Search

Mitogen-activated protein kinase (MAPK/MPK) cascades play crucial parts in plant growth, development processes, immune ability, and stress responses; however, the regulatory mechanism by which MAPK affects fruit ripening remains largely unexplored. Here, we reported that MaMPK14 cooperated with MaMYB4 to mediate postharvest banana fruit ripening. Transient overexpression of individual MaMPK14 and MaMYB4 in banana fruit delayed fruit ripening, confirming the negative roles in the ripening. The ripening negative regulator MaMYB4 could repress the transcription of genes associated with ethylene biosynthesis and fruit softening, such as MaACS1, MaXTH5, MaPG3, and MaEXPA15. Furthermore, MaMPK14 phosphorylated MaMYB4 at Ser160 via a direct interaction. Mutation at Ser160 of MaMYB4 reduced its interaction with MaMPK14 but did not affect its subcellular localization. Importantly, phosphorylation of MaMYB4 by MaMPK14 enhanced the MaMYB4-mediated transcriptional inhibition, binding strength, protein stability, and the repression of fruit ripening. Taken together, our results delineated the regulation pathway of MAPK module during banana fruit ripening, which involved the phosphorylation modification of MaMYB4 mediated by MaMPK14. [ABSTRACT FROM AUTHOR]

The ethylene insensitive 3/ethylene insensitive 3‐like (EIN3/EIL) plays an indispensable role in fruit ripening. However, the regulatory mechanism that links post‐translational modification of EIN3/EIL to fruit ripening is largely unknown. Here, we studied the expression of 13 MaEIL genes during banana fruit ripening, among which MaEIL9 displayed higher enhancement particularly in the ripening stage. Consistent with its transcript pattern, abundance of MaEIL9 protein gradually increased during the ripening process, with maximal enhancement in the ripening. DNA affinity purification (DAP)‐seq analysis revealed that MaEIL9 directly targets a subset of genes related to fruit ripening, such as the starch hydrolytic genes MaAMY3D and MaBAM1. Stably overexpressing MaEIL9 in tomato fruit hastened fruit ripening, whereas transiently silencing this gene in banana fruit retarded the ripening process, supporting a positive role of MaEIL9 in fruit ripening. Moreover, oxidation of methionines (Met‐129, Met‐130, and Met‐282) in MaEIL9 resulted in the loss of its DNA‐binding capacity and transcriptional activation activity. Importantly, we identified MaEIL9 as a potential substrate protein of methionine sulfoxide reductase A MaMsrA4, and oxidation of Met‐129, Met‐130, and Met‐282 in MaEIL9 could be restored by MaMsrA4. Collectively, our findings reveal a novel regulatory network controlling banana fruit ripening, which involves MaMsrA4‐mediated redox regulation of the ethylene signaling component MaEIL9. [ABSTRACT FROM AUTHOR]

Banana anthracnose, caused by Colletotrichum fructicola , significantly reduced the postharvest fruit quality. Employing biocontrol strategies offers a sustainable approach to enhance agricultural practices. The Burkholderia sp . strain BX1 hinders the growth and appressorium formation of C. fructicola , and its sterile filtrate lowers the anthracnose incidence while preserving the fruit quality. Scanning electron microscopy and genomic analyses confirmed BX1 as Burkholderia pyrrocinia . AntiSMASH analysis identified three siderophores with high similarity, and improved MALDI-TOF IMS confirmed the presence of the siderophore pyochelin. Furthermore, the BX1 filtrate suppressed the expression of virulence genes in C. fructicola and induced the expression of disease resistance genes in banana. However, the presence of 80 μM iron ions notably mitigated BX1's inhibitory effects and reversed the changes in related gene expression. These results underscore BX1's robust efficacy as a biocontrol agent in managing banana anthracnose, highlight the effective antifungal compounds, and elucidate the influence of environmental factors on biocontrol effectiveness.