Integrative QTL mapping and candidate gene analysis for main stem node number in soybean

Area of Science:

• Plant Genetics
• Agronomy
• Molecular Biology

Background:

• Main stem node number (MSNN) is a critical yield-determining trait in soybean (Glycine max), influencing plant architecture and seed production.
• Understanding the genetic basis of MSNN is essential for developing high-yielding soybean cultivars.

Purpose of the Study:

• To identify quantitative trait loci (QTLs) associated with MSNN in a soybean recombinant inbred line (RIL) population.
• To mine candidate genes underlying significant MSNN QTLs for future breeding applications.

Main Methods:

• A population of 325 RILs derived from a cross between 'Qihuang 34' and 'Dongsheng 16' was phenotyped for MSNN.
• Soybean Indel پتہSequencing (SLAF-seq) was employed to construct a high-density genetic map with 6297 markers.
• QTL analysis was performed using the genetic map, followed by candidate gene mining within identified QTL regions.

Main Results:

• Phenotypic analysis revealed continuous variation and transgressive segregation for MSNN in the RIL population.
• Five significant MSNN QTLs were identified on chromosomes 6, 17, 18, and 19, collectively explaining 3.46–43.56% of the phenotypic variance.
• A major QTL, qMSNN19.2, on chromosome 19 was highly stable and explained 43.56% of the variance. Sixty-four candidate genes within this QTL were identified, including those involved in stem cell division and hormone signaling.

Conclusions:

• The study successfully mapped major QTLs controlling MSNN in soybean, highlighting qMSNN19.2 as a key locus for genetic improvement.
• Identification of candidate genes and variations provides valuable resources for marker-assisted selection to enhance soybean yield potential.