Location: Floral and Nursery Plants ResearchTitle: Identification of genes associated with cold acclimation in perennial ryegrass.) Author
Submitted to: Journal of Plant Physiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/25/2009
Publication Date: 7/19/2009
Citation: Zhang, C., Fei, S., Warnke, S.E., Li, L., Hannapel, D. 2009. Identification of genes associated with cold acclimation in perennial ryegrass.. Journal of Plant Physiology. Available at http://dx.doi.org/10.1016/j.jplph.2009.03.001. Interpretive Summary: Sensitivity to cold temperatures restricts the cultivation of perennial ryegrass in some temperate areas. Understanding the way perennial ryegrass adapts to cold temperatures is important to managers and breeders of this grass. The objective of this research was to study the perennial ryegrass genes present during cold temperatures. A period of cold temperatures prior to freezing temperatures improved cold tolerance in perennial ryegrass cultivars but not annual ryegrass cultivars. Results indicate that an increase in cold resistance genes and a decrease of photosynthesis and respiration-related genes are important to increase cold tolerance of perennial ryegrass.
Technical Abstract: Sensitivity to cold temperatures restricts the cultivation of perennial ryegrass (Lolium perenne L.) in some temperate areas. Understanding cold-acclimation mechanisms is important for plant cultivation and breeding for cold tolerance. Our objective was to profile the transcriptome in perennial ryegrass during cold acclimation. Measurement of freezing-induced ion leakage indicated that cold tolerance greatly increased in ‘Caddyshack’ and ‘Lafayette’ of perennial ryegrass after cold acclimation, but did not increase in ‘Gulf’ and ‘Tur’ of annual ryegrass (Lolium multiflorum Lam. Two cDNA libraries, one from 14-d cold-acclimated (CA; LT50 = -12.2 °C) and the other from nonacclimated (NA) leaves (LT50 = -7.6 °C) of ‘Caddyshack’ were constructed. More than 1400 expressed sequence tags (ESTs) were generated by sequencing over 2000 clones from each library. Over 60 groups of ESTs were observed to be either up- or down-regulated three times or more in the CA than in the NA library. Functional classification showed that the ratio of ESTs between CA and NA libraries increased twice or more in 9 Gene Ontology subcategories, whereas decreased by half or more in 7 other Gene Ontology subcategories. Reverse transcriptase PCR analysis of 24 selected genes confirmed that 20 of them had similar expression trends as the EST abundances in the two libraries. Our results suggest that up-regulation of cold-regulated (COR), dehydration-responsive, and ice recrystalization inhibition (IRI) genes, and down-regulation of photosynthesis and respiration-related genes are important to increase cold tolerance of perennial ryegrass.