Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA.
Plant Methods. 2011 Mar 10;7(1):5. doi: 10.1186/1746-4811-7-5.
Plant defense against herbivory has been studied primarily in aerial tissues. However, complex defense mechanisms have evolved in all parts of the plant to combat herbivore attack and these mechanisms are likely to differ in the aerial and subterranean environment. Research investigating defense responses belowground has been hindered by experimental difficulties associated with the accessibility and quality of root tissue and the lack of bioassays using model plants with altered defense profiles.
We have developed an aeroponic culture system based on a calcined clay substrate that allows insect herbivores to feed on plant roots while providing easy recovery of the root tissue. The culture method was validated by a root-herbivore system developed for Arabidopsis thaliana and the herbivore Bradysia spp. (fungus gnat). Arabidopsis root mass obtained from aeroponically grown plants was comparable to that from other culture systems, and the plants were morphologically normal. Bradysia larvae caused considerable root damage resulting in reduced root biomass and water absorption. After feeding on the aeroponically grown root tissue, the larvae pupated and emerged as adults. Root damage of mature plants cultivated in aeroponic substrate was compared to that of Arabidopsis seedlings grown in potting mix. Seedlings were notably more susceptible to Bradysia feeding than mature plants and showed decreased overall growth and survival rates.
A root-herbivore system consisting of Arabidopsis thaliana and larvae of the opportunistic herbivore Bradysia spp. has been established that mimics herbivory in the rhizosphere. Bradysia infestation of Arabidopsis grown in this culture system significantly affects plant performance. The culture method will allow simple profiling and in vivo functional analysis of root defenses such as chemical defense metabolites that are released in response to belowground insect attack.
植物对草食性动物的防御主要在地上组织中进行研究。然而，为了抵御草食动物的攻击，植物在各个部位都进化出了复杂的防御机制，这些机制在地上和地下环境中可能有所不同。由于根系组织的可及性和质量以及缺乏使用具有改变防御特征的模式植物的生物测定方法等实验困难，对地下防御反应的研究受到了阻碍。
我们开发了一种基于煅烧粘土基质的气培培养系统，该系统允许昆虫草食动物在进食植物根系的同时，方便地回收根系组织。该培养方法通过为拟南芥和草食性生物布拉氏菌（真菌蝇）开发的根-草食性动物系统得到了验证。从气培植物中获得的拟南芥根质量与其他培养系统相当，且植物形态正常。布拉氏菌幼虫对根系造成了相当大的损害，导致根生物量和水分吸收减少。在气培根组织上取食后，幼虫化蛹并发育为成虫。与在气培基质中种植的成熟植物相比，在盆栽基质中种植的拟南芥幼苗的根系受损情况。与成熟植物相比，幼苗对布拉氏菌的取食明显更为敏感，且整体生长和存活率降低。
建立了一个由拟南芥和机会性草食性生物布拉氏菌幼虫组成的根-草食性动物系统，该系统模拟了根际的草食性动物侵害。在该培养系统中，布拉氏菌对拟南芥的侵害显著影响了植物的性能。该培养方法将允许对根系防御进行简单的分析和体内功能分析，例如化学防御代谢物，这些代谢物是对地下昆虫攻击的反应而释放的。
