Bacterial leaf blight (BLB), caused by Xanthomonas oryzae pv. oryzae (Xoo), poses a serious threat to rice cultivation. This study presents the green synthesis of zinc oxide nanoparticles (ZnO NPs) using an aqueous leaf extract of the medicinal plant Centella asiatica (L.) Urban and evaluates their potential as dual-function nanopesticides. The synthesized CA-ZnO NPs exhibited high crystallinity, a hexagonal to quasi-spherical morphology, and nanoscale dimensions (~22.5 nm), as confirmed by UV–Vis spectroscopy, XRD, FTIR, SEM, TEM, and SAED analyses. These nanoparticles demonstrated potent antibacterial activity against a highly virulent, field-derived Thai Xoo strain, with a minimum inhibitory concentration (MIC) of 8 µg/mL. Mechanistic investigations revealed substantial membrane disruption, intracellular nanoparticle penetration, and elevated reactive oxygen species (ROS) generation in treated cells. Cytotoxicity testing using human dermal fibroblasts (HDFs) revealed excellent biocompatibility, with no statistically significant reduction in cell viability at concentrations up to 500 µg/mL. In contrast, viability markedly declined at 1000 µg/mL. These findings underscore the selective antibacterial efficacy and minimal mammalian cytotoxicity of CA-ZnO NPs. Overall, CA-ZnO NPs offer a promising green nanopesticide platform that integrates potent antibacterial activity with biocompatibility, supporting future applications in sustainable crop protection and biomedical nanotechnology.

A cytological study was carried out on four Zingiber species from Thailand, namely, Z. chrysostachys, Z. isanense, Z. junceum, and Z. niveum, which are edible and beautiful ornamental plants. They all have somatic chromosomal numbers of 2n = 22. This research contributes to karyological knowledge regarding this species. The somatic chromosomal counts of Z. niveum and Z. isanense are reported for the first time, as are the NFs of all species, which were all discovered to be 44. All four edible and ornamental species had their karyotypes: 16m + 6sm for Z. chrysostachys, 4m + 18sm for Z. isanense, 12m + 10sm for Z. junceum, and 14m + 4sm + 4st for Z. niveum. The dominant characteristics of these four Zingiber species are as follows: Z. chrysostachys has yellow bracts, pale yellow flowers, and a red labellum with white dots; Z. isanensis has red-brown bracts, white flowers, and a white labellum; Z. junceum has green bracts, yellow flowers, and a yellow labellum; and Z. niveum has white bracts, yellow flowers, and a yellow labellum. Additionally, principal component analysis (PCA) of the karyotype formula was used to divide the four Zingiber species into two groups via various points using the chromosome indexes (CIs): Z. niveum (D) with Z. chrysostachys (A), and Z. junceum (C) with Z. isanensis (B). This finding implies that, while being in the same stage, the CIs of these four Zingiber species can be used to distinguish them, revealing their resemblance at unique stages and close relationship. Accordingly, the chromosomal structure, karyotype formulae, and CIs can be used to distinguish these four edibles and ornamental Zingiber species from Thailand.

Bacterial leaf blight (BLB), a destructive disease of rice caused by Xanthomonas oryzae pv. oryzae (Xoo), continues to limit rice productivity worldwide. Although biologically synthesized zinc oxide nanoparticles (ZnO NPs) have been extensively investigated, knowledge regarding the antibacterial activity and biocompatibility of commercially available ZnO NPs is still limited. In this study, commercial ZnO NPs were systematically characterized and evaluated for their antibacterial mechanisms and biocompatibility in mammalian cells. FE-SEM and TEM analyses revealed irregular polyhedral, hexagonal, and short rod-like morphologies with an average particle size of ~33 nm, consistent with crystallite sizes estimated by XRD. The nanoparticles exhibited pronounced antibacterial activity against Xoo, with a minimum inhibitory concentration (MIC) of 16 µg/mL and a clear dose-dependent response. Mechanistic assays confirmed multifaceted bactericidal actions involving membrane disruption, ROS generation, Zn²⁺ release, and ultrastructural damage. Biocompatibility testing in human dermal fibroblasts showed enhanced proliferation at 8–32 µg/mL, no cytotoxicity up to 256 µg/mL, and reduced viability only at ≥512 µg/mL. These findings represent the first mechanistic evaluation of commercial ZnO NPs against Xoo, together with cytotoxicity assessment in mammalian cells, highlighting their structural distinctness and dual functionality that combine potent antibacterial activity with minimal mammalian cytotoxicity. Overall, the results underscore their potential as safe nanobiocontrol agents for sustainable rice disease management.