Genome-wide member identification, phylogeny and expression analysis of PEBP gene family in wheat and its progenitors

Evolutionary origin and functional investigation of the widely conserved plant PEBP gene STEPMOTHER OF FT AND TFL1 (SMFT)

Genes of the family PHOSPHATIDYLETHANOLAMINE-BINDING PROTEINS (PEBP) have been intensely studied in plants for their role in cell (re)programming and meristem differentiation. Recently, sporadic reports of the presence of a new type of PEBP in plants became available, highly similar to the YY-PEBPs of prokaryotes. A comprehensive investigation of their spread, origin, and function revealed conservation across the plant kingdom. The YY-PEBP clade in plants seems to have resulted from a single Horizontal Gene Transfer (HGT) episode from a prokaryotic organism to an ancestral streptophyte. YY-PEBPs are also present in other eukaryotes, such as certain fungi, diatoms, and rotifers, and these cases derive from independent HGT events. Reciprocally, the occurrence of the eukaryotic CETS/RKIP type PEBPs (CR-PEBPs) was noticed in bacteria of the genus Nocardia, showing that HGT has occurred as well from eukaryotes to prokaryotes. Based on these observations, we propose that the current model of the PEBP family in plants needs to be updated with the clade STEPMOTHER OF FT AND TFL1 (SMFT). SMFT genes not only share high sequence conservation but also show specific expression in homologous plant structures that serve as propagules. Functional analysis of Arabidopsis smft mutant lines pointed to a function for this gene in regulating seed germination, both concerning primary dormancy release and in response to adverse high-temperature conditions. Overall, our study reveals an increasing complexity in the evolutionary history of the PEBP gene family, unlocking new potential in understanding the evolution and functional spectrum of these important key regulatory genes.

Flowering time genes branching out

Plants are sessile by nature, and as such they have evolved to sense changes in seasonality and their surrounding environment, and adapt to these changes. One prime example of this is the regulation of flowering time in angiosperms, which is precisely timed by the coordinated action of two proteins: FLOWERING LOCUS T (FT) and TERMINAL FLOWER 1 (TFL1). Both of these regulators are members of the PHOSPHATIDYLETHANOLAMINE BINDING PROTEIN (PEBP) family of proteins. These regulatory proteins do not interact with DNA themselves, but instead interact with transcriptional regulators, such as FLOWERING LOCUS D (FD). FT and TFL1 were initially identified as key regulators of flowering time, acting through binding with FD; however, PEBP family members are also involved in shaping plant architecture and development. In addition, PEBPs can interact with TCP transcriptional regulators, such as TEOSINTE BRANCHED 1 (TB1), a well-known regulator of plant architecture, and key domestication-related genes in many crops. Here, we review the role of PEBPs in flowering time, plant architecture, and development. As these are also key yield-related traits, we highlight examples from the model plant Arabidopsis as well as important food and feed crops such as, rice, barley, wheat, tomato, and potato.

Genome-wide identification of PEBP gene family in pineapple reveal its potential functions in flowering

Phosphatidylethanolamine binding protein (PEBP) plays an important role in regulating flowering time and morphogenesis of plants. However, the identification and functional analysis of PEBP gene in pineapple (AcPEBP) have not been systematically studied. The pineapple genome contained 11 PEBP family members, which were subsequently classified into three subfamilies (FT-like, TFL-like and MFT-like) based on phylogenetic relationships. The arrangement of these 11 shows an unequal pattern across the six chromosomes of pineapple the pineapple genome. The anticipated outcomes of the promoter cis-acting elements indicate that the PEBP gene is subject to regulation by diverse light signals and endogenous hormones such as ethylene. The findings from transcriptome examination and quantitative real-time polymerase chain reaction (qRT-PCR) indicate that FT-like members AcFT3 and AcFT4 display a heightened expression level, specifically within the floral structures. The expression of AcFT3 and AcFT4 increases sharply and remains at a high level after 4 days of ethylene induction, while the expression of AcFT7 and AcMFT1 decreases gradually during the flowering process. Additionally, AcFT3, AcFT4 and AcFT7 show specific expression in different floral organs of pineapple. These outcomes imply that members belonging to the FT-like subfamily may have a significant impact on the process of bud differentiation and flower development. Through transcriptional activation analysis, it was determined that AcFT4 possesses transcriptional activation capability and is situated in the nucleus and peripheral cytoplasm. Overexpression of AcFT4 in Arabidopsis resulted in the promotion of early flowering by 6-7 days. The protein interaction prediction network identified potential flower regulators, including CO, AP1, LFY and SOC1, that may interact with PEBP proteins. This study explores flower development in pineapple, thereby serving as a valuable reference for future research endeavors in this domain.

