YUCCA gene expression modulates Cercospora leaf spot (CLS) resistance, Leaf regeneration: A comparative analysis of sugar content and root yield in different Sugar beet (Beta vulgaris L.)

Auxin is one of the main endogenous plant hormones, playing a key role in regulating plant growth and development as well as stress responses. It is particularly noteworthy that the auxin plays a significant role in biotic stress. Cercospora leaf spot (CLS) is one of the three major diseases in sugar beet growth, which can reduce the efficiency of photosynthesis and even cause leaf death. When sugar beet is infected with CLS, in order to maintain its normal growth, new leaves continue to germinate and grow from the root of sugar beet for photosynthesis, which must have auxin participation. The YUCCA gene family, belonging to class B flavin-dependent monooxygenases, catalyzes the rate-limiting step in endogenous auxin biosynthesis and plays a crucial role in plant growth regulation and stress responses. Effective regulation of auxin synthesis and accumulation is a crucial objective for enhancing both total yield and sugar production in sugar beet, as well as a key focus in sugar beet breeding. Therefore, this study identified nine YUCCA genes in sugar beet (Beta vulgaris L.). Additionally, transcriptomic analysis revealed two significantly differentially expressed YUCCA genes, that exhibited significant differential expression in sugar beet before and after CLS infection. These YUCCA genes are key genes in the indole-3-pyruvic acid (IPyA) pathway, which is involved in one of the auxin biosynthesis pathways in sugar beet. And field experiment analysis revealed that susceptible sugar beet varieties exhibited higher root yield but lower sugar content, while resistant varieties showed higher sugar content but lower yield.