A mechanistic framework for auxin dependent Arabidopsis root hair elongation to low external phosphate (Nature Comms)

Plants respond to a low phosphate environment through increased elongation of root hairs. Bhosale et al. showed that low external P increases levels of the auxin (IAA) in Arabidopsis roots through the TAA1 (TRYPTOPHAN AMINO TRANSFERASE 1)-mediated auxin biosynthesis pathway. At the same time, the auxin influx carrier AUX1 facilitates shootward auxin transport in low-P stress condition; expressing AUX1 in lateral root cap (LRC) and epidermis is sufficient to complement the root hair phenotype of aux1 under low P stress. Increased IAA induces multiple transcription factors in a spatial manner such as ARF19 in the root apex, RSL2 (ROOT HAIR DEFECTIVE 6-LIKE 2) and RSL4 in the elongation and differentiation zones, respectively, to promote root hair elongation. This work provided a comprehensive molecular mechanism of root hair elongation under low P conditions. (Summary by Arif Ashraf) Nature Communications: 10.1038/s41467-018-03851-3