Abstract

BackgroundGrain size is a key determinant of grain weight and a trait having critical influence on grain quality in rice. While increasing evidences are shown for the importance of minor-effect QTL in controlling complex traits, the attention has not been given to grain size until recently. In previous studies, five QTL having small effects for grain size were resolved on the long arm of chromosome 1 using populations derived from indica rice cross Zhenshan 97///Zhenshan 97//Zhenshan 97/Milyang 46. One of them, qTGW1.2c that was located in a 2.1-Mb region, was targeted for fine-mapping in the present study.ResultsFirstly, the qTGW1.2c region was narrowed down into 1.1 Mb by determining genotypes of the cross-over regions using polymorphic markers newly developed. Then, one BC2F9 plant that was only heterozygous in the updated QTL region was identified. A total of 12 populations in generations from BC2F11:12 to BC2F15:16 were derived and used for QTL mapping. Two QTL linked in a 460-kb region were separated. The qGS1-35.2 was delimited into a 57.7-kb region, containing six annotated genes of which five showed nucleotide polymorphisms between the two parental lines. Quantitative real-time PCR detected expression differences between near isogenic lines for qGS1-35.2 at three of the six annotated genes. This QTL affected grain length and width with opposite allelic directions, exhibiting significant effect on ratio of grain length to width but showing little influence on yield traits. The other QTL, qGW1-35.5, was located within a 125.5-kb region and found to primarily control grain width and consequently affect grain weight.ConclusionsOur work lays a foundation for cloning of two minor QTL for grain size that have potential application in rice breeding. The qGS1-35.2 could be used to modify grain appearance quality without yield penalty because it affects grain shape but hardly influences grain yield, while qGW1-35.5 offers a new gene recourse for enhancing grain yield since it contributes to grain size and grain weight simultaneously.

Highlights

  • Grain size is a key determinant of grain weight and a trait having critical influence on grain quality in rice

  • The qGS1-35.2 was delimited into a 57.7-kb region starting from the position of 35.2 Mb, affecting grain length and width with opposite allelic directions and showing little influence on grain weight

  • The simple sequence repeat (SSR) markers were selected from the Gramene database, and the InDel markers were designed according to the differences between Zhenshan 97 (ZS97) and Milyang 46 (MY46) detected by whole genome re-sequencing

Read more

Summary

Introduction

Grain size is a key determinant of grain weight and a trait having critical influence on grain quality in rice. While increasing evidences are shown for the importance of minor-effect QTL in controlling complex traits, the attention has not been given to grain size until recently. Five QTL having small effects for grain size were resolved on the long arm of chromosome 1 using populations derived from indica rice cross Zhenshan 97///Zhenshan 97//Zhenshan 97/Milyang 46. Among them grain weight is mainly determined by grain size. Grain size and shape is an important quality trait that greatly influences the market value of grain products. Grain size and shape are largely determined by grain length and width. A total of 14 QTL having large effect

Methods
Results
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call