# Predominantly Independent Genetic Control Between Growth and Visceral White Nodules Disease Resistance Revealed by High-Density Linkage Map and QTL Mapping in Larimichthys crocea

## TL;DR

This study finds that growth and disease resistance in large yellow croaker are largely controlled by separate genes, offering hope for improving both traits in breeding.

## Contribution

A high-density genetic map and QTL analysis reveal independent genetic control of growth and disease resistance in Larimichthys crocea.

## Key findings

- 53 QTLs for growth and 20 for VWND resistance were identified with limited overlap.
- Only two genomic intervals showed co-localization between growth and resistance traits.
- Candidate genes in co-localized regions are involved in general cellular processes.

## Abstract

The large yellow croaker (Larimichthys crocea) is a key mariculture species in China, however, its industry is threatened by visceral white nodules disease (VWND) caused by the bacterium Pseudomonas plecoglossicida. A significant challenge in breeding is the potential genetic trade-off between growth and disease resistance. To investigate their genetic relationship, we constructed a high-density SNP-based genetic linkage map for L. crocea using a F1 full-sib family (n = 150). The map comprised 24 linkage groups with 32,429 bin markers and an average interval of 0.051 cM. Based on this map, we conducted QTL mapping for one yield trait (body weight), eight morphological traits, and three VWND-resistance traits (survival time, AT; spleen and liver pathogen loads). Phenotypic analysis revealed strong integration among growth traits and a moderate positive correlation between growth traits and AT. QTL mapping identified 53 QTLs for growth (PVE = 0.14–5.83%) and 20 for resistance (PVE = 0.78–8.93%). Notably, only two genomic intervals exhibited co-localization between a morphological trait (AL or BL) and AT, each explaining a modest phenotypic variance (0.66–5.99%). The largest-effect QTLs for growth and resistance were mapped to distinct linkage groups, and candidate genes within the co-localized intervals (Unc5d, SCN5A, HUS1) are involved in fundamental cellular processes rather than core growth or immune pathways. These results suggest that yield, morphological, and VWND-resistance traits in L. crocea are largely under independent genetic control within the studied family, indicating that simultaneous improvement of growth and disease resistance is feasible. This study provides a molecular basis for breeding strategies aimed at overcoming the trait trade-off bottleneck in this economically vital species.