Identification, evolution and expression analyses of the whole genome-wide PEBP gene family in Brassica napus L

BACKGROUND

With the release of genomic data for B.rapa, B.oleracea, and B.napus, research on the genetic and molecular functions of Brassica spp. has entered a new stage. PEBP genes in plants play an important role in the transition to flowering as well as seed development and germination. Molecular evolutionary and functional analyses of the PEBP gene family in B.napus based on molecular biology methods can provide a theoretical basis for subsequent investigations of related regulators.

RESULTS

In this paper, we identified a total of 29 PEBP genes from B.napus that were located on 14 chromosomes and 3 random locations. Most members contained 4 exons and 3 introns; motif 1 and motif 2 were the characteristic motifs of PEBP members. On the basis of intraspecific and interspecific collinearity analyses, it is speculated that fragment replication and genomic replication are the main drivers of for the amplification and evolution of the PEBP gene in the B.napus genome. The results of promoter cis-elements prediction suggest that BnPEBP family genes are inducible promoters, which may directly or indirectly participate in multiple regulatory pathways of plant growth cycle. Furthermore, the tissue-specific expression results show that the expression levels of BnPEBP family genes in different tissues were quite different, but the gene expression organization and patterns of the same subgroup were basically the same. qRT‒PCR revealed certain spatiotemporal patterns in the expression of the PEBP subgroups in roots, stems, leaves, buds, and siliques, was tissue-specific, and related to function.

CONCLUSIONS

A systematic comparative analysis of the B.napus PEBP gene family was carried out at here. The results of gene identification, phylogenetic tree construction, structural analysis, gene duplication analysis, prediction of promoter cis-elements and interacting proteins, and expression analysis provide a reference for exploring the molecular mechanisms of BnPEBP family genes in future research.

Genome-edited TaTFL1-5 mutation decreases tiller and spikelet numbers in common wheat

Tillering is a critical agronomic trait of wheat (Triticum aestivum L.) that determines the shoot architecture and affects grain yield. TERMINAL FLOWER 1 (TFL1), encoding a phosphatidylethanolamine-binding protein, is implicated in the transition to flowering and shoot architecture in plant development. However, the roles of TFL1 homologs is little known in wheat development. CRISPR/Cas9-mediated targeted mutagenesis was used in this study to generate a set of wheat (Fielder) mutants with single, double or triple-null tatfl1-5 alleles. The wheat tatfl1-5 mutations decreased the tiller number per plant in the vegetative growth stage and the effective tiller number per plant and spikelet number per spike at maturity in the field. RNA-seq analysis showed that the expression of the auxin signaling-related and cytokinin signaling-related genes was significantly changed in the axillary buds of tatfl1-5 mutant seedlings. The results suggested that wheat TaTFL1-5s were implicated in tiller regulation by auxin and cytokinin signaling.

