TWISTED DWARF1 regulates Arabidopsis stamen development by differential activation of ABCB-mediated auxin transport

Despite clear evidence that a local accumulation of auxin is likewise critical for male fertility, much less is known about the components that regulate auxin-controlled stamen development.In this study, we analyzed physiological and morphological parameters in mutants of key players of ABCB-mediated auxin transport and spatially and temporally dissected their expression on the protein level as well as auxin fluxes in the Arabidopsis stamens. Our analyses revealed that the FKBP42, TWISTED DWARF1 (TWD1), promotes stamen elongation and, to a lesser extent, anther dehiscence, as well as pollen maturation and thus is required for seed development. Most of the described developmental defects in twd1 are shared with the abcb1 abcb19 mutant, which can be attributed to the fact that TWD1 - as a described ABCB chaperon - is a positive regulator of ABCB1 and ABCB19-mediated auxin transport. However, reduced stamen number was dependent on TWD1 but not on investigated ABCBs, suggesting additional actors down-stream of TWD1. We predict an overall housekeeping function for ABCB1 during earlier stages, while ABCB19 seems to be responsible for the key event of rapid elongation at later stages of stamen development. Our data indicate that TWD1 controls stamen development by differential activation of ABCB-mediated auxin transport in the stamen.HighlightBy using a mix of phenotypical and imaging analyses, we here identify and functionally characterize a new master regulator of flower development.

Vellozia inselbergae (Velloziaceae), a new species from the Brazilian Atlantic Forest inselbergs†

Vellozia inselbergae Mello-Silva ex Andr.Cabral, a new species of Velloziaceae endemic to the Atlantic Forest inselbergs in the Brazilian state of Bahia, is here described. The new species is morphologically similar to Vellozia armata and Vellozia luteola, putatively belonging to the same clade, but is distinguished from them mainly by the longer pedicel, cylindrical-ellipsoid hypanthium, white and larger tepals, stamen number, longer anthers and style, and larger capsules. Detailed morphological and anatomical descriptions, illustration and photographic plates, distribution map, and conservation status of Vellozia inselbergae are provided.

Begonia handibadaganathensis (Begoniaceae), a new species from Western Ghats, India

A new species of Begonia, B. handibadaganathensis has been described from the northern Western Ghats of Karnataka. The species differs from all other Indian species of the genus in possessing axillary tubercles, a means of vegetative propagation. Begonia handibadaganathensis is closely allied to B. dipetala but differs mainly in the presence of tubercles in the leaf axils, flower size, stamen number and fruit morphology. The species appears to be a narrow endemic restricted to its type locality.

Early Eudicot flower and fruit: Dakotanthus gen. nov. from the Cretaceous Dakota Formation of Kansas and Nebraska, USA

An extinct plant that populated the eastern margin of the Cretaceous Midcontinental Seaway of North America about 100 million years ago has attracted interest as one of the earliest known bisexual flowers in the fossil record. Reexamination of the type specimen of Carpites cordiformis Lesq., and corresponding specimens from sandstones and clays of the Dakota Formation of Kansas and Nebraska and the correlative Woodbine Sandstone of Texas, with both light microscopy and micro CT scanning, leads to a revised concept of the morphology and affinities of the “Rose Creek flower”. The moderately large flowers (22–30 mm diameter) have two perianth whorls: five basally fused sepals and five free spatulate petals. The gynoecium is pentacarpellate with five styles. A crescent-shaped nectariferous pad occurs at the base of the gynoecium aligned with each sepal. Ten stamens are inserted at the level of the nectaries, one whorl organized opposite the sepals and another opposite the petals. In situ pollen is oblate, brevitricolporate and finely verrucate. The fruits are loculicidal capsules with persistent calyx and disk. Comparing the full suite of observed characters with those of extant angiosperms indicates particularly close similarity to the monogeneric fabalean family Quillajaceae, with shared features of perianth number and morphology, nectary position and morphology, stamen number and morphology, and gynoecium merosity, although the fossil differs from extant Quillaja in fruit type (capsule vs basally syncarpous follicles) and especially in pollen morphology (10 μm oblate, microverrucate, vs 30–40 μm prolate, striate).

