Comparative study on physiological responses and gene expression of bud endodormancy release between two herbaceous peony cultivars (Paeonia lactiflora Pall.) with contrasting chilling requirements

Authors: WANG, XIAOBIN - Zhejiang University; ZHANG, RUNLONG - Zhejiang University; HUANG, QIAOYU - Zhejiang A&f Univeristy; SHI, XIAOHUA - Zhejiang Institute Landscape Plants And Flowers; LI, DANQING - Zhejiang University; SAO, LINGMEI - Zhejiang University; XU, TONG - Zhejiang University; Horvath, David; ZHANG, JIAPING - Zhejiang University; XIA, YIPING - Zhejiang University

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/23/2021
Publication Date: 2/2/2022
Citation: Wang, X., Zhang, R., Huang, Q., Shi, X., Li, D., Sao, L., Xu, T., Horvath, D.P., Zhang, J., Xia, Y. 2022. Comparative study on physiological responses and gene expression of bud endodormancy release between two herbaceous peony cultivars (Paeonia lactiflora Pall.) with contrasting chilling requirements. Frontiers in Plant Science. 12. Article e772285. https://doi.org/10.3389/fpls.2021.772285.
DOI: https://doi.org/10.3389/fpls.2021.772285

Interpretive Summary: Many horticultural crops require a period of chilling before they can break dormancy and bloom. This can prevent northern varieties with desirable traits from growing in more southern regions. This study examined the molecular and developmental processes that differentiated a northern and southern variety of peony and identified processes and genes implicating oxidative stress protection. These genes control a specific protein complex required for growth in both plants and animals. The ability to manipulate these processes should allow us to modify northern varieties by engineering or classical breeding to mitigate stress caused by warmer winters and protect horticultural crops from global warming.

Technical Abstract: With the global temperature increase, diverse endogenous factors and environmental cues can lead to severe obstacles to bud endodormancy release (BER) for important economic plants, such as herbaceous peony (Paeonia lactiflora Pall.). Knowing the underlying mechanism in BER is vital for widely planting herbaceous peony at low latitudes with warm winter climates. A systematic study was carried out between the southern Chinese cultivar ‘Hang Baishao’ with smooth BER and the northern cultivar ‘Zhuguang’ with obvious BER obstacles. Physiology and morphology of peony buds were observed during the crucial BER stage, and the roles of reactive oxygen species (ROS) and relevant genes in BER regulation were also highlighted, which has been rather rare in previous bud dormancy studies of both herbaceous and tree peonies. Carbohydrate metabolism, abscisic acid (ABA), and ROS signaling were correlated with bud endodormancy release. The expression of the starch metabolism- and sucrose synthesis-related genes PlAMY PlSPS and PlSUS was lower in the high-CR ‘Zhuguang’ and corresponded to a lower content of soluble sugars. Expression of The ROS-generating gene PlPAO2 correlated with a higher level of H2O2 in ‘Zhuguang’ than in ‘Hang Baishao’ during bud endodormancy. Expression of PlMAPKKK5, an intermediate gene in the abscisic acid (ABA) response to ROS signaling, correlated with ROS levels and ABA content. We present the hypothesis that accumulation of ROS increases ABA content and signal transduction leading to reduced expression of PlSVP and lower expression of PlSOC1, and reduced expression of cell division and an increase in cellular damage as observed histologically and through expression of related genes and subsequent blockage of BER in ‘Zhuguang’. This research could provide new insights into the mechanism of bud dormancy of geophytes in an increasingly unsuitable environment.