A DNA2 Homolog Is Required for DNA Damage Repair, Cell Cycle Regulation, and Meristem Maintenance in Plants.

Hongbo Gao,Xiaomin Liu,Ning Jia

doi:10.1104/pp.16.00312

Abstract

Plant meristem cells divide and differentiate in a spatially and temporally regulated manner, ultimately giving rise to organs. In this study, we isolated the Arabidopsis jing he sheng 1 (jhs1) mutant, which exhibited retarded growth, an abnormal pattern of meristem cell division and differentiation, and morphological defects such as fasciation, an irregular arrangement of siliques, and short roots. We identified JHS1 as a homolog of human and yeast DNA Replication Helicase/Nuclease2, which is known to be involved in DNA replication and damage repair. JHS1 is strongly expressed in the meristem of Arabidopsis. The jhs1 mutant was sensitive to DNA damage stress and had an increased DNA damage response, including increased expression of genes involved in DNA damage repair and cell cycle regulation, and a higher frequency of homologous recombination. In the meristem of the mutant plants, cell cycle progression was delayed at the G2 or late S phase and genes essential for meristem maintenance were misregulated. These results suggest that JHS1 plays an important role in DNA replication and damage repair, meristem maintenance, and development in plants.

Highlights

Plant meristem cells divide and differentiate in a spatially and temporally regulated manner, giving rise to organs
Studies of DNA2 to date have mainly been performed in fungi and mammals (Kang et al, 2010)
The dna2D mutation is lethal in yeast, suggesting that the wild-type protein is essential for cell viability (Budd et al, 2011)

Summary

Introduction

Plant meristem cells divide and differentiate in a spatially and temporally regulated manner, giving rise to organs. The jhs mutant was sensitive to DNA damage stress and had an increased DNA damage response, including increased expression of genes involved in DNA damage repair and cell cycle regulation, and a higher frequency of homologous recombination. In the meristem of the mutant plants, cell cycle progression was delayed at the G2 or late S phase and genes essential for meristem maintenance were misregulated These results suggest that JHS1 plays an important role in DNA replication and damage repair, meristem maintenance, and development in plants. Mutants of MRE11 and BRCA2, which function in DNA damage repair, were shown to have a fasciated phenotype (Bundock and Hooykaas, 2002; Abe et al, 2009) These data together suggest that chromatin assembly, DNA replication, DNA damage repair, cell cycle regulation, and related events are important for meristem organization and plant development

Methods

Results

Conclusion