QTL mapping and transcriptomic analysis of fruit length in cucumber
Yanan Xing1, Yilin Cao1, Yanan Ma1
1Qingdao Agricultural University, Qingdao, China.
Frontiers in Plant Science
|September 6, 2023
Summary
Researchers identified key genes controlling cucumber fruit length using genetic mapping and RNA sequencing. A gene (Csa4G337340) was found to negatively regulate fruit length, offering insights into cucumber breeding.
Area of Science:
- Plant genetics and genomics
- Crop science
- Molecular biology
Background:
- Cucumber fruit length is a crucial trait for commercial cultivation.
- Understanding the genetic basis of fruit length is essential for breeding improved varieties.
- Previous studies have identified quantitative trait loci (QTLs) for cucumber fruit length, but major genes remain to be precisely located.
Purpose of the Study:
- To construct a high-density genetic map for a recombinant inbred line (RIL) population derived from a cross between wild and cultivated cucumbers.
- To identify and locate major quantitative trait loci (QTLs) controlling cucumber fruit length.
- To investigate the candidate genes and molecular mechanisms underlying fruit length regulation.
Main Methods:
- Resequencing was employed to construct a genetic map with 600 bin markers.
- Phenotypic data for fruit length were collected over two seasons (spring 2021 and autumn 2022).
- Quantitative trait locus (QTL) analysis and RNA sequencing (RNA-seq) were performed to identify and analyze genes controlling fruit length.
Main Results:
- Three major QTLs (Fl2.1, Fl4.1, and Fl6.1) for cucumber fruit length were consistently detected across both seasons, with Fl4.1 being the dominant QTL.
- The gene Csa4G337340, encoding an auxin efflux carrier family protein, was identified as a strong candidate gene within the Fl4.1 interval and showed lower expression in long-fruit lines.
- Transcriptomic analysis revealed differential expression of genes involved in plant hormone signal transduction and identified numerous transcription factors (e.g., bHLH, AP2/ERF, C2H2, NAC) associated with fruit length regulation.
Conclusions:
- The major gene controlling cucumber fruit length is located within the Fl4.1 interval, and Csa4G337340 is a potential candidate gene involved in negative regulation of fruit length.
- Plant hormone signaling pathways and various transcription factor families play significant roles in regulating cucumber fruit length.
- These findings provide a foundation for fine-mapping major genes and elucidating the molecular mechanisms governing cucumber fruit length.
