Abstract
<title>Abstract</title> <p> The TOPLESS/TOPLESS-related (TPL/TPR) gene family functions as pivotal transcriptional co-repressors in plants; however, its role in jute ( <italic>Corchorus</italic> L.), a major bast fiber crop, remains largely unexplored. In this study, we systematically identified 18 TPL/TPR family members in the jute genome. Candidate gene association studies pinpointed <italic>CcTPR4</italic> as the sole gene within this family exhibiting a significant association with fiber yield traits. Subcellular localization confirmed CcTPR4 as a nuclear protein, and its expression levels were negatively correlated with plant height in a natural population. Functionally, overexpression of <italic>CcTPR4</italic> in jute roots significantly downregulated key cellulose synthase genes ( <italic>CcCesA4</italic> , <italic>CcCesA7</italic> , <italic>CcCesA8</italic> ) and their transcriptional regulators ( <italic>CcMYB46</italic> / <italic>83</italic> ). Conversely, virus-induced gene silencing of its homolog in the bimli-jute resulted in the upregulation of cellulose synthase genes ( <italic>HcCesA7</italic> / <italic>8</italic> ) and the gibberellin (GA) biosynthesis gene <italic>HcKAO</italic> , concomitant with the downregulation of the GA catabolism gene <italic>HcGA2ox1</italic> . This study provides the first functional characterization of the TPL/TPR family in jute and highlights CcTPR4 as a prime candidate gene for molecular breeding aimed at enhancing fiber yield. </p>