Tolerance strategies revealed in tree peony ( Paeonia suffruticosa ; Paeoniaceae) ecotypes differentially adapted to desiccation.

Premise of the Study: Tree peony ( Paeonia suffruticosa ; Paeoniaceae) is well known for its ornamental value, edible oil, and medicinal properties. However, its growing area has been limited by drought that has been exacerbated by global climate change.

Methods: Gene expression profiles of a drought-tolerant cultivar and a drought-sensitive cultivar during dehydration and rehydration were investigated by transcriptome analysis. Expression patterns of unigenes related to drought and recovery response and unrelated to either cultivar were classified by hierarchical clustering and real-time quantitative PCR (qPCR).

Results: A total of 81,725 unigenes with a mean length of 762 nucleotides that may play roles in drought response were identified. Unigenes were characterized as being involved in lipid transport metabolism, proline metabolism, and photosynthesis. In addition, plant hormone signaling pathway genes were also characterized as potentially being involved in drought response. Expression patterns of the 20 drought-responsive unigenes verified by qPCR showed a differential expression pattern under either the drought or recovery treatment.

Discussion: This is the first report to identify and verify unigenes of tree peonies with differing water sensitivity during dehydration and rehydration. This study offers a valuable resource for candidate genes involved in drought and provides insight into the breeding of drought-resistant tree peony cultivars.