Fig. 8.

Hypothetical model of HvAP2 control of stem elongation. Both HvAP2 and JA inhibit internode cell proliferation and expansion, whereas GA promotes these processes following the reproductive transition. Loss of miR172 targeting of HvAP2 is associated with JA-associated gene expression, and JA induces HvAP2 expression, suggesting that HvAP2 and JA may interact to regulate reproductive maturation and stem elongation. Loss of miR172 targeting of HvAP2 also leads to lower responsiveness to GA-mediated promotion of stem growth. We propose that limiting HvAP2 function via miR172 targeting is important for repression of JA signalling and promotion of the GA-mediated internode elongation in the reproductive phase.