Functional Divergence Research Articles

Functional Diversity of Macroinvertebrate Communities in River Nature Reserves of Spain

In recent decades, aquatic ecosystems have suffered a series of impacts that have made them some of the most threatened ecosystems on a global scale. So, protection measures are needed to conserve the biodiversity we find in some of the less impacted ecosystems. In the Spanish legislation, a category arose for this purpose in lotic ecosystems, the River Natural Reserve (RNR). In this work, we analyse the taxonomic and functional diversity of 145 macroinvertebrate biocoenoses from 128 different RNRs belonging to 10 different basins and representing 18 typologies. Most of the analysed biocoenoses have an overall high taxonomic diversity, with some exceptions corresponding to particular reaches suffering occasional disturbances or with very special conditions. An intermediate functional homogeneity has been also detected, related to a relatively low average functional richness. We also found medium levels of functional evenness, a high functional divergence, and low functional dispersion and Rao index values, the latter supporting similarities among taxa in functional terms. In our studied systems, there is high taxa turnover, but functional turnover is very low. This means that most of the trait dissimilarity between taxa is found within a community, but not among communities, though there are relatively strong dissimilarities in community composition. Our results support the fact that the RNRs are protecting communities of great diversity, not only taxonomic, but also functional, which contributes to the proper functioning of the ecosystems found in these stream reaches. Thus, the analysis of the functional diversity of the communities, as in the present approach, should be implemented to identify and prioritize protection of reaches with higher functional diversity, where enhanced ecosystem functioning can be expected.

CRISPR-Based Editing of the Medicago truncatula LEC1 Gene

Arabidopsis thaliana LEAFY COTYLEDON1 (LEC1) gene is shown to have numerous diverse functions in plant development, including the regulation of embryo morphogenesis and maturation, hypocotyl elongation, flowering transition, etc. However, the functions of LEC1 orthologs in different plant species have not been extensively studied. In this study, we obtained a line of Medicago truncatula, a model leguminous plant, carrying the loss-of-function mutation in the MtLEC1 (MtNF-YB10) gene, orthologous to LEC1, using the Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR-associated proteins (CRISPR/Cas9) genome editing system. Edited plants with loss of MtNF-YB10 function did not demonstrate any severe abnormalities during their normal growth and gave viable seeds, but their capability for somatic embryogenesis in vitro was dramatically reduced. The T1 progeny of unedited plants with a Cas9-gRNA cassette insertion was also analyzed based on the suggestion that editing could occur during seed formation. However, no edited plants were found in the T1 generation. These results suggest divergent functions of LEC1 orthologs and make it possible to investigate potential specific MtNF-YB10 functions.

START domains generate paralog-specific regulons from a single network architecture.

Functional divergence of transcription factors (TFs) has driven cellular and organismal complexity throughout evolution, but its mechanistic drivers remain poorly understood. Here we test for new mechanisms using CORONA (CNA) and PHABULOSA (PHB), two functionally diverged paralogs in the CLASS III HOMEODOMAIN LEUCINE ZIPPER (HD-ZIPIII) family of TFs. We show that virtually all genes bound by PHB ( ~ 99%) are also bound by CNA, ruling out occupation of distinct sets of genes as a mechanism of functional divergence. Further, genes bound and regulated by both paralogs are almost always regulated in the same direction, ruling out opposite regulation of shared targets as a mechanistic driver. Functional divergence of CNA and PHB instead results from differential usage of shared binding sites, with hundreds of uniquely regulated genes emerging from a commonly bound genetic network. Regulation of a given gene by CNA or PHB is thus a function of whether a bound site is considered 'responsive' versus 'non-responsive' by each paralog. Discrimination between responsive and non-responsive sites is controlled, at least in part, by their lipid binding START domain. This suggests a model in which HD-ZIPIII TFs use information integrated by their START domain to generate paralog-specific transcriptional outcomes from a shared network architecture. Taken together, our study identifies a mechanism of HD-ZIPIII TF paralog divergence and proposes the ubiquitously distributed START evolutionary module as a driver of functional divergence.

Delineating Notch1 and Notch2: Receptor-Specific Significance and Therapeutic Importance of Pinpoint Targeting Strategies for Hematological Malignancies.

