<Emphasis Type="Italic">FORMOSA</Emphasis> controls cell division and expansion during floral development in <Emphasis Type="Italic">Antirrhinum</Emphasis><Emphasis Type="Italic">majus</Emphasis>

Control of organ size is the product of coordinated cell division and expansion. In plants where one of these pathways is perturbed, organ size is often unaffected as compensation mechanisms are brought into play. The number of founder cells in organ primordia, dividing cells, and the period of cell proliferation determine cell number in lateral organs. We have identified the Antirrhinum FORMOSA (FO) gene as a specific regulator of floral size. Analysis of cell size and number in the fo mutant, which has increased flower size, indicates that FO is an organ-specific inhibitor of cell division and activator of cell expansion. Increased cell number in fo floral organs correlated with upregulation of genes involved in the cell cycle. In Arabidopsis the AINTEGUMENTA (ANT) gene promotes cell division. In the fo mutant increased cell number also correlates with upregulation of an Antirrhinum ANT-like gene (Am-ANT) in inflorescences that is very closely related to ANT and shares a similar expression pattern, suggesting that they may be functional equivalents. Increased cell proliferation is thought to be compensated for by reduced cell expansion to maintain organ size. In Arabidopsis petal cell expansion is inhibited by the BIGPETAL (BPE) gene, and in the fo mutant reduced cell size corresponded to upregulation of an Antirrhinum BPE-like gene (Am-BPE). Our data suggest that FO inhibits cell proliferation by negatively regulating Am-ANT, and acts upstream of Am-BPE to coordinate floral organ size. This demonstrates that organ size is modulated by the organ-specific control of both general and local gene networks. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Floral development and systematic position of <Emphasis Type="Italic">Arillastrum</Emphasis>, <Emphasis Type="Italic">Allosyncarpia</Emphasis>, <Emphasis Type="Italic">Stockwellia</Emphasis> and <Emphasis Type="Italic">Eucalyptopsis</Emphasis> (Myrtaceae)

We have investigated the floral ontogeny of Arillastrum, Allosyncarpia, Stockwellia and Eucalyptopsis (of the eucalypt group, Myrtaceae) using scanning electron microscopy and light microscopy. Several critical characters for establishing relationships between these genera and to the eucalypts have been determined. The absence of compound petaline primordia in Arillastrum, Allosyncarpia, Stockwellia and Eucalyptopsis excludes these taxa from the eucalypt clade. Post-anthesis circumscissile abscission of the hypanthium above the ovary in Stockwellia, Eucalyptopsis and Allosyncarpia is evidence that these three taxa form a monophyletic group; undifferentiated perianth parts and elongated fusiform buds are characters that unite Stockwellia and Eucalyptopsis as sister taxa. No floral characters clearly associate Arillastrum with either the eucalypt clade or the clade of Stockwellia, Eucalyptopsis and Allosyncarpia.We gratefully acknowledge Clyde Dunlop and Bob Harwood (Northern Territory Herbarium) for collecting specimens of Allosyncarpia, and Bruce Gray (Atherton) for collecting specimens of Stockwellia. The Australian National Herbarium (CANB) kindly lent herbarium specimens of Eucalyptopsis for examination. This research was supported by a University of Melbourne Research Development Grant to Andrew Drinnan.     

Diversity of LTR-retrotransposons and <Emphasis Type="Italic">Enhancer/Suppressor</Emphasis><Emphasis Type="Italic">Mutator</Emphasis>-like transposons in cassava (<Emphasis Type="Italic">Manihot esculenta</Emphasis> Crantz)

