Poster: Temperature responses

Abs # 120: Cold acclimation genes in Poncirus trifoliata

Presenter:	Zhang, Cankui , zhangca@auburn.edu
Authors	Zhang, Cankui  (A)   Lang, Ping  (A)   Dane, Fenny  (A)   Ebel, Robert  (A)   Singh, Narendra  (B)   Locy, Robert  (B)   Dozier, William  (A)
Affiliations:	(A): Department of Horticulture, Auburn University (B): Department of Biological Sciences, Auburn University

While low temperature stress is a serious problem for Citrus production all over the world, information on changes in gene expression observed during cold acclimation is very limited. Poncirus trifoliata, a close relative of Citrus, is a popular and cold hardy rootstock used to reduce freeze risk of commercial Citrus. mRNA differential display-polymerase chain reaction (DDRT-PCR) and quantitative relative RT-PCR were used to study gene expression of P. trifoliata under a slow cold-acclimation temperature regime to increase our understanding of its cold acclimation mechanism. Eight up-regulated and six down regulated cDNA fragments were isolated and sequenced. They showed high similarities to genes that code for betaine/proline transporter, water channel protein, aldo-keto reductase, early light induced protein, nitrate transporter, tetratricopeptide-repeat protein, F-box protein, ribosomal protein L15, beta-galactosidase, chlorophyll a/b binding protein, photosystem II oxygen evolving complex, carbonic anhydrase, miraculin like protein and pyrrolidone carboxylate peptidase. Osmotic regulation, photo-oxidative tolerance and photosynthesis adjustment appear to be three of the most important mechanisms for cold acclimation of P. trifoliata. Genetic modification of synthesis or transport of osmo-protectants and scavengers of photo-oxidation products might improve cold tolerance of Citrus plants. More detailed characterization of proline/betaine transporter and early light induced protein is in process.