Notch1 and Notch2, transmembrane receptors belonging to the Notch family, are pivotal mediators of intercellular communication and have profound implications including cell fate determination, embryonic development, and tissue homeostasis in various cellular processes. Despite their structural homology, Notch1 and Notch2 exhibit discrete phenotypic characteristics and functional nuances that necessitate their individualized targeting in specific medical scenarios. Aberrant Notch signaling, often driven by the dysregulated activity of one receptor over the other, is implicated under various pathological conditions. Notch1 dysregulation is frequently associated with T-cell acute lymphoblastic leukemia, whereas Notch2 perturbations are linked to B-cell malignancies and solid tumors, including breast cancer. Hence, tailored therapeutic interventions that selectively inhibit the relevant Notch receptor need to be devised to disrupt the signaling pathways driving the specific disease phenotype. In this review, we emphasize the importance of distinct tissue-specific expression patterns, functional divergence, disease-specific considerations, and the necessity to minimize off-target effects that collectively underscore the significance of "individualized" targeting for Notch1 and Notch2. This comprehensive review sheds light on the receptor-specific characteristics of Notch1 and Notch2, providing insights into their roles in cellular processes and offering opportunities for developing tailored therapeutic interventions in the fields of biomedical research and clinical practice.

New insights into the evolution and function of the UMAMIT (USUALLY MULTIPLE ACIDS MOVE IN AND OUT TRANSPORTER) gene family.

UMAMIT proteins have been known as key players in amino acid transport. In Arabidopsis, functions of several UMAMITs have been characterized, but their precise mechanism, evolutionary history and functional divergence remain elusive. In this study, we conducted phylogenetic analysis of the UMAMIT gene family across key species in the evolutionary history of plants, ranging from algae to angiosperms. Our findings indicate that UMAMIT proteins underwent a substantial expansion from algae to angiosperms, accompanied by the stabilization of the EamA (the main domain of UMAMIT) structure. Phylogenetic studies suggest that UMAMITs may have originated from green algae and be divided into four subfamilies. These proteins first diversified in bryophytes and subsequently experienced gene duplication events in seed plants. Subfamily I was potentially associated with amino acid transport in seeds. Regarding subcellular localization, UMAMITs were predominantly localized in the plasma membrane and chloroplasts. However, members from clade 8 in subfamily III exhibited specific localization in the tonoplast. These members may have multiple functions, such as plant disease resistance and root development. Furthermore, our protein structure prediction revealed that the four-helix bundle motif is crucial in controlling the UMAMIT switch for exporting amino acid. We hypothesize that the specific amino acids in the amino acid binding region determine the type of amino acids being transported. Additionally, subfamily II contains genes that are specifically expressed in reproductive organs and roots in angiosperms, suggesting neofunctionalization. Our study highlights the evolutionary complexity of UMAMITs and underscores their crucial role in the adaptation and diversification of seed plants.

Integration of Genome-Wide Identification and Transcriptome Analysis of Class III Peroxidases in Paeonia ostii: Insight into Their Roles in Adventitious Roots, Heat Tolerance, and Petal Senescence

As a plant-specific gene family, class III peroxidases (PODs) play an important role in plant growth, development, and stress responses. However, the POD gene family has not been systematically studied in Paeonia ostii. In this study, a total of 57 PoPOD genes were identified in the P. ostii genome. Subsequently, phylogenetic analysis and chromosome mapping revealed that PoPODs were classified into six subgroups and were unevenly distributed across five chromosomes. The gene structure and conserved motifs indicated the potential for functional divergence among the different subgroups. Meanwhile, four PoPODs were identified as tandem duplicated genes, with no evidence of segmental duplication. Using RNA-seq data from eight different tissues, multiple PoPODs exhibited enhanced expression in apical and adventitious roots (ARs). Next, RNA-seq data from AR development combined with trend analysis showed that PoPOD30/34/43/46/47/57 are implicated in the formation of ARs in tree peony. Through WGCNA based on RNA-seq, two key genes, PoPOD5/15, might be involved in heat tolerance via ABA and MeJA signaling. In addition, real-time quantitative PCR (qRT-PCR) analysis indicated that PoPOD23 may play an important role in flower senescence. These findings deepened our understanding of POD-mediated AR development, heat tolerance, and petal senescence in tree peony.

