S. R. Yadav

Comparative pollen morphology in the early-divergent angiosperm family Hydatellaceae reveals variation at the infraspecific level

The small aquatic family Hydatellaceae was recently assigned to the early‐divergent angiosperm order Nymphaeales. Pollen morphology is described using both SEM and LM for all 12 species of Hydatellaceae, and using TEM for one species (T. submersa). These observations are compared with pollen data from the other two families of Nymphaeales, Nymphaeaceae and Cabombaceae, including original observations for both genera of Cabombaceae. No significant interspecific variation in pollen morphology occurs in Hydatellaceae, though both of the perennial species (Trithuria inconspicua and T. filamentosa), which could be apomictic, possess at least partially sterile and collapsed pollen. Pollen of Trithuria is small, oblong or rounded (viewed from the distal pole) and monosulcate. The aperture has a distinct margin and extends the full length of the pollen grain. The exine is tectate‐columellate. The tectum is perforate: discontinuous with numerous small perforations randomly scattered over the entire non‐apertural surface. The exine surface is microechinate. In most species of Trithuria, a small percentage of pollen grains possess a trichotomosulcate aperture. In two species, rare atypical grains with striate or partially striate exine sculpturing were found. This striate pattern is very similar to exine sculpturing in Gymnotheca (Saururaceae, Piperales). The presence of anasulcate pollen does not contradict placement of Hydatellaceae within Nymphaeales, but this pollen type is also common among other early‐divergent angiosperms and monocots. Exine sculpturing differs between Cabombaceae, Hydatellaceae and Nymphaeaceae, but this character also differs between the two genera of Cabombaceae and among genera of Nymphaeaceae. Compared with other families of Nymphaeales, Hydatellaceae are relatively uniform in pollen morphology.

Green remediation of textile dyes containing wastewater by Ipomoea hederifolia L.

Wild plant and tissue cultures of Ipomoea hederifolia decolorize Scarlet RR (SRR) dye at a concentration of 50 mg L−1 up to 96% and 90% within 60 and 96 h, respectively. Significant induction in the enzyme activities of Lignin peroxidase, laccase, 2,6-dichlorophenol indophenol reductase, superoxide dismutase, catalase and tyrosinase was found in the plant roots and shoots during decolorization. I. hederifolia was also able to treat a dye mixture and a real textile effluent efficiently with a reduction in the American Dye Manufacturers Institute (ADMI) value (color removal) up to 85% and 88%, BOD up to 65% and 63% and COD up to 62% and 68%, respectively. Detailed anatomical studies of the stem and root cells of I. hederifolia during uptake and degradation were carried out, showing a stepwise and mechanistic degradation of the model dye SRR. Products formed after dye degradation were analyzed by UV-Vis spectroscopy, FTIR, HPLC and HPTLC, which confirmed the phytotransformation of SRR, dye mixture and textile effluent. A possible pathway for the phytotransformation of SRR was proposed based on GC-MS analysis, which confirmed the formation of different metabolites with lower molecular weights. The phytotoxicity study revealed the non-toxic nature of the formed products.

Molecular phylogeny of Ceropegia (Asclepiadoideae, Apocynaceae) from Indian Western Ghats

Ceropegia includes more than 200 species distributed in the Old World ranging from the Canary Islands to Australia. In India, there are about 50 species described on a morphological basis as belonging to Ceropegia, and most of them are endemic to the Western Ghats. To investigate evolutionary relationships among Indian Ceropegia taxa and their allies, a phylogenetic analysis was conducted to include 31 Indian taxa of Ceropegia and Brachystelma and their congeners from other geographical regions using nuclear ribosomal internal transcribed spacer (ITS) and three noncoding chloroplast DNA (cpDNA) sequences, including intergenic spacers trnT-L and trnL-F, and trnL intron. The Western Ghats Ceropegia species were found to be most closely related to Indian Brachystelma, with the two genera being placed sister to each other in the ITS phylogeny or with the Brachystelma clade nested within one of the two subclades of Indian Ceropegia in the cpDNA phylogeny. In contrast, Ceropegia species from other regions and African Brachystelma all formed separate clades basal to the Indian Ceropegia–Brachystelma clade. Thus, it can be concluded that the classical morphology-based delineation of the two genera needs revision to reflect their phylogenetic relationships, which are more in accordance with their geographical origin than with morphology.

Contrasting biogeographic and diversification patterns in two Mediterranean-type ecosystems.

The five Mediterranean regions of the world comprise almost 50,000 plant species (ca 20% of the known vascular plants) despite accounting for less than 5% of the world’s land surface. The ecology and evolutionary history of two of these regions, the Cape Floristic Region and the Mediterranean Basin, have been extensively investigated, but there have been few studies aimed at understanding the historical relationships between them. Here, we examine the biogeographic and diversification processes that shaped the evolution of plant diversity in the Cape and the Mediterranean Basin using a large plastid data set for the geophyte family Hyacinthaceae (comprising ca. 25% of the total diversity of the group), a group found mainly throughout Africa and Eurasia. Hyacinthaceae is a predominant group in the Cape and the Mediterranean Basin both in terms of number of species and their morphological and ecological variability. Using state-of-the-art methods in biogeography and diversification, we found that the Old World members of the family originated in sub-Saharan Africa at the Paleocene–Eocene boundary and that the two Mediterranean regions both have high diversification rates, but contrasting biogeographic histories. While the Cape diversity has been greatly influenced by its relationship with sub-Saharan Africa throughout the history of the family, the Mediterranean Basin had no connection with the latter after the onset of the Mediterranean climate in the region and the aridification of the Sahara. The Mediterranean Basin subsequently contributed significantly to the diversity of neighbouring areas, especially Northern Europe and the Middle East, whereas the Cape can be seen as a biogeographical cul-de-sac, with only a few dispersals toward sub-Saharan Africa. The understanding of the evolutionary history of these two important repositories of biodiversity would benefit from the application of the framework developed here to other groups of plants present in the two regions.

