Variation of morphological structure, lignin and MYB61 gene revealed the adaptation of three Impatiens to different habitats

Abstract

Impatiens is a widely cultivated ornamental genus, exhibits high species diversity and broad ecological distribution, making it an excellent material for studying environmental adaptation. This study investigates the anatomical structure, lignin content and composition, and expression of lignin-related genes in the roots and leaves of three Impatiens species from distinct habitats: Impatiens chlorosepala (wet), Impatiens uliginosa (both aquatic and terrestrial) and Impatiens rubrostriata (terrestrial). The results show that the adaptability of roots to different habitats is closely associated with epidermis thickness, vessel diameter, xylem diameter, and the xylem-to-root area ratio. Leaf adaptation to different habitats, on the other hand, is mainly related to the thickness of palisade tissue and veins, the palisade-to-spongy tissue thickness ratio, the tightness of palisade tissue, the looseness of spongy tissue, and stomatal density. Additionally, the terrestrial species (I. rubrostriata) exhibited higher lignin content in both roots and leaves. The anatomical structure and degree of lignification are likely linked to the habitat adaptation of Impatiens (including inter-species and intra-species). Gene expression analysis revealed that the transcription factor MYB61 may regulate lignin biosynthesis by modulating the expression of structural genes. The observed variations between species across different habitats provide a foundation for subsequent molecular studies on Impatiens lignin biosynthesis and offer valuable insights into the mechanisms underlying the plant's adaptability.

Keywords: Impatiens; Lignin; MYB61 gene; Morphological anatomy.