Unravelling spatial scale effects on elevational diversity gradients: insights from montane small mammals in Kenya

BackgroundMontane ecosystems play crucial roles as global biodiversity hotspots. However, climatic changes and anthropogenic pressure increasingly threaten the stability of montane community dynamics, such as diversity-elevation interactions, creating a challenge in understanding species biogeography and community ecology dynamics in these crucial conservation areas. We examined how varying sampling spatial grains influence small mammal diversity patterns within Kenya’s tallest montane ecosystems.MethodsEmploying a combination of multidimensional alpha diversity metrics and multisite beta diversity characteristics (species richness, phylogenetic and functional diversity and divergence, and multisite beta diversity) alongside spatial generalized additive multivariate regression analyses, we tested how spatial scaling influences elevational diversity gradient patterns and their associations with environmental and human activity variables.ResultsThe diversity-elevation associations were generally homogeneous across spatial grains; however, idiosyncratic patterns emerged across mountains. The total (taxonomic, phylogenetic, and functional) beta diversity, nestedness, and turnover resultant components monotonically increased or decreased with varying spatial grains. The associations between the diversity patterns and the environmental and human footprint variables increased with spatial grain size but also presented variations across mountains and indices. Species richness and phylogenetic and functional richness indices were more strongly influenced by spatial scale variations than were the divergence and community structure indices in both the diversity distribution patterns and their associations with the environmental and human variables.ConclusionsThe diversity-elevation and diversity-environment (including human activity pressure) relationships across spatial grains suggest that montane small mammal diversity patterns portray subtle but systematic sensitivity to sampling spatial grain variation and underscore the importance of geographical context in shaping these elevational diversity gradients. For improved effectiveness, conservation efforts should consider these spatial effects and the unique geographical background of individual montane ecosystems.

Subtleties in Clathrin heavy chain binding boxes provide selectivity among adaptor proteins of budding yeast

Clathrin forms a triskelion, or three-legged, network that regulates cellular processes by facilitating cargo internalization and trafficking in eukaryotes. Its N-terminal domain is crucial for interacting with adaptor proteins, which link clathrin to the membrane and engage with specific cargo. The N-terminal domain contains up to four adaptor-binding sites, though their role in preferential occupancy by adaptor proteins remains unclear. In this study, we examine the binding hierarchy of adaptors for clathrin, using integrative biophysical and structural approaches, along with in vivo functional experiments. We find that yeast epsin Ent5 has the highest affinity for clathrin, highlighting its key role in cellular trafficking. Epsins Ent1 and Ent2, crucial for endocytosis but thought to have redundant functions, show distinct binding patterns. Ent1 exhibits stronger interactions with clathrin than Ent2, suggesting a functional divergence toward actin binding. These results offer molecular insights into adaptor protein selectivity, suggesting they competitively bind clathrin while also targeting three different clathrin sites.

Metagenomics reveals the divergence of gut microbiome composition and function in two common pika species (Ochotona curzoniae, Ochotona daurica) in China.

Gut microbiome plays crucial roles in animal adaptation and evolution. However, research on adaptation and evolution of small wild high-altitude mammals from the perspective of gut microbiome is still limited. In this study, we compared difference in intestinal microbiota composition and function in Plateau pikas (Ochotona curzoniae) and Daurian pikas (Ochotona daurica) using metagenomic sequencing. Our results showed that microbial community structure had distinct differences in different pika species. Prevotella, Methanosarcina, Rhizophagus and Podoviridae were abundant bacteria, archaea, eukaryotes and viruses in Plateau pikas, respectively. However, Prevotella, Methanosarcina, Ustilago and Retroviridae were dominated in Daurian pikas. Functional pathways related to carbohydrate metabolism that refer to utilization of pectin, hemicellulose and debranching enzymes were abundant in Plateau pikas, while the function for degradation of chitin, lignin and cellulose was more concentrated in Daurian pikas. Pika gut had abundant multidrug resistance genes, followed by glycopeptide and beta-lactamase resistance genes, as well as high-risk ARGs, such as mepA, tetM and bacA. Escherichia coli and Klebsiella pneumoniae may be potential hosts of mepA. This research provided new insights for adaptation and evolution of wild animals from perspective of gut microbiome, and broadened our understanding of high-risk ARGs and potential pathogens of wild animals.

