Figure 8

Hypothetical model of the ROS-mediated gene regulon involved in early responses to chilling in rice and its possible relationship with the CBF/DREB and ABA-mediated regulons. The proposed hierarchical organization of the as1/ocs regulatory cluster is shown in pathway-1. An unknown Myb is expressed constitutively and perhaps activated by change in redox state that is mediated by chilling stress-induced elevation of intracellular ROS. The ROS-activated Myb regulates the transcription of a low temperature-inducible bZIP-type transcription factor that functions as transcriptional activator of as1/ocs-like element-containing genes. A possible alternative or complementary route for regulating the as1/ocs-like element-containing genes is via a constitutively expressed Myb protein (dotted arrow). Pathway-2 shows a general overview of the CBF/DREB and ABA-mediated regulons involved in low temperature and dehydration stress response in plants [1, 2, 3, 4]. This hypothetical model proposes that some members of the putative ROS-bZIP – as1/ocs regulatory module might also be regulated by CBF/DREB.