1,720,995 research outputs found
Can We Use Gene-Editing to Induce Apomixis in Sexual Plants?
No full textApomixis, the asexual formation of seeds, is a potentially valuable agricultural trait. Inducing apomixis in sexual crop plants would, for example, allow breeders to fix heterosis in hybrid seeds and rapidly generate doubled haploid crop lines. Molecular models explain the emergence of functional apomixis, i.e., apomeiosis + parthenogenesis + endosperm development, as resulting from a combination of genetic or epigenetic changes that coordinate altered molecular and developmental steps to form clonal seeds. Apomixis-like features and synthetic clonal seeds have been induced with limited success in the sexual plants rice and maize by using gene editing to mutate genes related to meiosis and fertility or via egg-cell specific expression of embryogenesis genes. Inducing functional apomixis and increasing the penetrance of apomictic seed production will be important for commercial deployment of the trait. Optimizing the induction of apomixis with gene editing strategies that use known targets as well as identifying alternative targets will be possible by better understanding natural genetic variation in apomictic species. With the growing availability of genomic data and precise gene editing tools, we are making substantial progress towards engineering apomictic crops
Towards a monophyletic classification of Lejeuneaceae I: subtribe Leptolejeuneinae subtr. nov.
No full textHeinrichs, Jochen, Schäfer-Verwimp, Alfons, Czumay, Aleksandra, Dong, Shanshan, Scheben, Armin, Feldberg, Kathrin, Schneider, Harald (2014): Towards a monophyletic classification of Lejeuneaceae I: subtribe Leptolejeuneinae subtr. nov. Phytotaxa 156 (3): 165-174, DOI: 10.11646/phytotaxa.165.3.7, URL: https://www.mendeley.com/catalogue/fe4b753c-f465-3c61-b0c4-73bfd724cded
FIGURE 1 in Towards a monophyletic classification of Lejeuneaceae I: subtribe Leptolejeuneinae subtr. nov.
No full textFIGURE 1. Strict consensus of 81 equally parsimonious trees based on the combined nrITS- chloroplast DNA rbcL – trnL-trnF dataset with bootstrap percentage values ≥ 50 % at branches.Published as part of Heinrichs, Jochen, Schäfer-Verwimp, Alfons, Czumay, Aleksandra, Dong, Shanshan, Scheben, Armin, Feldberg, Kathrin & Schneider, Harald, 2014, Towards a monophyletic classification of Lejeuneaceae I: subtribe Leptolejeuneinae subtr. nov., pp. 165-174 in Phytotaxa 156 (3) on page 167, DOI: 10.11646/phytotaxa.165.3.7, http://zenodo.org/record/512787
Transfer of Lejeunea huctumalcensis to Physantholejeunea (Lejeuneaceae, Porellales)
No full textPhylogenetic analyses of a three-marker dataset of Lejeuneaceae (chloroplast genome rbcL gene and trnL-trnF region, and nuclear ribosomal ITS1-5.8S-ITS2 region) resolve Lejeunea huctumalcensis (synonym Ceratolejeunea dussiana) in a well supported lineage with Physantholejeunea portoricensis. Representatives of Lejeunea and Ceratolejeunea form independent lineages. Physantholejeunea and L. huctumalcensis share the presence of ocelli, pycnolejeuneoid innovations and keeled perianths, with keels forming horn-like projections. On the basis of the molecular phylogenetic and morphological evidence, we transfer L. huctumalcensis to Physantholejeunea
Towards a monophyletic classification of Lejeuneaceae I: subtribe Leptolejeuneinae subtr. nov.