Ancient duplications, multidimensional specializations, and defense role of hexokinases in wheat.

Hexokinases (HXKs), which sense and catalyze cellular sugar, play a critical role in the growth and development of various plants, including wheat, a primary source of human calories frequently attacked by fungal pathogens. However, the evolutionary dynamics and functional diversification of HXKs in wheat, particularly their roles in plant defense, remain unclear. Here, we discovered that the wheat hexokinase gene family originated through multiple ancient gene duplications across different plant lineages and has undergone comprehensive, multidimensional functional specialization in gene expression, subcellular localization, enzyme activity, and regulation of plant defense responses. Gene expression analysis suggests that two-thirds of the TaHXK genes are responsive to fungal infection. Subcellular analysis reveals that while six TaHXKs are localized in mitochondria, three TaHXKs from different phylogenetic branches are sorted into other cellular compartments. Notably, biochemical analysis shows that TaHXKs in mitochondria differ in their glucose-catalyzing activity, with TaHXK5 and TaHXK3 exhibiting the highest and lowest enzyme activity, respectively. Consistently, transient expression analysis suggests that TaHXK5 induces various plant defense responses, while TaHXK3 is defective in activating some plant defense responses. Furthermore, inactivation of the glucokinase activity of TaHXK5 compromised its function in defense activation, suggesting that mitochondrial TaHXKs display functional divergence in both enzyme activity and defense-inducing activity that are intrinsically connected. Overall, our findings reveal that the multidimensional specialization events following the ancient duplication events may have shaped the functional diversity of HXKs in wheat, shedding light on their evolutionary dynamics and potentially contributing to the improvement of wheat defense.

Structural analysis of the siderophore-interacting protein from Vibrio anguillarum and its implications in classification of Vibrio homologs

Bacteria secrete siderophores to sequester the scarce iron in the environments, then the iron is transported into the cell in a siderophore-complexed form, which can be released by siderophore-interacting protein (SIP). Vibrio species comprise an array of serious pathogens, whose iron releasing process by SIP remains poorly understood. Herein, we report the high-resolution (1.2 Å) structure of Vibrio anguillarum SIP (VaSIP) in complex with FAD, representing the first structure of Vibrio SIP. VaSIP consists of a FAD-bound β-barrel domain and a Rossmann-fold domain connected by a linker, like other subgroup I SIPs. FAD is bound to the inter-domain cavity by aromatic stacking and hydrogen bonding interactions. Structural comparison indicated a modified NAD(P)H-binding motif (DxTA–EVL–GE) for subgroup I SIPs. The putative siderophore-binding pocket of VaSIP contains three lysines to form the basic triad to bind siderophore. Phylogenetic analysis shows Vibrio SIPs are mainly divided into two clades, represented by VaSIP and Vibrio cholerae ViuB, respectively. Interestingly, the two clades adopt distinct siderophore-binding basic triads, suggesting functional divergence among Vibrio SIPs. Our results shed light on the structural and phylogenetic characteristics of Vibrio SIPs, providing molecular basis for understanding Vibrio iron metabolism and designing anti-Vibrio drugs.

The evolutionarily diverged single-stranded DNA-binding proteins SSB1/SSB2 differentially affect the replication, recombination, and mutation of organellar genomes in Arabidopsis thaliana

Single-stranded DNA-binding proteins (SSBs) play essential roles in the replication, recombination, and repair processes of organellar DNA molecules. In Arabidopsis thaliana, SSBs are encoded by a small family of two genes (SSB1 and SSB2). However, the functional divergence of these two SSB copies in plants remains largely unknown, and detailed studies regarding their roles in the replication and recombination of organellar genomes are still incomplete. In this study, phylogenetic, gene structure, and protein motif analyses all suggested that SSB1 and SSB2 probably diverged during the early evolution of seed plants. Based on accurate long-read sequencing results, ssb1, and ssb2 mutants had decreased copy numbers for both mitochondrial DNA (mtDNA) and plastid DNA (ptDNA), accompanied by a slight increase in structural rearrangements mediated by intermediate-sized repeats in mt genome and small-scale variants in both genomes. Our findings provide an important foundation for further investigating the effects of DNA dosage in the regulation of mutation frequencies in plant organellar genomes.

