Submitted to: Journal of Experimental Botany
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/1/2009
Publication Date: 11/25/2009
Citation: Xiangjun, Z., Cooke, P.H., Li, L. 2009. Eukaryotic release factor 1-2 affects Arabidopsis responses to glucose and phytohormones during germination and early seedling development. Journal of Experimental Botany. 61:357-367. Interpretive Summary: Carotenoids are highly beneficial for human nutrition and health. There is an increasing interest in development of food crops rich in carotenoids. We have isolated a cauliflower Orange gene that confers a high level of '-carotene accumulation. However this gene also exhibits pleiotropic effects in homozygous plants in causing a delayed plant development. To decipher how it affects plant growth and development in order to achieve carotenoid enhancement without potential deleterious effects on other physiology processes, we studied the eRF1-2 gene whose protein is associated with Orange protein. We showed that eRF1-2 can affect glucose and phytohormone responses in plant growth and development.
Technical Abstract: Germination and early seedling development are coordinately regulated by glucose and phytohormones such as ABA, GA and ethylene. However, the molecules that affect plant responses to glucose and phytohormones remain to be fully elucidated. Eukaryotic release factor 1 (eRF1) is responsible for recognition of the stop codons in mRNAs during protein synthesis. Accumulating evidence indicates that eRF1 functions in other processes in addition to translation termination. The physiological role of eRF1-2, a member of eRF1 family, in Arabidopsis was examined here. The eRF1-2 gene was found to be specifically induced by glucose. Arabidopsis plants overexpressing eRF1-2 was hypersensitive to glucose during germination and early seedling development. Such hypersensitivity to glucose was accompanied with a dramatic reduction of the expression of glucose-regulated genes, chlorophyll a/b binding protein and plastocyanin. The hypersensitive response was not due to enhanced accumulation of ABA. In addition, the eRF1-2 overexpressing plants showed increased sensitivity to paclobutrazol, an inhibitor of GA biosynthesis, and exogenous GA restored their normal growth. In contrast, the loss-of-function erf1-2 mutant exhibited resistance to paclobutrazol, suggesting that eRF1-2 may exert negative effect on the GA signaling pathway. Collectively, these data provide evidence in supporting a novel role of eRF1-2 in affecting glucose and phytohormone responses in modulating plant growth and development.