Beijing Key Laboratory of Ornamental Plants Germplasm Innovation & Molecular Breeding, Beijing, China.
National Engineering Research Center for Floriculture, Beijing, China.
PeerJ. 2023 Apr 13;11:e15166. doi: 10.7717/peerj.15166. eCollection 2023.
Herbaceous peony ( Pall.) is an ancient ornamental crop and, in recent decades, an emerging popular cut flower. Straight stems are a vital criterion for cut herbaceous peony selection, while many cultivars bend as the plant develops. Pectin helps maintain the mechanical strength of the cell wall. However, little is known about its role in the stem bending of herbaceous peony. Two herbaceous peony cultivars with contrasting stem morphologies ('Dong Fang Shao Nv', upright; 'Lan Tian Piao Xiang', bending gradually) at five developmental stages were used as materials to investigate the effects of pectin content and nanostructure on straightness using the carbazole colorimetric method and atomic force microscopy observations. The contents of water-soluble pectin (WSP), CDTA-soluble pectin (CSP), and sodium carbonate-soluble pectin (SSP) differed significantly between the two cultivars, and the contents and angle of the flower and branch showed correlations. For the pectin nanostructure, WSP showed agglomerates and long chains, with a higher proportion of broad agglomerates at the later stages of the bending cultivar than the upright cultivar. CSP showed branched chains, and the proportion of broad chains was higher in the upright cultivar at later stages, while CSP shape changed from agglomerates to chains in the bending cultivar. SSP mainly consisted of short linear main chains, and side chains in the upright stem were stacked, and the bent cultivar had more broad and short chains. It can be concluded that the contents, nanometric shape, and size of the three kinds of pectin are highly likely to affect herbaceous peony stem straightness. This study provides a theoretical basis for the role of pectin in the production and breeding of herbaceous peony cut flowers.
芍药（Pall.）是一种古老的观赏作物，近几十年来，已成为一种新兴的流行切花。直茎是切花芍药选择的重要标准，而许多品种在植物发育过程中会弯曲。果胶有助于维持细胞壁的机械强度。然而，果胶在芍药茎弯曲中的作用知之甚少。以两种具有相反茎形态的芍药品种（‘东方少女’，直立；‘蓝天飘香’，逐渐弯曲）为材料，在五个发育阶段，使用咔唑比色法和原子力显微镜观察，研究果胶含量和纳米结构对直度的影响。两种品种的水溶性果胶（WSP）、CDTA 可溶性果胶（CSP）和碳酸钠可溶性果胶（SSP）含量差异显著，花和枝的含量和角度呈相关性。对于果胶的纳米结构，WSP 显示出团聚体和长链，弯曲品种后期宽团聚体的比例高于直立品种。CSP 显示出支链，后期直立品种中宽链的比例较高，而弯曲品种中 CSP 形状从团聚体变为链状。SSP 主要由短的线性主链组成，直立茎的侧链堆积，弯曲品种有更多宽而短的链。可以得出结论，三种果胶的含量、纳米形状和大小极有可能影响芍药茎的直度。本研究为果胶在芍药切花生产和育种中的作用提供了理论依据。
