Zhang Haili, Huang Qiulan, Yi Ling, Song Xiaona, Li Lin, Deng Guangbing, Liang Junjun, Chen Fang, Yu Maoqun, Long Hai
Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, China.
College of Sichuan Tea, Yibin University, Yibin, Sichuan, 644000, China.
Plant J. 2021 Aug;107(3):698-712. doi: 10.1111/tpj.15316. Epub 2021 Jun 3.
The pathogen cereal cyst nematode (CCN) is deleterious to Triticeae crops and is a threat to the global crop yield. Accession no. 1 of Aegilops variabilis, a relative of Triticum aestivum (bread wheat), is highly resistant to CCN. Our previous study demonstrated that the expression of the phenylalanine ammonia lyase (PAL) gene AevPAL1 in Ae. variabilis is strongly induced by CCN. PAL, the first enzyme of phenylpropanoid metabolism, is involved in abiotic and biotic stress responses. However, its role in plant-CCN interaction remains unknown. In the present study, we proved that AevPAL1 helps to confer CCN resistance through affecting the synthesis of salicylic acid (SA) and downstream secondary metabolites. The silencing of AevPAL1 increased the incidence of CCN infection in roots and decreased the accumulation of SA and phenylalanine (Phe)-derived specialized metabolites. The exogenous pre-application of SA also improved CCN resistance. Additionally, the functions of PAL in phenylpropanoid metabolism correlated with tryptophan decarboxylase (TDC) functioning in tryptophan metabolism pathways. The silencing of either AevPAL1 or AevTDC1 exhibited a concomitant reduction in the expression of both genes and the contents of metabolites downstream of PAL and TDC. These results suggested that AevPAL1, possibly in coordination with AevTDC1, positively contributes to CCN resistance by altering the downstream secondary metabolites and SA content in Ae. variabilis. Moreover, AevPAL1 overexpression significantly enhanced CCN resistance in bread wheat and did not exhibit significant negative effects on yield-related traits, suggesting that AevPAL1 is valuable for the genetic improvement of CCN resistance in bread wheat.
病原物小麦粒线虫（CCN）对小麦族作物有害，且对全球作物产量构成威胁。普通小麦（面包小麦）的近缘种——易变山羊草的种质编号1对CCN具有高度抗性。我们之前的研究表明，苯丙氨酸解氨酶（PAL）基因AevPAL1在易变山羊草中的表达受到CCN的强烈诱导。PAL是苯丙烷代谢的首个酶，参与非生物和生物胁迫反应。然而，其在植物与CCN相互作用中的作用尚不清楚。在本研究中，我们证明AevPAL1通过影响水杨酸（SA）和下游次生代谢物的合成来帮助赋予对CCN的抗性。AevPAL1的沉默增加了根部CCN感染的发生率，并降低了SA和苯丙氨酸（Phe）衍生的特殊代谢物的积累。SA的外源预处理也提高了对CCN的抗性。此外，PAL在苯丙烷代谢中的功能与色氨酸脱羧酶（TDC）在色氨酸代谢途径中的功能相关。AevPAL1或AevTDC1的沉默均表现出两个基因的表达以及PAL和TDC下游代谢物含量的同时降低。这些结果表明，AevPAL1可能与AevTDC1协同作用，通过改变易变山羊草中的下游次生代谢物和SA含量，对CCN抗性产生积极作用。此外，AevPAL1的过表达显著增强了面包小麦对CCN的抗性，且对产量相关性状未表现出显著负面影响，这表明AevPAL1对面包小麦CCN抗性的遗传改良具有重要价值。
