Regulation of low temperature stress on gibberellin metabolism

The expression of genes involved in gibberellin ( GA) metabolism in model plants Arabidopsis thaliana and tobacco (Nicotiana tabacum) under the 4℃treatment was analyzed. The results indicated that the expressions of many genes in geranylgeranyl diphosphate ( GGPP) synthesis pathway were inhibited, while the expressions of GA deactivation genes and GA receptor genes were promoted. Analysis of GA1 content and the expression metabolism-related genes in over-expressed PtGA20ox, PtGA2ox1 and AtCBF1 transgenic and 4℃-treated wild type tobacco plants showed that the expression of GGPP synthesis genes and GA deactivation genes was active regulation, and the key player, CBF1 in cold response pathway, participated in this regulation process, while the expression of gibberellin receptor genes was feedback regulation by the low levels of GA. This study revealed that growth retardation of plants under cold stress may result from their positive response to the environment. Decreasing GA level by limiting the supply of precursor accumulation and accelerating the deactivation may play a vital role in the process of plants adapting to the cold stress.