Exploring the genetic basis of wound nectar secretion in Solanum dulcamara

花蜜是一种常见的植物特性，以吸引有益的动物，如传粉者。一般来说，花蜜是一种含糖溶液，但补充剂往往会增强其吸引力。除了花蜜腺外，许多植物的营养器官上也有蜜腺。它们所谓的花外花蜜（EFN）吸引捕食动物，通常是蚂蚁，它们保护植物免受食草动物的侵害。蜜腺显示出巨大的结构多样性，并在不同的植物类群中独立进化了无数次，因此它们的进化起源仍然是一个未解决的问题的debent.In Solanum dulcamara，我们最近发现了一种新形式的EFN，它不是从蜜腺分泌，而是直接在食草动物造成的伤口。这种伤口花蜜（WN）也吸引蚂蚁进行植物防御。由于有证据表明其他植物也会释放吸引蚂蚁的伤口汁液，因此出现了伤口花蜜分泌可能代表花蜜进化的早期步骤的假设。蜜腺可能已经进化为二级结构，通过塑造花蜜分泌的位置，时间和成分，专门为有益动物提供有价值的奖励。这种情况可以优雅地解释整个植物王国蜜腺的频繁获得和损失，因此需要进一步研究。这一假说是基于这样的假设，即花蜜分泌来自于基本的和进化的古老机制，可以很容易地被增选以释放花蜜。然而，这仍然是推测，直到WN释放的机制被确定，并可以从nectaries.To设置花蜜从伤口和蜜腺释放的机制比较的基础，该项目将解决三个主要目标：1）发现与S。2）阐明了S. dulcamara的WN分泌的分子机制的关键要素。通过检测这些基因是否在功能上参与了杜卡马拉的WN分泌。3）表征了S.为了追求这些目标，我们将筛选与WN分泌转录相关的候选基因。同时，我们将II）建立基于CRISPR-Cas9介导的基因编辑的反向遗传学方法。然后III）检查WN分泌和蚂蚁吸引中最可能的候选基因的参与。此外，我们将IV）调查是否S。杜卡马拉通过调整其WN的化学成分来增加投入同化物的效益，因为它以分泌具有结构化蜜腺的EFN植物而闻名。除了提供关于EFN释放的完全未知的遗传基础的全面数据之外，这个项目将进一步拓宽我们对新发现的WN的化学和生态学的知识。

Nectar is a common plant trait to attract beneficial animals like pollinators. In general, nectar is a sugary solution, but supplements often enhance its attractiveness. Besides floral nectaries, many plants also bear nectaries on vegetative parts. Their so called extrafloral nectar (EFN) attracts predacious animals, commonly ants, which defend the plant against herbivores. Nectaries show a huge structural diversity and have evolved numerous times independently all across diverse plant taxa, so that their evolutionary origin is still an unsolved matter of debate.In Solanum dulcamara, we recently discovered a novel form of EFN that is not secreted from nectaries but directly at herbivore-inflicted wounds. This wound nectar (WN) also attracts ants for plant defence. As there is evidence that also other plants release ant-attracting wound saps, the hypothesis arose that wound nectar secretion might represent an early step in nectar evolution. Nectaries could have evolved as secondary structures dedicating the valuable reward specifically to beneficial animals by shaping location, timing and composition of nectar secretion. Such a scenario could elegantly explain the frequent gains and losses of nectaries throughout the plant kingdom and thus calls for further examination. This hypothesis is based on the assumption that nectar secretion arises from fundamental and evolutionary ancient mechanisms that can be easily co-opted to release nectar. However, it remains speculative until the mechanisms of WN release are identified and can be compared to those of EFN release from nectaries.To set the foundation for mechanistic comparisons of nectar release from wounds and nectaries, this project will address the three major goals to:1) discover genes that are activated in association with S. dulcamara’s WN secretion.2) unravel the key elements of molecular mechanisms behind S. dulcamara’s WN secretion by testing whether these genes are functionally involved in WN secretion.3) characterize the chemical properties and the ecological functionality of the WN secreted by S. dulcamara beyond the attractive function of its main constituent sucrose.To pursue these goals, we will I) screen for candidate genes that are transcriptionally correlated with WN secretion. In parallel we will II) establish a reverse genetics approach based on CRISPR-Cas9 mediated gene editing. Then will III) examine the involvement of the most likely candidate genes in WN secretion and ant attraction. Moreover, we will IV) survey whether S. dulcamara tailors the chemical composition of its WN to increase the benefit of the invested assimilates, as it is known for EFN secreting plants with structured nectaries.Besides providing comprehensive data on the completely unknown genetic basis of EFN release, this project will further broaden our knowledge into the chemistry and ecology of the newly discovered WN.