Quantitative Trait Loci Analysis in Rice Seedling Vigor

Rice seedling vigor, encompassing rapid germination, robust mesocotyl and coleoptile elongation and early biomass accumulation, is fundamental to successful crop establishment, weed suppression and yield stability under direct‐seeded or deep‐sowing systems. Quantitative trait loci (QTL) analysis has elucidated the genetic architecture underlying these complex traits by integrating biparental linkage mapping, genome‐wide association studies (GWAS), transcriptome profiling and meta‐analysis. Key findings include the identification of major QTL clusters on multiple chromosomes that explain substantial proportions of phenotypic variation in germination rate, seedling length, root number and early biomass. Candidate genes within these loci often encode regulators of phytohormone biosynthesis and signal transduction, cell wall organisation and energy metabolism. Fine‐mapping, near‐isogenic lines and chromosome segment substitution lines have enabled the dissection of additive and epistatic interactions among loci. Translation of QTL findings into marker‐assisted selection pipelines is accelerating the development of rice cultivars with enhanced early vigor, mechanised‐seeding tolerance and improved competitiveness against weeds, thereby contributing to resource‐efficient and climate‐resilient rice production worldwide.

Research from Nature Portfolio

Natural variations in a GSK3‐like kinase (OsGSK2) have been shown to govern mesocotyl elongation by modulating brassinosteroid and strigolactone signalling. Variants of this kinase alter the phosphorylation status of a U‐type cyclin, thereby coordinating cell division and elongation in the mesocotyl. This locus underlies a major domestication QTL for deep‐sown rice and illustrates how hormonal crosstalk shapes seedling emergence.

Time‐course transcriptome and phytohormone profiling of the elongating mesocotyl revealed that light exposure rapidly downregulates indole‐3‐acetic acid, trans‐zeatin and gibberellin content while upregulating jasmonate pathways. Differentially expressed genes implicated in hormone signal transduction, cell wall remodelling and secondary metabolism form a regulatory network that mediates light‐induced inhibition of mesocotyl growth. Insights from this study highlight dynamic gene‐hormone interactions governing early seedling development in direct‐seeded cultivation.

Quantitative Trait Loci Analysis in Rice Seedling Vigor publication trend

The graph below shows the total number of articles in quantitative trait loci analysis in rice seedling vigor across all publications each year (not limited to Nature Index journals).

Technical terms

Quantitative Trait Locus (QTL): A genomic region containing one or more genes that contribute to the variation of a quantitative trait, identified through statistical linkage between genetic markers and phenotypic variation.

Mesocotyl: The stem‐like tissue between the seed and the coleoptile in grass seedlings, whose elongation pushes the shoot tip towards the soil surface during germination.

Coleoptile: The protective sheath enclosing the emerging shoot in monocot seedlings, enabling penetration of soil or water before exposure to light.

Genome‐Wide Association Study (GWAS): A mapping approach that correlates natural genetic variation across a diverse population with trait variation to identify loci associated with complex traits.

Marker‐Assisted Selection (MAS): A breeding strategy that uses DNA markers tightly linked to desirable QTL to accelerate the development of improved cultivars by selecting for favourable alleles.

References

1. Natural selection of a GSK3 determines rice mesocotyl domestication by coordinating strigolactone and brassinosteroid signaling. Nature Communications (2018).
2. Dynamic transcriptome and phytohormone profiling along the time of light exposure in the mesocotyl of rice seedling. Scientific Reports (2017).
3. Identification of a Seed Vigor–Related QTL Cluster Associated with Weed Competitive Ability in Direct–Seeded Rice (Oryza Sativa L.). Rice (2023).
4. Influence of isopropylmalate synthase OsIPMS1 on seed vigour associated with amino acid and energy metabolism in rice. Plant Biotechnology Journal (2018).
5. QTL Hotspots for Early Vigor and Related Traits under Dry Direct-Seeded System in Rice (Oryza sativa L.). Frontiers in Plant Science (2017).