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 selfassembly 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 PGA 42 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-PGA 42 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-PGA 42 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-PGA 42 nanopesticides have a great potential application prospect to control the pest and improve the drug utilization efficiency on agriculture.
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.
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