Receptor determinants for ß-arrestin functional specificity at C-X-C chemokine receptor 5 (CXCR5).

ß-arrestins are multi-faceted adaptor proteins that mediate G protein-coupled receptor (GPCR) desensitization, internalization, and signaling. It is emerging that receptor-specific determinants specify these divergent functions at GPCRs, yet this remains poorly understood. Here, we set out to identify the receptor determinants responsible for ß-arrestin-mediated regulation of the chemokine receptor CXCR5. Using bioluminescence resonance energy transfer (BRET) we show that ß-arrestin1 and ß-arrestin2 are dose-dependently recruited to CXCR5 by its cognate ligand CXCL13. The carboxy-terminal tail of CXCR5 contains several Ser/Thr residues that can be divided into 3 discrete phospho-site clusters based on their position relative to transmembrane domain 7. Mutagenesis experiments revealed that the distal and medial phospho-site clusters, but not the proximal, are required for agonist-stimulated ß-arrestin1 or ß-arrestin2 recruitment to CXCR5. Consistent with this, we provide evidence that the distal and medial, but not proximal, phospho-site clusters are required for receptor desensitization. Surprisingly, the individual phospho-site clusters are not required for agonist-stimulated internalization of CXCR5. Further, we show that CXCL13-stimulated CXCR5 internalization and ERK1/2 phosphorylation, but not desensitization, remain intact in HEK293 cells lacking ß-arrestin1 and ß-arrestin2. Our study provides evidence that b-arrestins are recruited to CXCR5 and are required for desensitization but are dispensable for internalization or signaling, suggesting that discrete receptor determinants specify the divergent functions of ß-arrestins. Significance Statement CXCL13 and CXCR5 are important in the immune system and are linked to diseases, yet regulation of CXCR5 signaling remains poorly understood. We provide evidence that a phospho-site cluster located at the extreme distal carboxyl-terminal tail of the receptor is responsible for ß-arrestin recruitment and receptor desensitization. ß-arrestins are not required for CXCL13-stimulated internalization or signaling, indicating that ß-arrestins perform only one of their functions at CXCR5 and that discrete receptor determinants specify the divergent functions of ß-arrestins.

Conservation Corridors With Many Small Waterbodies Support Dragonfly Functional Diversity Across a Transformed Landscape Mosaic

ABSTRACTAimHuman activities pose many challenges to freshwater biodiversity. Among these, is landscape transformation, such as conversion of natural grassland to plantation forestry, impacting both terrestrial and freshwater biodiversity. Functional diversity measures provide substantial information on current and emerging impacts on biological communities, and aid conservation decisions relative to anthropogenic impacts. We determined (1) environmental similarities among 10 freshwater biotope types; (2) whether freshwater biotopes in conservation corridor networks support equal levels of functional richness and divergence compared with an extensive neighbouring protected area; (3) whether certain biotopes are more important for maintaining functional richness and divergence than others; and (4) whether associations between traits and biotope types could be identified.LocationThe northeastern coastal region of South Africa.MethodsUsing dragonflies as model organisms, and data from 140 freshwater lotic and lentic sites, we investigated the distribution of dragonfly traits across a plantation forestry‐natural grassland landscape mosaic with a range of biotope types.ResultsLake sites were different in their environmental conditions compared with the other biotopes. Environmental conditions were variable among the other biotope types and were difficult to distinguish. Freshwater biotopes in the conservation corridors supported equal levels of functional richness and divergence compared with those in the protected area. Overall, dragonfly functional richness and divergence were low at lake sites and wallows, while all other biotopes supported high levels of functional richness and divergence. Trait associations were complex across the waterscape and driven by habitat selection, flight behaviour and ecological sensitivity.Main ConclusionsMaintaining a mosaic of small lentic and lotic habitats would best support dragonfly conservation in this transformed landscape. A combination of biotopes offers a wide range of environmental conditions essential for conserving the full range of dragonfly traits and species across the region.

