Functional Analysis of the Arabidopsis PAL Gene Family in Plant Growth, Development, and Response to Environmental Stress
Functional Analysis of the Arabidopsis PAL Gene Family in Plant Growth, Development, and Response to Environmental Stress
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DOI：
10.1104/pp.110.157370
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发表时间：
2010-08-01
期刊：
影响因子：
7.4
通讯作者：
Chen, Zhixiang
中科院分区：
文献类型：
--
作者：
Huang, Junli;Gu, Min;Chen, Zhixiang
苯丙氨酸解氨酶（PAL）催化类苯丙素途径的第一步，该途径产生多种重要次级代谢物的前体。拟南芥（Arabidopsis thaliana）含有四个PAL基因（PAL 1-PAL 4），但还没有遗传分析来评估整个基因家族的生物学功能。在这里，我们报告的四个拟南芥PAL基因的组合突变的产生和分析。相反，以前的报告，我们发现，三个独立的pal 1 pal 2双突变体是肥沃的，并产生黄色的种子，由于缺乏缩合单宁色素在种皮。pal 1 pal 2双突变体也缺乏花青素色素在各种植物组织中，这积累在野生型植物在胁迫条件下。因此，PAL 1和PAL 2在类黄酮生物合成中具有冗余作用。此外，pal 1 pal 2双突变体比野生型植株更敏感的紫外线-B光，但更耐旱。我们还产生了两个独立的pal 1 pal 2 pal 3 pal 4四重敲除突变体，这是发育不良和不育。四重敲除突变体仍含有约10%的野生型PAL活性，这可能是由于一个或多个泄漏PAL突变基因或其他未知PAL基因。四重突变体也积累了显著降低水平的水杨酸，并显示出对细菌病原体假单胞菌的强毒株的敏感性增加。这些结果为拟南芥PAL基因在植物生长发育和对环境胁迫的响应中的独特和重叠作用提供了进一步的证据。
Phenylalanine ammonia-lyase (PAL) catalyzes the first step of the phenylpropanoid pathway, which produces precursors to a variety of important secondary metabolites. Arabidopsis (Arabidopsis thaliana) contains four PAL genes (PAL1-PAL4), but there has been no genetic analysis to assess the biological functions of the entire gene family. Here, we report the generation and analysis of combined mutations for the four Arabidopsis PAL genes. Contrary to a previous report, we found that three independent pal1 pal2 double mutants were fertile and generated yellow seeds due to the lack of condensed tannin pigments in the seed coat. The pal1 pal2 double mutants were also deficient in anthocyanin pigments in various plant tissues, which accumulate in wild-type plants under stress conditions. Thus, PAL1 and PAL2 have a redundant role in flavonoid biosynthesis. Furthermore, the pal1 pal2 double mutants were more sensitive to ultraviolet-B light but more tolerant to drought than wildtype plants. We have also generated two independent pal1 pal2 pal3 pal4 quadruple knockout mutants, which are stunted and sterile. The quadruple knockout mutants still contained about 10% of the wild-type PAL activity, which might result from one or more leaky pal mutant genes or from other unknown PAL genes. The quadruple mutants also accumulated substantially reduced levels of salicylic acid and displayed increased susceptibility to a virulent strain of the bacterial pathogen Pseudomonas syringae. These results provide further evidence for both distinct and overlapping roles of the Arabidopsis PAL genes in plant growth, development, and responses to environmental stresses.