Comparative Study on Physiological Responses and Gene Expression of Bud Endodormancy Release Between Two Herbaceous Peony Cultivars (Paeonia lactiflora Pall.) With Contrasting Chilling Requirements

Xiaobin Wang; Runlong Zhang; Qiaoyu Huang; Xiaohua Shi; Danqing Li; Lingmei Shao; Tong Xu; David P Horvath; Yiping Xia; Jiaping Zhang

doi:10.3389/fpls.2021.772285

Comparative Study on Physiological Responses and Gene Expression of Bud Endodormancy Release Between Two Herbaceous Peony Cultivars (Paeonia lactiflora Pall.) With Contrasting Chilling Requirements

Front Plant Sci. 2022 Feb 2:12:772285. doi: 10.3389/fpls.2021.772285. eCollection 2021.

Authors

Affiliations

¹ Genomics and Genetic Engineering Laboratory of Ornamental Plants, Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, China.
² State Key Laboratory of Subtropical Silviculture, School of Forestry and Biotechnology, Zhejiang A&F University, Hangzhou, China.
³ Zhejiang Institute of Landscape Plants and Flowers, Hangzhou, China.
⁴ Agricultural Research Service, United States Department of Agriculture, Washington, DC, United States.

Abstract

With the global temperature increase, diverse endogenous factors and environmental cues can lead to severe obstacles to bud endodormancy release for important economic plants, such as herbaceous peony (Paeonia lactiflora Pall.). Knowing the underlying mechanism in bud endodormancy release 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 low-chilling requirement (CR) trait and the northern cultivar 'Zhuguang' with high-CR trait. Peony buds were sampled at regular intervals under natural cold during the crucial bud endodormancy release stage. Physiology and morphology of the buds were observed, and the roles of reactive oxygen species (ROS) and relevant genes in the regulation of bud endodormancy release were also highlighted, which has been rather rare in previous bud dormancy studies of both herbaceous and tree peonies. 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. The expression of polyamine oxidase gene PlPAO2 correlated with a higher level of hydrogen peroxide (H₂O₂) in high-CR 'Zhuguang' than in low CR '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 decreases GA₃ content and signal transduction leading to reduced expression of PlSVP and PlSOC1. Reduced cell division and increased cellular damage which probably blocked bud endodormancy release were also observed in high-CR 'Zhuguang' through histological observation and related genes expression. This study provides a comparative analysis on physiological responses and gene expression patterns of bud dormancy of geophytes in an increasingly unsuitable environment.

Keywords: Paeonia lactiflora; abscisic acid; bud endodormancy release; gene expression; geophyte; reactive oxygen species; underground bud; warm winter.