Antifungal Activity of Avocado Seed Recombinant GASA/Snakin PaSn

Unveiling the defensive role of Snakin-3, a member of the subfamily III of Snakin/GASA peptides in potatoes

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The first in-depth characterization of a subfamily III Snakin/GASA member was performed providing experimental evidence on promoter activity and subcellular localization and unveiling a role of potato Snakin-3 in defense Snakin/GASA proteins share 12 cysteines in conserved positions in the C-terminal region. Most of them were involved in different aspects of plant growth and development, while a small number of these peptides were reported to have antimicrobial activity or participate in abiotic stress tolerance. In potato, 18 Snakin/GASA genes were identified and classified into three groups based on phylogenetic analysis. Snakin-1 and Snakin-2 are members of subfamilies I and II, respectively, and were reported to be implicated not only in defense against pathogens but also in plant development. In this work, we present the first in-depth characterization of Snakin-3, a member of the subfamily III within the Snakin/GASA gene family of potato. Transient co-expression of Snakin-3 fused to the green fluorescent protein and organelle markers revealed that it is located in the endoplasmic reticulum. Furthermore, expression analyses via pSnakin-3::GUS transgenic plants showed GUS staining mainly in roots and vascular tissues of the stem. Moreover, GUS expression levels were increased after inoculation with Pseudomonas syringae pv. tabaci or Pectobacterium carotovorum subsp. carotovorum and also after auxin treatment mainly in roots and stems. To gain further insights into the function of Snakin-3 in planta, potato overexpressing lines were challenged against P. carotovorum subsp. carotovorum showing enhanced tolerance to this bacterial pathogen. In sum, here we report the first functional characterization of a Snakin/GASA gene from subfamily III in Solanaceae. Our findings provide experimental evidence on promoter activity and subcellular localization and reveal a role of potato Snakin-3 in plant defense.

Genome-Wide Identification and Bioinformatics Analyses of Host Defense Peptides Snakin/GASA in Mangrove Plants

Host defense peptides (HDPs) are components of plant defensive barriers that resist microbial infection. Members of the Snakin/GASA protein family in plants have functions of regulating plant growth, defense, and bacteriostasis. Most mangrove plants grow in coastal zones. In order to survive in harsh environments, mangrove plants have evolved complex adaptations against microbes. In this study, Snakin/GASA family members were identified and analyzed in the genomes of three mangrove species. Twenty-seven, thirteen, and nine candidate Snakin/GASA family members were found in Avicennia marina, Kandelia obovata, and Aegiceras corniculatum, respectively. These Snakin/GASA family members were identified and categorized into three subfamilies via phylogenetic analysis. The genes coding for the Snakin/GASA family members were unevenly distributed on chromosomes. Collinearity and conservative motif analyses showed that the Snakin/GASA family members in K. obovata and A. corniculatum underwent multiple gene duplication events. Snakin/GASA family member expression in normal leaves and leaves infected with pathogenic microorganisms of the three mangrove species was verified using real-time quantitative polymerase chain reaction. The expression of KoGASA3 and 4, AcGASA5 and 10, and AmGASA1, 4, 5, 15, 18, and 23 increased after microbial infection. This study provides a research basis for the verification of HDPs from mangrove plants and suggests directions for the development and utilization of marine biological antimicrobial peptides.