Cold sensing and responsive pathway in rice. (A) ABA signaling is initiated by ABA accumulation, and is transduced by ABF and the ABRE-containing OsNAC gene, which regulates the expression of a NACRS-containing target gene to increase cold tolerance. (B) The DREB-CRT/DRE pathway is initiated by a Ca2+-influx signal that is transduced by calcium-dependent protein kinases (CDPKs), OsMYB3R-2, OsMYB2, and OsICE1/2. The expression of OsDREB1B and OsDREB2A are down-regulated by MYBS3. (C) The MAPK cascade (OsMKK6-OsMPK3 and OsMPK6) is activated by ROS and is negatively regulated by OsTRX23. Solid arrows indicate direct activation; broken arrows indicate indirect activation; lines ending with a bar indicate negative regulation.