Zhen Li

Zhen Li — Postdoc
Joined the group in 2012

As a bioinformatician with a great passion for evolution, I would like to understand the mechanisms of evolution as well as apply the knowledge to solve practical issues when applicable. My passion for evolution has eventually landed on two primary research interests. The first is to discover how different plants have evolved and contributed to the extraordinary diversity of life on Earth by exploring novel plant genomes. I have joined several plant genome projects with different functional roles since my master's study. Such experience helped me develop various skills in annotating genomes and analyzing sequencing data. Also, these international genome projects urged me of the importance of communication in modern science and trained my scientific communication skills.

My other research interest is about polyploidy. Surprisingly, genomes of many, if not all, flowering plants illustrate the history of ancient polyploidization in their common ancestors. Therefore, understanding the effects and processes of polyploidization is essential to unveil its impacts on creating evolutionary novelties and increasing species adaptation. In a previous work, we used comparative genomics and phylogenomics to study the different fates of duplicated genes after genome duplication by integrating large omics datasets. We identified genes that are tolerant or intolerant to gene and genome duplications in flowering plants by comparing 37 angiosperm genomes. To further understand the underlying molecular mechanisms following polyploidization, natural and synthesized polyploids contain valuable information about both gene expression and natural selection on duplicated genes. Therefore, integrating the knowledge of gene duplicability and data from natural and synthesized polyploids is an innovative approach to investigate gene duplicate retention following polyploidization systematically.

May 2018 - present: Postdoctoral researcher, Bioinformatics & Evolutionary Genomics, Department of Plant Systems Biology, VIB, Gent, Belgium.
September 2012 - April 2018: PhD student, Bioinformatics & Evolutionary Genomics, Department of Plant Systems Biology, VIB, Gent, Belgium.
September 2008 - June 2011: Master of Science in Bioinformatics, Laboratory of Computational Molecular Biology, College of Life Sciences, Beijing Normal University
September 2004 - June 2008: Bachelor of Science in Biology, College of Life Sciences, Beijing Normal University

Publications

  1. Chen, Y.-C., Li, Z., Zhao, Y.-X., Gao, M., Wang, J.-Y., Liu, K.-W., … Wang, Y.-D. (2020). The Litsea genome and the evolution of the laurel family. NATURE COMMUNICATIONS, 11.
    The laurel family within the Magnoliids has attracted attentions owing to its scents, variable inflorescences, and controversial phylogenetic position. Here, we present a chromosome-level assembly of the Litsea cubeba genome, together with low-coverage genomic and transcriptomic data for many other Lauraceae. Phylogenomic analyses show phylogenetic discordance at the position of Magnoliids, suggesting incomplete lineage sorting during the divergence of monocots, eudicots, and Magnoliids. An ancient whole-genome duplication (WGD) event occurred just before the divergence of Laurales and Magnoliales; subsequently, independent WGDs occurred almost simultaneously in the three Lauralean lineages. The phylogenetic relationships within Lauraceae correspond to the divergence of inflorescences, as evidenced by the phylogeny of FUWA, a conserved gene involved in determining panicle architecture in Lauraceae. Monoterpene synthases responsible for production of specific volatile compounds in Lauraceae are functionally verified. Our work sheds light on the evolution of the Lauraceae, the genetic basis for floral evolution and specific scents.
  2. Pu, X., Li, Z., Tian, Y., Gao, R., Hao, L., Hu, Y., … Song, J. (2020). The honeysuckle genome provides insight into the molecular mechanism of carotenoid metabolism underlying dynamic flower coloration. NEW PHYTOLOGIST, 227(3), 930–943. https://doi.org/10.1111/nph.16552
    Lonicera japonica is a wide-spread member of the Caprifoliaceae (honeysuckle) family utilized in traditional medical practices. This twining vine honeysuckle is also a much-sought ornamental, in part due to its dynamic flower coloration, which changes from white to gold during development. The molecular mechanism underlying dynamic flower coloration in L. japonica was elucidated by integrating whole genome sequencing, transcriptomic analysis, and biochemical assays. Here, we report a chromosome-level genome assembly of L. japonica, comprising nine pseudo-chromosomes with a total size of 843.2 Mb. We also provide evidence for a whole genome duplication event in the lineage leading to L. japonica, which occurred after its divergence from Dipsacales and Asterales. Moreover, gene expression analysis not only revealed correlated expression of the relevant biosynthetic genes with carotenoid accumulation, but also suggested a role for carotenoid degradation in L. japonica's dynamic flower coloration. The variation of flower color is consistent with not only the observed carotenoid accumulation pattern, but also with the release of volatile apocarotenoids that presumably serve as pollinator attractants. Beyond novel insights into the evolution and dynamics of flower coloration, the high-quality L. japonica genome sequence also provides a foundation for molecular breeding to improve desired characteristics.
