The Plant journal : for cell and molecular biology 2016 2
The broadly effective recessive resistance gene xa5 of rice is a virulence effector-dependent quantitative trait for bacterial blight.
Mutations in disease susceptibility (S) genes, here referred to as recessive resistance genes, have promise for providing broad durable resistance in crop species. However, few recessive disease resistance genes have been characterized. Here, we show that the broadly effective resistance gene xa5,for resistance to bacterial blight of rice (Oryza sativa), is dependent on the effector genes present in the pathogen. Specifically, the effectiveness of xa5 in preventing disease by strains of Xanthomonas oryzae pv. oryzae is dependent on major transcription activation-like (TAL) effector genes, and correlates with reduced expression of the cognate S genes. xa5 is ineffective in preventing disease by strains containing the TAL effec' data-tid='1218' href='#term-1218'>tor gene pthXo1, which directs robust expression of the S gene OsSWEET11, a member of sucrose transporter gene family. Incompatibility is associated with href='#term-1221'>major TAL effectors that target the known alternative S genes OsSWEET14 and OsSWEET13. Incompatibility is defeated by transfer of pthXo1 to otherwise xa5-incompatible strains or by engineering a synthetic designer TAL effector to boost SWEET gene expression. In either case, compatible or incompatible, target gene expression and lesion formation are reduced in the presence of xa5. The results indicate that xa5 functions as a quantitative trait locus, dampening effector function, and, regardless of compatibility, target gene expression. Resistance is hypothesized to occur when S gene expression, and, by inference, sucrose leakage, falls below a threshold level.
|t i||Os05g0107700||Q0DLD3 B7EAK7|
|f the cog||Os08g0535200||Q6YZF3 A0A0P0XIY5|
|tor gene||Os11g0508600||Q2R3P9 A0A0P0Y2E6|
|' data-ti||Os12g0476200||Q2QR07 A0A0P0YA07 Q0INE1|