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Tonalli A (TnaA) is a Drosophila melanogaster protein with an XSPRING domain. The XSPRING domain harbors an SP-RING zinc-finger, which is characteristic of proteins with SUMO E3 ligase activity. TnaA is required for homeotic gene expression and is presumably involved in the SUMOylation pathway. Here we analyzed some aspects of the TnaA location in embryo and larval stages and its genetic and biochemical interaction with SUMOylation pathway proteins. We describe that there are at least two TnaA proteins (TnaA130 and TnaA123) differentially expressed throughout development. We show that TnaA is chromatin-associated at discrete sites on polytene salivary gland chromosomes of third instar larvae and that tna mutant individuals do not survive to adulthood, with most dying as third instar larvae or pupae. The tna mutants that ultimately die as third instar larvae have an extended life span of at least 4 to 15 days as other SUMOylation pathway mutants. We show that TnaA physically interacts with the SUMO E2 conjugating enzyme Ubc9, and with the BRM complex subunit Osa. Furthermore, we show that tna and osa interact genetically with SUMOylation pathway components and individuals carrying mutations for these genes show a phenotype that can be the consequence of misexpression of developmental-related genes.

Rhizobacteria emit bioactive metabolites with antifungal properties that could be used for biocontrol of fungal diseases. In this study, we evaluated the potential of diffusible and volatile organic compounds (VOCs) emitted by avocado rhizobacteria to inhibit the growth of Fusarium kuroshium, one of the causal agents of Fusarium dieback (FD) in avocado. Three bacterial isolates (INECOL-6004, INECOL-6005, and INECOL-6006), belonging to the Bacillus genus, were selected based on their capacity to inhibit several avocado fungal pathogens, and tested in antagonism assays against F. kuroshium. The three bacterial isolates significantly inhibited F. kuroshium mycelial growth by up to 48%. The composition of bacterial diffusible compounds was characterized by the analysis of EtOAc and n-BuOH extracts by using ultra-performance liquid chromatography (UPLC) coupled to high-resolution mass spectrometry (HRMS). The three bacterial isolates produced cyclo-lipopeptides belonging to the iturin, fengycin, and surfactin families. The antifungal activity of n-BuOH extracts was larger than that of EtOAc extracts, probably due to the greater relative abundance of fengycin in the former than in the latter. In addition, isolates INECOL-6004 and INECOL-6006 significantly inhibited F. kuroshium mycelial growth through VOC emission by up to 69.88%. The analysis of their VOC profiles by solid phase micro-extraction (SPME) coupled to gas chromatography and mass spectrometry (GC-MS) revealed the presence of ketones and pyrazine compounds, particularly of 2-nonanone, which was not detected in the VOC profile of isolate INECOL-6005. These results emphasize the need to further investigate the antifungal activity of each bioactive compound for the development of new formulations against fungal phytopathogens.

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