Background : Ginseng seeds are harvested in immature stages and take 3 - 4 month to be germinated following cold stratification. Improvement of germination speed can be a valuable traits to be characterized for economically important medicinal plant. Modulation of cell wall compositions is also considered as another agricultural trait when the crops can be processed for foods and forages. Here we show the functional characterization of ginseng pPLAIIIβ focused on its possible values on germination and modulation of cell wall compositions.
Methods and Results : Patatin-related phospholipase AIII family genes were identified from ginseng EST clones and further confirmed by PCR. Clone showing the highest homology with pPLAIIIβ was overexpressed in model plant Arabidopsis, and it displayed dwarf plants. qPCR analysis showed that pPLAIIIβ expressed in all organs of 2-years-old ginseng. Overexpression of ginseng pPLAIIIβ also displayed apparently enlarged seeds as well as altered germination speed in early stage compared to the control. Chemical stainings and direct quantification of lignin and cellulose were performed to understand the link of cell elongation patterns and cell wall compositions.
Conclusion : Overexpression of ginseng pPLAIIIβ inhibited longitudinal cell elongation in all tested organs except seeds which is enlarged in both directions than the control. Shorter root length is related with auxin responsive genes and its dwarf morphological phenotype is resulted in altered cell wall compositions.