Seed dispersal is an important moment in the life cycle of a plant species. In Arabidopsis thaliana, it is dependent on transcription factor INDEHISCENT （IND）-mediated specification of a separation layer in the dehi...Seed dispersal is an important moment in the life cycle of a plant species. In Arabidopsis thaliana, it is dependent on transcription factor INDEHISCENT （IND）-mediated specification of a separation layer in the dehiscence zone found in the margin between the valves （carpel walls） and the central replum of the developing fruit. It was proposed that IND specifies the separation layer by inducing a local auxin minimum at late stages of fruit development. Here we show that morphological differences between the ind mutant and wild-type fruit already arise at early stages of fruit development, coinciding with strong IND expression in the valve margin. We show that IND-reduced PIN-FORMED3 （PIN3） auxin efflux carrier abundance leads to an increased auxin response in the valve margin during early fruit develop- ment, and that the concomitant cell divisions that form the dehiscence zone are lacking in ind mutant fruit. Moreover, IND promoter-driven ectopic expression of the AGC kinases PINOID （PID） and WAG2 induced indehiscence by expelling auxin from the valve margin at stages 14-16 of fruit development through increased PIN3 abundance. Our results show that IND, besides its role at late stages of Arabi- dopsis fruit development, functions at early stages to facilitate the auxin-triggered cell divisions that form the dehiscence zone.展开更多
文摘Seed dispersal is an important moment in the life cycle of a plant species. In Arabidopsis thaliana, it is dependent on transcription factor INDEHISCENT （IND）-mediated specification of a separation layer in the dehiscence zone found in the margin between the valves （carpel walls） and the central replum of the developing fruit. It was proposed that IND specifies the separation layer by inducing a local auxin minimum at late stages of fruit development. Here we show that morphological differences between the ind mutant and wild-type fruit already arise at early stages of fruit development, coinciding with strong IND expression in the valve margin. We show that IND-reduced PIN-FORMED3 （PIN3） auxin efflux carrier abundance leads to an increased auxin response in the valve margin during early fruit develop- ment, and that the concomitant cell divisions that form the dehiscence zone are lacking in ind mutant fruit. Moreover, IND promoter-driven ectopic expression of the AGC kinases PINOID （PID） and WAG2 induced indehiscence by expelling auxin from the valve margin at stages 14-16 of fruit development through increased PIN3 abundance. Our results show that IND, besides its role at late stages of Arabi- dopsis fruit development, functions at early stages to facilitate the auxin-triggered cell divisions that form the dehiscence zone.
