Isolation and expression analysis of LoPIP2, a lily (Lilium Oriental Hybrids) aquaporin gene involved in desiccation-induced anther dehiscence

• LoPIP2 is the first PIP2 gene isolated from lily.
• LoPIP2 belongs to the class-2 subfamily of plasma membrane intrinsic proteins.
• The expression of LoPIP2 in lily anthers was reduced during extended water deficit.
• LoPIP2 silencing did not influence flower opening or anther development.
• LoPIP2 plays an important role in anther dehiscence during anther desiccation.

The anthers of many flowers accumulate water before undergoing desiccation and finally dehiscence. Here we report that an internal water deficit and ambient humidity inhibited the dehiscence of lily (Lilium Oriental Hybrids) anthers. This implies that this process also occurs during the dehiscence of lily anthers. Based on speculation that plasma membrane intrinsic proteins (PIPs) may facilitate the dehiscence of lily anthers by promoting the passage of water through lily anther cells, we isolated two PIP genes from lily, LoPIP1 and LoPIP2, and characterized their potential roles in anther dehiscence. Both LoPIP1 and LoPIP2 were constitutively expressed during different phases of anther development; however, only LoPIP2 showed significantly reduced levels of expression in anthers of cut lilies subjected to water deficit for >24 h. We silenced LoPIP2 in lily flowers by virus-induced gene silencing and found that this dramatically prevented anther dehiscence. Furthermore, whereas flowers subject to a water deficit had shrunken and indehiscent anthers, flowers in which LoPIP2 expression was silenced had plump and indehiscent anthers that resembled those of flowers exposed to high humidity. Thus the absence of LoPIP2 inhibited anther dehiscence mainly by blocking anther desiccation upon flower opening and not by preventing the earlier stage of water accumulation during anther development and maturation.