Key message

Vitrified shoots of strawberry tree propagated in vitro showed poor lignification when analysed by FTIR-ATR and by the acetyl bromide method, as well as marked disturbances on leaf tissues organization.

Abstract

Arbutus unedo (Ericaceae), commonly known as strawberry tree, is a bush or small tree grown mainly for the production of edible fruits that can be eaten fresh, processed or used to make liquors. In vitro propagation of A. unedo in liquid media is an advantageous procedure that reduces the time for multiplication. However, tissue culture in liquid media often leads to excessive accumulation of water in the apoplast that results in a physiological mechanism characterized by low lignification, impaired stomatal function and reduced mechanical strength of tissue culture-generated plants. Fourier-transform infrared spectroscopy in attenuated total reflectance mode (FTIR-ATR) was employed to assess the chemical-derived differences between vitrified and non-vitrified cell walls. FTIR-based spectral assignments suggested higher contents of aromatic compounds in leaves than in stems. Lignin measurements by the acetyl bromide procedure showed that there are no significant differences in the percentage of lignin by dry weight between the different types of leaves. Anatomical studies using light microscopy and scanning electron microscopy showed changes on epidermis organization of vitrified leaves as well as the presence of abnormal stomata in the abaxial surface. These observations may explain the difficulty of vitrified plants to balance absorption and evapotranspiration, and cope with hydric stress during the acclimatization phase. Moreover, cross-sectioned leaves revealed broad lacunar spaces and cross-sectioned stems had spaced-hypertrophic cortical parenchyma cells, where the water vapor may accumulate. Finally, the characterization of vitrified tissues was considered an important contribution to uncover the mechanisms that cause plant vitrification, not just by improving the methods developed for the micropropagation of this species, but also contributing for its agroeconomic valorization.

中文翻译：

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导致体外培养的杨梅的玻璃化的生理生化事件的研究

关键信息

用FTIR-ATR和乙酰溴法分析的草莓树的玻璃化芽显示出较差的木质化，并且对叶组织的组织有明显的干扰。

抽象

乌木（Ericaceae），通常称为草莓树，是一种灌木丛或小树，主要用于生产可食用的水果，可以将其新鲜食用，加工或制成酒。Unedo的体外繁殖在液体介质中进行灭菌是一种有利的程序，可减少乘法时间。但是，在液体培养基中进行组织培养通常会导致水在质外体中积累过多，从而导致生理机制，其特征是木质化程度低，气孔功能受损以及组织培养物生成的植物的机械强度降低。采用衰减全反射模式（FTIR-ATR）的傅立叶变换红外光谱法评估玻璃化和非玻璃化细胞壁之间的化学衍生差异。基于FTIR的光谱分配表明，叶片中的芳香族化合物含量高于茎中。通过乙酰溴程序对木质素的测量表明，不同类型的叶片之间木质素的百分比（以干重计）没有显着差异。使用光学显微镜和扫描电子显微镜的解剖学研究显示，玻璃化叶片的表皮组织发生了变化，并且在背面出现了异常气孔。这些观察结果可以解释玻璃化植物在适应阶段难以平衡吸收和蒸散以及应对水分胁迫的困难。此外，横切叶显示出宽阔的腔隙空间，横切茎具有间隔肥大的皮质实质细胞，水蒸气可能在此积聚。最后，玻璃化组织的表征被认为对揭示导致植物玻璃化的机制的重要贡献，不仅是通过改进为该物种的微繁殖而开发的方法，而且还为其农业经济价值做出了贡献。