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Study on Development of Japonica Breeding Lines Introgressed High Grain Number Gene through Marker-Assisted Backcross Approach
The breeding scheme of introgression of <i>Gn1</i> and different segment lengths of chromosome 1 from‘Habataki’ to ‘Tainung 71’ by marker-assisted backcross selection.
The breeding scheme of introgression of Gn1 and different segment lengths of chromosome 1 from‘Habataki’ to ‘Tainung 71’ by marker-assisted backcross selection.

Author:Ming-Hsing Lai, Charng-Pei Li, Woei-Shyuan Jwo, Hsing-Mu Yen, Kae-Kang Hwu, and Dong-Hong Wu*

Abstract:

    Rice grain number, a quantitative trait, is difficult to be selected in early generations and needs to be evaluated its genetic gain number based on replicate filed trials during breeding procedure. In order to improve the introgressed efficiency of grain yield related genes and validate QTL effect between japonica-indica cross, this study introduced the high grain number gene, Gn1, from ‘Habataki’ (indica type) into ‘Tainung71’ (‘TNG71’), a japonica cultivar with high eating quality, to assess the yield potential of the near-isogenic lines through marker-assisted backcross approach. The development of near-isogenic lines used 6 flanking markers of Gn1 locus for foreground selection and 152 SSR and InDel markers with an average of 10.8 cM for background selection. Genotyping assay showed that one BC3F2 plant (TNG71-Gn1) has completely recovered the recurrent ‘TNG71’ genome except a 30 cM segment harboring Gn1 on the short arm of chromosome 1. TNG71-Gn1 had the same heading date, panicle number, and plant height as the recurrent parent, ‘TNG71’, while TNG71-Gn1 had higher grain number per panicle than ‘TNG71’. In addition, four ‘TNG71’ stepped aligned inbred recombinant lines different from their introgressed chromosmal region harboring Gn1 gene on chromosomal 1 were developed in order to investigate the relationship among Gn1a, Gn1b, and qSBN1 loci for genetic effects on rachis branch and spikelet number. Genetic analysis showed that Gn1a locus increased secondary branch number and average grain number of secondary branch, but not average grain number of primary branch. Gn1b locus, which located in upstream region, would be beneficial on second branch number resulting in increased grain number. The qSNB1 locus consisted of two sub-loci and explained 38.4% and 11.7% of the difference in the second secondary branch number between ‘Habataki’ and ‘TNG71’, respectively.

Key words:Oryza sativa L., Grain number, Marker assisted backcross, Grain yield

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Journal of
Taiwan Agricultural Research
Vol. 72, No.3 (2023) ISSN: 2790-086X Vol. 72, No.3 (2023)
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