  3. Li, L., Wang, S., Wang, H., Sahu, S. K., Marin, B., Li, H., … Liu, H. (2020). The genome of Prasinoderma coloniale unveils the existence of a third phylum within green plants. NATURE ECOLOGY & EVOLUTION. https://doi.org/10.1038/s41559-020-1221-7
    Genome analysis of the pico-eukaryotic marine green algaPrasinoderma colonialeCCMP 1413 unveils the existence of a novel phylum within green plants (Viridiplantae), the Prasinodermophyta, which diverged before the split of Chlorophyta and Streptophyta. Structural features of the genome and gene family comparisons revealed an intermediate position of theP. colonialegenome (25.3 Mb) between the extremely compact, small genomes of picoplanktonic Mamiellophyceae (Chlorophyta) and the larger, more complex genomes of early-diverging streptophyte algae. Reconstruction of the minimal core genome of Viridiplantae allowed identification of an ancestral toolkit of transcription factors and flagellar proteins. Adaptations ofP. colonialeto its deep-water, oligotrophic environment involved expansion of light-harvesting proteins, reduction of early light-induced proteins, evolution of a distinct type of C(4)photosynthesis and carbon-concentrating mechanism, synthesis of the metal-complexing metabolite picolinic acid, and vitamin B-1, B(7)and B(12)auxotrophy. TheP. colonialegenome provides first insights into the dawn of green plant evolution. Genome analysis of the pico-eukaryotic marine green algaPrasinoderma colonialeCCMP 1413 unveils the existence of a novel phylum within green plants (Viridiplantae), the Prasinodermophyta, which diverged before the split of Chlorophyta and Streptophyta.
  4. Zhang, L., Chen, F., Zhang, X., Li, Z., Zhao, Y., Lohaus, R., … Tang, H. (2020). The water lily genome and the early evolution of flowering plants. NATURE, 577(7788), 79–84.
    Water lilies belong to the angiosperm order Nymphaeales. Amborellales, Nymphaeales and Austrobaileyales together form the so-called ANA-grade of angiosperms, which are extant representatives of lineages that diverged the earliest from the lineage leading to the extant mesangiosperms1,2,3. Here we report the 409-megabase genome sequence of the blue-petal water lily (Nymphaea colorata). Our phylogenomic analyses support Amborellales and Nymphaeales as successive sister lineages to all other extant angiosperms. The N. colorata genome and 19 other water lily transcriptomes reveal a Nymphaealean whole-genome duplication event, which is shared by Nymphaeaceae and possibly Cabombaceae. Among the genes retained from this whole-genome duplication are homologues of genes that regulate flowering transition and flower development. The broad expression of homologues of floral ABCE genes in N. colorata might support a similarly broadly active ancestral ABCE model of floral organ determination in early angiosperms. Water lilies have evolved attractive floral scents and colours, which are features shared with mesangiosperms, and we identified their putative biosynthetic genes in N. colorata. The chemical compounds and biosynthetic genes behind floral scents suggest that they have evolved in parallel to those in mesangiosperms. Because of its unique phylogenetic position, the N. colorata genome sheds light on the early evolution of angiosperms.
