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首页> 外文学位 >Molecular basis of plant defense against aphids: Role of the Arabidopsis thaliana PAD4 and MPL1 genes.
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Molecular basis of plant defense against aphids: Role of the Arabidopsis thaliana PAD4 and MPL1 genes.

机译：植物防御蚜虫的分子基础：拟南芥PAD4和MPL1基因的作用。

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摘要

Myzus persicae (Sulzer), commonly known as green peach aphid (GPA), utilizes its slender stylet to penetrate the plant tissues intercellularly and consume copious amounts of photoassimilates present in the phloem sap causing extensive damage to host plants. The compatible interaction between GPA and Arabidopsis thaliana enabled us to characterize plant response to aphid infestation. Upon GPA infestation, Arabidopsis PAD4 (PHYTOALEXIN DEFICIENT4) gene modulates premature leaf senescence, which is involved in the programmed degradation of cellular components and the export of nutrients out of the senescing leaf. Senescence mechanism is utilized by plants to limit aphid growth. In addition, PAD4 provides antixenosis (deters insect settling and feeding) and antibiosis (impair aphid fecundity) against GPA and adversely impact sieve element availability to GPA. Basal expression of PAD4 contributes to antibiosis, and the GPA-induced expression of PAD4 contributes to antixenosis. Mutation in the Arabidopsis stearoyl-ACP desaturase encoding SSI2 (suppressor of SALICYLIC ACID [SA] insensitivity2) gene that results in an accelerated cell death phenotype and dwarfing, also conferred heightened antibiosis to GPA. Results of this study indicate that PAD4 is required for the ssi2-mediated enhanced antibiosis to GPA. The PAD4 protein contains conserved Ser, Asp and His residues that form the catalytic triad of many alpha/beta fold acyl hydrolases. Arabidopsis plants expressing mutant versions of PAD4 [PAD4(S118A) and PAD4(D178A)] supported higher numbers of GPA as compared to wild type (WT) plants in no-choice tests. Furthermore, Electrical Penetration Graph (EPG) studies revealed that S118 residue in PAD4 is essential to limit GPA feeding from the sieve elements. However, the ability to deter insect settling in choice tests was not impacted by the PAD4(S118A) and PAD4(D178A) mutations, thus suggesting that PAD4s involvement in deterring insect settling and in antibiosis are determined by separate regions of PAD4. The MPL1 (MYZUS PERSICAE INDUCED LIPASE1 ) gene is another critical component of Arabidopsis defense against GPA. Like PAD4, MPL1 expression is induced in response to GPA infestation. However, MPL1 is required only for antibiosis and is not essential for antixenosis against GPA. EPG analysis suggests that the mpl1 mutant allele does not impact aphid feeding behavior. Since, MPL1 exhibits lipase activity, and ssi2 petiole exudates contain elevated levels of antibiosis, we propose that antibiosis to GPA requires a lipid(s), or a product thereof.
机译：桃蚜（Sulzer），俗称绿桃蚜（GPA），利用其纤细的管心针穿透细胞组织并消耗韧皮液中大量的光同化物，从而对寄主植物造成广泛损害。 GPA和拟南芥之间的相容相互作用使我们能够表征植物对蚜虫侵染的反应。 GPA侵染后，拟南芥PAD4（PHYTOALEXIN DEFICIENT4）基因调节叶片过早衰老，这参与了细胞组分的程序性降解以及营养从衰老叶片中的输出。植物利用衰老机制来限制蚜虫的生长。此外，PAD4还提供抗GPA的抗氧剂（防止昆虫沉降和进食）和抗微生物性（损害蚜虫的繁殖力），并对GPA的筛分元素利用率产生不利影响。 PAD4的基础表达有助于抗菌作用，而GPA诱导的PAD4的表达有助于抗氧血症。编码SSI2（水杨酸[SA]不敏感性2的抑制因子）基因的拟南芥硬脂酰ACP去饱和酶中的突变导致细胞死亡表型加快和矮化，还赋予GPA更高的抗菌性。这项研究的结果表明，PAD4是ssi2介导的对GPA增强抗菌作用所必需的。 PAD4蛋白包含保守的Ser，Asp和His残基，形成许多α/β折叠酰基水解酶的催化三联体。在无选择测试中，与野生型（WT）植物相比，表达PAD4突变型[PAD4（S118A）和PAD4（D178A）]的拟南芥植物支持更高数量的GPA。此外，电渗透图（EPG）研究表明，PAD4中的S118残留物对于限制从筛分元素进料的GPA至关重要。但是，选择测试中阻止昆虫沉降的能力不受PAD4（S118A）和PAD4（D178A）突变的影响，因此表明PAD4参与阻止昆虫沉降和抗菌的作用是由PAD4的不同区域决定的。 MPL1（MYZUS PERSICAE诱导的LIPASE1）基因是拟南芥对GPA防御的另一个重要组成部分。像PAD4一样，响应GPA侵染也诱导了MPL1表达。但是，MPL1仅对于抗生菌是必需的，而对于抗GPA的抗生菌不是必需的。 EPG分析表明，mpl1突变体等位基因不会影响蚜虫的摄食行为。由于MPL1表现出脂肪酶活性，而ssi2叶柄渗出液中抗生素的含量较高，因此我们建议对GPA的抗菌作用需要脂质或其产物。

著录项

  • 作者

    Louis, Joe.;

  • 作者单位

    University of North Texas.;

  • 授予单位 University of North Texas.;
  • 学科 Biology Molecular.
  • 学位 Ph.D.
  • 年度 2011
  • 页码 169 p.
  • 总页数 169
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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