Etxeberria Ed, Gonzalez Pedro, Fanton Borges Ana, Brodersen Craig
Citrus Research and Education Center (CREC), University of Florida, 700 Experiment Station Road, Lake Alfred, Florida 33850 USA.
Citrus Research and Education Center (CREC), University of Florida, 700 Experiment Station Road, Lake Alfred, Florida 33850 USA; Yale School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511 USA.
Appl Plant Sci. 2016 Jan 11;4(1). doi: 10.3732/apps.1500106. eCollection 2016 Jan.
Uptake of foliar-applied substances across the leaf cuticle is central to world food production as well as for physiological investigations into phloem structure and function. Yet, despite the presence of stomata, foliar application as a delivery system can be extremely inefficient due to the low permeability of leaf surfaces to polar compounds.
Using laser light to generate microscopic perforations in the leaf cuticle, we tested the penetration of several substances into the leaf, their uptake into the phloem, and their subsequent movement through the phloem tissue. Substances varied in their size, charge, and Stokes radius.
The phloem-mobile compounds 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxyglucose (2-NBDG), lysine, Biocillin, adenosine triphosphate (ATP), trehalose, carboxyfluorescein-SE, and poly(amidomine) (PAMAM) dendrimer G-4 nanoparticles (4.5 nm in size) showed a high degree of mobility and were able to penetrate and be transported in the phloem.
Our investigation demonstrated the effectiveness of laser light technology in enhancing the penetration of foliar-applied substances into citrus leaves. The technology is also applicable to the study of phloem mobility of substances by providing a less invasive, highly repeatable, and more quantifiable delivery method. The implied superficial lesions to the leaf can be mitigated by applying a waxy coating.
叶片角质层对叶面喷施物质的吸收，对于世界粮食生产以及韧皮部结构和功能的生理学研究至关重要。然而，尽管存在气孔，但由于叶片表面对极性化合物的低渗透性，叶面喷施作为一种输送系统可能极其低效。
利用激光在叶片角质层产生微观穿孔，我们测试了几种物质进入叶片的渗透情况、它们在韧皮部的吸收情况以及随后在韧皮部组织中的移动情况。物质在大小、电荷和斯托克斯半径方面存在差异。
可在韧皮部移动的化合物2-[N-(7-硝基苯并-2-恶唑-1,3-二氮杂环丁烷-4-基)氨基]-2-脱氧葡萄糖（2-NBDG）、赖氨酸、生物青霉素、三磷酸腺苷（ATP）、海藻糖、羧基荧光素-SE和聚（酰胺胺）（PAMAM）树枝状大分子G-4纳米颗粒（尺寸为4.5纳米）表现出高度的移动性，能够穿透并在韧皮部中运输。
我们的研究证明了激光技术在增强叶面喷施物质进入柑橘叶片的渗透性方面的有效性。该技术还可用于物质韧皮部移动性的研究，因为它提供了一种侵入性较小、高度可重复且更可量化的输送方法。通过涂抹蜡质涂层可以减轻对叶片表面造成的损伤。
