Small Anthers Research Articles

A bifunctional selectable marker for wheat transformation contributes to the characterization of male-sterile phenotype induced by a synthetic Ms2 gene.

An engineered selectable marker combining herbicide resistance and yellow fluorescence contributes to the characterization of male-sterile phenotype in wheat, the severity of which correlates with expression levels of a synthetic Ms2 gene. Genetic transformation of wheat is conducted using selectable markers, such as herbicide and antibiotic resistance genes. Despite their proven effectiveness, they do not provide visual control of the transformation process and transgene status in progeny, which creates uncertainty and prolongs screening procedures. To overcome this limitation, this study developed a fusion protein by combining gene sequences encoding phosphinothricin acetyltransferase and mCitrine fluorescent protein. The fusion gene, introduced into wheat cells by particle bombardment, enabled herbicide selection, and visual identification of primary transformants along with their progeny. This marker was then used to select transgenic plants containing a synthetic Ms2 gene. Ms2 is a dominant gene whose activation in wheat anthers leads to male sterility, but the relationship between the expression levels and the male-sterile phenotype is unknown. The Ms2 gene was driven either by a truncated Ms2 promoter containing a TRIM element or a rice promoter OsLTP6. The expression of these synthetic genes resulted in complete male sterility or partial fertility, respectively. The low-fertility phenotype was characterized by smaller anthers than the wild type, many defective pollen grains, and low seed sets. The reduction in the size of anthers was observed at earlier and later stages of their development. Consistently, Ms2 transcripts were detected in these organs, but their levels were significantly lower than those in completely sterile Ms2TRIM::Ms2 plants. These results suggested that the severity of the male-sterile phenotype was modulated by Ms2 expression levels and that higher levels may be key to activating total male sterility.

Inselbergs Again: Four New Species ofMandevilla(Apocynaceae) from Brazil

Abstract—Four new species ofMandevillafrom inselbergs in Espírito Santo, Brazil are described, including illustrations, and maps.Mandevilla declinataresemblesM. crassinodabut differs by leaf blades acuminate to long acuminate and longer corolla.Mandevilla fornograndensisis distinguished from morphologically similar species by its yellow corolla.Mandevilla mysteriosais morphologically similar toM. lucidabut differs by its longer petioles, leaf blade characters, shorter corolla tube, and smaller anthers;Mandevilla obovataresemblesM. hatschbachii,but it is separated by its puberulent leaves, longer sepals, and white corolla. An informal evaluation of the conservation status according to IUCN guidelines is proposed for each species:M. declinata(VU: D2),M. fornograndensis(VU: D2),M. mysteriosa(VU: D2), andM. obovata(VU: B1ab(i,ii,iii)+2ab(i,ii,iii)). A key to the species ofMandevillain Espírito Santo is included.

Loss of Function of the RRMF Domain in OsROS1a Causes Sterility in Rice (Oryza sativa L.).

For crop seed production, the development of anthers and male fertility are the main agronomic traits and key biological processes for flowering plants. Active DNA demethylation regulates many plant developmental processes and is ensured by 5-meC DNA glycosylase enzymes. To find out the role of OsROS1a, OsROS1a gene editing mutants were generated using the CRISPR/Cas9 system. The osros1a mutants had shrink spikelets, smaller anthers and pollen grains, and were not stained by iodine staining showing a significant reduction in total soluble sugar and starch contents as compared to wildtype (WT), which caused complete male sterility. Similarly, the expression of genes involved in pollen and anther development was decreased in osros1a mutants as compared to WT. Furthermore, bisulfite sequencing showed that the CG and CHG methylation of the OsPKS2 gene promoter was significantly increased in the osros1a mutant, which caused a reduced expression of OsPKS2 in osros1a mutants. DNA methylation of the TDR gene promoter was similar between WT and osros1a mutants, indicating that the DNA methylation effect by OsROS1a was gene specific. The expression of OsROS1a in the mutants was not changed, but it produced a frame-shift mutation to truncate the Pem-CXXC and RRMF domains. Combined with previous studies, our findings suggested that the RRMF domain in OsROS1a is the functional domain and loss of RRMF for OsROS1a causes sterility in rice.