A nonlinear filter based on GSK for relative navigation using relative orbital elements

Due to the sensitivity of the relative orbital elements model to the measurement noise, the non-stationary heavy-tailed noise(NSHT) induced by the time-varying environment during the relative navigation usually leads to filter divergence. To address this problem, a new nonlinear filter based on Gaussian-Student's-Multivariate K(GSK) mixture distribution is proposed in this paper. A Dirichlet stochastic mixture vector fusing Gaussian, Student's t, and Multivariate K distributions is introduced, thus proposing a GSK mixture distribution modeling measurement likelihood; then the Kullback-Leibler Divergence (KLD) of the true posteriori probability density function(PDF) and the approximate posteriori PDF are minimized by a variational Bayesian(VB) technique to solve for the state and parameter approximate a posteriori estimations, and finally a new nonlinear filter based on the GSK mixture distribution is derived for angles-only relative navigation in time-varying environments. Simulation outcomes indicate that the filter can realize state estimation in non-stationary states effectively with 45.16% higher estimation accuracy than the existing advanced filters.

Graph neural processes for molecules: an evaluation on docking scores and strategies to improve generalization

Neural processes (NPs) are models for meta-learning which output uncertainty estimates. So far, most studies of NPs have focused on low-dimensional datasets of highly-correlated tasks. While these homogeneous datasets are useful for benchmarking, they may not be representative of realistic transfer learning. In particular, applications in scientific research may prove especially challenging due to the potential novelty of meta-testing tasks. Molecular property prediction is one such research area that is characterized by sparse datasets of many functions on a shared molecular space. In this paper, we study the application of graph NPs to molecular property prediction with DOCKSTRING, a diverse dataset of docking scores. Graph NPs show competitive performance in few-shot learning tasks relative to supervised learning baselines common in chemoinformatics, as well as alternative techniques for transfer learning and meta-learning. In order to increase meta-generalization to divergent test functions, we propose fine-tuning strategies that adapt the parameters of NPs. We find that adaptation can substantially increase NPs' regression performance while maintaining good calibration of uncertainty estimates. Finally, we present a Bayesian optimization experiment which showcases the potential advantages of NPs over Gaussian processes in iterative screening. Overall, our results suggest that NPs on molecular graphs hold great potential for molecular property prediction in the low-data setting.Scientific contributionNeural processes are a family of meta-learning algorithms which deal with data scarcity by transferring information across tasks and making probabilistic predictions. We evaluate their performance on regression and optimization molecular tasks using docking scores, finding them to outperform classical single-task and transfer-learning models. We examine the issue of generalization to divergent test tasks, which is a general concern of meta-learning algorithms in science, and propose strategies to alleviate it.

Expression and functional divergence of a type-A response regulator paralog pair formed by dispersed duplication during Populus deltoides evolution

Gene duplication and divergence are essential to plant evolution. The Arabidopsis type-A response regulator (ARR) family, negative regulators in cytokinin signaling, exemplifies gene expansion and differential retention. Despite extensive research, the understanding of type-A RR homologs in woody plants remains limited. In this study, the evolution history of type-A RR gene families across four rosids and one monocot has been comprehensively investigated. Focusing on Populus deltoides, a unique pair of dispersed duplicates, PdRR8 and PdFERR, is identified, and their duplication is estimated to have occurred in the common ancestor of the four rosids. The duplication remnants corresponding to PdRR8 have been retained in all rosids but the counterpart of PdFERR has been lost. In poplar, PdRR8 shows the highest expression levels in leaves, while PdFERR is specifically expressed in female floral buds. Among various external stimuli, cold strongly represses PdRR8 promoter activity, whereas 6-BA markedly inhibits that of PdFERR. Overexpression of PdRR8 in the Arabidopsis arr16arr17 double-mutant fully complements the reduced hydrotropic response. In contrast, PdFERR fails to rescue the hydrotropic defects of the mutant. Results of evolutionary, expression and functional analyses indicate that PdRR8, rather than PdFERR, is the true ortholog of the ARR16-ARR17 paralogs. Though PdRR8 and PdFERR originate from a common ancestral gene and evolve under strong negative selection, these two dispersed duplicates have exhibited differential expression and some degree of functional divergence.

