Apetalous Flowers Research Articles

A MITE insertion abolishes the AP3-3 self-maintenance regulatory loop in apetalous flowers of Nigella damascena.

MADS-box transcription factors are important regulators of floral organ identity through their binding to specific motifs, termed CArG, in the promoter of their target genes. Petal initiation and development depend on class A and B genes, but MADS-box genes of the APETALA3 (AP3) clade are key regulators of this process. In the early diverging eudicot Nigella damascena, an apetalous [T] morph is characterized by the lack of expression of the NdAP3-3 gene, with its expression being petal-specific in the wild-type [P] morph. All [T] morph plants are homozygous for an NdAP3-3 allele with a Miniature Inverted-repeat Transposable Element (MITE) insertion in the second intron of the gene. Here, we investigated to which extent the MITE insertion impairs regulation of the NdAP3-3 gene. We found that expression of NdAP3-3 is initiated in the [T] morph, but the MITE insertion prevents its positive self-maintenance by affecting the correct splicing of the mRNA. We also found specific CArG features in the promoter of the NdAP3-3 genes with petal-specific expression. However, they are not sufficient to drive expression only in petals of transgenic Arabidopsis, highlighting the existence of Nigella-specific cis/trans-acting factors in regulating AP3 paralogs.

Flower morphogenesis and gametophyte fertility attest to the rare condition of gynomonoecy in Parietaria debilis (Urticaceae)

Parietaria debilis G. Forst. is gynomonoecious, which is a rare condition in the Urticaceae family and among angiosperms. Apetalous flowers of two different morph types (monoclinous, pistillate) occur in the same inflorescence and are reduced in size and in the number of whorls and of organs per whorl. The objective of this study was to compare the morphogenesis of monoclinous and pistillate flowers to determine whether the monoclinous flowers produce fertile gametophytes, and elucidate the pathways leading to the absence of stamens and to the changes in number of whorls and organs per whorl. Flower buds and flowers (non-fertilized, fertilized) were processed for surface and anatomical studies. Pollen ultrastructure and viability were determined. Inflorescences with fertilized flowers were checked for the presence and location of fruits/viable seeds. The monoclinous flower has four sepals, four stamens, and a uniovulate pseudomonomerous gynoecium. In the pistillate flower, the stamens are absent or, rarely, aborted. No petals are formed. The gynoecium is pseudomonomerous, originated as a central primordium that differentiates into two carpels, but only one develops and houses an ovule. Monoclinous and pistillate flowers produce viable seeds. Thus, our data confirmed that this species is indeed gynomonoecious.

Taxonomic notes on the New Zealand flora: the status of the extinct herb Stellaria elatinoides (Caryophyllaceae) and recognition of Stellaria multiflora subsp. multiflora from New Zealand

ABSTRACTThe New Zealand endemic and presumed extinct Stellaria elatinoides Hook.f. is shown to be conspecific with the Australian Stellaria multiflora Hook. subsp. multiflora and is treated as a heterotypic synonym. A suite of morphological characters unifies these two taxa, including an annual growth habit, glabrous stems and leaves, sessile leaves, monochasial inflorescences, usually apetalous flowers, short styles and stamens, broadly ellipsoid capsule with valve apices strongly revolute, and the seeds suborbicular and with uniformly-sized prominent tubercles. The biostatus of Stellaria multiflora subsp. multiflora is reviewed and it is treated as indigenous to Australia and New Zealand, and since it was last collected from New Zealand in 1921 its conservation status there is confirmed as extinct.

Prockia jaliscana (Salicaceae), a new species from Jalisco, Mexico

Prockia jaliscana is described and illustrated as a new species from the state of Jalisco, Mexico. This species is similar to P. oaxacana; however, it differs from the latter because it is dioecious, presents linear or lanceolate to foliaceous stipules, has male and female flowers different from those of P. oxacana, apetalous staminate flowers and presents an ovary with ovules in both basal and parietal placentae.

