Abstract
AUXIN BINDING PROTEIN1 (ABP1) has long been proposed as a candidate of auxin receptor to mediate auxin action in plants. It is essential for plant organ development. The function of ABP1 in the development of ramie (Boehmeria nivea L.) remains unclear. Here, we examined the role of the ABP1 gene in the development of shoot in ramie, especially in leaf venation ontogeny, by transforming ABP1 antisense construct into the plants. We showed that ABP1 expression was decreased in ABP1 antisense transgenic plantlets. The decrease of ABP1 expression led to defects in plant growth including dwarf plant, and decreased apical dominance in the intact plant. In addition, ABP1 antisense lines exhibited a serious retard of leaf development involving small and twisted leaves, sparse trichome, and a decreased cell expansion. Moreover, the decreased ABP1 expression repressed the development of leaf venation. ABP1 antisense lines developed an incomplete leaf venation, which became smaller and lacked in some leaf tissues. Though the cell arrangement was normal in midrib and lateral vein, cell size was decrease and some cell layers were missing in midrib. The abnormal phenotype of leaf venation was attributed to the decreases in cell number and size. Our data support that ABP1 is necessary for shoot growth in ramie. More importantly, it plays a key role for the development of ramie leaf venation by regulating both cell expansion and division.
Highlights
AUXIN BINDING PROTEIN1 (ABP1) has long been proposed as a candidate of auxin receptor to mediate auxin action in plants
It is reported that mutations in genes, such as auxin response factor 5 (AFR5), auxin resistant 6 (AXR6), and bodenlos (BDL)/IAA12, which are involved in the nuclear TIR1/AFB pathway, have resulted in incomplete vascular systems and defects [17,19,20]
The results showed that the transcript levels of ABP1 in four independent transgenic lines (3, 5, 6 and 8) were significantly reduced (Figure 2B), which indicated that the expressions of the ABP1 gene were down-regulated by antisense constructs
Summary
AUXIN BINDING PROTEIN1 (ABP1) has long been proposed as a candidate of auxin receptor to mediate auxin action in plants. Our data support that ABP1 is necessary for shoot growth in ramie It plays a key role for the development of ramie leaf venation by regulating both cell expansion and division. It has shown that ABP1 may be an important candidate for auxin receptor, and essential for a set of auxin responses, including early auxin response at the plasma membrane, cell division and expansion, and auxin regulated gene expression [5,6] It is important throughout the life of plants, such as embryogenesis and postembryonic shoot and root development [7]. We conclude that the auxin-ABP1 signal pathway is involved in shoot growth in ramie It is necessary for the development of ramie leaf venation
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