Cassava (Manihot esculenta Crantz), though a major world crop with enormous potential, is very under studied. Little is known about its genome structure and organisation. Transposable elements have a key role in the evolution of genome structure, and can be used as important tools in applied genetics. This paper sets out to survey the diversity of members of three major classes of transposable element within the cassava genome and in relation to similar elements in other plants. Members of two classes of LTR-retrotransposons, Ty1/copia-like and Ty3/gypsy-like, and of Enhancer/Suppressor Mutator (En/Spm)-like transposons were isolated and characterised. Analyses revealed 59 families of Ty1/copia, 26 families of Ty3/gypsy retrotransposons, and 40 families of En/Spm in the cassava genome. In the comparative analyses, the predicted amino acid sequences for these transposon classes were compared with those of related elements from other plant species. These revealed that there were multiple lineages of Ty1/copia-like retrotransposons in the genome of cassava and suggested that vertical and horizontal transmission as the source of cassava Mecops may not be mutually exclusive. For the Ty3/gypsy elements network, two groups of cassava Megyps were evident including the Arabidopsis Athila lineage. However, cassava En/Spm-like elements (Meens) constituted a single group within a network of plant En/Spm-like elements. Hybridisation analysis supported the presence of transposons in the genome of cassava in medium (Ty3/gypsy and En/Spm) to high (Ty1/copia) copy numbers. Thus the cassava genome was shown to contain diverse members of three major classes of transposable element; however, the different classes exhibited contrasting evolutionary histories.     

<Emphasis Type="Italic">Anaconda</Emphasis>, a new class of transposon belonging to the <Emphasis Type="Italic">Mu</Emphasis> superfamily,has diversified by acquiring host genes during rice evolution

A new type of transposon, named Anaconda (Anac) has been found in rice (Oryza sativa). In this paper, we demonstrate that Anaconda elements have diversified by acquisition of host cellular genes, amplification of the elements, and substitution and deletion of short segments. We identified four Anaconda elements in studies of rice alternative oxidase (AOX) genes, and subsequently isolated an additional 23 elements based on the identity of their terminal inverted repeats (TIRs). The Anaconda elements have long TIRs (114–458 bp). They also have direct repeats of 9 or 10 bp in their flanking regions that are thought to have been generated upon transposition. These structural features reveal that the Anaconda elements belong to the Mu superfamily. The most prominent feature of the Anaconda elements is the high frequency with which they have acquired host cellular genes. Of the 27 elements found here, 19 appear to have sequences presumably derived from rice genes, for example, the genes for AOX1c (four elements), cytochrome P450 (five elements), l-asparaginase (five elements), and PCF8 (two elements). Four elements, AnacA1–A4, have both the AOX1c and P450 genes. One element, AnacB14, involves a gene similar to mudrA of maize MuDR. Database analyses revealed that the loci of 26 of the 27 Anaconda elements in the subspecies japonica are the same as those in the subspecies indica. This suggests that these elements were incorporated before the divergence of these two subspecies.     

Germ line transformation of the silkworm, <Emphasis Type="Italic">Bombyx mori</Emphasis>, using the transposable element <Emphasis Type="Italic">Minos</Emphasis>

We investigated the use of Minos as a vector for transgenesis in the silkworm, Bombyx mori. We first constructed a vector plasmid with the green fluorescent protein (GFP) gene fused with the silkworm cytoplasmic actin gene (A3) promoter, and a helper plasmid with the Minos transposase gene controlled by the same A3 promoter. Injection of the vector and helper plasmid DNA into silkworm eggs produced transgenic animals in the following generation. The efficiency of transgenic silkworm production using this method was much lower than that obtained using piggyBac-mediated germ line transformation. However, >40-fold increase in the efficiency of producing transgenic silkworms was obtained using an in vitro synthesized source of Minos transposase mRNA. We conclude that the Minos transposon is a useful vector for construction of transgenic silkworms, particularly when in vitro synthesized mRNA is used. This is the first report showing that Minos can be used as a vector for germ-line transformation in lepidopteran insects.     

