Mapping and identification of QTLs for low light tolerance traits in grapevine

Low light is a major limiting factor in greenhouse grapevine cultivation, particularly during winter and early spring. To investigate the genetic basis of low light tolerance, a population of 198 F₁ individuals derived from a cross between low light-tolerant and low light-sensitive grapevine varieties was used in this study.

SNP markers were converted into bin markers using the self-developed VCF_to_binMap analysis pipeline, and a genetic map was constructed containing 19 linkage groups with a total length of 1161.95 cM and an average marker distance of 0.71 cM. Phenotypic analysis revealed significant segregation for chlorophyll content and light compensation point (LCP) in the F1 population, with traits approximately following a normal distribution. QTL mapping identified three significant QTLs associated with chlorophyll a content, four with chlorophyll b content, and one with total chlorophyll content, all located on linkage group LG17. Additionally, one significant QTL related to LCP was mapped to LG8. Transcriptome sequencing of extreme phenotype plants and correlation analysis identified two MYB transcription factors (Vitvi17g00232 and Vitvi17g00309) and one STN8-encoding gene (Vitvi08g02097) within the QTL intervals, suggesting their potential roles in low light tolerance.

This study provides insights into the genetic mechanisms underlying low light tolerance in grapevines and identifies candidate genes for further functional validation. The findings contribute to the development of grapevine varieties with improved low light tolerance, supporting sustainable greenhouse cultivation practices.