Alectryon vitiensis: A New Species of Sapindaceae Endemic to Fiji

Abstract. A new species of Alectryon Gaertn. (Sapindaceae) endemic to the Fijian archipelago is described as A. vitiensis Buerki, Lowry, Munzinger & Callm. based on morphological and molecular evidence. It can easily be distinguished from the two congeners currently known from Fiji by its smaller leaves, subsessile leaflets, apetalous flowers, and crested fruits. A phylogenetic analysis using ITS sequence data shows that the new species is closely related to two Australian endemics, A. diversifolius (F. Muell.) S. T. Reynolds and A. oleifolius (Desf.) S. T. Reynolds, but differs in having compound leaves covered with a golden indument. Moreover, the Australian taxa are associated with dry habitats, whereas the new species from Fiji is confined to evergreen humid forests. Among apetalous species (all of which belong to a well-supported clade), A. vitiensis morphologically most closely resembles the generic type, A. excelsus Gaertn., endemic to New Zealand, but they differ from one another in the type of in...

Blyxa kasaragodensis,a new species of Hydrocharitaceae from the ponds in the laterite plateau of Malabar coast, Kerala, India

A new aquatic species Blyxa kasaragodensis, collected from the ponds in the lateritc plateau of the Malabar coast, Kerala, India, is described and illustrated. This new species is similar to Blyxa octandra and Blyxa quadricostata in the dioecious nature, elongation of petals at the anthesis and in the number of stamens, but it shows many variations from the similar species such as purplish leaves, submerged male flowers, globular anther lobes, presence of compound pollen grain, large pollen grains, apetalous female flowers and long tail of the seeds. The pollination of Blyxa kasaragodensis takes place with the help of water and the mechanism is new to the genus Blyxa.

LECTOTYPIFICATION OF STEPHANIA PIERREI (MENISPERMACEAE)

Stephania pierrei Diels (Menispermaceae) is a species recorded from the Indo-Chinese Peninsula. It is the only species of the genus bearing apetalous flowers. Diels did not cite a holotype in his publication in 1910. We provide here a more precise description of Stephania pierrei and select a lectotype for this name.

Molecular systematics and character evolution in Caryophyllaceae

AbstractThe aim of the present study was to infer a substantially larger, more evenly sampled, phylogenetic tree for Caryophyllaceae in order to more confidently resolve relationships within this clade. This would allow us to evaluate previous classification schemes and to infer the evolution of a number of characters that have figured prominently in higher–level taxonomic treatments. We have inferred a 630–tip phylogeny (ca. 30% of the 2200 species) using maximum likelihood analyses of data from the nuclear ribosomal ITS region and five chloroplast genes and intergenic spacers: matK, ndhF, trnL–trnF, trnQ–rps16, and trnS–trnfM. Our results confirm that subfamily Paronychioideae is paraphyletic at the base of Caryophyllaceae. Alsinoideae and Caryophylloideae together form a clade, within which neither subfamily is monophyletic. With only a few exceptions, our results support the tribal classification presented by Harbaugh & al. (2010). In agreement with other recent studies, it appears that many of the larger genera are not strictly monophyletic. Our results imply that the first Caryophyllaceae had stipules, free sepals, small apetalous flowers with few stamens, and single–seeded indehiscent or irregularly dehiscing utricles. Stipules were lost along the branch to the Alsinoideae–Caryophylloideae clade, and the evolution of a tubular calyx marks Caryophylloideae. The evolution of petals, 10 stamens, and capsule fruits is inferred to have taken place along the branch subtending a clade that includes Sperguleae (mostly containing former members of Paronychioideae) and the remainder of Caryophyllaceae. As this previously unnamed major group is both well–supported in molecular phylogenetic studies and marked by clear–cut apomorphies, we propose the name Plurcaryophyllaceae for this clade and provide a phylogenetic definition.

Allophylastrum: a new genus of Sapindaceae from northern South America

The new genus Allophylastrum (Sapindaceae) is described from Roraima, Brazil and Guyana. Allophylastrum resembles the genus Allophylus in its vegetative morphology but differs by its apetalous flowers with a cupular nectary disc, 5–6 unequal stamens, and 4- to 5- porate pollen grains. A key is provided to differentiate Allophylastrum from Allophylus. The new species Allophylastrum frutescens is described and illustrated.

