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bioRxiv · 10.1101/2019.12.12.874222

Boron deficiency-induced root growth inhibition is mediated by BR signal regulation in Arabidopsis

Xu, F.·Zhang, C.·He, M. L.·Wang, S.·Chu, L.·Wang, C.·Yang, N.·Ding, G. D.·Cai, H.·Shi, L.
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Abstract

Brassinosteroid (BR) is a pivotal phytohormone involved in regulating root development. Boron (B) is an essential micronutrient for plant growth and development, and root growth of plants is rapidly inhibited under B deficiency condition, but the mechanisms are still elusive. Here, we demonstrate that BR plays crucial roles in these processes. We identify BR-related processes underlying B deficiency at the physiological, genetic, molecular/cell biological and transcriptome levels, and provide strong evidences that B deficiency can affect BR signalling, thereby altering root growth. RNA-sequencing analysis reveals a high co-regulation between BR-regulated genes and B deficiency-responsive genes. We found that low B negatively regulates BR signalling to control BR signalling-dependent root elongation, bes1-D exhibits insensitivity to low B stress, and bri1-301 mutants fails to respond to B depletion. Exogenous eBL application can rescue the inhibition of root growth under B deficiency condition, and application of BR biosynthesis inhibitor BRZ aggravates root growth inhibition of wild-type under B deficiency condition. B deficiency reduces the nuclear signal of BES1. We further found that B deficiency reduces the accumulation of brassinolide (BL) by reducing BR6ox1 and BR6ox2 mRNA level to down-regulate BR signalling and modulate root elongation. Altogether, our results uncover a role of BR signalling in root elongation under B deficiency. One-sentence summaryB deficiency reduces the accumulation of brassinolide by reducing BR6ox1 and BR6ox2 mRNA level to down-regulate BR signalling and modulate root elongation.

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Xu, F., Zhang, C., He, M. L., Wang, S., Chu, L., Wang, C., Yang, N., Ding, G. D., Cai, H., Shi, L.. 2019-12-13. Boron deficiency-induced root growth inhibition is mediated by BR signal regulation in Arabidopsis. https://doi.org/10.1101/2019.12.12.874222

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