Morphological Variability of Nitraria Species in Central and Southern Kazakhstan

The variability of metric traits has been studied in 20 Kazakhstan populations of three Nitraria species (N. schoberi L., N. sibirica Pall., and N. komarovii Iljin & Lava ex Bobrov). According to the results, N. sibirica differs from N. schoberi and N. komarovii in small leaves, fruits, and seeds, as well as in the structural features of inflorescences and flowers. N. sibirica is characterized by a greater number of flowers per inflorescence (25–66 on average) than N. schoberi and N. komarovii (14–28 on average). Additionally, N. sibirica differs from N. schoberi by narrower (1.3×) petals and smaller anthers (1.46× in length and 1.2× in width) and pistils (1.25× in length and 1.44× in width). N. komarovii differs from N. schoberi by narrower leaves (1.7×). N. komarovii is characterized by relatively large (especially in width) size of anthers that, together with smaller petals, makes it possible to distinguish this species during flowering. Flowers of N. komarovii are bright yellow, while those in N. schoberi and N. sibirica are white and light purple, respectively. N. komarovii fruits are orange, pale red, or bright red. Fruits of N. schoberi and N. sibirica are dark burgundy and black, respectively. At the intraspecific level, most of the studied metric traits (except for the habitus of N. sibirica plants) are stable and do not depend on the 16 climatic parameters of plant habitats. At the same time, a number of morphological features have been revealed in N. sibirica plants from the Ili Depression. In these populations, N. sibirica plants form shrubs up to 1.8 m in height with a large (up to 90) number of flowers per inflorescence, large petals (3.5 mm in length and 2.2 mm in width on average), small (~0.6 mm) anthers, small (5–5.5 mm in length) fruits, and small (~4 mm in length) narrow ovate stones. These features indicate the ecological–geographical differentiation of N. sibirica under the extra-arid conditions of the stony desert of the depression and evidence a separate taxonomic rank of these populations.

Haploid Bio-Induction in Plant through Mock Sexual Reproduction.

SummaryHaploidization is invaluable for basic genetic research and crop breeding. The haploid bio-induction principle is an important topic that remains largely unexplored. In this study, both CenH3 RNAi and in vitro inhibition were used to simulate and induce haploids in allopolyploid crop. Notably, in vitro CenH3 inhibition showed that the results were much the same to that of RNAi in phenotype, chromosome behavior, microspore production, and haploid induction. Cytological analyses of RNAi and inhibitor-treated progenies revealed elimination of chromosomes, defective microspores with empty nuclei, thereby giving rise to pseudo male gametes, and haploid parthenogenesis induction. We found distinct defective empty microspores that were positively correlated with the decrease of CenH3 during RNAi manipulation. Investigation through both in vivo and in vitro studies revealed that haploidization was induced through the pseudo male gamete-mediated mock sexual reproduction. The present results provide insights for the haploid parthenogenesis induction process.

Structure and development of anthers and connective glands in two species of Stigmaphyllon (Malpighiaceae): are heteromorphic anthers related to division of labour?

Heteranthery has been largely associated with a division of labour between anthers. Most species of Stigmaphyllon (Malpighiaceae) present heteromorphic anthers and glandular connectives of different development; yet, the functional meaning of this condition has never been explored in the genus. The aims of this study were to provide a comparative description of the structure and development of anthers and their connective glands in S. bonariense and S. jatrophifolium and to assess the existence of division of functions. Natural populations were selected to collect flowers at different stages. Anthers were subjected to morpho-anatomical, histochemical and pollen viability studies. For both species, abundance of pollen grains and size of anther and their connective glands were estimated. Three types of stamens are recognized: stamen with small, intermediate and large anthers. Anthers of both species exhibit a similar glandular tissue in the connective, and the histochemical analysis revealed that it produce a mucilagous secretion. The pattern of anther wall development, stainability and release of pollen grains was identical among anther types. For both species, we observed a positive relationship between anther size and abundance of pollen grains, but an inverse relationship between area of anthers and size (area and thickness) of connective glands in small anthers vs. intermediate and large ones. Our results evidence a specialization of anthers related to division of labour between heteromorphic stamens in two species of Stigmaphyllon. Thus, one set of anthers produces large amount of pollen grains for pollination and another sets large quantities of mucilage, which would improve pollen transport (better adherence to pollinator body and dampness maintenance). Nevertheless, heteranthery in both Stigmaphyllon species would represent a transitional state towards the division of labour rather than a stable state.

