New paper and a spotlight from the Gutjahr lab in collaboration with Jianhua Zhang’s lab (Chinese University Hong Kong) showing how plants regulate arbuscular mycorrhiza in accordance with their phosphate status.

PHOSPHATE STARVATION RESPONSE transcription factors enable arbuscular mycorrhiza symbiosis.

Nature Communications 13:477

Debatosh Das, Michael Paries, Karen Hobecker, Michael Gigl, Corinna Dawid, Hon-Ming Lam, Jianhua Zhang, Moxian Chen, Caroline Gutjahr (2022)

Arbuscular mycorrhiza (AM) is a widespread symbiosis between roots of the majority of land plants and Glomeromycotina fungi. AM is important for ecosystem health and functioning as the fungi critically support plant performance by providing essential mineral nutrients, particularly the poorly accessible phosphate, in exchange for organic carbon. AM fungi colonize the inside of roots and this is promoted at low but inhibited at high plant phosphate status, while the mechanistic basis for this phosphate-dependence remained obscure. Here we demonstrate that a major transcriptional regulator of phosphate starvation responses in rice PHOSPHATE STARVATION RESPONSE 2 (PHR2) regulates AM. Root colonization of phr2 mutants is drastically reduced, and PHR2 is required for root colonization, mycorrhizal phosphate uptake, and yield increase in field soil. PHR2 promotes AM by targeting genes required for pre-contact signaling, root colonization, and AM function. Thus, this important symbiosis is directly wired to the PHR2-controlled plant phosphate starvation response.

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Old dog, new trick: The PHOSPHATE STARVATION RESPONSE (PHR)-SPX system regulates arbuscular mycorrhiza symbiosis.

Molecular Plant, Spotlight

Debatosh Das, Caroline Gutjahr (2022)

Plant growth depends on the continuous availability of the macronutrient phosphate (P_i). However, in most soils, P_i is only poorly accessible to plants, resulting in P_i deficiency and triggering a number of P_i starvation responses. One strategy of plants to overcome P_i limitation is to form a symbiosis with arbuscular mycorrhizal (AM) fungi (Smith et al., 2011 ), which occurs with approximately 80% of land plants. AM fungi improve the uptake of P_i and other mineral nutrients and thereby increase plant performance and stress tolerance. They collect these minerals with an extraradical hyphal network from the soil and release them from highly branched structures, called arbuscules, into root cortex cells. Interestingly, P_i sufficiency causes inhibition of internal root colonization ( Balzergue et al., 2011 ; Breuillin et al., 2010 ). The mechanistic basis for this has long remained obscure. Two studies have now solved this long-standing mystery and demonstrated that a canonical P_i-response regulatory module regulates AM symbiosis in accordance with the plant P_i status ( Shi et al., 2021 ; Das et al., 2022 ).

 

 

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