Phloem Delivery of Fludioxonil by Plant Amino Acid Transporter-Mediated Polysuccinimide Nanocarriers for Controlling Fusarium Wilt in Banana.

Fusarium wilt disease poses a serious threat to the global production of bananas. The targeted delivery of fungicides to banana phloem tissues may offer new hope for controlling this hard-to-treat vascular disease. In this study, fludioxonil (FLU)-loaded glycine methyl ester-conjugated polysuccinimide nanoparticles (PGA) were prepared with a loading efficiency (LE) of 27.9%. The obtained nanoparticles (FLU@PGA) exhibited pH-sensitive controlled release, specifically under an alkaline pH in plant phloem. In vivo experiments in potted bananas demonstrated that FLU@PGA can achieve the downward delivery of FLU to banana rhizomes and roots after foliar application, reducing disease severity by 50.4%. The phloem transport studies showed that the phloem loading of FLU@PGA was involved in an active transport mechanism at the organ level (castor bean seedlings). The observation of fluorescein-5-isothiocyanate cadaverine-labeled PGA nanocarriers showed that they could be absorbed by mesophyll cells and loaded into vascular tissues through the symplastic pathway. Furthermore, the interaction of FLU@PGA with the plant amino acid transporter AtLHT1 was observed to enhance transmembrane uptake at the cellular level (Xenopus oocytes). These results suggested that the phloem-targeted delivery of fungicide by transporter-mediated nanocarriers could be a promising new strategy for the management of Fusarium wilt in bananas.

Development of Multifunctional Avermectin Poly(succinimide) Nanoparticles to Improve Bioactivity and Transportation in Rice.

Avermectin (AVM) as a nonsystemic pesticide possesses a low effective utilization rate. Studies of the multifunctional pesticide delivery system for improving biological activity are developing prosperously. In this study, multifunctional avermectin/polysuccinimide with glycine methyl ester nanoparticles (AVM-PGA) were prepared by the self-assembly process. The AVM loading capacity was up to 23.7%. After 24 h of UV irradiation, there was still about 70% of AVM remaining in PGA42 nanocarriers, as opposed to less than 5% of the free-form AVM. The rising ambient pH promoted the release of AVM using an in vitro releasing test, revealing a favorable pH-responsively controlled-release property. The mortality rate of Plutella xylostella with 2.5 µg/mL of AVM content of AVM-PGA42 was 96.3% after 48 h, while that of free AVM was only 51.5%. In addition, the AVM could be detected in stems and all leaves treated with AVM-PGA42 nanoparticles, whereas rare AVM was detected only in treated leaves for the free-form AVM, which achieved the transportation of nanocarriers carrying AVM in rice for the first time. Furthermore, the PGA nanoparticles performed a good growth promoting effect on rice. These results show that the AVM-PGA42 nanopesticides have a great potential application prospect to control the pest and improve the drug utilization efficiency on agriculture.

A novel water-based chitosan-La pesticide nanocarrier enhancing defense responses in rice (Oryza sativa L) growth.

To relieve the environmental pressure from overusing conventional pesticides formulations, the study of a new environmentally friendly and multifunctional formulation is so very urgent. Here, we firstly reported a lanthanum-modified chitosan oligosaccharide nanoparticles (Cos-La) prepared by a simple ionic cross-linking method to load avermectin (AVM). The loading capacity of AVM-loaded Cos-La was up to 46.3%. As a water-based formulation, Cos-La could effectively improve the persistence of AVM over 25% and reduce the photolysis rate of AVM around 20%. Furthermore, different concentrations of Cos-La were used to cultivate rice. The treated rice exhibited growth promotion effects in terms of plant height and fresh weight. With the increase in the treating concentration of Cos-La nanoparticles, the wettability of rice tended to reduce, which indicated it might lower the risk of plant diseases and pests. Further, Cos-La treated rice showed significant defense response for rice blast and the effect was two times more than equivalent Cos and LaCl3·7H2O mixture solution. These results showed that Cos-La not only could improve the stability and persistence of pesticides, but also could effectively promote the growth and improve the disease resistance of crops. Cos-La nanoparticles would be a promising and environmentally friendly nanocarrier of pesticides in agricultural scenarios.