Critical research challenges facing Mucoromycotina 'fine root endophytes'
Critical research challenges facing Mucoromycotina 'fine root endophytes'
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毛霉菌亚门“细根内生菌”面临的关键研究挑战
DOI：
10.1111/nph.17684
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发表时间：
2021
期刊：
影响因子：
9.4
通讯作者：
Sinanaj B
中科院分区：
文献类型：
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作者：
Sinanaj B
Mucoromycotina“细根内生菌”（MFRE），以前被称为Glomus tenue （Greenall）或最近的Planticonsortium tenue (Walker等人，2018)，是一种全球分布的土壤真菌（Orchard等人，2017a），与大多数陆地植物系统发育的植物形成内共生关系（Hoysted等人，2018,2019；Rimington等人，2019）。尽管在过去十年中在植物- mfre共生特征方面取得了很大进展，但仍然存在重大挑战。在这里，我们指出了这些挑战，并讨论了在这个快速发展的领域促进研究的未来方向。MFRE属于内生菌门（Mucoromycotina, Mucoromycota），被认为在系统发育上（Bidartondo等人，2011；Spatafora等人，2016；Orchard等人，2017b）和功能上（Field等人，2015,2019；Hoysted等人，2019）不同于更常见的丛枝菌根真菌（AMF），后者属于小球菌门（或小球菌科）（Spatafora等人，2016）。利用同位素示踪剂进行的研究表明，MFRE在与苔类植物（Field等人，2015、2016、2019）和维管植物石松（Hoysted等人，2019、2021b）结合时，可以将磷和氮交换为植物固定碳，而低温扫描电镜（SEM）和x射线微分析研究表明，MFRE可能在地下三叶草（Trifolium subterraneum）的磷同化中发挥作用（Albornoz等人，2020）。在已测量的地方，MFRE已被证明向其宿主植物转移了大量的氮（Field等人，2016年，2019年；Hoysted等人，2019年，2021a），这表明这些真菌共生体可能与AMF一起发挥互补作用。与AMF在植物磷营养中已确立的作用相反，AMF对宿主植物氮营养的直接贡献程度一直存在一些争议（Smith & Smith, 2011; Hodge & Storer, 2015； Thirkell等人，2016），考虑到真菌内共生菌（包括MFRE）被广泛误认为AMF，这一点现在是相关的（Orchard等人，2017a； Field等人，2019）。对MFRE文献的荟析显示，由于难以区分MFRE和AMF形态（Orchard et al., 2017a），分离MFRE的挑战，以及样品储存条件和持续时间导致的降解导致植物标本中缺乏MFRE (Orchard et al., 2017c)，许多过去的研究都忽视了对MFRE的关注。随着MFRE在植物营养中的重要性日益凸显
Mucoromycotina ‘fine root endophytes’(MFRE), referred to previously as Glomus tenue (Greenall) or more recently Planticonsortium tenue (Walker et al., 2018), are a globally distributed group of soil fungi (Orchard et al., 2017a) that form endosymbioses with plants from across most of the land plant phylogeny (Hoysted et al., 2018, 2019; Rimington et al., 2019). Despite much progress having been made in characterizing plant–MFRE symbioses in the last decade, significant challenges remain. Here, we mark out these challenges and discuss future directions for promoting research in this rapidly developing field.MFRE, within Endogonales (Mucoromycotina, Mucoromycota), are recognized as phylogenetically (Bidartondo et al., 2011; Spatafora et al., 2016; Orchard et al., 2017b) and functionally (Field et al., 2015, 2019; Hoysted et al., 2019) distinct from the more commonly studied arbuscular mycorrhizal fungi (AMF), which belong to the Glomeromycotina (or Glomeromycota)(Spatafora et al., 2016). Research using isotope tracers has shown that MFRE exchange both phosphorus and nitrogen for plant-fixed carbon when in association with liverworts (Field et al., 2015, 2016, 2019) and with the vascular plant Lycopodiella inundata (Hoysted et al., 2019, 2021b), while a cryo-scanning electron microscopy (SEM) and X-ray microanalysis study suggests MFRE may play a role in phosphorus assimilation in Trifolium subterraneum (Albornoz et al., 2020). Where it has been measured, MFRE have been shown to transfer a significant amount of nitrogen to their host plant (Field et al., 2016, 2019; Hoysted et al., 2019, 2021a), suggesting that there may be a complementary role for these fungal symbionts alongside AMF. In contrast to their wellestablished role in plant phosphorus nutrition, the extent to which AMF contribute directly to host plant nitrogen nutrition has been subject to some debate (Smith & Smith, 2011; Hodge & Storer, 2015; Thirkell et al., 2016) which is now pertinent given the widespread misidentification of fungal endosymbionts, including MFRE, as AMF (Orchard et al., 2017a; Field et al., 2019). A metaanalysis of the literature on MFRE revealed that many past studies have neglected to focus on MFRE due to difficulties in distinguishing between MFRE and AMF morphologies (Orchard et al., 2017a), the challenge of isolating MFRE, and the absence of MFRE from plant specimens as a result of degradation brought about by sample storage conditions and duration (Orchard et al., 2017c). As the importance of MFRE in plant nutrition is increasingly