The Phenylalanine Ammonia Lyase Gene LjPAL1 Is Involved in Plant Defense Responses to Pathogens and Plays Diverse Roles in Lotus japonicus-Rhizobium Symbioses
The Phenylalanine Ammonia Lyase Gene LjPAL1 Is Involved in Plant Defense Responses to Pathogens and Plays Diverse Roles in Lotus japonicus-Rhizobium Symbioses
复制标题
苯丙氨酸氨裂解酶基因 LjPAL1 参与植物对病原体的防御反应，并在百脉根瘤菌共生中发挥多种作用
DOI：
10.1094/mpmi-04-17-0080-r
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发表时间：
2017-09-01
影响因子：
3.5
通讯作者：
Wu, Guojiang
中科院分区：
文献类型：
--
作者：
Chen, Yaping;Li, Fengjiao;Wu, Guojiang
苯丙氨酸解氨酶（PAL）在植物次生代谢产物的生物合成中起着重要作用。虽然PAL基因在多种植物中的功能已经得到了很好的证实，但是其在植物发育中的功能意义还不清楚。在这里，我们证明了莲花PAL（LjPAL 1）基因是由中生根瘤菌loti感染和茉莉酸甲酯（Me-JA）处理根诱导。LjPAL 1改变PAL活性，导致木质素含量和厚度的变化，在转基因植物的根和根瘤的细胞壁，因此，在根和根瘤的结构变化。LjPAL 1基因敲减的植株（LjPAL 1 i）表现出增加的侵染线和根瘤数，以及M.洛蒂感染。相反，LjPAL 1过表达延迟了感染过程，并减少了M.洛蒂接种。LjPAL 1 i植物还表现出降低的内源水杨酸（SA）积累和SA依赖性标记基因的表达。外源SA或Me-JA可部分恢复其感染表型。我们的数据表明LjPAL 1在L.大豆根瘤菌-根瘤菌共生，影响根瘤菌感染进程和根瘤结构，可能通过诱导木质素修饰，调节内源SA生物合成和调节SA信号传导。
Phenylalanine ammonia lyase (PAL) is important in the biosynthesis of plant secondary metabolites that regulate growth responses. Although its function is well-established in various plants, the functional significance of PAL genes in nodulation is poorly understood. Here, we demonstrate that the Lotus japonicus PAL (LjPAL1) gene is induced by Mesorhizobium loti infection and methyl-jasmonate (Me-JA) treatment in roots. LjPAL1 altered PAL activity, leading to changes in lignin contents and thicknesses of cell walls in roots and nodules of transgenic plants and, hence, to structural changes in roots and nodules. LjPAL1-knockdown plants (LjPAL1i) exhibited increased infection thread and nodule numbers and the induced upregulation of nodulin gene expression after M. loti infection. Conversely, LjPAL1 overexpression delayed the infection process and reduced infection thread and nodule numbers after M. loti inoculation. LjPAL1i plants also exhibited reduced endogenous salicylic acid (SA) accumulation and expression of the SA-dependent marker gene. Their infection phenotype could be partially restored by exogenous SA or Me-JA application. Our data demonstrate that LjPAL1 plays diverse roles in L. japonicus-rhizobium symbiosis, affecting rhizobial infection progress and nodule structure, likely by inducing lignin modification, regulating endogenous SA biosynthesis, and modulating SA signaling.