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
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