Evolution of the PEBP gene family in Juglandaceae and their regulation of flowering pathway under the synergistic effect of JrCO and JrNF-Y proteins

Phosphatidyl ethanolamine-binding protein (PEBP) has a conserved PEBP domain and plays an important role in regulating the flowering time and growth of angiosperms. To understand the evolution of PEBP family genes in walnut family and the mechanism of regulating flowering in photoperiod pathway, 53 genes with PEBP domain were identified from 5 Juglandaceae plants. The PEBP gene family of Juglandaceae can be divided into four subgroups, FT-like, TFL-like, MFT-like and PEBP-like subgroups. These genes all show very high homology for motifs and gene structure in Juglandaceae. In addition, the results of gene replication and collinearity analysis showed that the evolution of PEBP genes was mainly purified and selected, and segmental repetition was the main driving force for the evolution of PEBP gene family in walnut family. We found that PEBP gene family played an important role in female flower bud differentiation, and most JrPEBP genes were highly expressed in leaf bud and female flower bud by qRT-PCR. In Arabidopsis, AtCO can not only directly bind to CORE2, but also interact with NF-Y complex to positively regulate the expression of AtFT gene. In this study, we proved that JrCO (the lineal homologue of AtCO) could not directly regulate the expression of JrFT gene, but could enhance the binding of JrNF-YB4/6 protein to the promoter of JrFT gene by forming a heteropolymer with NF-YB4/NF-YB6. We also confirmed that JrNF-YC1/3/7, JrNF-YB4/6 and JrCO can form a trimer structure similar to AtNF-YB-YC-CO of Arabidopsis, and then bind to the promoter of JrFT gene to promote the transcription of JrFT gene. In a word, through identification and analysis of PEBP gene family in Juglandaceae and study on the mechanism of photoperiod pathway regulating flowering in walnut, we have found that nuclear transcription factor NF-YB/YC plays a more important role in the trimer structure of NF-YB-YC-CO in walnut species. Our study has further perfected the flowering regulatory network of walnut species.

Genome-wide analysis and identification of the PEBP genes of Brassica juncea var. Tumida

Background

Phosphatidylethanolamine-binding protein (PEBP) is widely present in animals, plants, and microorganisms. Plant PEBP genes are mainly involved in flowering transition and nutritional growth. These genes have been studied in several plants; however, to the best of our knowledge, no studies have explored them in Brassica juncea var. tumida. This study identified and characterized the entire PEBP gene family of Brassica juncea var. tumida.

Results

A total of 21 PEBP genes were identified from Brassica juncea var. tumida. Through phylogenetic analysis, the 21 corresponding proteins were classified into the following four clusters: TERMINAL FLOWER 1 (TFL1)-like proteins (n = 8), MOTHER OF FT AND TFL1 (MFT)-like proteins (n = 5), FLOWERING LOCUS T (FT)-like proteins (n = 6), and ybhB-like proteins (n = 2). A total of 18 genes contained four exons and had similar gene structures in each subfamily except BjMFT1, BjPYBHB1, and Arabidopsis thaliana CENTRORADIALIS homolog of Brassica juncea var. tumida (BjATC1). In the analysis of conserved motif composition, the BjPEBP genes exhibited similar characteristics, except for BjFT3, BjMFT1, BjPYBHB1, BjPYBHB2, and BjATC1. The BjPEBP promoter includes multiple cis-acting elements such as the G-box and I-box elements that respond to light, ABRE and GARE-motif elements that respond to hormones, and MBSI and CAT-box elements that are associated with plant growth and development. Analysis of RNA-Seq data revealed that the expression of a few BjPEBP genes may be associated with the development of a tumorous stem. The results of qRT–PCR showed that BjTFL1 and BjPYBHB1 were highly expressed in the flower tissue, BjFT1 and BjATC1 were mainly expressed in the root, and BjMFT4 were highly detected in the stem. The results of yeast two-hybrid screening suggested that BjFT interacts with Bj14-3-3. These results indicate that BjFT is involved in flowering regulation.

Conclusions

To the best of our knowledge, this study is the first to perform a genome-wide analysis of PEBP genes family in Brassica juncea var. tumida. The findings of this study may help improve the yield and molecular breeding of Brassica juncea var. tumida.

