Protein S-acyltransferases and acyl protein thioesterases, regulation executors of protein S-acylation in plants

Hop stunt viroid infection induces heterochromatin reorganization

Viroids are pathogenic noncoding RNAs that completely rely on their host molecular machinery to accomplish their life cycle. Several interactions between viroids and their host molecular machinery have been identified, including interference with epigenetic mechanisms such as DNA methylation. Despite this, whether viroids influence changes in other epigenetic marks such as histone modifications remained unknown. Epigenetic regulation is particularly important during pathogenesis processes because it might be a key regulator of the dynamism of the defense response. Here we have analyzed the changes taking place in Cucumis sativus (cucumber) facultative and constitutive heterochromatin during hop stunt viroid (HSVd) infection using chromatin immunoprecipitation (ChIP) of the two main heterochromatic marks: H3K9me2 and H3K27me3. We find that HSVd infection is associated with changes in both H3K27me3 and H3K9me2, with a tendency to decrease the levels of repressive epigenetic marks through infection progression. These epigenetic changes are connected to the transcriptional regulation of their expected targets, genes, and transposable elements. Indeed, several genes related to the defense response are targets of both epigenetic marks. Our results highlight another host regulatory mechanism affected by viroid infection, providing further information about the complexity of the multiple layers of interactions between pathogens/viroids and hosts/plants.

Protein S-acylation, a new panacea for plant fitness

Protein S-acylation or palmitoylation is a reversible post-translational modification that influences many proteins encoded in plant genomes. Exciting progress in the past 3 years demonstrates that S-acylation modulates subcellular localization, interacting profiles, activity, or turnover of substrate proteins in plants, participating in developmental processes and responses to abiotic or biotic stresses. In this review, we summarize and discuss the role of S-acylation in the targeting of substrate proteins. We highlight complex roles of S-acylation in receptor signaling. We also point out that feedbacks of protein S-acyl transferase by signaling initiated from their substrate proteins may be a recurring theme. Finally, the reversibility of S-acylation makes it a rapid and efficient way to respond to environmental cues. Future efforts on exploring these important aspects of S-acylation will give a better understanding of how plants enhance their fitness under ever changing and often harsh environments.

Development of Gene-Based InDel Markers on Putative Drought Stress-Responsive Genes and Genetic Diversity of Durian (Durio zibethinus)

Insertion-deletion (InDel) markers are co-dominant, relatively abundant and practical for agarose gel genotyping. InDel polymorphism usually affects gene functions. Nucleotide sequences of durian (Durio zibethinus) are available, but InDel makers have not been well established. This study aimed to develop drought-related gene-based InDel markers for durian through bioinformatic analysis of RNA-Seq datasets. The polymorphism of the markers was verified in 24 durian genotypes local to Thailand. Bioinformatic analysis indicated 496 InDel loci having lengths more than 9 bp. To evaluate these InDel markers, 15 InDel loci were selected. Nine markers were successfully amplified a clear polymorphic band pattern on 2% agarose gel. The polymorphic information content (PIC) of these nine markers ranged from 0.1103 to 0.5808. The genetic distance between the 24 genotypes ranged from 0.222 to 0.889. The phylogeny based on the nine InDel loci distinguished the 24 genotypes and divided samples into four groups. This set of gene-based InDel markers on putative drought-responsive genes will be useful for genetic studies.

The role of lipid-modified proteins in cell wall synthesis and signaling

The plant cell wall is a complex and dynamic extracellular matrix. Plant primary cell walls are the first line of defense against pathogens and regulate cell expansion. Specialized cells deposit a secondary cell wall that provides support and permits water transport. The composition and organization of the cell wall varies between cell types and species, contributing to the extensibility, stiffness, and hydrophobicity required for its proper function. Recently, many of the proteins involved in the biosynthesis, maintenance, and remodeling of the cell wall have been identified as being post-translationally modified with lipids. These modifications exhibit diverse structures and attach to proteins at different sites, which defines the specific role played by each lipid modification. The introduction of relatively hydrophobic lipid moieties promotes the interaction of proteins with membranes and can act as sorting signals, allowing targeted delivery to the plasma membrane regions and secretion into the apoplast. Disruption of lipid modification results in aberrant deposition of cell wall components and defective cell wall remodeling in response to stresses, demonstrating the essential nature of these modifications. Although much is known about which proteins bear lipid modifications, many questions remain regarding the contribution of lipid-driven membrane domain localization and lipid heterogeneity to protein function in cell wall metabolism. In this update, we highlight the contribution of lipid modifications to proteins involved in the formation and maintenance of plant cell walls, with a focus on the addition of glycosylphosphatidylinositol anchors, N-myristoylation, prenylation, and S-acylation.

Genome-Wide Identification and Expression Pattern Profiling of the Aquaporin Gene Family in Papaya (Carica papaya L.)

Aquaporins (AQPs) are mainly responsible for the transportation of water and other small molecules such as CO2 and H2O2, and they perform diverse functions in plant growth, in development, and under stress conditions. They are also active participants in cell signal transduction in plants. However, little is known about AQP diversity, biological functions, and protein characteristics in papaya. To better understand the structure and function of CpAQPs in papaya, a total of 29 CpAQPs were identified and classified into five subfamilies. Analysis of gene structure and conserved motifs revealed that CpAQPs exhibited a degree of conservation, with some differentiation among subfamilies. The predicted interaction network showed that the PIP subfamily had the strongest protein interactions within the subfamily, while the SIP subfamily showed extensive interaction with members of the PIP, TIP, NIP, and XIP subfamilies. Furthermore, the analysis of CpAQPs' promoters revealed a large number of cis-elements participating in light, hormone, and stress responses. CpAQPs exhibited different expression patterns in various tissues and under different stress conditions. Collectively, these results provided a foundation for further functional investigations of CpAQPs in ripening, as well as leaf, flower, fruit, and seed development. They also shed light on the potential roles of CpAQP genes in response to environmental factors, offering valuable insights into their biological functions in papaya.