SYL3-k increases style length and yield of F1 seeds via enhancement of endogenous GA4 content in Oryza sativa L. pistils

Xiaojing Dang,Yanhui Li,Zhiyao Dong,Jianhua Jiang,Yuanqing Zhang,Dong She,Delin Hong,Hui Wang,Xiaoxiao Hu,Siqi Chen,Shangshang Zhu,Bingjie Fang,Dalu Li,Qiangming Liu,Yulong Li,Erbao Liu,Zhilan Fan

doi:10.1007/s00122-021-03968-y

Abstract

Key messageSYL3-k allele increases the outcrossing rate of male sterile line and the yield of hybrid F1 seeds via enhancement of endogenous GA4 content in Oryza sativa L. pistils. The change in style length might be an adaptation of rice cultivation from south to north in the northern hemisphere.The style length (SYL) in rice is one of the major factors influencing the stigma exertion, which affects the outcross rate of male sterile line and the yield of hybrid F1 seeds. However, the biological mechanisms underlying SYL elongation remain elusive. Here, we report a map-based cloning and characterisation of the allele qSYL3-k. The qSYL3-k allele encodes a MADS-box family transcription factor, and it is expressed in various rice organs. The qSYL3-k allele increases SYL via the elongation of cell length in the style, which is associated with a higher GA4 content in the pistil. The expression level of OsGA3ox2 in pistils with qSYL3-k alleles is significantly higher than that in pistils with qSYL3-n allele on the same genome background of Nipponbare. The yield of F1 seeds harvested from plants with 7001SSYL3−k alleles was 16% higher than that from plants with 7001SSYL3−n allele. The sequence data at the qSYL3 locus in 136 accessions showed that alleles containing the haplotypes qSYL3AA, qSYL3AG, and qSYL3GA increased SYL, whereas those containing the haplotype qSYL3GG decreased it. The frequency of the haplotype qSYL3GG increases gradually from the south to north in the northern hemisphere. These findings will facilitate improvement in SYL and yield of F1 seeds henceforward.

Highlights

Rice (Oryza sativa L.) is one of the important cereal crops and is consumed by 3.5 billion people worldwide
We evaluated the potential importance of the SYL3-k allele in hybrid rice seed production utilising field experiments and elucidated the allelic polymorphism at the SYL3 locus in 136 accessions collected from different geographic zones
We found that the structure of LOC_Os03g14850 is different from that of the other members in the MADS-box family because it contained the least number of exons (Supplementary Fig. S2C)

Summary

Introduction

Rice (Oryza sativa L.) is one of the important cereal crops and is consumed by 3.5 billion people worldwide. With an increase in the human population and the decrease in the effective area for food production, it is imperative to raise the yield of rice per unit area to ensure food security for millions of people globally in the near future. Cultivating hybrid varieties of rice is an effective and feasible strategy to enhance the rice grain yield. The annual production of fresh F1 hybrid seeds is required for large-scale hybrid rice cultivation. The area and yield of hybrid F 1 seeds in previous seasons determine the acreage of hybrid rice planting for the season. For a given amount of spikelets per unit area, the yield of F1 hybrid rice seeds is largely determined by the outcrossing seed setting rate, which is mainly affected by the stigma exertion. Increasing the percentage of exerted stigmas (PES) of male sterile lines

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Results

Conclusion