The <Emphasis Type="Italic">Caenorhabditis</Emphasis><Emphasis Type="Italic">briggsae</Emphasis> genome contains active <Emphasis Type="Italic">CbmaT1</Emphasis> and <Emphasis Type="Italic">Tcb1</Emphasis> transposons

The maT clade of transposons is a group of transposable elements intermediate in sequence and predicted protein structure to mariner and Tc transposons, with a distribution thus far limited to a few invertebrate species. We present evidence, based on searches of publicly available databases, that the nematode Caenorhabditis briggsae has several maT-like transposons, which we have designated as CbmaT elements, dispersed throughout its genome. We also describe two additional transposon sequences that probably share their evolutionary history with the CbmaT transposons. One resembles a fold back variant of a CbmaT element, with long (380-bp) inverted terminal repeats (ITRs) that show a high degree (71%) of identity to CbmaT1. The other, which shares only the 26-bp ITR sequences with one of the CbmaT variants, is present in eight nearly identical copies, but does not have a transposase gene and may therefore be cross mobilised by a CbmaT transposase. Using PCR-based mobility assays, we show that CbmaT1 transposons are capable of excising from the C. briggsae genome. CbmaT1 excised approximately 500 times less frequently than Tcb1 in the reference strain AF16, but both CbmaT1 and Tcb1 excised at extremely high frequencies in the HK105 strain. The HK105 strain also exhibited a high frequency of spontaneous induction of unc-22 mutants, suggesting that it may be a mutator strain of C. briggsae.     

The Madagascan genus <Emphasis Type="Italic">Vaughania</Emphasis> is reduced to synonymy under <Emphasis Type="Italic">Indigofera</Emphasis> (<Emphasis Type="Italic">Leguminosae-Papilionoideae-Indigofereae</Emphasis>)

Summary  Eleven species comprising the Madagascan genus Vaughania are subsumed within the large pantropical genus Indigofera. Six new combinations are made; the remaining species were originally described in Indigofera.     

Characterization of <Emphasis Type="Italic">EamaT1</Emphasis>, a member of <Emphasis Type="Italic">maT</Emphasis> family of transposable elements from the earthworm <Emphasis Type="Italic">Eisenia andrei</Emphasis> (Annelida,Oligochaeta)

The maT family is a unique clade within the Tc1-mariner superfamily, and their distribution is to date known as being limited to invertebrates. A novel transposon named EamaT1 is described from the genome of the earthworm Eisenia andrei. The full sized EamaT1 was obtained by degenerate and inverse PCR-based amplification. Sequence analysis of multiple copies of the EamaT1, which consisted of 0.9 and 1.4 kb elements, showed that the consensual EamaT1 with inverted terminal repeats (ITRs) of 69 bp was 1,422 bp long and flanked by a duplicated TA dinucleotide. The EamaT1 is present in approximately 120–250 copies per diploid genome but undergoes an inactivation process as a result of accumulating multiple mutations and is nonfunctional. The open reading frame (ORF) of the EamaT1 consensus encoding 356 amino acid sequences of transposase contained a DD37D signature and a conserved paired-like DNA binding motif for the transposition mechanism. The result of ITRs comparison confirmed their consensus terminal sequences (5′-CAGGGTG-3′) and AT-rich region on the internal bases for ITRs-transposase interaction.     

<Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated transformation of <Emphasis Type="Italic">Cry1C,Cry2A</Emphasis> and <Emphasis Type="Italic">Cry9C</Emphasis> genes into <Emphasis Type="Italic">Gossypium hirsutum</Emphasis> and plant regeneration

Three constructs harbouring novel Bacillus thuringiensis genes (Cry1C, Cry2A, Cry9C) and bar gene were transformed into four upland cotton cultivars, Ekangmian10, Emian22, Coker201 and YZ1 via Agrobacterium-mediated transformation. With the bar gene as a selectable marker, about 84.8 % of resistant calli have been confirmed positive by polymerase chain reaction (PCR) tests, and totally 50 transgenic plants were regenerated. The insertions were verified by means of Southern blotting. Bioassay showed 80 % of the transgenic plantlets generated resistance to both herbicide and insect. We optimized conditions for improving the transformation efficiency. A modified in vitro shoot-tip grafting technique was introduced to help entire transplantation. This result showed that bar gene can replace antibiotic marker genes (ex. npt II gene) used in cotton transformation.     

