Department of Environment and Genetics, La Trobe University, Bundoora, VIC 3086, Australia.
Research Centre for Future Landscapes, La Trobe University, Bundoora, VIC 3086, Australia.
Microsc Microanal. 2024 Jul 4;30(3):607-618. doi: 10.1093/micmic/ozae008.
Manipulation of host plant physiology by leaf-galling insects is a multifaceted process. Among fundamental knowledge gaps surrounding this scientifically intriguing phenomenon is the appropriation of plant mineral nutrients and moisture for galling advantage. Small, soluble mineral ions and watery cell contents in dense gall tissues risk disruption during routine sample preparations. In this study, an X-ray microanalysis was applied to investigate gall mineral nutrition. Morphologically diverse leaf galls were sampled from three Australian rainforest tree species. Using cryo-analytical scanning electron microscopy, real-time X-ray analytical maps of cellular mineral nutrients and water were integrated with anatomical images of gall and leaf cross-sectional surfaces. A comparison of host-leaf and gall anatomies bore direct evidence of drastic changes to leaf cells through the galling process. Distinct "wet" and "dry" regions within galls were anatomically and/or chemically differentiated, suggesting specific functionality. "Wet" regions comprising hydrated cells including soft gall-cavity linings where larvae are known to feed contained soluble plant mineral nutrients, while C-rich "dry" tissues largely devoid of mineral nutrients likely contribute structural support. Mapping immobile nutrients such as Mn may provide a means of "matching" specific gall cell types to those in ungalled host-leaf tissues. The findings here provided otherwise inaccessible insights into leaf-gall mineral nutrition.
叶瘿昆虫对寄主植物生理学的操纵是一个多方面的过程。在围绕这一具有科学吸引力的现象的基本知识空白中，有一个是为瘿虫优势而获取植物矿物质营养和水分。在常规样品制备过程中，小的、可溶性的矿物质离子和密集瘿组织中的水样细胞内容物有被破坏的风险。在这项研究中，应用了 X 射线微量分析来研究瘿矿营养。从三种澳大利亚雨林树种中采集了形态多样的叶瘿。使用 cryo 分析扫描电子显微镜，实时 X 射线分析细胞矿物质营养和水分的地图与瘿和叶横切面表面的解剖图像相结合。对寄主叶和瘿的解剖结构的比较直接证明了在瘿形成过程中对叶细胞的剧烈变化。瘿内的“湿”区和“干”区在解剖学上和/或化学上是有区别的，这表明它们具有特定的功能。“湿”区包括含水细胞，包括幼虫已知在此进食的软瘿腔衬里，其中含有可溶性植物矿物质营养，而富含 C 的“干”组织则几乎不含矿物质营养，可能提供结构支撑。对诸如 Mn 等不可移动养分的映射可能提供一种“匹配”特定瘿细胞类型与未瘿化的寄主叶组织的方法。这些发现为叶瘿矿营养提供了其他无法获得的见解。