OsMS1 functions as a transcriptional activator to regulate programmed tapetum development and pollen exine formation in rice.

OsMS1 functions as a transcriptional activator and interacts with known tapetal regulatory factors through its plant homeodomain (PHD) regulating tapetal programmed cell death (PCD) and pollen exine formation in rice. The tapetum, a hallmark tissue in the stamen, undergoes degradation triggered by PCD during post-meiotic anther development. This degradation process is indispensable for anther cuticle and pollen exine formation. Previous study has shown that PTC1 plays a critical role in the regulation of tapetal PCD. However, it remained unclear how this occurs. To further investigate the role of this gene in rice, we used CRISPR/Cas9 system to generate the homozygous mutant named as osms1, which showed complete male sterility with slightly yellow and small anthers, as well as invisible pollen grains. In addition, cytological observation revealed delayed tapetal PCD, defective pollen exine formation and a lack of DNA fragmentation according to a TUNEL analysis in the anthers of osms1 mutant. OsMS1, which encodes a PHD finger protein, was located in the nucleus of rice protoplasts and functioned as a transcription factor with transcriptional activation activity. Y2H and BiFC assays demonstrated that OsMS1 can interact with OsMADS15 and TDR INTERACTING PROTEIN2 (TIP2). It has been reported that TIP2 coordinated with TDR to modulate the expression of EAT1 and further regulated tapetal PCD in rice. Results of qPCR suggested that the expression of the genes associated with tapetal PCD and pollen wall biosynthesis, such as EAT1, AP37, AP25, OsC6 and OsC4, were significantly reduced in osms1 mutant. Taken together, our results demonstrate that the interaction of OsMS1 with known tapetal regulatory factors through its PHD finger regulates tapetal PCD and pollen exine formation in rice.

<i>Dimeria kalerii</i> (Poaceae: Panicoideae), A new species from northern Kerala, India

Dimeria kalerii, a new species collected from the lateritic plateaus of NorthernKerala, India is described and illustrated. It is allied to Dimeria gracilis in robust habit, densely bearded nodes, lax racemes, long clavate pedicels with cupuliform apex but differs in ciliate apex of ligules, numerous racemes on the peduncles (7-32), hairy pedicels, smaller spikelets (3.8–4.2 mm), shorter cilia on the upper and lower glume, long bristly hairs at the apex of upper glume, hairy column of awns and smaller anthers (1.8–2.0 mm).Bangladesh J. Plant Taxon. 25(1): 13-18, 2018 (June)

Pollinator availability, mating system and variation in flower morphology in a tropical savanna tree

ABSTRACT Widely distributed organisms face different ecological scenarios throughout their range, which can potentially lead to micro-evolutionary differentiation at specific localities. Mating systems of animal pollinated plants are supposed to evolve in response to the availability of local pollinators, with consequent changes in flower morphology. We tested the relationship among pollination , mating system, and flower morphology over a large spatial scale in Brazilian savannas using the tree Curatella americana (Dilleniaceae). We compared fruit set with and without pollinators in the field, and analyzed pollen tube growth from self- and cross-pollinated flowers in different populations. Populations with higher natural fruit set also had lower fruit set in bagged flowers, suggesting stronger barriers to self-fertilization. Furthermore, higher levels of autogamy in field experiments were associated with more pollen tubes reaching ovules in self-pollinated flowers. Morphometric studies of floral and leaf traits indicate closer-set reproductive organs, larger stigmas and smaller anthers in populations with more autogamy. We show that the spatial variation in mating system, flower morphology and pollination previously described for herbs also applies to long-lived, perennial tropical trees, thus reemphasizing that mating systems are a population-based attribute that vary according to the ecological scenario where the plants occur.