<Emphasis Type="Italic">MDM</Emphasis>-1 and <Emphasis Type="Italic">MDM</Emphasis>-2: Two <Emphasis Type="Italic">Mutator</Emphasis>-Derived MITE Families in Rice

Abstract Numerous miniature inverted repeat transposable elements (MITEs) are present in the rice genome but their transposition mechanisms are unknown. In this report, we present evidence that two novel MITE families may have arisen from Mutator-related transposable elements and thus may use a transposition mechanism similar to that of Mutator elements. Two families of novel MITEs, namely, MDM-1 and MDM-2, were identified by searching for MITEs nested with Kiddo, a previously identified MITE family. MDM-1 and MDM-2 bear hallmarks of Mutator elements, such as long terminal inverted repeats (LTIRs), 9-bp target-site duplications (TSDs), and putative transposase binding sites. Strikingly, the MDM-1 family has a 9-bp terminus identical to that of a rice Mutator-like element (MULE-9) and the MDM-2 family has an 8-bp terminus identical to that of the maize autonomous Mutator element MuDR. A putative transposase homologous to MURA protein is identified for the MDM-2 family. Thus, these two novel MITE families, with a total copy number of several hundred in rice, are designated Mutator-derived MITEs (MDMs). Interestingly, sequence decay analysis of MDM families revealed a number of insertion site duplications (ISDs) in the alignment gaps, and widespread historical nesting events are proposed to account for the existence of these ISDs. In addition to its value for discovering new MITEs, the nesting analysis approach used in this study simultaneously identifies MITE insertion polymorphisms.     

<Emphasis Type="Italic">Phuphanochloa,</Emphasis> a new bamboo genus (<Emphasis Type="Italic">Poaceae</Emphasis>: <Emphasis Type="Italic">Bambusoideae</Emphasis>) from Thailand

Summary  A new monotypic bamboo genus Phuphanochloa (Poaceae: Bambusoideae) from north-eastern Thailand is described, together with a new species, P. speciosa.     

Isolation and characterization of the <Emphasis Type="Italic">Larix gmelinii </Emphasis><Emphasis Type="Italic">ANGUSTIFOLIA</Emphasis> (<Emphasis Type="Italic">LgAN</Emphasis>) gene

ANGUSTIFOLIA (AN), a plant homolog of C-terminal binding protein, controls the polar elongation of leaf cells and the trichome-branching pattern in Arabidopsis thaliana. In the present study, degenerate PCR was used to isolate an ortholog of AN, referred to as LgAN, from larch (Larix gmelinii). The LgAN cDNA is predicted to encode a protein of 646 amino acids that shows striking sequence similarity to AN proteins from other plants. The predicted amino acid sequence has a conserved NAD-dependent 2-hydroxy acid dehydrogenase (D2-HDH) motif and a plant AN-specific LxCxE/D motif at its N-terminus, as well as a plant-specific long C-terminal region. The LgAN gene is a single-copy gene that is expressed in all larch tissues. Expression of the LgAN cDNA rescued the leaf width and trichome-branching pattern defects in the angustifolia-1 (an-1) mutant of Arabidopsis, showing that the LgAN gene has effects complementary to those of AN. These results suggest that the LgAN gene has the same function as the AN gene.     

<Emphasis Type="Italic">Drosophila</Emphasis><Emphasis Type="Italic">P</Emphasis> transposons of the urochordata <Emphasis Type="Italic">Ciona intestinalis</Emphasis>

P transposons belong to the eukaryotic DNA transposons, which are transposed by a cut and paste mechanism using a P-element-coded transposase. They have been detected in Drosophila, and reside as single copies and stable homologous sequences in many vertebrate species. We present the P elements Pcin1, Pcin2 and Pcin3 from Ciona intestinalis, a species of the most primitive chordates, and compare them with those from Ciona savignyi. They showed typical DNA transposon structures, namely terminal inverted repeats and target site duplications. The coding region of Pcin1 consisted of 13 small exons that could be translated into a P-transposon-homologous protein. C. intestinalis and C. savignyi displayed nearly the same phenotype. However, their P elements were highly divergent and the assumed P transposase from C. intestinalis was more closely related to the transposase from Drosophila melanogaster than to the transposase of C. savignyi. The present study showed that P elements with typical features of transposable DNA elements may be found already at the base of the chordate lineage. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.