Molecular mechanisms of cold acclimation in overwintering azaleas

ISHS Secretariat
Molecular mechanisms of cold acclimation in overwintering azaleas

Bing Liu is a postdoc in Ornamental Horticulture at the Department of Horticulture in Zhejiang University, China. She graduated with a Ph.D. in philosophy from the same university. During her studies as a graduate student, she worked for two years with Dr. Rajeev Arora at Iowa State University, on the photoprotective strategies employed by evergreen rhododendrons. Currently, her research explores the molecular mechanisms of cold acclimation in overwintering azaleas via RNA-seq. Obtaining maximum mid-winter freezing tolerance through full cold acclimation (CA) is key for winter survival of wintergreen shrubs, especially in winter when air temperatures are increasing and unseasonably warm temperatures are frequent. Though mechanisms of CA in woody perennials have been mostly studied in environmental chambers, Bing determined that artificial CAs had limitations to understand the field full CA. Bing compared field and artificial CAs in Rhododendron ‘Elsie Lee’. The light signals, such as changes in photoperiod, light intensity, and light quality in autumn could induce the accumulations of abscisic acid (ABA) and jasmonic acid (JA). This would activate the ABA and JA signal transductions before the occurrence of low temperatures, while light conditions in the chamber were constant. The photoprotection-related pathways were only enriched in the field CA, and the significant upregulated differentially expressed genes (DEGs), like HY5, in the circadian rhythm of the plants in the field CA showed no change in artificial CAs. Although carbon metabolism was commonly enriched in both field and artificial CAs, DEGs in the carbon metabolism pathway were mostly upregulated in the field CA, but downregulated in artificial CAs. Furthermore, ABA and JA contents in overwintering leaves gradually decreased from autumn to winter. The cause of this unusual finding may be due to zeaxanthin and unsaturated fatty acids. Zeaxanthin biosynthesis and unsaturated fatty acids metabolism are upstream of ABA and JA biosynthesis.

Bing Liu won the ISHS Young Minds Award for the best oral presentation at the IV International Symposium on Woody Ornamentals of the Temperate Zone, which was held virtually in Italy in March 2021.

Bing Liu, Department of Horticulture, Zhejiang University, 866 Yuhangtang Road, Zhejiang 310058, China, e-mail: binger@zju.edu.cn

The article is available in Chronica Horticulturae

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azalea
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Young Minds Award Winners