Morphological and Transcriptomic Analyses Reveal the Involvement of Key Metabolic Pathways in Male Sterility in Chimonanthus praecox (L.) Genotypes

<i>Chimonanthus praecox</i> (Calycanthaceae family) is a unique ornamental and economic flowering tree in China, and after thousands of years of cultivation, it has produced several varieties and varietal types. Notably, male sterility is common in flowering plants and is an important tool for the genetic improvement in plants and optimization using hybrid plant technology; however, there have been no reports on male-sterile material or related studies on <i>C. praecox</i>. To our knowledge, this is the first time that <i>C. praecox</i> male sterility is dissected unveiling the involvement of key metabolic pathways. Notably, male sterility in <i>C. praecox</i> was observed during the budding period and likely occurred during the premature stage of pollen cell maturation. Additionally, differentially expressed genes in the starch and sucrose metabolism pathway and the plant hormone signal transduction pathway showed regular expression trends. This study reports on significant genetic differences that contribute to male sterility in <i>C. praecox</i> and provides a basis for further research and breeding strategies.