# Genome-Wide Analysis of Callose Synthase (CALS) Genes in Cabbage (Brassica oleracea var. capitata L.): Identification and Expression Profiling During Hyaloperonospora parasitica Infection

## TL;DR

This study identifies and analyzes CALS genes in cabbage, revealing their potential role in resistance to a plant disease caused by Hyaloperonospora parasitica.

## Contribution

The first comprehensive characterization of the BoCALS gene family in Brassica oleracea and their expression during downy mildew infection.

## Key findings

- Fifteen BoCALS genes were identified in the B. oleracea genome, distributed across eight chromosomes.
- BoCALS6 expression was significantly higher in resistant cabbage varieties and up-regulated during H. parasitica infection.
- Phylogenetic and collinearity analyses revealed conserved evolutionary relationships between BoCALS and homologs in Arabidopsis and Brassica rapa.

## Abstract

Callose synthase (CALS) genes are known to play critical roles in microspore development and in plant responses to diverse biotic and abiotic stresses. While the role of CALS genes has been extensively characterized in several plant species, their homologs in Brassica oleracea (BoCALS) remain understudied. In this study, 15 BoCALS genes were identified in B. oleracea genome, distributed across eight chromosomes. All BoCALS proteins contain Glucan-synthase and Fks1 domains. Phylogenetic analysis grouped BoCALS and their homologs from Arabidopsis thaliana and Brassica rapa into three distinct Clusters (Ⅰ–Ⅲ), revealing conserved evolutionary relationships within the Brassicaceae family. Collinearity analysis showed that AtCALS genes of Arabidopsis have multiple orthologs in B. oleracea. Analysis of RNA-Seq data from public databases suggested that most of the BoCALS genes exhibit tissue-specific expression patterns, indicating their potential roles in organ differentiation and development. QRT-PCR analysis elucidated a different expression level of BoCALS genes in response to Hyaloperonospora parasitica infection. Notably, BoCALS6 expression was significantly higher in resistant varieties compared to susceptible varieties and further up-regulated following H. parasitica infection, indicating its potential role in downy mildew resistance. This study presents the first comprehensive characterization of BoCALS gene family in B. oleracea and provides a foundation for further functional investigations into their roles in downy mildew resistance.