Copper deficiency alters shoot architecture and reduces fertility of both gynoecium and androecium in Arabidopsis thaliana

Copper deficiency reduces plant growth, male fertility and seed set. The contribution of copper to female fertility and the underlying molecular aspects of copper deficiency-caused phenotypes are not well-known. We show that among copper deficiency-caused defects in Arabidopsis thaliana were the increased shoot branching, delayed flowering and senescence, and entirely abolished gynoecium fertility. The increased shoot branching of copper-deficient plants was rescued by the exogenous application of auxin or copper. The delayed flowering was associated with the decreased expression of the floral activator, FT. Copper deficiency also decreased the expression of senescence-associated genes, WRKY53 and SAG13, but increased the expression of SAG12. The reduced fertility of copper-deficient plants stemmed from multiple factors including the abnormal stigma papillae development, the abolished gynoecium fertility, and the failure of anthers to dehisce. The latter defect was associated with reduced lignification, the upregulation of copper microRNAs and the downregulation of their targets, laccases, implicated in lignin synthesis. Copper-deficient plants accumulated ROS in pollen and had reduced cytochrome c oxidase activity in leaves. This study opens new avenues for the investigation into the relationship between copper homeostasis, hormone-mediated shoot architecture, gynoecium fertility and copper deficiency-derived nutritional signals leading to the delay in flowering and senescence.HighlightCopper deficiency alters shoot architecture, delays flowering and senescence, and compromises fertility by altering stigma morphology, disrupting anther lignification and dehiscence, and pollen redox status in Arabidopsis thaliana.

New circumscription of Cryptanthus and new Cryptanthoid genera and subgenera (Bromeliaceae: Bromelioideae) based on neglected morphological traits and molecular phylogeny

The authors provide a new circumscription for genera of the “Cryptanthoid complex” of Bromeliaceae subfam. Bromelioideae, originally composed of Cryptanthus, Lapanthus, Orthophytum, and Sincoraea, on the basis of new or re-evaluated ecological, geographical and morphological evidence, as well as molecular phylogenies. A new generic status is proposed for Cryptanthus subg. Hoplocryptanthus and two new genera, Forzzaea, and Rokautskyia, as well as four new subgenera in Orthophytum (Capixabanthus, Clavanthus, Krenakanthus, and Orthocryptanthus) are described to render taxonomic units monophyletic. The recognized taxa are well circumscribed by the combination of geographical range, ecology and morphological characters (sex distribution, leaf succulence, sepal and petal size and connation, petal appendages, pollen and stigma morphology, fruit size, calyx persistency, seed size and number per fruit). Field collected living specimens of 78 of the 81 species of Cryptanthus s.l., all species of Lapanthus, 58 of the 59 species of Orthophytum, and all species of Sincoraea were analysed in habitat and/or in cultivation, allowing the documentation and illustration of new and underutilized characters. The molecular analysis incorporated 91 accessions representing 33 species of Cryptanthus, all species (3) of Lapanthus, 42 species of Orthophytum, and 9 species of Sincoraea, including the type species for the first three genera and four outgroup taxa. The results suggest, that some morphological characters generally considered homoplasious for Bromelioideae, for the “Cryptanthoid complex”, are not homoplasious at least within the obtained, biogeographycally well delimited clades and their taxonomical utility is redeemed.

Taxonomic revision of Bromeliaceae subfam. Tillandsioideae based on a multi-locus DNA sequence phylogeny and morphology

A taxonomic revision of Bromeliaceae subfam. Tillandsioideae is presented based on a multi-locus DNA sequence phylogeny (viz., plastid DNA loci rpoB-trnC-petN, trnK-matK-trnK, and ycf1, and the nuclear DNA gene PHYC) and new or re-evaluated morphology (e.g., leaf, inflorescence, sepal, petal, ovary, stigma, stamen, pollen, ovule, and seed morphology). This enables the circumscription of monophyletic units using synapomorphic combinations of diagnostic morphological characters. Stigma morphology has proven to be indicative for super-specific taxa in Tillandsioideae. One new stigma type and several subtypes of previously described stigmas were found. The four tribes proposed earlier are mostly confirmed, but Catopsideae replaces the formerly used name Pogospermeae for the monotypic tribe of Catopsis. In addition, the two new subtribes Cipuropsidinae and Vrieseinae are proposed within tribe Vrieseeae. Several new genera are established to render taxonomic units monophyletic and morphologically well circumscribed. They represent segregates of either Mezobromelia (Gregbrownia: 4 spp.), Tillandsia (viz., Barfussia: 3 spp., Josemania: 5 spp., Lemeltonia: 7 spp., Pseudalcantarea: 3 spp., and Wallisia: 4 spp. and 1 hybrid), or Vriesea (viz., Goudaea: 2 spp., Jagrantia: 1 sp., Lutheria: 4 spp., Stigmatodon: 18 spp., and Zizkaea: 1 spp.). The new subgenera Tillandsia subg. Pseudovriesea and T. subg. Viridantha are established, and T. subg. Aerobia is resurrected. An identification key to all accepted genera of Bromeliaceae subfam. Tillandsioideae is provided. Furthermore, to clarify nomenclatural uncertainties, typifications are proposed for Catopsis subg. Tridynandra, Thecophyllum [unranked] Biflorae, Tillandsia subg. Aerobia, T. sect. Caricifoliae, T. sect. Conostachys, T. sect. Cyathophora, T. sect. Eriophyllum, T. sect. Macrocyathus, T. sect. Platystachys Baker auct. non al., Tillandsia sect. Strepsia, Vriesea subg. Conostachys Mez auct. non al., T. lindenii K. Koch auct. non al., and T. macropetala.

Taxonomic novelties in Jacquemontia Choisy (Convolvulaceae) from Southeastern Brazil

Two additional species are recognised in Jacquemontia. The new combination Jacquemontia frankeana is proposed, based on Convolvulus frankeanus, since this species is clearly referable to Jacquemontia rather than Convolvulus based on its stigma morphology and possession of stellate hairs. It is distinguished from closely related species of Jacquemontia by the glabrescent leaves, the stellate adpressed hairs with 4–5-rays, and the two outer sepals being smaller than the inner. Jacquemontia glabrescens is also recognized at specific rank, based on Jacquemontia grandiflora var. glabrescens. It is distinguished from the morphologically similar J. ferruginea and J. cataractae by a combination of glabrescent leaves, bigger flowers, rhombic to ovate outer sepals and glabrous to glabrescent. Synonymy of these taxa and typification are also addressed.

Floral morphology and pollination system in the native Australian perennial pasture legume Cullen australasicum (syn. Psoralea australasica)

Cullen australasicum (syn. Psoralea australasica) is a native perennial legume with potential in the low-rainfall wheatbelt of southern Australia. The objective of this study was to investigate the reproductive biology of C. australasicum utilising five accessions. Glasshouse and field pollination experiments were conducted in Adelaide, South Australia. Floral morphology, stigma receptivity and pollen : ovule ratios were determined. Pollen tube growth and stigma morphology were examined using fluorescence and scanning electron microscopes. Glasshouse pollination studies indicated that four of the accessions showed the need for an external tripping agent to bring about pollination and that hand-tripping was the most efficient method. A scanning electron microscopy study revealed there are two types of stigmas in this species. Stigma receptivity was significantly lower at the early bud stage before anther dehiscence. The results show that C. australasicum is a self-compatible species comprising accessions with a wide range of outcrossing potential.