Comparative Genomic and Expression Analysis Insight into Evolutionary Characteristics of PEBP Genes in Cultivated Peanuts and Their Roles in Floral Induction

Phosphatidyl ethanolamine-binding proteins (PEBPs) are involved in regulating flowering time and various developmental processes. Functions and expression patterns in cultivated peanuts (Arachis hypogaea L.) remain unknown. In this study, 33 PEBP genes in cultivated peanuts were identified and divided into four subgroups: FT, TFL, MFT and FT-like. Gene structure analysis showed that orthologs from A and B genomes in cultivated peanuts had highly similar structures, but some orthologous genes have subgenomic dominance. Gene collinearity and phylogenetic analysis explain that some PEBP genes play key roles in evolution. Cis-element analysis revealed that PEBP genes are mainly regulated by hormones, light signals and stress-related pathways. Multiple PEPB genes had different expression patterns between early and late-flowering genotypes. Further detection of its response to temperature and photoperiod revealed that PEBPs ArahyM2THPA, ArahyEM6VH3, Arahy4GAQ4U, ArahyIZ8FG5, ArahyG6F3P2, ArahyLUT2QN, ArahyDYRS20 and ArahyBBG51B were the key genes controlling the flowering response to different flowering time genotypes, photoperiods and temperature. This study laid the foundation for the functional study of the PEBP gene in cultivated peanuts and the adaptation of peanuts to different environments.

Genome-Wide Identification and Expression Analysis of the Zinc Finger Protein Gene Subfamilies under Drought Stress in Triticum aestivum

The zinc finger protein (ZFP) family is one of plants’ most diverse family of transcription factors. These proteins with finger-like structural domains have been shown to play a critical role in plant responses to abiotic stresses such as drought. This study aimed to systematically characterize Triticum aestivum ZFPs (TaZFPs) and understand their roles under drought stress. A total of 9 TaC2H2, 38 TaC3HC4, 79 TaCCCH, and 143 TaPHD were identified, which were divided into 4, 7, 12, and 14 distinct subgroups based on their phylogenetic relationships, respectively. Segmental duplication dominated the evolution of four subfamilies and made important contributions to the large-scale amplification of gene families. Syntenic relationships, gene duplications, and Ka/Ks result consistently indicate a potential strong purifying selection on TaZFPs. Additionally, TaZFPs have various abiotic stress-associated cis-acting regulatory elements and have tissue-specific expression patterns showing different responses to drought and heat stress. Therefore, these genes may play multiple functions in plant growth and stress resistance responses. This is the first comprehensive genome-wide analysis of ZFP gene families in T. aestivum to elucidate the basis of their function and resistance mechanisms, providing a reference for precise manipulation of genetic engineering for drought resistance in T. aestivum.

Comparative Transcriptomic Analysis of Root and Leaf Transcript Profiles Reveals the Coordinated Mechanisms in Response to Salinity Stress in Common Vetch

Owing to its strong environmental suitability to adverse abiotic stress conditions, common vetch (Vicia sativa) is grown worldwide for both forage and green manure purposes and is an important protein source for human consumption and livestock feed. The germination of common vetch seeds and growth of seedlings are severely affected by salinity stress, and the response of common vetch to salinity stress at the molecular level is still poorly understood. In this study, we report the first comparative transcriptomic analysis of the leaves and roots of common vetch under salinity stress. A total of 6361 differentially expressed genes were identified in leaves and roots. In the roots, the stress response was dominated by genes involved in peroxidase activity. However, the genes in leaves focused mainly on Ca²⁺ transport. Overexpression of six salinity-inducible transcription factors in yeast further confirmed their biological functions in the salinity stress response. Our study provides the most comprehensive transcriptomic analysis of common vetch leaf and root responses to salinity stress. Our findings broaden the knowledge of the common and distinct intrinsic molecular mechanisms within the leaves and roots of common vetch and could help to develop common vetch cultivars with high salinity tolerance.