Chloroplast development at low temperature requires the pseudouridine synthase gene TCD3 in rice

Dongzhi Lin,Yanjun Dong,Zhongze Piao,Yulu Wang,Gangseob Lee,Lu Chen,Lanlan Wu,Rongrong Kong,Jianlong Xu

doi:10.1038/s41598-020-65467-2

Abstract

Low temperature affects a broad spectrum of cellular components in plants, such as chloroplasts, as well as plant metabolism. On the other hand, pseudouridine (Ψ) synthases are required for the most abundant post-transcriptional modification of RNA in Escherichia coli. However, the role of rice Ψ synthases in regulating chloroplast development at low temperature remains elusive. In this study, we identified the rice thermo-sensitive chlorophyll-deficient (tcd3) mutant, which displays an albino phenotype before the 4-leaf stage and ultimately dies when grown at 20 °C, but can grow normally at 32 °C. Genetic analysis showed that the mutant trait is controlled by a single recessive nuclear gene (tcd3). Map-based cloning, complementation and knockout tests revealed that TCD3 encodes a chloroplast-localized Ψ synthase. TCD3 is a cold-induced gene that is mainly expressed in leaves. The disruption of TCD3 severely affected the transcript levels of various chloroplast-associated genes, as well as ribosomal genes involved in chloroplast rRNA assembly at low temperature (20 °C), whereas the transcript levels of these genes were normal at high temperature (32 °C). These results provide a first glimpse into the importance of rice Ψ synthase gene in chloroplast development at low temperatures.

Highlights

Rice is one of the most important food crops worldwide
We identified and characterized TCD3, a pseudouridine (Ψ) synthase required for chloroplast development at low temperatures in rice
Our results provide evidence that cold-induced TCD3 plays an important role in chloroplast development in rice at low temperatures

Summary

Introduction

Rice is one of the most important food crops worldwide. Its yield potential is limited by the photosynthetic capacity of leaves that, as carbohy-drate factories, are unable to fill the larger number of florets of modern rice plants[1]. NEPs are mainly responsible for transcribing the components of the transcriptional/translational machinery, such as rpoA and rpoB, while PEPs are required for the transcription of photosynthetic genes such as psbA, psbD, and rbcL Mutations of those genes directly or indirectly affect chlorophyll biosynthesis or degradation pathways as well as photosynthesis, resulting in differences in leaf color or even plant death[5,6,7,8,9]. Pseudouridine (5-ribosyluracil; Ψ) synthases, responsible for the most abundant post-transcriptional modification of cellular RNAs (pseudouridine), share a common core fold and active site structure This core structure is modified by peripheral domains comprising accessory proteins with different amino acid sequences (depending on the family) and guide RNAs, giving rise to remarkable substrate versatility. The chloroplast-localized Ψ synthase TCD3 appears to play an essential role in chloroplast development at low temperature in rice

Methods

Results

Conclusion