초록
<P><B>Abstract</B><P>Background<P><I>Impatiens</I> is an important genus with rich species of garden plants, and its distribution is extremely extensive, which is reflected in its diverse ecological environment. However, the specific mechanisms of <I>Impatiens</I>’ adaptation to various environments and the mechanism related to lignin remain unclear.</P></P><P>Results<P>Three representative <I>Impatiens</I> species,<I>Impatiens chlorosepala</I> (wet, low degree of lignification), <I>Impatiens uliginosa</I> (aquatic, moderate degree of lignification) and <I>Impatiens rubrostriata</I> (terrestrial, high degree of lignification), were selected and analyzed for their anatomical structures, lignin content and composition, and lignin-related gene expression. There are significant differences in anatomical parameters among the stems of three <I>Impatiens</I> species, and the anatomical structure is consistent with the determination results of lignin content. Furthermore, the thickness of the xylem and cell walls, as well as the ratio of cell wall thickness to stem diameter have a strong correlation with lignin content. The anatomical structure and degree of lignification in <I>Impatiens</I> can be attributed to the plant's growth environment, morphology, and growth rate. Our analysis of lignin-related genes revealed a negative correlation between the <I>MYB4</I> gene and lignin content. The <I>MYB4</I> gene may control the lignin synthesis in <I>Impatiens</I> by controlling the structural genes involved in the lignin synthesis pathway, such as <I>HCT</I>, <I>C3H</I>, and <I>COMT</I>. Nonetheless, the regulation pathway differs between species of <I>Impatiens</I>.</P></P><P>Conclusions<P>This study demonstrated consistency between the stem anatomy of <I>Impatiens</I> and the results obtained from lignin content and composition analyses. It is speculated that <I>MYB4</I> negatively regulates the lignin synthesis in the stems of three <I>Impatiens</I> species by regulating the expression of structural genes, and its regulation mechanism appears to vary across different <I>Impatiens</I> species. This study analyses the variations among different <I>Impatiens</I> plants in diverse habitats, and can guide further molecular investigations of lignin biosynthesis in <I>Impatiens</I>.</P></P></P>