Summary Most plants form mycorrhizal associations with mutualistic soil fungi. Through these partnerships, resources are exchanged including photosynthetically fixed carbon for fungal‐acquired nutrients. Recently, it was shown that the diversity of associated fungi is greater than previously assumed, extending to Mucoromycotina fungi. These Mucoromycotina ‘fine root endophytes’ (MFRE) are widespread and generally co‐colonise plant roots together with Glomeromycotina ‘coarse’ arbuscular mycorrhizal fungi (AMF). Until now, this co‐occurrence has hindered the determination of the direct function of MFRE symbiosis. To overcome this major barrier, we developed new techniques for fungal isolation and culture and established the first monoxenic in vitro cultures of MFRE colonising a flowering plant, clover. Using radio‐ and stable‐isotope tracers in these in vitro systems, we measured the transfer of 33P, 15N and 14C between MFRE hyphae and the host plant. Our results provide the first unequivocal evidence that MFRE fungi are nutritional mutualists with a flowering plant by showing that clover gained both 15N and 33P tracers directly from fungus in exchange for plant‐fixed C in the absence of other micro‐organisms. Our findings and methods pave the way for a new era in mycorrhizal research, firmly establishing MFRE as both mycorrhizal and functionally important in terrestrial ecosystems.

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Fruit consumption is fundamental to a balanced diet. The contemporary challenge of maintaining a steady food supply to meet the demands of a growing population is driving the development of strategies to improve the production and nutritional quality of fruit. Plasmodesmata, the structures that mediate symplasmic transport between plant cells, play an important role in phloem unloading and distribution of sugars and signalling molecules into developing organs. Targeted modifications to the structures and functioning of plasmodesmata have the potential to improve fruit development; however, knowledge on the mechanisms underpinning plasmodesmata regulation in this context is scarce. In this review, we have compiled current knowledge on plasmodesmata and their structural characterisation during the development of fruit organs. We discuss key questions on phloem unloading, including the pathway shift from symplasmic to apoplastic that takes place during the onset of ripening as potential targets for improving fruit quality.

Over 85% of land plants engage in symbiotic relationships with mycorrhiza-forming soil fungi that colonise their roots. These mycorrhizal symbioses, which involve the exchange of fungal-acquired nutrients and water for photosynthetically fixed plant carbon, are considered a promising nature-based solution to making agricultural practices more sustainable. In order to implement the widespread use of mycorrhizal fungi in agriculture, a more complete awareness of mycorrhizal fungal diversity and range of plant hosts is needed. Mucoromycotina Fine Root Endophytes (MFRE) are a group of mycorrhiza-forming fungi that have recently been shown to be phylogenetically and functionally distinct from arbuscular mycorrhizal fungi (AMF). Here, we provide the first molecular evidence of MFRE colonisation of winter wheat, winter barley, spring wheat and strawberry roots. Fungal symbionts were identified from partial DNA sequences of the 18S ribosomal RNA gene, obtained through a workflow involving molecular cloning and Sanger sequencing. Our findings shed light on the true distribution of plant-MFRE associations and give rise to new questions regarding their functional significance within agricultural plants.