Flora of Bokor National Park, Cambodia VI: A new species of Wikstroemia (Thymelaeaceae), W. bokorensis

A new species, Wikstroemia bokorensis (Thymelaeaceae), from Bokor National Park, Kampot Province, Cambodia, is described and illustrated. This species is morphologically most similar to W. nutans distributed in southern China and Vietnam, but differs in having pubescent branches and leaves, smaller anthers, a single disk scale, and glabrous ovary. DNA barcodes of ITS, rbcL, trnT-F, rps16, and rpl16 regions for the new species are also provided.

Morphological and phylogenetic relationships of the threatened geophyte Wurmbea novae-zelandiae (Colchicaceae) from New Zealand, with notes on typification

The new combination Wurmbea novae-zelandiae was recently made based on published phylogenetic studies, but little information was provided on its relationships based on morphology. This species was originally described as Anguillaria novae-zelandiae, for which a lectotype is designated. Morphological characters of W. novae-zelandiae are re-evaluated and shown to be characteristic of Wurmbea, thereby supporting the revised generic placement. However, W. novae-zelandiae differs from all other Wurmbea species in its diminutive stature, fewer tepals and stamens, and variable floral morphology, with 1–3 carpels, often leaf-like tepals, and aberrant tepal shape and number. DNA sequence data places W. novae-zelandiae as the sister species of W. uniflora, a species not included in earlier phylogenetic studies. These two species share mostly solitary flowers with white tepals, nectaries two per tepal and similar in form and position, small yellow anthers, and styles that are relatively short and recurve as flowering proceeds, with the inner style surface stigmatic for up to half of its length. A revised generic description of Wurmbea is provided to take account of the recently widened concept.

Transcriptome Profiling of Wheat Inflorescence Development from Spikelet Initiation to Floral Patterning Identified Stage-Specific Regulatory Genes.

Early reproductive development in cereals is crucial for final grain number per spike and hence the yield potential of the crop. To date, however, no systematic analyses of gene expression profiles during this important process have been conducted for common wheat (Triticum aestivum). Here, we studied the transcriptome profiles at four stages of early wheat reproductive development, from spikelet initiation to floral organ differentiation. K-means clustering and stage-specific transcript identification detected dynamically expressed homeologs of important transcription regulators in spikelet and floral meristems that may be involved in spikelet initiation, floret meristem specification, and floral organ patterning, as inferred from their homologs in model plants. Small RNA transcriptome sequencing discovered key microRNAs that were differentially expressed during wheat inflorescence development alongside their target genes, suggesting that miRNA-mediated regulatory mechanisms for floral development may be conserved in cereals and Arabidopsis. Our analysis was further substantiated by the functional characterization of the ARGONAUTE1d (AGO1d) gene, which was initially expressed in stamen primordia and later in the tapetum during anther maturation. In agreement with its stage-specific expression pattern, the loss of function of the predominantly expressed B homeolog of AGO1d in a tetraploid durum wheat mutant resulted in smaller anthers with more infertile pollens than the wild type and a reduced grain number per spike. Together, our work provides a first glimpse of the gene regulatory networks in wheat inflorescence development that may be pivotal for floral and grain development, highlighting potential targets for genetic manipulation to improve future wheat yields.

Argostemma laotica (Rubiaceae), a new species from Laos

Argostemma laotica, a new species from Laos, is described and illustrated. The species appears most similar to A. concinnum but differs in having pubescent stem, corolla and ovaries, oblique leaf base, shorter pedicel and smaller anthers which a dehiscence by an apical pore. The conservation status of this new species is vulnerable (VU D2).