An ortholog of MIXTA‐like2 controls epidermal cell shape in flowers of Thalictrum

Here, we investigated the genetic underpinnings of pollination-related floral phenotypes in Thalictrum, a ranunculid with apetalous flowers. The variable presence of petaloid features in other floral organs correlates with distinct adaptations to insect vs. wind pollination. Conical cells are present in sepals or stamens of insect-pollinated species, and in stigmas. We characterized a Thalictrum ortholog of the Antirrhinum majus transcription factor MIXTA-like2, responsible for conical cells, from three species with distinct floral morphologies, representing two pollination syndromes. Genes were cloned by PCR and analysed phylogenetically. Expression analyses were conducted by quantitative PCR and in situ hybridization, followed by functional studies in transgenic tobacco. The cloned genes encode R2R3 MYB proteins closely related to Antirrhinum AmMYBML2 and Petunia hybrida PhMYB1. Spatial expression by in situ hybridization overlaps areas of conical cells. Overexpression in tobacco induces cell outgrowths in carpel epidermis and significantly increases the height of petal conical cells. We have described the first orthologs of AmMIXTA-like2 outside the core eudicots, likely ancestral to the MIXTA/MIXTA-like1 duplication. The conserved role in epidermal cell elongation results in conical cells, micromorphological markers for petaloidy. This adaptation to attract insect pollinators was apparently lost after the evolution of wind pollination in Thalictrum.

Nueva especie de Romanschulzia (Brassicaceae) del estado de Guerrero, México

Se describe y se ilustra Romanschulzia guerrerensis, una nueva especie del estado de Guerrero. Se asemeja a R. apetala, R. subclavata y R. rzedowskii en que tienen flores apétalas, pero difiere de las dos primeras por presentar sépalos libres en lugar de connados y frutos sésiles en vez de estipitados. Se parece a R. rzedowskii en sus sépalos libres, anteras pequeñas y frutos sésiles y cilíndricos, pero difiere de ésta en tener frutos y pedúnculos reflejos vs. erectos y ascendentes. Se incluye una clave para las cuatro especies y una tabla en la cual se comparan las características de las mismas. R. guerrerensis crece en una zona templada y húmeda cerca del cerro Teotepec en Guerrero.

The Biological Flora of Coastal Dunes and Wetlands: Croton punctatus N. von Jacquin

Abstract Croton punctatus N. von Jacquin is a New World tropical and subtropical dioecious, rhizomatous, subshrub or herb with apetalous flowers that is common on coastal beaches. Herein, we present a review of the biology of this important pioneer species. Large colonies of C. punctatus promote embryonic dune formation in belts parallel to the shoreline. Colonies act to intercept wind-transported sand. Colony success is related, in part, to a large seed bank and a relatively high germination potential. Other factors contributing to successful colonization include tolerance of sand scouring, salt spray deposition, burial, high substrate temperatures, and low levels of soil nutrients. Its northern distribution limits appear to be determined by the frequency, duration, and severity of freezing temperatures. Transplanted seedlings have relatively high survival rates. Therefore, C. punctatus has been useful in stabilizing sandy dredged material.

Analyses of the floral organ morphogenesis and the differentially expressed genes of an apetalous flower mutant in Brassica napus

