Explore the vast range of titles available.

The transition from an aquatic ancestral condition to a terrestrial environment exposed the first land plants to the desiccating effects of air and potentially large fluctuations in temperature and light intensity. To be successful, this transition necessitated metabolic, physiological, and morphological modifications, among which one of the most important was the capacity to synthesize hydrophobic extracellular biopolymers such as those found in the cuticular membrane, suberin, lignin, and sporopollenin, which collectively reduce the loss of water, provide barriers to pathogens, protect against harmful levels of UV radiation, and rigidify targeted cell walls. Here, we review phylogenetic and molecular data from extant members of the green plant clade (Chlorobionta) and show that the capacity to synthesize the monomeric precursors of all four biopolymers is ancestral and extends in some cases to unicellular plants (e.g. Chlamydomonas). We also review evidence from extant algae, bryophytes, and early-divergent tracheophytes and show that gene duplication, subsequent neo-functionalization, and the co-option of fundamental and ancestral metabolic pathways contributed to the early evolutionary success of the land plants.

Fleshy tomato fruit typically lacks stomata; therefore, a proper cuticle is particularly vital for fruit development and interaction with the surroundings. Here, we characterized the tomato SlSHINE3 (SlSHN3) transcription factor to extend our limited knowledge regarding the regulation of cuticle formation in fleshy fruits. We created SlSHN3 overexpressing and silenced plants, and used them for detailed analysis of cuticular lipid compositions, phenotypic characterization, and the study on the mode of SlSHN3 action. Heterologous expression of SlSHN3 in Arabidopsis phenocopied overexpression of the Arabidopsis SHNs. Silencing of SlSHN3 results in profound morphological alterations of the fruit epidermis and significant reduction in cuticular lipids. We demonstrated that SlSHN3 activity is mediated by control of genes associated with cutin metabolism and epidermal cell patterning. As with SlSHN3 RNAi lines, mutation in the SlSHN3 target gene, SlCYP86A69, resulted in severe cutin deficiency and altered fruit surface architecture. In vitro activity assays demonstrated that SlCYP86A69 possesses NADPH-dependent ω-hydroxylation activity, particularly of C18:1 fatty acid to the 18-hydroxyoleic acid cutin monomer. This study provided insights into transcriptional mechanisms mediating fleshy fruit cuticle formation and highlighted the link between cutin metabolism and the process of fruit epidermal cell patterning.

Rosellinia necatrix is the causal agent of avocado white root rot (WRR). Control of this soilborne disease is difficult, and the use of tolerant rootstocks may present an effective method to lessen its impact. To date, no studies on the molecular mechanisms regulating the avocado plant response towards this pathogen have been undertaken. To shed light on the mechanisms underpinning disease susceptibility and tolerance, molecular analysis of the gene’s response in two avocado rootstocks with a contrasting disease reaction was assessed. Gene expression profiles against R. necatrix were carried out in the susceptible ‘Dusa’ and the tolerant selection BG83 avocado genotypes by micro-array analysis. In ‘Dusa’, the early response was mainly related to redox processes and cell-wall degradation activities, all becoming enhanced after disease progression affected photosynthetic capacity, whereas tolerance to R. necatrix in BG83 relied on the induction of protease inhibitors and their negative regulators, as well as genes related to tolerance to salt and osmotic stress such as aspartic peptidase domain-containing proteins and gdsl esterase lipase proteins. In addition, three protease inhibitors were identified, glu protease, trypsin and endopeptidase inhibitors, which were highly overexpressed in the tolerant genotype when compared to susceptible ‘Dusa’, after infection with R. necatrix, reaching fold change values of 52, 19 and 38, respectively. The contrasting results between ‘Dusa’ and BG83 provide new insights into the different mechanisms involved in avocado tolerance to Phytophthora cinnamomi and R. necatrix, which are consistent with their biotrophic and necrotrophic lifestyles, respectively. The differential induction of genes involved in salt and osmotic stress in BG83 could indicate that R. necatrix penetration into the roots is associated with osmotic effects, suggesting that BG83’s tolerance to R. necatrix is related to the ability to withstand osmotic imbalance. In addition, the high expression of protease inhibitors in tolerant BG83 compared to susceptible ‘Dusa’ after infection with the pathogen suggests the important role that these proteins may play in the defence of avocado rootstocks against R. necatrix.

