The Arabidopsis thaliana F-box gene HAWAIIAN SKIRT is a new player in the microRNA pathway.

Xuebin Zhang,Jeremy A Roberts,Janny L Peters,Judit Szecsi,Zinnia H González-Carranza,Mohammed Bendahmane,Dasuni Jayaweera,Yun Zheng

doi:10.1371/journal.pone.0189788

Abstract

In Arabidopsis, the F-box HAWAIIAN SKIRT (HWS) protein is important for organ growth. Loss of function of HWS exhibits pleiotropic phenotypes including sepal fusion. To dissect the HWS role, we EMS-mutagenized hws-1 seeds and screened for mutations that suppress hws-1 associated phenotypes. We identified shs-2 and shs-3 (suppressor of hws-2 and 3) mutants in which the sepal fusion phenotype of hws-1 was suppressed. shs-2 and shs-3 (renamed hst-23/hws-1 and hst-24/hws-1) carry transition mutations that result in premature terminations in the plant homolog of Exportin-5 HASTY (HST), known to be important in miRNA biogenesis, function and transport. Genetic crosses between hws-1 and mutant lines for genes in the miRNA pathway also suppress the phenotypes associated with HWS loss of function, corroborating epistatic relations between the miRNA pathway genes and HWS. In agreement with these data, accumulation of miRNA is modified in HWS loss or gain of function mutants. Our data propose HWS as a new player in the miRNA pathway, important for plant growth.

Highlights

Selective degradation of proteins is carried out via the ubiquitin-proteasome pathway which is fundamental for many cellular processes, including development, hormonal signalling, abiotic stress and immunity in plants [1, 2]
Screening of 308 individuals from 43 M2 populations resulted in the identification of two suppressor lines shs-2/hws-1 and shs-3/hws-1 that displayed no sepal fusion, suggesting suppression of the hws-1 phenotype (Fig 1I, 1J, 1K, 1M, 1Q, 1R, 1S and 1U)
HST has been implicated in the export of an unidentified component of the miRNA pathway, miRNA biogenesis or miRNA function [48]

Summary

Introduction

Selective degradation of proteins is carried out via the ubiquitin-proteasome pathway which is fundamental for many cellular processes, including development, hormonal signalling, abiotic stress and immunity in plants [1, 2]. The abundance of key brakes and/or accelerators that control these processes is regulated by the 26S proteasome using complex mechanisms to avoid destruction of crucial proteins and the release of partially degraded polypeptides [2, 3]. E1, E2 and E3 enzymes sequentially attach the small soluble protein ubiquitin to the proteins.

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Conclusion