The avocado fruit (Persea americana) has become a significant fruit in the human diet for its nutritional properties. However, the seed is a source of bioactive molecules and has been poorly utilized. Previously, we reported that the PaSn gene is expressed in the avocado seeds, a cysteine-rich antimicrobial peptide (GASA/Snakin), and demonstrated its antibacterial activity. In this work, we report the recombinant production of PaSn in the Escherichia coli system and evaluate its antifungal activity against plant and human pathogen fungi. The recombinant peptide showed antifungal activity at 200 μg/mL against phytopathogens Colletotrichum gloeosporioides and Fusarium oxysporum and human pathogens Candida albicans and C. glabrata. Our results demonstrate the usefulness of a prokaryotic expression system for avocado antimicrobial peptide production. In conclusion, the snakin PaSn could be helpful in the control of postharvest avocado and other fruits’ fungal diseases and human fungal pathogens.

Soil salinity is one of the main challenges that modern agriculture faces. Avocado, which is classified as a glycophyte, is very sensitive to salt stress. There are botanical varieties of avocado that differ in their salt tolerance. This study investigated how salt stress affects the in vitro germination of two avocado botanical varieties americana (West Indian breed) and drymifolia (Mexican native) with different salt tolerances. This study also assessed the potential role of the avocado PaHAK2 high-affinity K⁺ transporter HAK/KUP/KT in response to saline stress during germination. Salinity (60 mM NaCl) delayed the germination speed of the drymifolia variety relative to the americana variety. A computational 3D inference protein model of the PaHAK2 protein showed 10 highly conserved transmembrane domains. During the imbibition period, there was a differential increase in the expression of the PaHAK2 gene at 60 mM NaCl in both varieties, which suggests the presence of osmotic adjustment and regulation. The enhanced expression of PaHAK2 in the americana variety suggests an adaptive advantage to salinity. We conclude that PaHAK2 participates in the response of avocado to salt stress during seed germination.

Avocado native “Mexicano” (Persea americana var drymifolia) has been a really important species in agricultural and indigenous medicine. In the agricultural world, it has been the germplasm source for the generation of economically important cultivars like Hass and it is the main source of rootstocks for the world production of Hass avocado fruit. In spite of its importance, little is known about the molecular network of seed-fruit development. The aim of this work was to know the expressed genes (ESTs) during the early avocado native “Mexicano” seed development. Using total RNA we constructed cDNA libraries of fourth months seed development, sequencing, assembling and bioinformatic analysis was made. For validation, a semi-quantitative PCR experiments with the most abundant genes were made. About 5005 ESTs from the 5’ representing 1653 possible unigenes were isolated. After assembling process, we have 171 genes that are closely related to Nelumbo nucifera sequences. The transcriptome is dominating by one bHLH transcription factor, three metallothioneins and snakin, suggesting its main role in seed development. Until now, there are no molecular studies in avocado seed development.

Soil salinity is a major environmental constraint affecting avocado (Persea americana Mill.) productivity. In this study, we evaluate the physio-morphological and molecular responses of two avocado varieties, drymifolia (sensitive) and americana (tolerant), subjected to increasing NaCl concentrations for 60 days. Our results reveal distinct adaptive strategies. While salinity reduced total biomass in both genotypes, var. americana exhibited superior resilience, characterized by preferential biomass allocation to the root system. Ion analysis demonstrated that tolerance was not mediated by K⁺ homeostasis, but rather by the differential management of toxic ions. var. americana effectively sequestered chloride Cl⁻ in the roots, whereas var. drymifolia exhibited a breakdown of the exclusion mechanism at 60 mM NaCl, with shoot Cl⁻ concentrations exceeding those of the root, leading to severe toxicity. At the molecular level, qPCR analysis of the Na⁺ transporters PaHKT1 and PaSOS1 showed no expression pattern correlated with salt stress. Bioinformatic assessment revealed significant structural divergences and a lack of conserved functional domains in these proteins. These findings challenge the applicability of the classical sodium-exclusion model (typical of Liliopsida and Magnoliopsida) to avocado. We conclude that salt tolerance in this Lauraceae species is primarily driven by root-mediated Cl⁻ exclusion rather than canonical Na⁺ transport pathways.

Plants lack an adaptive immune system; instead, they have developed an innate immunity system to defend themselves against pathogenic organisms. Antimicrobial peptides (AMPs) represent one of the most effective components of this protection system. These molecules have attracted considerable attention because of their broad-spectrum antimicrobial activity, structural stability, and low toxicity toward mammalian cells, making them promising candidates for the development of novel antifungal agents. Avocado fruit has become an important food in the human diet and is also rich in bioactive compounds, including AMPs. Two AMPs from avocado have been indentified: 1) The defensin (PaDef1) and 2) Snakin (PaSn1) that are expressed abundantly in the fruit. The most common fungal infections in humans are those caused by Candida species, which are responsible for significant morbidity and mortality worldwide. These pathogens have shown reduced susceptibility to fungicides commonly used for their control. In this study, both peptides were characterized and evaluated for their antifungal activity against the clinically relevant human pathogens Candida albicans and Candida glabrata. PaDef was chemically synthesized from its mature peptide sequence, whereas recombinant PaSn was produced through heterologous expression. Sequence analyses confirmed that PaDef conserves the characteristic structural features of type-1 plant defensins, including the conserved cysteine residues, CSαβ fold, and γ-core motif, while PaSn exhibited the typical GASA/Snakin domain with 12 conserved cysteine residues. Results showed that both peptides exhibited antifungal activity against Candida species at different concentrations, suggesting that avocado-derived AMPs may represent promising alternatives or complementary agents for the development of new antifungal therapies.