1 CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, Telangana State, India.
Mol Plant Microbe Interact. 2016 Aug;29(8):599-608. doi: 10.1094/MPMI-02-16-0039-R. Epub 2016 Jul 19.
Xanthomonas oryzae pv. oryzae secretes a number of plant cell wall-degrading enzymes (CWDEs) whose purified preparations induce defense responses in rice. These defense responses are suppressed by X. oryzae pv. oryzae using type 3 secretion system (T3SS) effectors and a type 3 secretion system mutant (T3SS(-)) of X. oryzae pv. oryzae is an inducer of rice defense responses. We assessed the role of individual CWDEs in induction of rice defense responses during infection, by mutating them in the genetic background of a T3SS(-). We mutated the genes for five different plant CWDEs secreted by X. oryzae pv. oryzae, including two cellulases (clsA and cbsA), one xylanase (xyn), one pectinase (pglA), and an esterase (lipA), singly in a T3SS(-) background. We have demonstrated that, as compared with a T3SS(-) of X. oryzae pv. oryzae, a cbsA(-)T3SS(-), a clsA(-)T3SS(-), and a xyn(-)T3SS(-) are deficient in induction of rice immune responses such as callose deposits and programmed cell death. In comparison, a lipA(-) T3SS(-) and a pglA(-)T3SS(-) is as efficient in induction of host defense responses as a T3SS(-). Overall, these results indicate that the collective action of X. oryzae pv. oryzae-secreted ClsA, CbsA, and Xyn proteins is required for induction of rice defense responses during infection.
稻黄单胞菌 pv. 稻分泌多种植物细胞壁降解酶(CWDEs),其纯化制剂在水稻中诱导防御反应。这些防御反应被稻黄单胞菌 pv. 稻的 3 型分泌系统(T3SS)效应子抑制,稻黄单胞菌 pv. 稻的 3 型分泌系统突变体(T3SS(-))是水稻防御反应的诱导剂。我们通过在 T3SS(-)的遗传背景中突变它们,评估了单个 CWDE 在感染过程中诱导水稻防御反应的作用。我们突变了 5 种不同的由稻黄单胞菌 pv. 稻分泌的植物 CWDEs 的基因,包括 2 种纤维素酶(clsA 和 cbsA)、1 种木聚糖酶(xyn)、1 种果胶酶(pglA)和 1 种酯酶(lipA),分别在 T3SS(-)背景下突变。与稻黄单胞菌 pv. 稻的 T3SS(-)相比,我们已经证明 cbsA(-)T3SS(-)、clsA(-)T3SS(-)和 xyn(-)T3SS(-)在诱导水稻免疫反应(如几丁质沉积和程序性细胞死亡)方面存在缺陷,而 lipA(-) T3SS(-)和 pglA(-)T3SS(-)在诱导宿主防御反应方面与 T3SS(-)一样有效。总的来说,这些结果表明,稻黄单胞菌 pv. 稻分泌的 ClsA、CbsA 和 Xyn 蛋白的集体作用是在感染过程中诱导水稻防御反应所必需的。