Abstract Citrus plants heavily depend on soil arbuscular mycorrhizal fungi (AMF), while the application of AMF in citrus is limited because of no propagation in vitro. The present work tried to apply a culturable (in vitro) endophytic fungus Piriformospora indica into trifoliate orange (Poncirus trifoliata) and to compare the role of P. indica in plant growth and nutrient acquisition especially phosphorus (P), relative to an arbuscular mycorrhizal fungus Funneliformis mosseae. After 20 weeks, roots of trifoliate orange could be colonized by P. indica, and both P. indica and F. mosseae existed in roots together. Root fungal colonization and soil easily extractable, difficultly extractable, and total glomalin-related protein concentrations were higher under single F. mosseae inoculation than under single P. indica and dual inoculation of F. mosseae and P. indica. Single or dual microbial inoculant collectively improved plant growth including plant height, leaf number, and leaf, stem, and root biomass, compared with non-inoculation. In addition, single fungal treatment raised the content of root N, P, and Mg, and dual inoculation increased only Mg and B contents. The improvement of P by single microbial inoculant was associated with the fungi-accelerated soil phosphatase activity and the fungi-induced root phosphate transporter genes (PT3, PT5, and PT6) expression levels. The positive effects on growth and nutrients were more significant under single F. mosseae than under single P. indica and dual inoculations. It concluded that P. indica has the stimulated roles in plant growth and P acquisition of trifoliate orange, and thus has more applied potentiality in citriculture than AMF as a biofertilizer.

中文翻译：

---

有益内生真菌接种剂对三叶橙幼苗生长及养分吸收的影响

摘要 柑橘类植物严重依赖土壤丛枝菌根真菌（AMF），而AMF在柑橘类植物中的应用因不能在体外繁殖而受到限制。目前的工作试图将可培养的（体外）内生真菌 Piriformospora indica 应用到三叶橙 (Poncirus trifoliata) 中，并比较 P. indica 在植物生长和营养获取中的作用，尤其是磷 (P)，相对于丛枝菌根真菌Funneliformis mosseae。20周后，三叶橙的根可以被P. indica定殖，并且P. indica和F. mosseae同时存在于根中。单一 F. mosseae 接种下的根真菌定植和土壤易提取、难提取和总球蛋白相关蛋白浓度高于单一 P. indica 和双重接种 F. mosseae 下。mosseae 和 P. indica。与未接种相比，单一或双重微生物接种剂共同改善了植物生长，包括植物高度、叶数以及叶、茎和根生物量。此外，单菌处理提高了根系N、P、Mg的含量，双接种只提高了Mg、B的含量。单一微生物接种剂对磷的改善与真菌加速的土壤磷酸酶活性和真菌诱导的根磷酸盐转运蛋白基因（PT3、PT5 和 PT6）表达水平有关。单一接种 F. mosseae 比单一接种和双重接种对生长和养分的积极影响更显着。得出的结论是，籼稻在植物生长和三叶橙磷的获取中具有刺激作用，