No full textWe employed sequences of two chloroplast regions (trnL-trnF, rbcL) and the nuclear ribosomal ITS region of seven accessions of Leptolejeunea to explore its phylogenetic position. Maximum parsimony and maximum likelihood analyses led to similar topologies but deeper nodes received good bootstrap support only with maximum likelihood methods. Leptolejeunea formed an early diverging, robust monophyletic lineage within Lejeuneaceae tribe Lejeuneeae. Contrary to earlier belief, it is not closely related to Drepanolejeunea. To amend the current classification of Lejeuneeae into subtribes, we propose Leptolejeuneinae, subtr. nov
Integrative taxonomy of Lepidolejeunea (Jungermanniopsida: Porellales): Ocelli allow the recognition of two neglected species
No full textLepidolejeunea is a largely epiphytic, pantropical genus of leafy liverworts. While the phylogenetic position of Lepidolejeunea has been the subject of recent molecular investigations, the relationships within this genus have been little studied. We employed sequences of two chloroplast regions (trnL-trnF, rbcL) and the nuclear ribosomal ITS region from 32 accessions of Lepidolejeunea to reconstruct its phylogeny. Two accessions of Rectolejeunea were used as outgroup. Maximum parsimony and likelihood analyses indicate that the diversity of Lepidolejeunea is underestimated by current morphological classification, and that Lepidolejeunea involuta consists of two independent entities, Lepidolejeunea involuta s.str. and Lepidolejeunea cuspidata comb.nov. Despite being treated as synonymous in earlier studies, both species nest in different main clades of Lepidolejeunea. Lepidolejeunea involuta belongs to L. subg. Kingiolejeunea which includes species with ocelli of the same size as the surrounding leaf cells. Lepidolejeunea cuspidata instead belongs to the recircumscribed L. subg. Perilejeunea which includes species having ocelli of at least partly smaller size than the surrounding leaf cells. Lepidolejeunea auriculata is introduced as a new species based on molecular and morphological evidence. Our results highlight the need for integrative taxonomic studies to clarify the status of many binomials within Lejeuneaceae. They also suggest that as integrative approaches are applied across liverworts estimates of global diversity will be revised upwards.German Research Foundation [HE 3584/2, HE 3584/4
Integrative taxonomy of Lepidolejeunea (Jungermanniopsida: Porellales): Ocelli allow the recognition of two neglected species
No full textLepidolejeunea is a largely epiphytic, pantropical genus of leafy liverworts. While the phylogenetic position of Lepidolejeunea has been the subject of recent molecular investigations, the relationships within this genus have been little studied. We employed sequences of two chloroplast regions (trnL-trnF, rbcL) and the nuclear ribosomal ITS region from 32 accessions of Lepidolejeunea to reconstruct its phylogeny. Two accessions of Rectolejeunea were used as outgroup. Maximum parsimony and likelihood analyses indicate that the diversity of Lepidolejeunea is underestimated by current morphological classification, and that Lepidolejeunea involuta consists of two independent entities, Lepidolejeunea involuta s.str. and Lepidolejeunea cuspidata comb.nov. Despite being treated as synonymous in earlier studies, both species nest in different main clades of Lepidolejeunea. Lepidolejeunea involuta belongs to L. subg. Kingiolejeunea which includes species with ocelli of the same size as the surrounding leaf cells. Lepidolejeunea cuspidata instead belongs to the recircumscribed L. subg. Perilejeunea which includes species having ocelli of at least partly smaller size than the surrounding leaf cells. Lepidolejeunea auriculata is introduced as a new species based on molecular and morphological evidence. Our results highlight the need for integrative taxonomic studies to clarify the status of many binomials within Lejeuneaceae. They also suggest that as integrative approaches are applied across liverworts estimates of global diversity will be revised upwards.German Research Foundation [HE 3584/2, HE 3584/4
ITS polymorphisms shed light on hybrid evolution in apomictic plants: a case study on the Ranunculus auricomus complex.
No full textThe reconstruction of reticulate evolutionary histories in plants is still a major methodological challenge. Sequences of the ITS nrDNA are a popular marker to analyze hybrid relationships, but variation of this multicopy spacer region is affected by concerted evolution, high intraindividual polymorphism, and shifts in mode of reproduction. The relevance of changes in secondary structure is still under dispute. We aim to shed light on the extent of polymorphism within and between sexual species and their putative natural as well as synthetic hybrid derivatives in the Ranunculus auricomus complex to test morphology-based hypotheses of hybrid origin and parentage of taxa. We employed direct sequencing of ITS nrDNA from 68 individuals representing three sexuals, their synthetic hybrids and one sympatric natural apomict, as well as cloning of ITS copies in four representative individuals, RNA secondary structure analysis, and landmark geometric morphometric analysis on leaves. Phylogenetic network analyses indicate additivity of parental ITS variants in both synthetic and natural hybrids. The triploid synthetic hybrids are genetically much closer to their maternal progenitors, probably due to ploidy dosage effects, although exhibiting a paternal-like leaf morphology. The natural hybrids are genetically and morphologically closer to the putative paternal progenitor species. Secondary structures of ITS1-5.8S-ITS2 were rather conserved in all taxa. The observed similarities in ITS polymorphisms suggest that the natural apomict R. variabilis is an ancient hybrid of the diploid sexual species R. notabilis and the sexual species R. cassubicifolius. The additivity pattern shared by R. variabilis and the synthetic hybrids supports an evolutionary and biogeographical scenario that R. variabilis originated from ancient hybridization. Concerted evolution of ITS copies in R. variabilis is incomplete, probably due to a shift to asexual reproduction. Under the condition of comprehensive inter- and intraspecific sampling, ITS polymorphisms are powerful for elucidating reticulate evolutionary histories
The first ptychanthoid Lejeuneaceae in Miocene Mexican amber
Full text linkTwo inclusions of leafy liverworts in Miocene Mexican amber are tentatively assigned to the extant genus Mastigolejeunea (Lejeuneaceae subfam. Ptychanthoideae). Both specimens share complicate bilobed leaves with a rounded lobe apex, a lobule with an oblique free margin continuing into the ventral margin of the leaf lobe, elongated leaf cells, a broad ventral merophyte, and undivided underleaves with a truncate to slightly emarginated, recurved apex. The lack of generative structures prevents a more thorough taxonomic treatment. Nevertheless, the inclusions represent the first ptychanthoid Lejeuneaceae from Mexican amber
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