As a mutualistic endophyte, the host range of Piriformospora indica is very broad and its promoting effects on host plant growth and development have been increasingly reported. In this study, we investigated the influence of P. indica colonization on the growth of longan (Dimocarpus longan Lour.) seedlings and found that the root length and root number, chlorophyll content in leaf, and flavonoid contents in both leaf and stem of P. indica colonized longan seedlings were significantly higher than those of the noncolonized controls. To reveal its promoting mechanism, activities of several antioxidant enzymes, contents of some antioxidant related molecules and phytohormones were measured. Results showed that the peroxidase (POD) activity (indicator of rooting ability) and indole-3-acetic acid (IAA, a root growth promoting phytohormone) content in P. indica colonized roots were both significantly higher than controls. Moreover, P. indica colonization reduced the accumulations of hydrogen peroxide (H₂O₂), malondialdehyde (MDA) and jasmonic acid (JA) in longan roots. Our results indicated that P. indica colonization improved the rooting ability of longan through inducing the IAA biosynthesis and POD activity, facilitated and accelerated the root growth by reducing H₂O₂ accumulation and suppressing the JA accumulation.

Piriformospora indica作为一种共生内生菌，寄主范围非常广泛，其对寄主植物生长发育的促进作用越来越被报道。在本研究中，我们调查了P. indica定植对龙眼 ( Dimocarpus longan Lour.) 幼苗生长的影响，发现P. indica的根长和根数、叶中叶绿素含量以及叶和茎中的黄酮含量籼稻定殖的龙眼幼苗显着高于未定殖的对照。为了揭示其促进机制，测定了几种抗氧化酶的活性、一些抗氧化相关分子和植物激素的含量。结果表明，籼稻定植根中的过氧化物酶（POD）活性（生根能力指标）和吲哚-3-乙酸（IAA，一种促进根系生长的植物激素）含量均显着高于对照。此外，P. indica定植减少了龙眼根中过氧化氢 (H ₂ O ₂ )、丙二醛 (MDA) 和茉莉酸 (JA) 的积累。我们的结果表明P. indica定植通过诱导IAA生物合成和POD活性提高龙眼的生根能力，通过减少H ₂ O ₂积累和抑制JA积累促进和加速根系生长。