# Quantitative Trait Loci Sequencing and Genetic Mapping Reveal Two Main Regulatory Genes for Stem Color in Wax Gourds

## TL;DR

This study identifies two key genes that regulate stem color in wax gourds using genetic mapping and sequencing.

## Contribution

The discovery of two main regulatory genes for stem color in wax gourds provides new insights for breeding programs.

## Key findings

- Two quantitative trait loci, qSC5 and qSC12, were identified as regulators of stem color in wax gourds.
- BchAPRR2 (Bch05G003950) and Bch12G020400 were confirmed as candidate genes for stem color regulation.
- InDel markers linked to BchAPRR2 predicted stem color traits with 81.8% accuracy in 55 germplasm lines.

## Abstract

Stem color is an important agronomic trait of wax gourds. However, its regulatory genes have not been identified. In this study, 105 inbred lines constructed from two parents (GX-71 and MY-1) were sequenced and quantitative trait loci sequencing was used to mine the genes that regulate stem color in wax gourds. The results identified two quantitative trait loci related to stem color, qSC5 and qSC12, located on Chr05 (11,134,567–16,459,268) and Chr12 (74,618,168–75,712,335), respectively. The qSC5 had a phenotypic variation rate of 36.9% and a maximum limit of detection of 16.9. And the qSC12 had a phenotypic variation rate of 20.9%, and a maximum limit of detection of 11.2. Bch05G003950 (named BchAPRR2) and Bch12G020400 were identified as candidate genes involved in stem color regulation in wax gourds. The chlorophyll content and expression of BchAPRR2 and Bch12G020400 were significantly higher in green-stemmed wax gourds than in white-stemmed ones. Therefore, BchAPRR2 and Bch12G020400 were considered the main and secondary regulatory genes for wax gourd stem color, respectively. Finally, InDel markers closely linked to BchAPRR2 were developed to validate the prediction of wax gourd stem color traits in 55 germplasm lines, with an accuracy of 81.8%. These findings lay the foundation for exploring the genetic regulation of wax gourd stem color and future research on wax gourd breeding.