Mapping of a mutation in a tomato deficient in the plant cuticle component cutin yields the first cutin synthase, as shown via accumulation of polymer precursors and in vitro oligomerization of synthetic substrates. A hydrophobic cuticle consisting of waxes and the polyester cutin covers the aerial epidermis of all land plants, providing essential protection from desiccation and other stresses. We have determined the enzymatic basis of cutin polymerization through characterization of a tomato extracellular acyltransferase, CD1, and its substrate, 2-mono(10,16-dihydroxyhexadecanoyl)glycerol. CD1 has in vitro polyester synthesis activity and is required for cutin accumulation in vivo , indicating that it is a cutin synthase.

NAC proteins are a family of transcription factors which have a variety of important regulatory roles in plants. They present a very well conserved group of NAC subdomains in the N-terminal region and a highly variable domain at the C-terminus. Currently, knowledge concerning NAC family in the strawberry plant remains very limited. In this work, we analyzed the NAC family of Fragaria vesca, and a total of 112 NAC proteins were identified after we curated the annotations from the version 4.0.a1 genome. They were placed into the ligation groups (pseudo-chromosomes) and described its physicochemical and genetic features. A microarray transcriptomic analysis showed six of them expressed during the development and ripening of the Fragaria x ananassa fruit. Their expression patterns were studied in fruit (receptacle and achenes) in different stages of development and in vegetative tissues. Also, the expression level under different hormonal treatments (auxins, ABA) and drought stress was investigated. In addition, they were clustered with other NAC transcription factor with known function related to growth and development, senescence, fruit ripening, stress response, and secondary cell wall and vascular development. Our results indicate that these six strawberry NAC proteins could play different important regulatory roles in the process of development and ripening of the fruit, providing the basis for further functional studies and the selection for NAC candidates suitable for biotechnological applications.

Martin et al . describe a protocol to use laser microdissection to isolate specific cells or tissues from tomato fruit. This can be used to perform cell type–specific transcriptome studies in fleshy fruits, as well as in other plant tissues. This protocol enables transcriptome profiling of specific cell or tissue types that are isolated from tomato using laser microdissection (LM). To prepare tissue for LM, fruit samples are first fixed in optimal cutting temperature (OCT) medium and frozen in molds. The tissue is then sectioned using a cryostat before being dissected using an LM instrument. The RNAs contained in the harvested cells are purified and subjected to two rounds of amplification to yield sufficient quantities of RNA to generate cDNA libraries. Unlike several other techniques that are used to isolate specific cell types, LM has the advantage of being readily applied to any plant species without having to generate transgenic plants. Using the protocols described here, LM-mediated cell-type transcriptomic analysis of two samples requires ∼8 d from tissue harvest to RNA sequencing (RNA-seq), whereas each additional sample, up to a total of 12 samples, requires ∼1 additional day for the LM step. RNA obtained using this method has been successfully used for deep-coverage transcriptome profiling, which is a particularly effective strategy for identifying genes that are differentially expressed between cell or tissue types.

Societal Impact Statement Cherimoya has been an important food source since Pre‐Columbian times in the Americas. Although it is currently considered an underutilized fruit crop, it is still important at the local level in several regions of Central and South America, and has a clear niche for expansion in regions with subtropical climates. However, the availability of genomic resources to facilitate breeding programs and improve the understanding of Annonaceae genetic diversity is limited. In this work, we provide an important resource to fill this knowledge gap, with the hope that it will ultimately increase this crop's resilience under different climate change scenarios, which will increase food security in regions with subtropical climates. Summary Cherimoya (Annona cherimola Mill.) is a perennial fruit tree crop native to the Neotropics valued since pre‐Columbian times by different native American civilizations. It belongs to the Annonaceae, the largest family of the Magnoliid clade, sister to the eudicot and monocot clades of angiosperms. Despite its excellent organoleptic and nutritive qualities, this crop remains underutilized, although it has a clear niche for expansion in regions with subtropical climates. To date, no previous significant genomic information is available for this species, which would be a key tool to optimize breeding programs and advance in the study and conservation of its extant genetic diversity. A combination of different sequencing technologies (Illumina, Pacific Biosciences) has been implemented in order to assemble a chromosome‐level reference genome of A. cherimola. The final reference genome resulted in an assembly of 1.13 Gb and N50 of 170.86 Mb, anchored into seven pseudomolecules and with a completeness of 95.6%. A total of 41,413 protein‐coding genes were identified, many of which were related to secondary metabolism, defense mechanisms, stress response, and development. The results of this study provide novel significant genomic resources not only for cherimoya and other species of the Annonaceae but also for understanding the evolution of the earlier divergent angiosperms. Alternative language Societal Impact Statements El chirimoyo ha sido muy apreciado como alimento desde tiempos precolombinos por diferentes culturas de las Américas. Es actualmente considerado un cultivo infrautilizado, aunque es importante a nivel local en diferentes países de Centro y Sudamérica, y tiene un claro nicho de expansión en regiones subtropicales. Sin embargo, la disponibilidad de recursos genómicos para facilitar los programas de mejora e incrementar el conocimiento de la diversidad genética de las Annonaceae es limitada. En este trabajo proporcionamos un importante recurso con el fin de reducir esta brecha, con la esperanza de que en última instancia permita una mejor adaptación de este cultivo a los desafíos planteados por el cambio climático y, por tanto, facilite la seguridad alimentaria en regiones subtropicales. Cherimoya has been an important food source since Pre‐Columbian times in the Americas. Although it is currently considered an underutilized fruit crop, it is still important at the local level in several regions of Central and South America, and has a clear niche for expansion in regions with subtropical climates. However, the availability of genomic resources to facilitate breeding programs and improve the understanding of Annonaceae genetic diversity is limited. In this work, we provide an important resource to fill this knowledge gap, with the hope that it will ultimately increase this crop's resilience under different climate change scenarios, which will increase food security in regions with subtropical climates.

