Data from: Increased root herbivory under elevated atmospheric carbon dioxide concentrations is reversed by silicon-based plant defences

Predicted increases in atmospheric concentrations of CO2 may alter the susceptibility of many plants to insect herbivores due to changes in plant nutrition and defences. Silicon plays a critical role in plant defence against herbivores, so increasing such silicon-based defences in plants may help remediate situations where plants become more susceptible to herbivores. Sugarcane (Saccharum spp. hybrid) were subjected to fully factorial treatment combinations of ambient (aCO2) or elevated (eCO2) atmospheric CO2 concentrations; ambient silicon or silicon supplementation; insect-free or subject to root herbivory by greyback canegrub (Dermolepida albohirtum). A glasshouse study was used to determine how these factors affected rates of photosynthesis, growth, chemistry (concentrations of silicon, carbon, nitrogen and non-structural carbohydrates). Changes in canegrub mass were determined in the glasshouse pot study, together with more detailed assessment of how eCO2 and silicon supplementation affected performance and feeding behaviour (relative growth rate and relative consumption) in a 24-hour feeding efficiency assay. eCO2 and silicon supplementation increased rates of photosynthesis (+32% and 14%, respectively) sugarcane biomass (+45% and 69%, respectively). Silicon supplementation increased silicon concentrations in both leaves and roots by 54% and 75%, respectively. eCO2 caused root C:N to increase by 12%. Canegrub performance and consumption increased under eCO2; relative growth rate (RGR) increased by 116% and consumed 57% more root material (suggestive of compensatory feeding). Silicon application reversed these effects, with large decreases in mass change, RGR and root consumption (65% less root mass consumed). Synthesis and applications. Our results suggest future atmospheric carbon dioxide concentrations could lead to increased crop damage by a below-ground herbivore. Increasing bioavailable silicon in soil stimulated silicon-based defences which dramatically decreased herbivory and herbivore performance. Our findings suggest future pest management strategies could benefit from characterising deficiencies in bioavailable silicon in agricultural soils and targeted application of silicon fertilisers. Moreover, future breeding programmes should exploit variation in silicon uptake between cultivars to enhance silicon uptake in new crop varieties. Silicon-based plant defence proved to be highly beneficial for remediating the negative effects of atmospheric change on sugarcane susceptibility to herbivory and could be applicable in other crops.
Usage notes
Insect feeding trial data
File containing data from the feeding trials. The column 'plant' is the identifier and can be used in conjunction with 'treatments' file for analysis.
canegrub_feedingtrial.csv
Leaf CN
Carbon and nitrogen data from sugarcane leaves. The 'plant' column is the identifier to be used in conjunction with the 'treatments' file for analysis.
leaf_CN.csv
Sugarcane photosynthesis
Photosynthesis data from each measuring 'event' throughout the experiment. The 'plant' column is the identifier to be used in conjunction with the 'treatments' file for analysis.
photosynthesis.csv
Root CN
Carbon and nitrogen data from sugarcane roots. The 'plant' column is the identifier to be used in conjunction with the 'treatments' file for analysis.
root_CN.csv
Leaf silicon
Data from silicon analysis of sugarcane leaves. The 'plant' column is the identifier to be used in conjunction with the 'treatments' file for analysis.
silicon_leaves.csv
Root silicon
Data from silicon analysis of sugarcane roots. The 'plant' column is the identifier to be used in conjunction with the 'treatments' file for analysis.
silicon_roots.csv
treatments
Identifier file to allow allocation of 'plant' to treatment combinations for analysis.
Root total non structural carbs
Data from the total non-structural carbohydrate analysis of sugarcane roots. The 'plant' column is the identifier and should be used in combination with the 'treatments' file for analysis.
TNC_roots.csv
biomass
Biomass data from sugarcane plants. The column 'plant' is the identifier and can be used in conjunction with 'treatments' file for analysis.
pot trial
Data from pot trial on insect performance including controls accounting for direct effects of treatments on insects.

大气中二氧化碳（CO₂）浓度的预期升高可能会通过改变植物营养和防御机制，影响多种植物对植食性昆虫的敏感性。硅（Silicon）在植物抵御植食性昆虫的防御中起着关键作用，因此增强植物的硅基防御可能有助于缓解植物对植食性昆虫敏感性增加的情况。

甘蔗（Saccharum spp. hybrid）接受了全因子处理组合：大气CO₂浓度为常态（aCO₂）或升高（eCO₂）；硅水平为常态或补充硅；无昆虫或遭受灰背甘蔗金龟（greyback canegrub，学名Dermolepida albohirtum）的根部取食。通过温室研究，测定了这些因素对甘蔗光合作用速率、生长及化学特性（硅、碳、氮和非结构性碳水化合物浓度）的影响。在温室盆栽研究中测定了甘蔗金龟体重的变化，并通过24小时取食效率试验，更详细地评估了eCO₂和硅补充对其表现及取食行为（相对生长率和相对取食量）的影响。

结果显示，eCO₂和补充硅分别使甘蔗光合作用速率提高32%和14%，生物量分别增加45%和69%。补充硅使叶片和根部的硅浓度分别提高54%和75%。eCO₂使根部碳氮比（C:N）增加12%。在eCO₂条件下，甘蔗金龟的表现和取食量均有所提升：相对生长率（RGR）增加116%，根部取食量增加57%（表明存在补偿性取食）。施用硅则逆转了这些效应，显著降低了甘蔗金龟的体重变化、RGR和根部取食量（根部取食量减少65%）。

综合与应用：我们的结果表明，未来大气CO₂浓度升高可能导致地下植食性昆虫对作物的损害增加。增加土壤中可利用硅（bioavailable silicon）可激发硅基防御，显著降低取食行为和植食性昆虫的表现。我们的研究发现提示，未来的害虫管理策略可通过表征农业土壤中可利用硅的缺乏状况及针对性施用硅肥而获益。此外，未来育种计划应利用不同品种间硅吸收能力的差异，提高新品种的硅吸收效率。硅基植物防御被证明对缓解大气变化导致的甘蔗对植食性昆虫敏感性增加的负面影响非常有效，且可能适用于其他作物。

Usage notes
昆虫取食试验数据
包含取食试验数据的文件。列'plant'为标识符，可与'treatments'文件结合用于分析。
canegrub_feedingtrial.csv
叶片碳氮数据
甘蔗叶片的碳和氮数据。列'plant'为标识符，需与'treatments'文件结合用于分析。
leaf_CN.csv
甘蔗光合作用数据
整个实验期间各测量事件的光合作用数据。列'plant'为标识符，可与'treatments'文件结合用于分析。
photosynthesis.csv
根部碳氮数据
甘蔗根部的碳和氮数据。列'plant'为标识符，可与'treatments'文件结合用于分析。
root_CN.csv
叶片硅数据
甘蔗叶片硅分析的数据。列'plant'为标识符，可与'treatments'文件结合用于分析。
silicon_leaves.csv
根部硅数据
甘蔗根部硅分析的数据。列'plant'为标识符，可与'treatments'文件结合用于分析。
silicon_roots.csv
treatments
用于将'plant'分配到处理组合的标识符文件，以便分析。
根部总非结构性碳水化合物
甘蔗根部总非结构性碳水化合物分析的数据。列'plant'为标识符，应与'treatments'文件结合用于分析。
TNC_roots.csv
生物量数据
甘蔗植株的生物量数据。列'plant'为标识符，可与'treatments'文件结合用于分析。
盆栽试验数据
盆栽试验中昆虫表现的数据，包括考虑处理对昆虫直接影响的对照。