  5. Li, Z., & Van de Peer, Y. (2020). ’Winter is coming’ : how did polyploid plants survive? MOLECULAR PLANT, 13(1), 4–5.
  6. Verlinden, H., Sterck, L., Li, J., Li, Z., Yssel, A., Gansemans, Y., … Vanden Broeck, J. (2020). First draft genome assembly of the desert locust, Schistocerca gregaria. F1000Research, 9. https://doi.org/10.12688/f1000research.25148.1
    Background: At the time of publication, the most devastating desert locust crisis in decades is affecting East Africa, the Arabian Peninsula and South-West Asia. The situation is extremely alarming in East Africa, where Kenya, Ethiopia and Somalia face an unprecedented threat to food security and livelihoods. Most of the time, however, locusts do not occur in swarms, but live as relatively harmless solitary insects. The phenotypically distinct solitarious and gregarious locust phases differ markedly in many aspects of behaviour, physiology and morphology, making them an excellent model to study how environmental factors shape behaviour and development. A better understanding of the extreme phenotypic plasticity in desert locusts will offer new, more environmentally sustainable ways of fighting devastating swarms. Methods: High molecular weight DNA derived from two adult males was used for Mate Pair and Paired End Illumina sequencing and PacBio sequencing. A reliable reference genome of Schistocerca gregaria was assembled using the ABySS pipeline, scaffolding was improved using LINKS. Results: In total, 1,316 Gb Illumina reads and 112 Gb PacBio reads were produced and assembled. The resulting draft genome consists of 8,817,834,205 bp organised in 955,015 scaffolds with an N50 of 157,705 bp, making the desert locust genome the largest insect genome sequenced and assembled to date. In total, 18,815 protein-encoding genes are predicted in the desert locust genome, of which 13,646 (72.53%) obtained at least one functional assignment based on similarity to known proteins. Conclusions: The desert locust genome data will contribute greatly to studies of phenotypic plasticity, physiology, neurobiology, molecular ecology, evolutionary genetics and comparative genomics, and will promote the desert locust’s use as a model system. The data will also facilitate the development of novel, more sustainable strategies for preventing or combating swarms of these infamous insects.
  7. Zwaenepoel, A., Li, Z., Lohaus, R., & Van de Peer, Y. (2019). Finding evidence for whole genome duplications : a reappraisal. MOLECULAR PLANT, 12(2), 133–136.
  8. Roodt, D., Li, Z., Van de Peer, Y., & Mizrachi, E. (2019). Loss of wood formation genes in monocot genomes. GENOME BIOLOGY AND EVOLUTION, 11(7), 1986–1996.
    Woodiness (secondary xylem derived from vascular cambium) has been gained and lost multiple times in the angiosperms, but has been lost ancestrally in all monocots. Here, we investigate the conservation of genes involved in xylogenesis in fully sequenced angiosperm genomes, hypothesising that monocots have lost some essential orthologs involved in this process. We analysed the conservation of genes preferentially expressed in the developing secondary xylem of two eudicot trees in the sequenced genomes of 26 eudicot and seven monocot species, and the early-diverging angiosperm Amborella trichopoda. We also reconstructed a regulatory model of early vascular cambial cell identity and differentiation and investigated the conservation of orthologs across the angiosperms. Additionally, we analysed the genome of the aquatic seagrass Zostera marina for additional losses of genes otherwise essential to, especially, secondary cell wall formation. Despite almost complete conservation of orthology within the early cambial differentiation gene network, we show a clear pattern of loss of genes preferentially expressed in secondary xylem in the monocots that are highly conserved across eudicot species. Our study provides candidate genes that may have led to the loss of vascular cambium in the monocots, and, by comparing terrestrial angiosperms to an aquatic monocot, highlights genes essential to vasculature on land.
  9. Li, Zhen. (2018). The study of plant genome evolution by means of phylogenomics. Ghent University. Faculty of Sciences, Ghent, Belgium.
  10. Wan, T., Liu, Z.-M., Li, L.-F., Leitch, A. R., Leitch, I. J., Lohaus, R., Liu, Z.-J., et al. (2018). A genome for gnetophytes and early evolution of seed plants. NATURE PLANTS, 4(2), 82–89.
