OsPRR37 Alternatively Promotes Heading Date Through Suppressing the Expression of Ghd7 in the Japonica Variety Zhonghua 11 under Natural Long-Day Conditions

Haiyang Liu,Yong Hu,Shuangle Li,Qin He,Yongzhong Xing,Hu Zhao,Xiaowei Fan,Bo Zhang,Xin Zhou,Qiuping Li,Mohammed Ayaad,Jia Zhang,Aiqing You

doi:10.1186/s12284-021-00464-1

Abstract

Heading date is an important agronomic trait of rice (Oryza sativa L.) and is regulated by numerous genes, some of which exhibit functional divergence in a genetic background-dependent manner. Here, we identified a late heading date 7 (lhd7) mutant that flowered later than wild-type Zhonghua 11 (ZH11) under natural long-day (NLD) conditions. Map-based cloning facilitated by the MutMap strategy revealed that LHD7 was on the same locus as OsPRR37 but exhibited a novel function as a promoter of heading date. A single-nucleotide mutation of G-to-A in the coding region caused a substitution of aspartic acid for glycine at site 159 within the pseudo-receiver (PR) domain of OsPRR37. Transcriptional analysis revealed that OsPRR37 suppressed Ghd7 expression in both ZH11 background under NLD conditions and the Zhenshan 97 background under natural short-day conditions. Consistently, the expression of Ehd1, Hd3a and RFT1 was enhanced by OsPRR37 in the ZH11 background. Genetic analysis indicated that the promotion of heading date and reduction in grain yield by OsPRR37 were partially dependent on Ghd7. Further investigation showed that the alternative function of OsPRR37 required an intact Ghd7-related regulatory pathway involving not only its upstream regulators OsGI and PhyB but also its interacting partner Hd1. Our study revealed the distinct role of OsPRR37 in the ZH11 background, which provides a more comprehensive understanding of OsPRR37 function and enriches the theoretical bases for improvement of rice heading date in the future.

Highlights

The heading date of rice is defined as the time from sowing date to the emergence of the first panicle
Phenotype of Late Heading Date 7 Mutant The late heading date mutant lhd7 was identified from the M2 plants of ethyl methane sulfonate (EMS)-treated rice cultivar Zhonghua 11 (ZH11)
Red arrow indicates the amino acid Gly (G) at position 159 which mutated to Asp (D) in osprr37. g-h Phenotype of heading date and yield per plant of complementary lines compared with ZH11 and lhd7 mutant arm of chromosome 7 (Fig. 2b, Table 1)

Summary

Introduction

The heading date ( known as flowering time) of rice is defined as the time from sowing date to the emergence of the first panicle. It largely determines the regional and seasonal adaptation of a specific variety. A previous study demonstrated that OsPRR37 delays heading date, increases plant height and enhances grain yield (Gao et al 2014; Liu et al 2015; Hu et al Rice (2021) 14:20. Other variants in the PR domain and the region between the PR and CCT domains were detected, but their effects on the function of OsPRR37 were not demonstrated (Gao et al 2014; Koo et al 2013; Yan et al 2013)

Methods

Results

Discussion

Conclusion