Potassium is the most abundant macronutrient in plants, participating in essential physiological processes such as turgor maintenance. A reduction in cell turgor is a hallmark of the ripening process associated with fruit softening. The dynamic of K+ fluxes in fleshy fruits is largely unknown; however, the reallocation of K+ into the apoplast has been proposed as a contributing factor to the decrease in fruit turgor, contributing to fruit softening. High-affinity K+ transporters belonging to the KUP/HT/HAK transporter family have been implicated in this process in some fruits. In this study, a comprehensive genome-wide analysis of the KUP/KT/HAK family of high-affinity K+ transporters in strawberry (Fragaria × ananassa Duch.) was conducted, identifying 60 putative transporter genes. The chromosomal distribution of the FaKUP gene family and phylogenetic relationship and structure of predicted proteins were thoroughly examined. Transcriptomic profiling revealed the expression of 19 FaKUP genes within the fruit receptacle, with a predominant downregulation observed during ripening, particularly in FaKUP14, 24 and 47. This pattern suggests their functional relevance in early fruit development and turgor maintenance. Mineral composition analyses confirmed that K+ is the most abundant macronutrient in strawberry fruits, exhibiting a slight decrease as ripening progressed. Membrane potential (Em) and diffusion potentials (ED) at increasing external K+ concentrations were measured by electrophysiology in parenchymal cells of green and white fruits. The results obtained suggest a significant diminution in cytosolic K+ levels in white compared to green fruits. Furthermore, the slope of change in ED at increasing external K+ concentration indicated a lower K+ permeability of the plasma membrane in white fruits, aligning with transcriptomic data. This study provides critical insights into the regulatory mechanisms of K+ transport during strawberry ripening and identifies potential targets for genetic modifications aimed at enhancing fruit firmness and shelf life.

Most studies of the biochemical and regulatory pathways that are associated with, and control, fruit expansion and ripening are based on homogenized bulk tissues, and do not take into consideration the multiplicity of different cell types from which the analytes, be they transcripts, proteins or metabolites, are extracted. Consequently, potentially valuable spatial information is lost and the lower abundance cellular components that are expressed only in certain cell types can be diluted below the level of detection. In this study, laser microdissection (LMD) was used to isolate epidermal and subepidermal cells from green, expanding Citrus clementina fruit and their transcriptomes were compared using a 20k citrus cDNA microarray and quantitative real-time PCR. The results show striking differences in gene expression profiles between the two cell types, revealing specific metabolic pathways that can be related to their respective organelle composition and cell wall specialization. Microscopy provided additional evidence of tissue specialization that could be associated with the transcript profiles with distinct differences in organelle and metabolite accumulation. Subepidermis predominant genes are primarily involved in photosynthesis- and energy-related processes, as well as cell wall biosynthesis and restructuring. By contrast, the most epidermis predominant genes are related to the biosynthesis of the cuticle, flavonoids, and defence responses. Furthermore, the epidermis transcript profile showed a high proportion of genes with no known function, supporting the original hypothesis that analysis at the tissue/cell specific levels can promote gene discovery and lead to a better understanding of the specialized contribution of each tissue to fruit physiology.