    Gnetophytes are an enigmatic gymnosperm lineage comprising three genera, Gnetum, Welwitschia and Ephedra, which are morphologically distinct from all other seed plants. Their distinctiveness has triggered much debate as to their origin, evolution and phylogenetic placement among seed plants. To increase our understanding of the evolution of gnetophytes, and their relation to other seed plants, we report here a high-quality draft genome sequence for Gnetum montanum, the first for any gnetophyte. By using a novel genome assembly strategy to deal with high levels of heterozygosity, we assembled >4 Gb of sequence encoding 27,491 protein-coding genes. Comparative analysis of the G. montanum genome with other gymnosperm genomes unveiled some remarkable and distinctive genomic features, such as a diverse assemblage of retrotransposons with evidence for elevated frequencies of elimination rather than accumulation, considerable differences in intron architecture, including both length distribution and proportions of (retro) transposon elements, and distinctive patterns of proliferation of functional protein domains. Furthermore, a few gene families showed Gnetum-specific copy number expansions (for example, cellulose synthase) or contractions (for example, Late Embryogenesis Abundant protein), which could be connected with Gnetum's distinctive morphological innovations associated with their adaptation to warm, mesic environments. Overall, the G. montanum genome enables a better resolution of ancestral genomic features within seed plants, and the identification of genomic characters that distinguish Gnetum from other gymnosperms.
  11. De La Torre, A. R., Li, Z., Van de Peer, Y., & Ingvarsson, P. K. (2017). Contrasting rates of molecular evolution and patterns of selection among gymnosperms and flowering plants. MOLECULAR BIOLOGY AND EVOLUTION, 34(6), 1363–1377.
    The majority of variation in rates of molecular evolution among seed plants remains both unexplored and unexplained. Although some attention has been given to flowering plants, reports of molecular evolutionary rates for their sister plant clade (gymnosperms) are scarce, and to our knowledge differences in molecular evolution among seed plant clades have never been tested in a phylogenetic framework. Angiosperms and gymnosperms differ in a number of features, of which contrasting reproductive biology, life spans, and population sizes are the most prominent. The highly conserved morphology of gymnosperms evidenced by similarity of extant species to fossil records and the high levels of macrosynteny at the genomic level have led scientists to believe that gymnosperms are slow-evolving plants, although some studies have offered contradictory results. Here, we used 31,968 nucleotide sites obtained from orthologous genes across a wide taxonomic sampling that includes representatives of most conifers, cycads, ginkgo, and many angiosperms with a sequenced genome. Our results suggest that angiosperms and gymnosperms differ considerably in their rates of molecular evolution per unit time, with gymnosperm rates being, on average, seven times lower than angiosperm species. Longer generation times and larger genome sizes are some of the factors explaining the slow rates of molecular evolution found in gymnosperms. In contrast to their slow rates of molecular evolution, gymnosperms possess higher substitution rate ratios than angiosperm taxa. Finally, our study suggests stronger and more efficient purifying and diversifying selection in gymnosperm than in angiosperm species, probably in relation to larger effective population sizes.
  12. Causier, B., Li, Z., De Smet, R., Lloyd, J. P., Van de Peer, Y., & Davies, B. (2017). Conservation of nonsense-mediated mRNA decay complex components throughout eukaryotic evolution. SCIENTIFIC REPORTS, 7.
    Nonsense-mediated mRNA decay (NMD) is an essential eukaryotic process regulating transcript quality and abundance, and is involved in diverse processes including brain development and plant defenses. Although some of the NMD machinery is conserved between kingdoms, little is known about its evolution. Phosphorylation of the core NMD component UPF1 is critical for NMD and is regulated in mammals by the SURF complex (UPF1, SMG1 kinase, SMG8, SMG9 and eukaryotic release factors). However, since SMG1 is reportedly missing from the genomes of fungi and the plant Arabidopsis thaliana, it remains unclear how UPF1 is activated outside the metazoa. We used comparative genomics to determine the conservation of the NMD pathway across eukaryotic evolution. We show that SURF components are present in all major eukaryotic lineages, including fungi, suggesting that in addition to UPF1 and SMG1, SMG8 and SMG9 also existed in the last eukaryotic common ancestor, 1.8 billion years ago. However, despite the ancient origins of the SURF complex, we also found that SURF factors have been independently lost across the Eukarya, pointing to genetic buffering within the essential NMD pathway. We infer an ancient role for SURF in regulating UPF1, and the intriguing possibility of undiscovered NMD regulatory pathways.
  13. Tasdighian, S., Van Bel, M., Li, Z., Van de Peer, Y., Carretero-Paulet, L., & Maere, S. (2017). Reciprocally retained genes in the angiosperm lineage show the hallmarks of dosage balance sensitivity. PLANT CELL, 29(11), 2766–2785.
