The Model System

 

 

The major exterior parts of an Arabidopsis fruit include the valves, the replum, and the valve  margin, where fruit opening occurs.  The valve margin differentiates into a narrow stripe of cells consisting of a separation layer and a layer of lignified cells  both of which contribute to the process of fruit opening.

SEM image of the apical

part of an Arabidopsis fruit

at stage 17b, bar 100pm

 

Valve margin formation requires the activities of the SHATTERPROOF proteins (SHP1 and 2) as well as INDEHISCENT (IND) [1,2].  The SHP and IND genes are expressed in stripes where the valve margin will subsequently differentiate, and the IND gene acts largely downstream of the SHP genes.  Recently, hormonal and genetic events that occur downstream of IND have been revealed, and we now know that for example an auxin minimum are required for separation layer (sl) formation [3], and that polygalacturonases (PGs) mediate the separation event [4].  For additional reading about the regulation of Arabidopsis fruit development please see refs [5,6].

Arabidopsis fruit at stage 17b, bar 1mm

IND::GUS

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