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Summary Vascular bundles transport water and photosynthate to all organs, and increased bundle number contributes to crop lodging resistance. However, the regulation of vascular bundle formation is poorly understood in the Arabidopsis stem.We report a novel semi‐dominant mutant with high vascular activity,hva‐d, showing increased vascular bundle number and enhanced cambium proliferation in the stem. The activation of a C2H2 zinc finger transcription factor,AT5G27880/HVA, is responsible for thehva‐dphenotype. Genetic, biochemical, and fluorescent microscopic analyses were used to dissect the functions of HVA.HVA functions as a repressor and interacts with TOPLESS via the conserved Ethylene‐responsive element binding factor‐associated Amphiphilic Repression motif. In contrast to the HVA activation line, knockout ofHVAfunction with a CRISPR‐Cas9 approach or expression of HVA fused with an activation domain VP16 (HVA‐VP16) resulted in fewer vascular bundles. Further, HVA directly regulates the expression of the auxin transport efflux facilitatorPIN1, as a result affecting auxin accumulation. Genetics analysis demonstrated that PIN1 is epistatic to HVA in controlling bundle number.This research identifies HVA as a positive regulator of vascular initiation through negatively modulating auxin transport and sheds new light on the mechanism of bundle formation in the stem.
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Two tonoplast proton pumps function in Arabidopsis embryo development
Summary Two types of tonoplast proton pumps, H+‐pyrophosphatase (V‐PPase) and the H+‐ATPase (V‐ATPase), establish the proton gradient that powers molecular traffic across the tonoplast thereby facilitating turgor regulation and nutrient homeostasis. However, how proton pumps regulate development remains unclear.In this study, we investigated the function of two types of proton pumps in Arabidopsis embryo development and pattern formation. While disruption of either V‐PPase or V‐ATPase had no obvious effect on plant embryo development, knocking out both resulted in severe defects in embryo pattern formation from the early stage.While the first division in wild‐type zygote was asymmetrical, a nearly symmetrical division occurred in the mutant, followed by abnormal pattern formation at all stages of embryo development. The embryonic defects were accompanied by dramatic differences in vacuole morphology and distribution, as well as disturbed localisation of PIN1. The development of mutant cotyledons and root, and the auxin response of mutant seedlings supported the hypothesis that mutants lacking tonoplast proton pumps were defective in auxin transport and distribution.Taking together, we proposed that two tonoplast proton pumps are required for vacuole morphology and PIN1 localisation, thereby controlling vacuole and auxin‐related developmental processes in Arabidopsis embryos and seedlings.
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- Award ID(s):
- 1714795
- PAR ID:
- 10455118
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- New Phytologist
- Volume:
- 225
- Issue:
- 4
- ISSN:
- 0028-646X
- Page Range / eLocation ID:
- p. 1606-1617
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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