Testing the optimal defense theory and the growth-differentiation balance hypothesis in Arabidopsis thaliana
Testing the optimal defense theory and the growth-differentiation balance hypothesis in Arabidopsis thaliana
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DOI：
10.1007/s00442-005-0207-0
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发表时间：
2005-12-01
期刊：
影响因子：
2.7
通讯作者：
Cipollini, D
中科院分区：
文献类型：
--
作者：
Barto, EK;Cipollini, D
最优防御理论(ODT)和生长分化平衡假说(GDBH)是解释植物化学防御表达模式的两种重要理论。ODT预测，具有高适合度价值的植物部分将受到高度防御，GDBH预测，生长缓慢的植物部分将有更多可用于防御的资源，因此比生长较快的组织具有更高的防御水平。我们检测了野生和实验室生态型拟南芥叶片的生长速度、适合度和防御蛋白水平，以确定这种植物中防御蛋白的表达模式是否符合ODT或GDBH的预测。根据营养生长期、抽苔期和开花期三个发育阶段，我们将海棠的叶片分为六个叶级，每个阶段都有两个叶龄：幼叶和老叶。我们通过确定去除每一叶类对总种子产量和发芽率的影响来评估叶片的适合度。虽然沙冬青对落叶有很强的耐受性，但总体来说，幼叶比老叶更有价值，尤其是抽苔植株上的幼叶是最有价值的叶类。营养植物的幼叶在两种生态型中生长最快，而抽苔期和开花植物的老叶生长最慢。最后，通过量化四个防御相关蛋白的结构性和诱导性表达来评估每个叶类的防御水平。愈创木酚过氧化物酶的表达和几丁质酶活性与GDBH的预测基本一致。胰酶抑制物的表达和多酚氧化酶活性因叶片类型和处理而异，但与GDBH和ODT的预测都不一致。
Two prominent theories proposed to explain patterns of chemical defense expression in plants are the optimal defense theory (ODT) and the growth-differentiation balance hypothesis (GDBH). The ODT predicts that plant parts with high fitness value will be highly defended, and the GDBH predicts that slow growing plant parts will have more resources available for defense and thus will have higher defense levels than faster growing tissues. We examined growth rate, fitness value, and defense protein levels in leaves of a wild and lab ecotype of Arabidopsis thaliana to address whether patterns of defense protein expression in this plant conform to predictions of either the ODT or the GDBH. We divided leaves of A. thaliana into six leaf classes based o three developmental stages: vegetative, bolting, and flowering; with two leaf ages at each stage: young and old. We assessed the fitness value of leaves by determining the impact of the removal of each leaf class on total seed production and germination rates. Although A. thaliana was highly tolerant to defoliation, young leaves were more valuable than old in general, and young leaves on bolting plants were the most valuable leaf class in particular. Young leaves on vegetative plants grew fastest in both ecotypes, while old leaves on bolting and flowering plants grew slowest. Finally, defense levels were assessed in each leaf class by quantifying the constitutive and inducible expression of four defense-related proteins. Expression of guaiacol peroxidase and chitinase activity conformed largely to GDBH predictions. Expression of trypsin inhibitor and polyphenoloxidase activity varied by leaf class and treatment, but conformed to neither GDBH nor ODT predictions.