Laboratory of Plant Pathology, Multidisciplinary Institute for Environment Studies (MIES) Ramón Margalef, Department of Marine Sciences and Applied Biology, University of Alicante, Alicante, Spain.
Departament d'Enginyeria Agroalimentària i Biotecnologia, Universitat Politècnica de Catalunya, Barcelona, Spain.
Sci Rep. 2017 Dec 1;7(1):16813. doi: 10.1038/s41598-017-16874-5.
Chitosan is a natural polymer with applications in agriculture, which causes plasma membrane permeabilisation and induction of intracellular reactive oxygen species (ROS) in plants. Chitosan has been mostly applied in the phylloplane to control plant diseases and to enhance plant defences, but has also been considered for controlling root pests. However, the effect of chitosan on roots is virtually unknown. In this work, we show that chitosan interfered with auxin homeostasis in Arabidopsis roots, promoting a 2-3 fold accumulation of indole acetic acid (IAA). We observed chitosan dose-dependent alterations of auxin synthesis, transport and signalling in Arabidopsis roots. As a consequence, high doses of chitosan reduce WOX5 expression in the root apical meristem and arrest root growth. Chitosan also propitiates accumulation of salicylic (SA) and jasmonic (JA) acids in Arabidopsis roots by induction of genes involved in their biosynthesis and signalling. In addition, high-dose chitosan irrigation of tomato and barley plants also arrests root development. Tomato root apices treated with chitosan showed isodiametric cells respect to rectangular cells in the controls. We found that chitosan causes strong alterations in root cell morphology. Our results highlight the importance of considering chitosan dose during agronomical applications to the rhizosphere.
壳聚糖是一种天然聚合物，在农业中有广泛的应用，它会导致植物质膜通透性增加，并诱导细胞内活性氧（ROS）的产生。壳聚糖主要应用于叶片表面来控制植物病害和增强植物防御，但也被认为可用于控制根部害虫。然而，壳聚糖对根部的影响实际上是未知的。在这项工作中，我们表明壳聚糖干扰了拟南芥根部的生长素稳态，促进了吲哚乙酸（IAA）积累 2-3 倍。我们观察到壳聚糖在拟南芥根部的生长素合成、运输和信号传导方面存在剂量依赖性的改变。因此，高剂量的壳聚糖会降低根尖分生组织中 WOX5 的表达并抑制根的生长。壳聚糖还通过诱导其生物合成和信号转导相关基因的表达，促进了拟南芥根部水杨酸（SA）和茉莉酸（JA）的积累。此外，对番茄和大麦植株进行高剂量壳聚糖灌溉也会抑制根的发育。用壳聚糖处理的番茄根端显示出等径细胞，而对照中则为矩形细胞。我们发现壳聚糖会导致根细胞形态发生强烈改变。我们的结果强调了在根际进行农业应用时考虑壳聚糖剂量的重要性。