An updated checklist and key to the open-panicled species of Poa L. (Poaceae) in Peru including three new species, Poa ramoniana, Poa tayacajaensis, and Poa urubambensis.

We provide an updated checklist and key to the 30 Poa species with open panicles from Peru which includes previously circumscribed Dissanthelium and Aphanelytrum species, new taxon records, and three undescribed species. Poa compressa, Poa grisebachii, and Poa leioclada are recorded from Peru for the first time. A number of species are placed in synonymy: Poa carazensis, Poa ferreyrae and Poa tovarii are synonymized under the name Poa fibrifera; Poa adusta (tentatively) and Poa pilgeri are synonymized under Poa candamoana; Poa superata is synonymized under Poa grisebachii; and Poa paramoensis is synonymized under Poa huancavelicae. Included within this treatment are three new species, Poa ramoniana, Poa tayacajaensis and Poa urubambensis, which are described and illustrated. Poa ramoniana, found growing near lakes in high elevation Puna grasslands of Junín, is similar to a small form of Poa glaberrima, but differs in having rhizomes and growing to only 5 cm tall. Poa tayacajaensis, found from shrublands on Andean slopes of Huancavelica and Huánuco, bears similarities to Poa aequatoriensis but differs in having shorter lemmas which are pubescent between the veins, densely scabrous sheaths with smooth, glabrous throats, and shorter ligules. Poa urubambensis, a common element of the undisturbed Polylepis forest understory of the Cordillera Urubamba, Cusco, is distinct from all other members of open-panicled Poa’s by having glabrous lemmas with a smooth and glabrous callus, and notably small anthers. The type material for the name Poa adusta is discussed and a lectotype is selected.

Three new species of the genus Cypella (Iridaceae, Tigridieae)

Three new species of Cypella section Nais from South America are described and illustrated: C. charruana, C. gloriana , and C. uliginosa . Cypella charruana occurs in Santana do Livramento (southern Brazil) and in Rivera and Artigas (northern Uruguay). It is related to C. suffusa ; however, it can be easily separated by its one-flowered spathes, outer tepals with narrowed claws, longer antheral filaments, and bigger anthers. Cypella gloriana is only found in Sao Vicente do Sul (central-western Rio Grande do Sul State, Brazil); this species is closely related to C. pusilla from which it can be separated by its larger perigone with shallower and broader concavity, outer tepals with narrowed claws, inner tepals with blades markedly narrowed and longer towards the apex, and with glandular trichomes spreading in a small area, stamens shorter, with porrect filaments, smaller anthers, and broader connective tissue. Cypella uliginosa occurs in bogs from Entre Rios and Corrientes in northeastern Argentina; it morphologically resembles C. crenata and C. laxa ; however, C. uliginosa can be distinguished from both species by its flowers with pale translucent and shallow central concavity, inner tepals blade plicate with a deep central depression, marked by a darker area covered by ochraceous glandular trichomes, and erect or slightly porrect style branches, with the stigmatic trichomes prolonged on the proximal portion of the adaxial crests. Cypella charruana and C. gloriana are recognized as critically endangered, while the data of C. uliginosa are insufficient to establish criteria of threat. Data about phenology, geographic distribution, conservation, plus comparative tables to segregate these three new species from the related taxa, and a key to differentiate species of the section Nais are supplied.

Floral structure in Acrocomia aculeata (Arecaceae): evolutionary and ecological aspects

