DOI: 10.5061/dryad.4f4qrfjp1
title: Role of silicon in legume-insect interactions: Insights from a plant experiencing different levels of herbivory

description: Silicon (Si) supplementation can enhance symbiotic functions in some
 legumes (Fabaceae) with their nitrogen-fixing rhizobia, such as root
 nodulation and nitrogen fixation. However, it is still poorly understood
 how Si influences legume-insect interactions. Here, we investigated how a
 symbiotic legume responds not only to Si supplementation, but also to
 herbivory treatment with varying infestation levels in two events. We
 conducted a controlled climate chamber experiment by growing Medicago
 truncatula plants inoculated with rhizobia. For half of the plants, the
 soil was kept without Si (-Si), whereas the other half was regularly
 supplemented with Si (+Si). We then infested the plants with caterpillars
 of Spodoptera littoralis with 0, 1, or 3 larvae and 0, 1, or 1 larva in
 single herbivory attack and in double herbivory attack, respectively. To
 understand plant responses to such treatment combinations, we examined 16
 functional traits. Nodule number, nodule fresh mass, and nodule
 leghaemoglobin concentrations were not affected in single attack plants.
 However, increasing levels of herbivory led to decreases in such measured
 traits in double attack plants. Foliar C to N ratio increased in single
 attack plants, but decreased in double attack plants with increasing
 levels of herbivory, indicating contrasting resource allocation. Herbivory
 did not affect the content of foliar Si, which was higher in +Si than -Si
 plants. Si and herbivory led to reduced foliar phenolics in double attack
 plants, suggesting a potential trade-off between silicification and
 phenolic production. Si and herbivory led to increased trichome densities
 in single attack plants, but patterns were less clear in double attack
 plants. Herbivory but not Si reduced plant biomass with increasing levels
 of herbivory in double attack plants. Relative growth rates of the
 caterpillars, as proxy for plant resistance, decreased mainly due to
 herbivory treatment, when fed on single attack plants. Using a trait-based
 approach, we provide novel insights to better understand responses of a
 legume to Si supplementation and different herbivory levels and events. We
 conclude that herbivory predominantly exerts much stronger effects than Si
 on various plant traits, pointing to a necessity to respond to herbivory
 by induced defence strategies.
description: Dataset was collected under controlled experiments involving a
 rhizobial strain, a legume species, and a caterpillar species. Some data
 were gathered using analytical instruments, particularly for plant
 chemical and symbiotic traits. After gathering all data, data were
 organised, tabulated, and statistically analysed using the R
 programme. This dataset consists of data from
 'single attack plants' and 'double attack plants' and
 was compiled into a single Excel file. The file contains seven tabs,
 namely: Labels Single
 Attack Plants Leghaemoglobin_Single
 Insect RGR_Single Double Attack
 Plants Leghaemoglobin_Double
 Insect RGR_Double
description: # Role of silicon in legume-insect interactions: Insights from a plant
 experiencing different levels of herbivory
 [https://doi.org/10.5061/dryad.4f4qrfjp1](https://doi.org/10.5061/dryad.4f4qrfjp1) ## Description of the data and file structure In the first tab of the Excel file called 'Labels', all data are explained. ## Code/software Data were statistically analysed using the R programme version 4.3.3. All used R packages have been clearly described in materials and methods of the article in 'Statistical Analyses' section 2.7. Full codes are not disclosed.