Abstract
Reactive oxygen species (ROS) play important roles as root growth regulators. We previously reported a comprehensive transcriptomic atlas, which we named ROS-map, that revealed ROS-responsible genes in Arabidopsis root tips. By using ROS-map, we have characterised an early ROS response key transcription factor, MYB30, as a regulator of root cell elongation under ROS signals. However, there are other ROS-responsible transcription factors which have the potential to regulate root growth. In the present study, we characterised the function of another early ROS-responsible transcription factor, ANAC032, that was selected from ROS-map. Overexpression of ANAC032 fused with the transcriptional activation domain, VP16, inhibited root growth, especially decreasing cell elongation. By transcriptome analysis, we revealed that ANAC032 regulated many stress-responsible genes in the roots. Intriguingly, ANAC032 upregulated MYB30 and its target genes. The upregulation of MYB30 target genes was completely abolished in the ANAC032-VP16x2 OX and ANAC032 estradiol-inducible line in myb30-2 mutants. Moreover, root growth inhibition was alleviated in ANAC032-OX in myb30-2 mutants. Overall, we characterised an upstream transcription factor, ANAC032, of the MYB30 transcriptional cascade which is a key regulator for root cell elongation under ROS signalling.
Highlights
Plant roots are important organs for supporting the plant body because they absorb nutrients and water from soil and communicate with the surrounding environment
We have previously reported that at least 50 transcription factors were upregulated by the hydrogen peroxide (H2O2) treatment at root tips within 6 h
We reported that MYB30 was one of the important root growth regulators under the H2O2 treatment[10]
Summary
Plant roots are important organs for supporting the plant body because they absorb nutrients and water from soil and communicate with the surrounding environment. Plant root growth depends on the balance between cellular proliferation and differentiation at the root tip[1] Many small molecules, such as plant hormones, regulate this balance through a gene regulatory network[2]. There remains many genes for which expression changed under H2O2 treatment even in myb[30] mutants This indicated that there were other transcriptional regulatory pathways for root development under ROS signalling. ANAC032 regulated several important transcription factors that are involved in plant immune response in the leaf[19]. Since ANAC032 activates salicylic acid (SA) signalling and at the same time downregulates genes responsible for jasmonic acid (JA), it is a key mediator between SA- and JA-dependent defence signalling According to these previous studies, ANAC032 plays important roles in plant stress responses
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