    In several organisms, particular functional categories of genes, such as regulatory and complex-forming genes, are preferentially retained after whole-genome multiplications but rarely duplicate through small-scale duplication, a pattern referred to as reciprocal retention. This peculiar duplication behavior is hypothesized to stem from constraints on the dosage balance between the genes concerned and their interaction context. However, the evidence for a relationship between reciprocal retention and dosage balance sensitivity remains fragmentary. Here, we identified which gene families are most strongly reciprocally retained in the angiosperm lineage and studied their functional and evolutionary characteristics. Reciprocally retained gene families exhibit stronger sequence divergence constraints and lower rates of functional and expression divergence than other gene families, suggesting that dosage balance sensitivity is a general characteristic of reciprocally retained genes. Gene families functioning in regulatory and signaling processes are much more strongly represented at the top of the reciprocal retention ranking than those functioning in multiprotein complexes, suggesting that regulatory imbalances may lead to stronger fitness effects than classical stoichiometric protein complex imbalances. Finally, reciprocally retained duplicates are often subject to dosage balance constraints for prolonged evolutionary times, which may have repercussions for the ease with which genome multiplications can engender evolutionary innovation.
  14. Cañas, R. A., Li, Z., Pascual, M. B., Castro-Rodríguez, V., Ávila, C., Sterck, L., Van de Peer, Y., et al. (2017). The gene expression landscape of pine seedling tissues. PLANT JOURNAL, 91(6), 1064–1087.
    Conifers dominate vast regions of the Northern hemisphere. They are the main source of raw materials for timber industry as well as a wide range of biomaterials. Despite their inherent difficulties as experimental models for classical plant biology research, the technological advances in genomics research are enabling fundamental studies on these plants. The use of laser capture microdissection followed by transcriptomic analysis is a powerful tool for unravelling the molecular and functional organization of conifer tissues and specialized cells. In the present work, 14 different tissues from 1-month-old maritime pine (Pinus pinaster) seedlings have been isolated and their transcriptomes analysed. The results increased the sequence information and number of full-length transcripts from a previous reference transcriptome and added 39 841 new transcripts. In total, 2376 transcripts were ubiquitously expressed in all of the examined tissues. These transcripts could be considered the core 'housekeeping genes' in pine. The genes have been clustered in function to their expression profiles. This analysis reduced the number of profiles to 38, most of these defined by their expression in a unique tissue that is much higher than in the other tissues. The expression and localization data are accessible at ConGenIE.org (http://v22.popgenie.org/microdisection/). This study presents an overview of the gene expression distribution in different pine tissues, specifically highlighting the relationships between tissue gene expression and function. This transcriptome atlas is a valuable resource for functional genomics research in conifers.
  15. Zhang, G.-Q., Liu, K.-W., Li, Z., Lohaus, R., Hsiao, Y.-Y., Niu, S.-C., Wang, J.-Y., et al. (2017). The Apostasia genome and the evolution of orchids. NATURE, 549(7672), 379–383.
    Constituting approximately 10% of flowering plant species, orchids (Orchidaceae) display unique flower morphologies, possess an extraordinary diversity in lifestyle, and have successfully colonized almost every habitat on Earth(1-3). Here we report the draft genome sequence of Apostasia shenzhenica(4), a representative of one of two genera that form a sister lineage to the rest of the Orchidaceae, providing a reference for inferring the genome content and structure of the most recent common ancestor of all extant orchids and improving our understanding of their origins and evolution. In addition, we present transcriptome data for representatives of Vanilloideae, Cypripedioideae and Orchidoideae, and novel third-generation genome data for two species of Epidendroideae, covering all five orchid subfamilies. A. shenzhenica shows clear evidence of a whole-genome duplication, which is shared by all orchids and occurred shortly before their divergence. Comparisons between A. shenzhenica and other orchids and angiosperms also permitted the reconstruction of an ancestral orchid gene toolkit. We identify new gene families, gene family expansions and contractions, and changes within MADS-box gene classes, which control a diverse suite of developmental processes, during orchid evolution. This study sheds new light on the genetic mechanisms underpinning key orchid innovations, including the development of the labellum and gynostemium, pollinia, and seeds without endosperm, as well as the evolution of epiphytism; reveals relationships between the Orchidaceae subfamilies; and helps clarify the evolutionary history of orchids within the angiosperms.