The floral organ morphogenesis of the apetalous flower mutant Apet33-10 in Brassica napus was investigated and the result showed that all the floral organ morphogenesis was normal except that petal primordium was not observed during flower development. Eighteen genes were found to be down regulated in early floral buds (less than 200 mum in length) of Apet33-10 at the stage of floral organ initiation by means of suppressive subtraction hybridization (SSH) and RT-PCR. These genes were involved in petal identity, calcium iron signal transduction, mRNA processing, protein synthesis and degradation, construction of cytoskeleton, hydrogen transportation, nucleic acid binding, alkaloid biosynthesis and unknown function. Three overall coding region cDNAs of APETALA3 (AP3) gene, BnAP3-2, BnAP3-3 and BnAP3-4 were obtained by RT-PCR, respectively. Real-time quantitative PCR analysis showed that the expression ratio among BnAP3-2, BnAP3-3 and BnAP3-4 was 3.67:3.68:1 in early floral buds of wild type Pet33-10. The expression level of BnAP3-2, BnAP3-3 and BnAP3-4 in early floral buds of Apet33-10 was down-regulated to 36.6, 28.3 and 66.8% with the comparison of that of wild type, respectively, and the overall expression level of AP3 genes in apetalous mutant amounted to 45.0% of that in wild type. The difference in the expression level of each AP3 gene in stamen between apetalous and wild type lines was not significant. It is suggested that lower abundant expression of AP3 genes during the early flower development might be enough for stamen primordium initiation, but not enough for petal primordium initiation in the apetalous line Apet33-10.

Morphology of Hydatellaceae, an anomalous aquatic family recently recognized as an early‐divergent angiosperm lineage

The family Hydatellaceae was recently reassigned to the early-divergent angiosperm order Nymphaeales rather than the monocot order Poales. This dramatic taxonomic adjustment allows comparison with other early-divergent angiosperms, both extant and extinct. Hydatellaceae possess some monocot-like features that could represent adaptations to an aquatic habit. Ecophysiological parallels can also be drawn from fossil taxa that are known from small achene-like diaspores, as in Hydatellaceae. Reproductive units of Hydatellaceae consist of perianthlike bracts enclosing several pistils and/or stamens. In species with bisexual reproductive units, a single unit resembles an "inside-out" flower, in which stamens are surrounded by carpels that are initiated centrifugally. Furthermore, involucre development in Trithuria submersa, with delayed growth of second whorl bracts, resembles similar delayed development of the second perianth whorl in Cabomba. Several hypotheses on the homologies of reproductive units in Hydatellaceae are explored. Currently, the most plausible interpretation is that each reproductive unit represents an aggregation of reduced unisexual apetalous flowers, which are thus very different from flowers of Nymphaeales. Each pistil in Hydatellaceae is morphologically and developmentally consistent with a solitary ascidiate carpel. However, ascidiate carpel development, consistent with placement in Nymphaeales, is closely similar to pseudomonomerous pistil development as in Poaes.

Inheritance and agronomic performance of an apetalous flower mutant in Brassica napus L

A spontaneous mutant with apetalous flowers was obtained from a hybrid progeny in Brassica napus. The result of genetic analysis showed that the apetalous character was controlled by only one gene locus, petalous flower exhibited incomplete dominance over apetalous flower and that its expression was not affected by cytoplasmic factors. Sixteen agronomically important characteristics of the apetalous line Apet33-10 were compared with those of its petalled near-isogenic line Pet33-10. Results from 4 years of tests indicated that there was no difference between Apet33-10 and Pet33-10 in all tested agronomic characteristics, except for the pod number of main inflorescence and second-order branches at low sclerotinia disease incidence. The Sclerotinia sclerotiorum disease severity index of Apet33-10 was significantly lower than that of Pet33-10, and correspondingly, the plot yield of Apet33-10 was increased obviously in comparison to that of Pet33-10 if sclerotinia disease was serious. The pod number of main inflorescence of Apet33-10 was significantly lower than that of Pet33-10. On the other hand, the pod number of second-order branches of Apet33-10 was significantly higher than that of Pet33-10, hence no overage difference of the pod number per plant was observed between the two lines.

Inheritance of Apetalous Flowers in a Mutant of Oilseed Rape

Oilseed rape (Brassica napus L.) genotypes with reduced petal size are thought to have advantages in photosynthetic capacity and in disease resistance. This study was conducted to analyze the inheritance of a completely apetalous mutant that was induced by mutagenic treatment. The mutant ap-Tengbe was crossed with the German winter rapeseed cultivar Falcon. The F1, the F2, and both backcrosses including reciprocal generations were grown in field experiments at Göttingen, Germany, in 1997-1998 and at Hangzhou, China, in 1998-1999. The apetalous character of ap-Tengbe is regulated by an interaction of cytoplasmic genes and two pairs of nuclear genes. Completely apetalous flowers are only expressed in genotypes with the ap cytoplasm and two homozygous recessive genes. In conclusion, the mutant ap-Tengbe is useful to produce completely apetalous genotypes, but cytoplasmic effects have to be considered.