Two new species of Commiphora (Burseraceae) from southern Africa

Commiphora steynii Swanepoel and C. gariepensis Swanepoel, here described as new species, are known only from the Kaokoveld and Gariep Centres of Endemism respectively. Illustrations of the plants and distribution maps are provided. Diagnostic characters of C. steynii include the pale ashy grey, non-peeling bark and the lack of wart-like projections around the large lenticels. Diagnostic characters of C. gariepensis include the stamen number which varies between four and eight, and the milky-watery latex which does not squirt when branches are damaged. When without leaves or fruit, C. gariepensis can easily be confused with several other species. Comprehensive tables with diagnostic morphological features to distinguish between the new species and closely related taxa are presented.

Comparative study of different fertile groups in plums

The plum traditional fruit species in Hungary, several local cultivars was born in the different grower's districts. The author that investigated, that are morphological differences between an odds find self-fertile, self sterile (with functional stamens) and male sterile plum cultivars. For it thought about main questions of a scientific debate sown up and the study this way gave reactions totalize. There were in three fertile groups 8-8 type of feature plum cultivars in periods of 1992-2001, respectively 1993-1999. It was founded by author big odds found the troops on the basis of 9 traits between. Pistil length of self sterile cultivars very typical, such as sesquipedalian flower peduncle of the self-fertile plums and the hypoandry of male sterile cultivars. The relative stamen number and the pollen viability as well significant odds gave. The average fruit mass and sharka infection of self-fertile plums this troops extreme work. According to cultivar's averages the shark symptoms standard the right correlation the singular traits, but those one part of her with each other not shown connection. The annuity potencies underdeveloped the troops behind and the troops within cultivar's differences had case significance. The results usable the male sterile cultivars and progeny further its investments.

REVISION OF PLETHIANDRA HOOK.F.: A POLYSTAMINATE, EAST ASIAN GENUS OF MELASTOMATACEAE

Plethiandra (Melastomataceae–Melastomatoideae–Dissochaeteae) comprises seven species in Borneo and one (P. sessiliflora) in the southern part of Peninsular Malaysia and central Sumatra. Plethiandra is easily recognized by its polystaminate androecium, having 16–40 stamens with short, straight, inappendiculate anthers. The closely related Medinilla has a diplostemonous androecium with 8–12 stamens and variously appendaged anthers. Ontogenetic studies in P. hookeri show that the increase in stamen number in Plethiandra results from subdivision of the stamen primordia into three or more subprimordia.This paper provides a key, genus and species descriptions including diagnostic characters, distribution maps and ecological notes. One species, P. tomentosa, is newly described. During field observations on P. hookeri and P. cuneata pollination by bees and dispersal by birds and squirrels were observed.

Long term investigations of flowers and leaves on mainly non-domestica plums

The author dealt with plum species representing different eco-geographic areas by their genetic adaptation and their hybrids, as European (P. domestica, P. italica, P. cerasifera), Asian (P. salicina, P. simonii, P. ussuriensis), American (P. americana, P. besseyi, P. munsoniana, P. tomentosa). The rootstocks of the trees examined were seedlings of C. 679 myrobalan with the exception of Laroda and Santa Rosa II, which were grown on three different stocks: seedlings of C. 174 myrobalan, C. 449 bitter almond and C. 471 sweet almond. The size of peduncle, length of pistil, stamen number per flower, relative stamen number (SN/PL) have been suitable for description and distinction of varieties. Similarly shape of leaves, length of petiole, length and width of blade helped the identification. The ratio of the dimensions of leaves, length of petiole and of leaf blade, also contributed to the distinction of European, Asian and American plum species, notwithstanding their relations with ecological conditions as well as historical, technical properties, pomological features, etc. Computed indicators (relative stamen number and shape-index of leaves) also have been useful data. Significant correlations have been found between colour of nectaries and mean values of variety-groups. The potential values of non-European varieties for purposes of commercial production could be forecasted from the point of view of quality, ecological, pomological as well as market value. It is important, however, to know the effect of the rootstock and growing site as well as their interaction, on the one hand, whereas the resistance or tolerance of the varieties as limiting factors, at least to the sharka (Plum pox) virus, Xanthomonas pruni, on the other hand (cf. Surányi & Erdős, 2004a and 2004b).