  16. Unver, T., Wu, Z., Sterck, L., Turktas, M., Lohaus, R., Li, Z., Yang, M., et al. (2017). Genome of wild olive and the evolution of oil biosynthesis. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 114(44), E9413–E9422.
    Here we present the genome sequence and annotation of the wild olive tree (Olea europaea var. sylvestris), called oleaster, which is considered an ancestor of cultivated olive trees. More than 50,000 protein-coding genes were predicted, a majority of which could be anchored to 23 pseudochromosomes obtained through a newly constructed genetic map. The oleaster genome contains signatures of two Oleaceae lineage-specific paleopolyploidy events, dated at similar to 28 and similar to 59 Mya. These events contributed to the expansion and neo-functionalization of genes and gene families that play important roles in oil biosynthesis. The functional divergence of oil biosynthesis pathway genes, such as FAD2, SACPD, EAR, and ACPTE, following duplication, has been responsible for the differential accumulation of oleic and linoleic acids produced in olive compared with sesame, a closely related oil crop. Duplicated oleaster FAD2 genes are regulated by an siRNA derived from a transposable element-rich region, leading to suppressed levels of FAD2 gene expression. Additionally, neofunctionalization of members of the SACPD gene family has led to increased expression of SACPD2,3, 5, and 7, consequently resulting in an increased desaturation of steric acid. Taken together, decreased FAD2 expression and increased SACPD expression likely explain the accumulation of exceptionally high levels of oleic acid in olive. The oleaster genome thus provides important insights into the evolution of oil biosynthesis and will be a valuable resource for oil crop genomics.
  17. Li, Zhen, De La Torre, A. R., Sterck, L., Cánovas, F. M., Avila, C., Merino, I., Cabezas, J. A., et al. (2017). Single-copy genes as molecular markers for phylogenomic studies in seed plants. GENOME BIOLOGY AND EVOLUTION, 9(5), 1130–1147.
    Phylogenetic relationships among seed plant taxa, especially within the gymnosperms, remain contested. In contrast to angio-sperms, for which several genomic, transcriptomic and phylogenetic resources are available, there are few, if any, molecular markers that allow broad comparisons among gymnosperm species. With few gymnosperm genomes available, recently obtained transcriptomes in gymnosperms are a great addition to identifying single-copy gene families as molecular markers for phylogenomic analysis in seed plants. Taking advantage of an increasing number of available genomes and transcriptomes, we identified single-copy genes in a broad collection of seed plants and used these to infer phylogenetic relationships between major seed plant taxa. This study aims at extending the current phylogenetic toolkit for seed plants, assessing its ability for resolving seed plant phylogeny, and discussing potential factors affecting phylogenetic reconstruction. In total, we identified 3,072 single-copy genes in 31 gymnosperms and 2,156 single-copy genes in 34 angiosperms. All studied seed plants shared 1,469 single-copy genes, which are generally involved in functions like DNA metabolism, cell cycle, and photosynthesis. A selected set of 106 single-copy genes provided good resolution for the seed plant phylogeny except for gnetophytes. Although some of our analyses support a sister relationship between gnetophytes and other gymnosperms, phylogenetic trees from concatenated alignments without 3rd codon positions and amino acid alignments under the CAT + GTR model, support gnetophytes as a sister group to Pinaceae. Our phylogenomic analyses demonstrate that, in general, single-copy genes can uncover both recent and deep divergences of seed plant phylogeny.
  18. De Smet, R., Sabaghian, E., Li, Z., Saeys, Y., & Van de Peer, Y. (2017). Coordinated functional divergence of genes after genome duplication in Arabidopsis thaliana. PLANT CELL, 29(11), 2786–2800.
