Phillip E Marucci Center for Blueberry and Cranberry Research and Extension, Rutgers-The State University of New Jersey, 125A Lake Oswego Rd, Chatsworth, NJ 08019, USA.
J Exp Bot. 2011 May;62(8):2633-44. doi: 10.1093/jxb/erq466. Epub 2011 Feb 2.
The process of selecting certain desirable traits for plant breeding may compromise other potentially important traits, such as defences against pests; however, specific phenotypic changes occurring over the course of domestication are unknown for most domesticated plants. Cranberry (Vaccinium macrocarpon) offers a unique opportunity to study such changes: its domestication occurred recently, and we have access to the wild ancestors and intermediate varieties used in past crosses. In order to investigate whether breeding for increased yield and fruit quality traits may indirectly affect anti-herbivore defences, the chemical defences have been examined of five related cranberry varieties that span the history of domestication against a common folivore, the gypsy moth (Lymantria dispar). Direct defences were assessed by measuring the performance of gypsy moth caterpillars and levels of phenolic compounds in leaves, and indirect defences by assaying induced leaf volatile emissions. Our results suggest that breeding in cranberry has compromised plant defences: caterpillars performed best on the derived NJS98-23 (the highest-yielding variety) and its parent Ben Lear. Moreover, NJS98-23 showed reduced induction of volatile sesquiterpenes, and had lower concentrations of the defence-related hormone cis-jasmonic acid (JA) than ancestral varieties. However, induced direct defences were not obviously affected by breeding, as exogenous JA applications reduced caterpillar growth and increased the amounts of phenolics independent of variety. Our results suggest that compromised chemical defences in high-yielding cranberry varieties may lead to greater herbivore damage which, in turn, may require more intensive pesticide control measures. This finding should inform the direction of future breeding programmes.
在植物育种过程中，选择某些理想的特征可能会损害其他潜在重要的特征，例如对害虫的防御；然而，对于大多数驯化植物，我们还不知道在驯化过程中发生的具体表型变化。蔓越莓（Vaccinium macrocarpon）为研究这种变化提供了一个独特的机会：它的驯化时间较近，我们可以获得野生祖先和过去杂交中使用的中间品种。为了研究增加产量和果实品质特性的育种是否可能间接地影响抗草食动物防御，我们研究了五个相关的蔓越莓品种的化学防御，这些品种跨越了驯化的历史，针对一种常见的食叶昆虫——舞毒蛾（Lymantria dispar）。通过测量舞毒蛾幼虫的表现和叶片中酚类化合物的水平来评估直接防御，通过测定诱导的叶片挥发性排放物来评估间接防御。我们的结果表明，蔓越莓的选育削弱了植物的防御能力：幼虫在衍生品种 NJS98-23（产量最高的品种）及其亲本 Ben Lear 上表现最佳。此外，NJS98-23 表现出挥发性倍半萜的诱导减少，并且与祖先品种相比，防御相关激素顺式茉莉酸（JA）的浓度较低。然而，诱导的直接防御似乎不受选育的影响，因为外源 JA 的应用降低了幼虫的生长速度，并增加了与品种无关的酚类物质的含量。我们的结果表明，高产量蔓越莓品种中防御能力的削弱可能导致更多的草食性动物损害，这反过来又可能需要更密集的农药控制措施。这一发现应该为未来的育种计划指明方向。