Inheritance of Apetalous Flowers in a Mutant of Oilseed Rape

Inheritance of Apetalous Flowers in a Mutant of Oilseed Rape

TheCerastium scaposumgroup(Caryophyllaceae):three annual taxa endemic to Crete (Greece), two of them new

Greuter, W., Böhling, N. & Jahn, R.: The Cerastium scaposum group (Caryophyllaceae): three annual taxa endemic to Crete (Greece), two of them new. — Willdenowia 32: 45–54. 2002. — ISSN 0511-9618.Cerastium deschatresii and C. scaposum subsp. peninsularum are described as two closely related taxa new to science. C. scaposum (subsp. scaposum) was described from the White Mountains (Lefka Ori) and was long believed to be restricted to the western segment of Crete, but it has been gathered once, in 1942, at the island's opposite end. It is a large-flowered, obviously outbreeding, locally abundant plant. C. scaposum subsp. peninsularum has smaller flowers, reduced petal size, and is a (perhaps facultative) selfer; it is known from several gatherings in the northwestern coastlands of Crete. C. deschatresii is more widespread, growing in scattered populations from west to east central Crete; it has minute, apetalous flowers, a distinctive capsule shape, and is a cleistogamous selfer.

Parthenocarpic apple fruit production conferred by transposon insertion mutations in a MADS-box transcription factor

Fruit development in higher plants normally requires pollination and fertilization to stimulate cell division of specific floral tissues. In some cases, parthenocarpic fruit development proceeds without either pollination or fertilization. Parthenocarpic fruit without seed has higher commercial value than seeded fruit. Several apple (Malus domestica) mutants (Rae Ime, Spencer Seedless and Wellington Bloomless) are known to produce only apetalous flowers that readily go on to develop into parthenocarpic fruit. Through genetics, a single recessive gene has been identified to control this trait in apple. Flower phenotypes of these apple mutants are strikingly similar to those of the Arabidopsis mutant pistillata (pi), which produces flowers where petals are transformed to sepals and stamens to carpels. In this study, we have cloned the apple PI homolog (MdPI) that shows 64% amino acid sequence identity and closely conserved intron positions and mRNA expression patterns to the Arabidopsis PI. We have identified that in the apetalous mutants MdPI has been mutated by a retrotransposon insertion in intron 4 in the case of Rae Ime and in intron 6 in the case of Spencer Seedless and Wellington Bloomless. The insertion apparently abolishes the normal expression of the MdPI gene. We conclude that the loss of function mutation in the MdPI MADS-box transcription factor confers parthenocarpic fruit development in these apple varieties and demonstrates another function for the MADS- box gene family. The knowledge generated here could be used to produce parthenocarpic fruit cultivars through genetic engineering.

Development of two new cytoplasmic male‐sterile lines in Brassica juncea through wide hybridization

AbstractTwo new cytoplasmic male‐sterile (CMS) lines have been developed in Brassica juncea using the bridgecross hybrids (Diplotaxis erucoides×Brassica campestris)×B. juncea and (Diplotaxis berthautii×B. campestris)×B. juncea. These were backcrossed ×ve times with pollen of B. juncea. The CMS line (D. erucoides) B. juncea segregated into tall and short true breeding types; both resembled the cultivar B. juncea in vegetative and floral morphology and in cytology, except for a greater number of secondary branches and smaller anthers with empty sterile pollen in the CMS line. Female fertility was as good in the CMS line as in the cultivar. The other CMS line (D. berthautii) B. juncea resembled the cultivar in vegetative morphology and cytology. Four true breeding floral types were isolated as follows: (1) smaller and indehiscent anthers containing empty, sterile pollen, (2) all six stamens petaloid, (3) one petaloid stamen and five stamens antherless, and (4) apetalous flowers with all six stamens antherless.