Acrocomia aculeata is an oleaginous palm widely distributed through the tropical and subtropical Americas that shows significant potential for agroindustrial use. Studies of floral structures can contribute to our knowledge of the evolutionary diversification of this genus and ecological aspects of its species as well as assist management and domestication programs. With the objective of characterizing the morphoanatomy of the flowers of A. aculeata, 20 inflorescences were collected in each of three natural populations growing in the northern region of Minas Gerais State, Brazil. Flowers at anthesis were evaluated biometrically and using standard plant anatomical procedures, and observed under light and scanning electron microscopy. The flowers showed wide biometric variability that was influenced by the collection area, the individuals examined, and the positions of the flowers on the inflorescence. Staminate flowers can have two whorls of petals, small anthers, and vestigial structures, with the development of an infertile carpel and rudimentary ovules. Defenses against herbivory include the presence of raphides in the anthers and pistillate flowers, fiber bundles, stegmata, and idioblasts containing phenols and raphides. Pollinators are attracted by the liberation of intense odors produced by osmophores located in the corolla, with pollen being the principal resource offered. Phenotypic plasticity, the structures involved in defending against herbivores and attracting pollinators, the numbers of flowers, and flowering synchrony contribute to the reproductive success of this species. The short period during which the stigmas remain receptive determines synchronous fertilization within the inflorescence.

Changes in oat (Avena sativa L.) flowers and inflorescences under conditions of copper deficiency

The anatomy and morphology of oat (<i>Avena sativa</i> L.) cv. 'Udycz Żółty' flowers and inflorescences formed at different copper levels (0, 5, 125 mg Cu/pot) was investigated. Considerable changes in the structure of the generative elements of oat flowers occurred under conditions of severe copper deficiency (Cu = 0): the stamens showed considerably smaller anthers, with changed shape; the anther chambers were significantly diminished in size and did not open after the formation of pollen; the pollen grains were sterile, deformed and of smaller dimensions. The pistils and ovules were also smaller; outgrowths on the pistil stigmas were smaller and of a different shape. A decrease in the dimensions of the inflorescences was observed in both early and later phases of development. In moderately copper-deficient plants (Cu = 5) the flowers were heteromorphic: functionally male - with great anthers and small pistils, functionally female - with great pistils and small anthers and hermaphrodite - with great pistils and anthers.

The male sterile 8 mutation of maize disrupts the temporal progression of the transcriptome and results in the mis-regulation of metabolic functions.

Maize anther ontogeny is complex, with the expression of more than 30,000 genes over 4 days of cell proliferation, cell fate acquisition and the start of meiosis. Although many male-sterile mutants disrupt these key steps, few have been investigated in detail. The terminal phenotypes of Zea mays (maize) male sterile 8 (ms8) are small anthers exhibiting meiotic failure. Here, we document much earlier defects: ms8 epidermal cells are normal in number but fail to elongate, and there are fewer, larger tapetal cells that retain, rather than secrete, their contents. ms8 meiocytes separate early, have extra space between them, occupied by excess callose, and the meiotic dyads abort. Thousands of transcriptome changes occur in ms8, including ectopic activation of genes not expressed in fertile siblings, failure to express some genes, differential expression compared with fertile siblings and about 40% of the differentially expressed transcripts appear precociously. There is a high correlation between mRNA accumulation assessed by microarray hybridization and quantitative real-time reverse transcriptase polymerase chain reaction. Sixty-three differentially expressed proteins were identified after two-dimensional gel electrophoresis followed by liquid chromatography tandem mass spectroscopy, including those involved in metabolism, plasmodesmatal remodeling and cell division. The majority of these were not identified by differential RNA expression, demonstrating the importance of proteomics in defining developmental mutants.

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.

Phylogenetic position and relationships of Lobelia glaberrima (Lobeliaceae), a new alpine species from southern South Island (New Zealand)

Lobelia glaberrima is a newly described species from mountainous parts of the southern South Island of New Zealand. The morphology of L. glaberrima is most similar to L. macrodon, but it is distinguished from that species by a suite of mainly floral characters. These include L. glaberrima having narrower calyx lobes, a corolla with a shorter tube and smaller lobes, shorter stamens with smaller anthers, a smaller ovary with a shorter style, and a weakly pungent scent. Chloroplast DNA evidence indicates that L. glaberrima is most closely related to L. linnaeoides. However, it differs from that species by shorter peduncles, wider corolla lobes, and an indehiscent globose capsule. The chromosome number of L. glaberrima is 2n = 28, and this also distinguishes it from L. linnaeoides and L. macrodon #OP2n = 14).