14CONFAP: Brazil-UK Partnership on Delivering Pest Resilience in Brazilian Smallholder Maize Crops

植物已经进化出复杂的防御策略，利用各种可诱导的防御机制来对抗生物胁迫（害虫），这些防御机制可用于作物保护。它们直接产生对害虫具有拮抗作用的挥发性亲脂小分子（SLMs），间接释放SLMs作为胁迫信号吸引害虫天敌。此外，邻近的植物已经进化到通过诱导或增强（启动）它们的防御反应来响应应激信号。在检测到植物胁迫信号后诱导或诱导作物进行防御的能力为开发新的混合种植系统提供了机会，由此，与哨兵（守卫）作物的初始害虫攻击相关的已识别的胁迫信号可用于激活主要作物的防御。该项目的总体目标是联合英国和巴西的合作伙伴，在巴西的小农农场开发玉米抵御秋粘虫（Spodoptera frugiperda）的能力。这将基于玉米/S的化学生态学。Frugiperda互作，用于部署混合种植系统，该系统利用最初受攻击植物的植物/植物信号，在主要作物中进行保护（天敌）生物防治。不同的玉米品种和地方品种将被评估，以表征S. frugiperda诱导的胁迫信号的释放。植物将不受S. frugiperda胁迫或受S. frugiperda胁迫，顶空提取物将通过空气夹带获得诱导胁迫信号。应力信号将使用气相色谱- fid进行分析，并使用气相色谱-质谱进行鉴定。为了确认已识别的胁迫信号的生物活性，将进行生物测定以评估其对害虫天敌觅食行为的影响。为了评估胁迫信号对相邻玉米品种和地方品种防御的诱导作用，我们将未受损的相邻玉米植株（受体）暴露于受S. frugiperda损害的植株（供体）释放的胁迫信号中。然后将从受体植物中收集诱导的信号，并通过GC-FID和GC-MS鉴定供体压力信号是否在受体中引发了防御反应。为了确认受体释放的应激信号的生物活性，将进行生物测定，以评估其对天敌觅食行为的影响。为了评估胁迫信号暴露和未暴露的受体植物之间胁迫信号生物合成基因的差异表达，将从信号暴露和未暴露的玉米品种和地方品种中提取信使RNA，并进行下一代测序转录组分析。可能的生物合成基因的差异表达特异性编码酶参与胁迫信号的生物合成将通过实时PCR分析证实。这些基因将被确定为玉米品种和地方品种选择的目标，在这些品种和地方品种中，基因表达可以通过暴露于所鉴定的胁迫信号而被诱导。实地研究将在米纳斯吉拉斯州Embrapa玉米和高粱试验田进行。将组织玉米品种和地方品种的混合种植，这些品种要么对秋粘虫的伤害非常敏感，并发出植物胁迫信号（哨兵作物），要么通过激发它们自己的防御（主要作物）对胁迫信号做出反应。田间试验完成后，Embrapa公司将带熟悉的农民和推广人员参加农民田间学校/农民田间论坛的培训，向他们传授保护玉米的混合种植策略。一旦制定了防治秋粘虫的混合种植制度战略，并在农民田间学校/论坛上成功地进行了演示，就将用简单的语言在概况介绍和图文手册中进行记录。

Plants have evolved sophisticated defence strategies against biotic stress (pests) using a variety of inducible defence mechanisms that can be exploited in crop protection. Directly, they produce volatile small lipophilic molecules (SLMs) that are antagonistic to pests, and indirectly, they release SLMs as stress signals to attract pest natural enemies. Furthermore, neighbouring plants have evolved to respond to the stress signalling by induction or augmentation (priming) of their defence response. The ability to elicit or prime crop plants for defence upon detection of plant stress signalling provides an opportunity to develop new mixed cropping systems, whereby the identified stress signals associated with initial pest attack on sentinel (guard) crops can be used for the activation of defence in main crops. The overall aim of this project is to bring together UK and Brazilian partners to develop resilience in maize against fall armyworm, Spodoptera frugiperda, in smallholder farms in Brazil. This will be based upon the chemical ecology of maize/S. frugiperda interactions, for the deployment of a mixed cropping system that exploits plant/plant signalling from initially attacked plants for conservation (natural enemy) biocontrol in main crops. Different cultivars and landraces of maize will be evaluated to characterise the emission of S. frugiperda-induced stress signalling. Plants will be either unchallenged or challenged with S. frugiperda and headspace extracts containing the induced stress signals will be obtained by air entrainment. The stress signals will be analysed using GC-FID and identified using GC-MS. To confirm the biological activity of the identified stress signals, bioassays will be conducted to evaluate their influence on the foraging behaviour of pest natural enemies. To evaluate stress signal induction of defence in neighbouring maize cultivars and landraces, undamaged neighbouring maize plants (recipients) will be exposed to the stress signals released by S. frugiperda-damaged plants (donors). The induced signalling will then be collected from recipient plants and identified by GC-FID and GC-MS to see if the donor stress signalling has elicited a defence response in recipients. To confirm the biological activity of the stress signals released by recipients, bioassays will be conducted to evaluate their influence on the foraging behaviour of natural enemies. To evaluate differential expression of stress signal biosynthesis genes between stress-signal exposed and unexposed recipient plants, messenger RNA will be extracted from signal-exposed and unexposed recipient maize cultivars and landraces and subjected to Next Generation Sequencing transcriptome analysis. The differential expression of putative biosynthesis genes that specifically encode enzymes involved in stress signal biosynthesis will be confirmed using real time PCR analysis. These genes will be identified as targets for selection of maize cultivars and landraces with resilience to S. frugiperda, in which gene expression can be elicited by exposure to the stress signals identified. Field studies will be carried out on experimental-based plots at Embrapa Maize and Sorghum in Minas Gerais. Plots will be organised with mixed cropping of the maize cultivars and landraces that are shown to be either highly susceptible to fall armyworm damage and emit plant stress signalling (sentinel crops), or respond to stress signalling though elicitation of their own defence (main crops). After completion of the field experiment, farmers and extension officers known to Embrapa will be taken though Farmers Field Schools/Farmers Field Forum training where they will be educated on the mixed cropping strategy for maize protection. Once the mixed cropping system strategy for control of fall armyworm is developed and successfully demonstrated in farmer field schools/forums, it will be documented in simple language in factsheets and illustrated handbooks.