Decrease in purifying selection pressures on wheat homoeologous genes: tetraploidization versus hexaploidization.

A series of polyploidizations in higher-order polyploids is the main event affecting gene content in a genome. Each polyploidization event can lead to massive functional divergence because of the subsequent decrease in selection pressure on duplicated genes; however, the causal relationship between multiple rounds of polyploidization and the functional divergence of duplicated genes is poorly understood. We focused on the Triticum-Aegilops complex lineage and compared selection pressure before and after tetraploidization and hexaploidization events. Although both events led to decreased selection pressure on homoeologous gene pairs (compared with diploids and tetraploids), the initial tetraploidization had a greater impact on selection pressure on homoeologous gene pairs than did subsequent hexaploidization. Consistent with this, selection pressure on expression patterns for the initial event relaxed more than those for the subsequent event. Surprisingly, the decreased selection pressure on these homoeologous genes was independent of the existence of in-paralogs within the same subgenome. Wheat homoeologous pairs had different evolutionary consequences compared with orthologs related to other mechanisms (ancient allopolyploidization, ancient autopolyploidization, and small-scale duplication). Furthermore, tetraploidization and hexaploidization also seemed to have different evolutionary consequences. This suggests that homoeologous genes retain unique functions, including functions that are unlikely to be preserved in genes generated by the other duplication mechanisms. We found that their unique functions differed between tetraploidization and hexaploidization (e.g., reproductive and chromosome segregation processes). These findings imply that the substantial number of gene pairs resulting from multiple allopolyploidization events, especially initial tetraploidization, may have been a unique source of functional divergence.

Phylogenomic Analysis and Functional Characterization of the APETALA2/Ethylene-Responsive Factor Transcription Factor Across Solanaceae.

The AP2/ERF family constitutes one of the largest groups of transcription factors in the Solanaceae. AP2/ERF contributes to various plant biological processes, including growth, development, and responses to various stresses. The origins and functional diversification of AP2/ERF within the Solanaceae family remain poorly understood, primarily because of the complex interactions between whole-genome duplications (WGDs) and tandem duplications. In this study, a total of 1282 AP2/ERF proteins are identified from 7 Solanaceae genomes. The amplification of AP2/ERF genes was driven not only by WGDs but also by the presence of clusters of tandem duplicated genes. The conservation of synteny across different chromosomes provides compelling evidence for the impact of the WGD event on the distribution pattern of AP2/ERF genes. Distinct expression patterns suggest that the multiple copies of AP2/ERF genes evolved in different functional directions, catalyzing the diversification of roles among the duplicated genes, which was of great significance for the adaptability of Solanaceae. Gene silencing and overexpression assays suggest that ERF-1 members' role in regulating the timing of floral initiation in C. annuum. Our findings provide insights into the genomic origins, duplication events, and function divergence of the Solanaceae AP2/ERF.

Evolutionary and Expression Analyses of the bZIP Family in Tea Plants (Camellia sinensis) and Functional Characterization of CsbZIP3/42/6 in Response to Environmental Stresses.

Basic leucine zipper (bZIP) transcription factors play crucial roles in various biological processes and responses to environmental stresses. However, the functions of the bZIP family in tea plants remain largely unexplored. Here, we identified 74 bZIP genes in tea plants (Camellia sinensis) and classified them into 12 phylogenetic groups, supported by analyses of conserved motifs and gene structures. Cis-element analysis provided insights into the potential roles of CsbZIP genes in phytohormone signaling and stress responses. Tissue-specific expression analysis demonstrated differential expression profiles of CsbZIP genes, suggesting their tissue- and stage-specific functions. Additionally, varying expression levels under different abiotic stresses indicated functional divergence of the CsbZIP family during the long-term evolution. Notably, CsbZIP3/42/6 were identified as positive regulators of drought and salt stress responses but negative regulators in response to pathogen infection, and CsbZIP42 could interact with CsbZIP3 and CsbZIP6 in regulating these environmental stresses. This study provides valuable information on potential applications for improving stress tolerance and overall plant health of tea plants.