    Gene and genome duplications have been rampant during the evolution of flowering plants. Unlike small-scale gene duplications, whole-genome duplications (WGDs) copy entire pathways or networks, and as such create the unique situation in which such duplicated pathways or networks could evolve novel functionality through the coordinated sub-or neofunctionalization of its constituent genes. Here, we describe a remarkable case of coordinated gene expression divergence following WGDs in Arabidopsis thaliana. We identified a set of 92 homoeologous gene pairs that all show a similar pattern of tissue-specific gene expression divergence following WGD, with one homoeolog showing predominant expression in aerial tissues and the other homoeolog showing biased expression in tip-growth tissues. We provide evidence that this pattern of gene expression divergence seems to involve genes with a role in cell polarity and that likely function in the maintenance of cell wall integrity. Following WGD, many of these duplicated genes evolved separate functions through subfunctionalization in growth/development and stress response. Uncoupling these processes through genome duplications likely provided important adaptations with respect to growth and morphogenesis and defense against biotic and abiotic stress.
  19. Li, Zhen, Defoort, J., Tasdighian, S., Maere, S., Van de Peer, Y., & De Smet, R. (2016). Gene duplicability of core genes is highly consistent across all angiosperms. PLANT CELL, 28(2), 326–344.
    Gene duplication is an important mechanism for adding to genomic novelty. Hence, which genes undergo duplication and are preserved following duplication is an important question. It has been observed that gene duplicability, or the ability of genes to be retained following duplication, is a nonrandom process, with certain genes being more amenable to survive duplication events than others. Primarily, gene essentiality and the type of duplication (small-scale versus large-scale) have been shown in different species to influence the (long-term) survival of novel genes. However, an overarching view of "gene duplicability" is lacking, mainly due to the fact that previous studies usually focused on individual species and did not account for the influence of genomic context and the time of duplication. Here, we present a large-scale study in which we investigated duplicate retention for 9178 gene families shared between 37 flowering plant species, referred to as angiosperm core gene families. For most gene families, we observe a strikingly consistent pattern of gene duplicability across species, with gene families being either primarily single-copy or multicopy in all species. An intermediate class contains gene families that are often retained in duplicate for periods extending to tens of millions of years after whole-genome duplication, but ultimately appear to be largely restored to singleton status, suggesting that these genes may be dosage balance sensitive. The distinction between single-copy and multicopy gene families is reflected in their functional annotation, with single-copy genes being mainly involved in the maintenance of genome stability and organelle function and multicopy genes in signaling, transport, and metabolism. The intermediate class was overrepresented in regulatory genes, further suggesting that these represent putative dosage-balance-sensitive genes.
  20. Kerchev, P., Waszczak, C., Lewandowska, A., Willems, P., Shapiguzov, A., Li, Z., … Van Breusegem, F. (2016). Lack of GLYCOLATE OXIDASE1, but not GLYCOLATE OXIDASE2, attenuates the photorespiratory phenotype of CATALASE2-deficient Arabidopsis. PLANT PHYSIOLOGY, 171(3), 1704–1719.
    The genes coding for the core metabolic enzymes of the photorespiratory pathway that allows plants with C3-type photosynthesis to survive in an oxygen-rich atmosphere, have been largely discovered in genetic screens aimed to isolate mutants that are unviable under ambient air. As an exception, glycolate oxidase (GOX) mutants with a photorespiratory phenotype have not been described yet in C3 species. Using Arabidopsis (Arabidopsis thaliana) mutants lacking the peroxisomal CATALASE2 (cat2-2) that display stunted growth and cell death lesions under ambient air, we isolated a second-site loss-of-function mutation in GLYCOLATE OXIDASE1 (GOX1) that attenuated the photorespiratory phenotype of cat2-2. Interestingly, knocking out the nearly identical GOX2 in the cat2-2 background did not affect the photorespiratory phenotype, indicating that GOX1 and GOX2 play distinct metabolic roles. We further investigated their individual functions in single gox1-1 and gox2-1 mutants and revealed that their phenotypes can be modulated by environmental conditions that increase the metabolic flux through the photorespiratory pathway. High light negatively affected the photosynthetic performance and growth of both gox1-1 and gox2-1 mutants, but the negative consequences of severe photorespiration were more pronounced in the absence of GOX1, which was accompanied with lesser ability to process glycolate. Taken together, our results point toward divergent functions of the two photorespiratory GOX isoforms in Arabidopsis and contribute to a better understanding of the photorespiratory pathway.

Other publications

  1. Li, Z., Zhang, Z., Yan, P., Huang, S, Fei, Z., & Lin, K. (2011). RNA-Seq improves annotation of protein-coding genes in the cucumber genome. BMC GENOMICS, 12(1), 540.