affairs of China(2016ZX08009003-001)the National Natural Science Foundation of China(32071987,31871605)the Natural Science Foundation of Zhejiang Province(LD19C130001).
文摘Bacterial blight(BB)is a globally devastating rice disease caused by Xanthomonas oryzae pv.oryzae(Xoo).The use of disease resistance(R)genes in rice breeding is an effective and economical strategy for the control of this disease.Nevertheless,a majority of R genes lack durable resistance for long-term use under global warming conditions.Here,we report the isolation of a novel executor R gene,Xa7,that confers extremely durable,broad-spectrum,and heat-tolerant resistance to Xoo.The expression of Xa7 was induced by incompatible Xoo strains that secreted the transcription activator-like effector(TALE)AvrXa7 or PthXo3,which recognized effector binding elements(EBEs)in the Xa7 promoter.Furthermore,Xa7 induction was faster and stronger under high temperatures.Overexpression of Xa7 or co-transformation of Xa7 with avrXa7 triggered a hypersensitive response in plants.Constitutive expression of Xa7 activated a defense response in the absence of Xoo but inhibited the growth of transgenic rice plants.In addition,analysis of over 3000 rice varieties showed that the Xa7 locuswas found primarily in the indica and aus subgroups.A variation consisting of an 11-bp insertion and a base substitution(G to T)was found in EBEAvrXa7 in the tested varieties,resulting in a loss of Xa7 BB resistance.Through a decade of effort,we have identified an important BB resistance gene and characterized its distinctive interaction with Xoo strains;these findings will greatly facilitate research on the molecular mechanism of Xa7-mediated resistance and promote the use of this valuable gene in breeding.
基金This work was supported by grants from the National Program on the Development of Basic Research in China，the National Natural Science Foundation of China
文摘The rice disease resistance （R） gene Xa3/Xa26 （having also been named Xa3 and Xa26） against Xanthomonas oryzae pv. oryzae （Xoo）, which causes bacterial blight disease, belongs to a multiple gene family clustered in chromosome 11 and is from an AA genome rice cultivar （Oryza sativa L.）. This family encodes leucine-rich repeat （LRR） receptor kinase- type proteins, Here, we show that the orthologs （alleles） of Xa3/Xa26, Xa3/Xa26-2, and Xa3/Xa26-3, from wild Oryza spe- cies O. officinalis （CC genome） and O. minuta （BBCC genome）, respectively, were also R genes against Xoo. Xa3/Xa26-2 and Xa3/Xa26-3 conferred resistance to 16 of the 18 Xoo strains examined. Comparative sequence analysis of the Xa3/Xa26 families in the two wild Oryza species showed that Xa3/Xa26-3 appeared to have originated from the CC genome of O. minuta. The predicted proteins encoded by Xa3/Xa26, Xa3/Xa26-2, and Xa3/Xa26-3 share 91-99% sequence identity and 94-99% sequence similarity. Transgenic plants carrying a single copy of Xa3/Xa26, Xa3/Xa26-2, or Xa3PXa26-3, in the same genetic background, showed a similar resistance spectrum to a set of Xoo strains, although plants carrying Xa3/Xa26-2 or Xa3/Xa26-3 showed lower resistance levels than the plants carrying Xa3/Xa26. These results suggest that the Xa3/Xa26 locus predates the speciation of A and C genome, which is approximately 7.5 million years ago. Thus, the resistance spec- ificity of this locus has been conserved for a long time.
