Data_Sheet_1_Interactive impact of potassium and arbuscular mycorrhizal fungi on the root morphology and nutrient uptake of sweet potato (Ipomoea batatas L.).docx

Sweet potato is a typical “potassium (K)-favoring” food crop and strongly dependent on arbuscular mycorrhizal fungi (AMF). Recent studies show the importance of K and AMF to morphology optimization and nutrient uptake regulation of sweet potato; meanwhile, the interaction exists between K and K use efficiency (KIUE) in sweet potato. To date, only a few studies have shown that AMF can improve plant K nutrition, and whether the benefits conferred by AMF on plant are related to K remains unclear. In this study, low-KIUE genotype “N1” and high-KIUE genotype “Xu28” were used as experimental sweet potato; Funneliformis mosseae (FM) and Claroideoglomus etunicatum (CE) were used as experimental AMF. In a pot experiment, plants “N1” and “Xu28” were inoculated with FM or CE, and applied with or without K fertilizer to uncover the effects of K application and AMF inoculation on the root morphology and nutrient absorption of sweet potato during their growing period. Results demonstrated that AMF inoculation-improved root morphology of sweet potato highly relied on K application. With K application, AMF inoculation significantly increased root tip number of “N1” in the swelling stage and optimized multiple root morphological indexes (total root length, root surface area, root volume, root diameter, root branch number, and root tip number) of “Xu28” and CE had the best optimization effect on the root morphology of “Xu28”. In addition, CE inoculation significantly promoted root dry matter accumulation of “Xu28” in the swelling and harvesting stages, coordinated aerial part and root growth of “Xu28”, reduced the dry matter to leaf and petiole, and was beneficial to dry matter allocation to the root under conditions of K supply. Another promising finding was that CE inoculation could limit K allocation to the aboveground and promote root K accumulation of “Xu28” under the condition with K application. The above results lead to the conclusion that K and CE displayed a synergistic effect on root development and K acquisition of high-KIUE “Xu28”. This study could provide a theoretical basis for more scientific application of AMF in sweet potato cultivation and will help further clarify the outcomes of plant-K–AMF interactions.

甘薯是典型的喜钾（K）粮食作物，且高度依赖丛枝菌根真菌（arbuscular mycorrhizal fungi, AMF）。已有研究表明，钾（K）与丛枝菌根真菌对甘薯的形态优化及养分吸收调控具有重要作用；同时，甘薯体内钾与钾利用效率（K use efficiency, KIUE）之间存在交互效应。截至目前，仅有少量研究证实丛枝菌根真菌可提升植物钾营养水平，而丛枝菌根真菌对植物的有益效应是否与钾元素相关仍不明确。本研究以低钾利用效率基因型"N1"与高钾利用效率基因型"Xu28"作为供试甘薯材料，以摩西管柄囊霉（Funneliformis mosseae, FM）与近明球囊霉（Claroideoglomus etunicatum, CE）作为供试丛枝菌根真菌菌株。通过盆栽试验，对"N1"与"Xu28"分别接种FM或CE，并设置施钾与不施钾处理，以探究施钾及丛枝菌根真菌接种对甘薯生育期内根系形态与养分吸收的影响。结果表明，丛枝菌根真菌接种对甘薯根系形态的改善效应高度依赖于钾素施用。施钾条件下，丛枝菌根真菌接种可显著提升"N1"块根膨大期的根尖数，并优化"Xu28"的多项根系形态指标（总根长、根表面积、根体积、根直径、根分枝数及根尖数）；其中CE对"Xu28"根系形态的优化效果最佳。此外，在施钾条件下，CE接种可显著促进"Xu28"在块根膨大期与收获期的根系干物质积累，协调"Xu28"地上部与根系的生长，减少干物质向叶片及叶柄的分配，利于干物质向根系转运。另一项重要发现为：施钾条件下，CE接种可限制钾素向地上部的分配，并促进"Xu28"的根系钾素积累。综上结果可得出结论：钾素与CE对高钾利用效率基因型"Xu28"的根系发育及钾素获取具有协同效应。本研究可为丛枝菌根真菌在甘薯栽培中的科学应用提供理论依据，同时有助于进一步阐明植物-钾-丛枝菌根真菌三者间的互作效应。