Aerial surfaces of most land plants have epidermal hairs (trichomes).Both Arabidopsis thaliana trichomes and cotton fibers (seed hairs) are nonglandular hairs with unicellular structure.Here we out-line the recent progress on molecular dissection of Arabidopsis trichome development,including the transcription factors regulating trichome initiation,phytohormones influencing trichome density,and the cytoskeleton formation system governing trichome morphogenesis.There is increasing evidence showing that these processes also control cotton fiber production.As several cotton fiber genes are able to rescue the Arabidopsis trichome mutants,we discuss the conservation between Arabidopsis trichome and cotton fiber development.
Plant morphology is specified by leaves and flowers, and the shoot apical meristem (SAM) defines the architecture of plant leaves and flowers. Here, we reported the characterization of a soybean KNOX gene GmKNT1, which was highly homologous to Arabidopsis STM. The GmKNT1 was strongly expressed in roots, flowers and developing seeds. Its expression could be induced by IAA, ABA and JA, but inhibited by GA or cytokinin. Staining of the transgenic plants overexpressing GmKNT1-GUS fusion protein revealed that the GmKNT1 was mainly expressed at lobe region, SAM of young leaves, sepal and carpel, not in seed and mature leaves. Scanning electron micros-copy (SEM) disclosed multiple changes in morphology of the epidermal cells and stigma. The transgenic Arabidopsis plants overexpress-ing the GmKNT1 showed small and lobed leaves, shortened internodes and small clustered inflorescence. The lobed leaves might result from the function of the meristems located at the boundary of the leaf. Compared with wild type plants, transgenic plants had higher ex-pression of the SAM-related genes including the CUP, WUS, CUC1, KNAT2 and KNAT6. These results indicated that the GmKNT1 could affect multiple aspects of plant growth and development by regulation of downstream genes expression.
Jun Liu Da Ha Zongming Xie Chunmei Wang Huiwen Wang Wanke Zhang Jinsong Zhang Shouyi Chen
