National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, The Center of Crop Nanobiotechnology, College of Plant Science & Technology, Huazhong Agricultural University, Wuhan 430070, China.
Hubei Hongshan Laboratory, Wuhan 430070, China.
ACS Nano. 2024 Aug 27;18(34):23154-23167. doi: 10.1021/acsnano.4c05362. Epub 2024 Aug 14.
Efficient delivery of nanoparticles (NPs) to plants is important for agricultural application. However, to date, we still lack knowledge about how NPs' charge matters for its translocation pathway, i.e., symplastic and apoplastic pathways, in plants. In this study, we synthesized and used negatively charged citrate sourced carbon dots (C-CDs, -37.97 ± 1.89 mV), Cy5 coated C-CDs (Cy5-C-CDs, -41.90 ± 2.55 mV), positively charged PEI coated carbon dots (P-CDs, +43.03 ± 1.71 mV), and Cy5 coated P-CDs (Cy5-P-CDs, +48.80 ± 1.21 mV) to investigate the role of surface charges and coatings on the employed translocation pathways (symplastic and apoplastic pathways) of charged NPs in plants. Our results showed that, different from the higher fluorescence intensity of P-CDs and Cy5-P-CDs in extracellular than intracellular space, the fluorescence intensity of C-CDs and Cy5-C-CDs was similar between intracellular and extracellular space in cucumber and cotton roots. It suggests that the negatively charged CDs were translocated via both symplastic and apoplastic pathways, but the positively charged CDs were mainly translocated via the apoplastic pathway. Furthermore, our results showed that root applied negatively charged C-CDs demonstrated higher leaf fluorescence than did positively charged P-CDs in both cucumber (8.09 ± 0.99 vs 3.75 ± 0.23) and cotton (7.27 ± 1.06 vs 3.23 ± 0.22), indicating that negatively charged CDs have a higher translocation efficiency from root to leaf than do positively charged CDs. It should be noted that CDs do not affect root cell activities, ROS level, and photosynthetic performance in cucumber and cotton, showing its good biocompatibility. Overall, this study not only figured out that root applied negatively charged CDs employed both symplastic and apoplastic pathways to do the transportation in roots compared with mainly the employment of apoplastic pathway for positively charge CDs, but also found that negatively charge CDs could be more efficiently translocated from root to leaf than positively charged CDs, indicating that imparting negative charge to NPs, at least CDs, matters for its efficient delivery in crops.
纳米颗粒（NPs）向植物的有效传递对于农业应用很重要。然而，迄今为止，我们仍然缺乏关于 NPs 电荷如何影响其在植物中的转运途径（即质外体和共质体途径）的知识。在这项研究中，我们合成并使用了带负电荷的柠檬酸源碳点（C-CDs，-37.97 ± 1.89 mV）、Cy5 包覆的 C-CDs（Cy5-C-CDs，-41.90 ± 2.55 mV）、带正电荷的聚乙烯亚胺包覆的碳点（P-CDs，+43.03 ± 1.71 mV）和 Cy5 包覆的 P-CDs（Cy5-P-CDs，+48.80 ± 1.21 mV）来研究表面电荷和涂层对带电荷的 NPs 在植物中所采用的转运途径（质外体和共质体途径）的作用。我们的结果表明，与 P-CDs 和 Cy5-P-CDs 在细胞外空间的荧光强度高于细胞内空间的情况不同，C-CDs 和 Cy5-C-CDs 在黄瓜和棉花根的细胞内和细胞外空间的荧光强度相似。这表明带负电荷的 CDs 通过质外体和共质体途径进行转运，而带正电荷的 CDs 主要通过质外体途径进行转运。此外，我们的结果表明，与正电荷的 P-CDs 相比，根部施加的带负电荷的 C-CDs 在黄瓜（8.09 ± 0.99 比 3.75 ± 0.23）和棉花（7.27 ± 1.06 比 3.23 ± 0.22）中的叶片荧光更高，这表明带负电荷的 CDs 从根部到叶片的转运效率高于带正电荷的 CDs。应该注意的是，CDs 不会影响黄瓜和棉花的根细胞活性、ROS 水平和光合作用性能，表现出良好的生物相容性。总的来说，这项研究不仅阐明了与主要通过质外体途径用于正电荷 CDs 的转运相比，根部施加的带负电荷的 CDs 采用质外体和共质体途径在根部进行转运，而且还发现带负电荷的 CDs 比带正电荷的 CDs 更有效地从根部转运到叶片，这表明赋予 NPs（至少是 CDs）负电荷对于其在作物中的有效传递很重要。