Unique stigmatic hairs and pollen-tube growth within the stigmatic cell wall in the early-divergent angiosperm family Hydatellaceae

BACKGROUND AND AIMS The ultrastructure of the pollen tubes and the unusual multicellular stigmatic hairs of Trithuria, the sole genus of Hydatellaceae, are described in the context of comparative studies of stigmatic and transmitting tissue in other early-divergent angiosperms. METHODS Scanning and transmission electron microscopy and immunocytochemistry are used to study the structure and composition of both mature and immature stigmatic hair cells and pollen-tube growth in Trithuria. KEY RESULTS Trithuria possesses a dry-type stigma. Pollen tubes grow within the cell walls of the long multicellular stigmatic hairs. Immunocytochemistry results suggest that arabinogalactan proteins are involved in attracting the pollen tubes through the stigmatic cuticle. Most tubes grow along the hair axis towards its base, but some grow towards the hair apex, suggesting that pollen tubes are guided by both physical constraints such as microfibril orientation and the presence of binding factors such as unesterified pectins and adhesive proteins. CONCLUSIONS The presence of a dry-type stigma in Trithuria supports the hypothesis that this condition is ancestral in angiosperms. Each multicellular stigmatic hair of Hydatellaceae is morphologically homologous with a stigmatic papilla of other angiosperms, but functions as an independent stigma and style. This unusual combination of factors makes Hydatellaceae a useful model for comparative studies of pollen-tube growth in early angiosperms.

Highly efficient in vitro proliferation and genetic stability analysis of micropropagated Ceropegiaevansii by RAPD and ISSR markers: A critically endangered plant of Western Ghats

Ceropegiaevansii McCann (family: Asclepiadaceae), a critically endangered plant of Western Ghats has acquired significant importance due to its medicinal implications, edible tubers, and ornamental flowers. This study deals with the optimization of axillary bud proliferation using nodal explants followed by genetic stability analysis of regenerants. Maximum number of shoots (11.6 ± 1.1) was observed on the Murashige and Skoog (MS) medium supplemented with 6-benzylaminopurine (4.0 mg/l) and indole-3-acetic acid (0.3 mg/l) with 85% shoot multiplication frequency. In vitro-grown shoots were rooted best in 1/2 MS medium supplemented with indole-3-butyric acid (1.0 mg/l) with an average of 10.3 ± 0.9 roots per shoot and 92% rooting frequency. Plantlets were acclimatized best (90%) in a mixture of sterile soil, sand, and coco peat (1:2:1). Micropropagated plants were subjected to random amplified polymorphic DNA and inter simple sequence repeat markers analyses. Collectively, 759 bands were generated which were monomorphic and similar to the mother plant. Findings of this study are the first report on micropropagation and assessment of genetic stability of micropropagated plantlets in C. evansii which suggests that axillary shoot proliferation can safely be used as an effective tool for propagation and conservation of C. evansii.

Two new species of Brachystelma Sims (Apocynaceae: Asclepiadoideae-Ceropegieae) from the Western Ghats of India

Summary. Two new species of Brachystelma: B. mahajanii Kambale & S. R. Yadav from Ebbanad, Nilgiri District, Tamil Nadu and B. vartakii Kambale & S. R. Yadav from Periya, Kasargod District, Kerala are described and illustrated.

Eriocaulon epedunculatum , a new species of Eriocaulaceae from the Western Ghats, India

SummaryA new species of Eriocaulon, E. epedunculatum (Eriocaulaceae) is described and illustrated from the Western Ghats, India.

Chlorophytum gothanense, a new species of Anthericaceae from the Western Ghats of India

SummaryA new species of Chlorophytum is described and illustrated. It is adapted to grow on the open, exposed lateritic plateaus in the Northern Western Ghats of India. The chromosome number of the species is 2n = 28.

Reconstructing the age and historical biogeography of the ancient flowering-plant family Hydatellaceae (Nymphaeales).

BackgroundThe aquatic flowering-plant family Hydatellaceae has a classic Gondwanan distribution, as it is found in Australia, India and New Zealand. To shed light on the biogeographic history of this apparently ancient branch of angiosperm phylogeny, we dated the family in the context of other seed-plant divergences, and evaluated its biogeography using parsimony and likelihood methods. We also explicitly tested the effect of different extinction rates on biogeographic inferences.ResultsWe infer that the stem lineage of Hydatellaceae originated in the Lower Cretaceous; in contrast, its crown originated much more recently, in the early Miocene, with the bulk of its diversification after the onset of the Pliocene. Biogeographic reconstructions predict a mix of dispersal and vicariance events, but considerations of geological history preclude most vicariance events, besides a split at the root of the family between southern and northern clades. High extinction rates are plausible in the family, and when these are taken into account there is greater uncertainty in biogeographic inferences.ConclusionsA stem origin for Hydatellaceae in the Lower Cretaceous is consistent with the initial appearance of fossils attributed to its sister clade, the water lilies. In contrast, the crown clade is young, indicating that vicariant explanations for species outside Australia are improbable. Although long-distance dispersal is likely the primary driver of biogeographic distribution in Hydatellaceae, we infer that the recent drying out of central Australia divided the family into tropical vs. subtropical/temperate clades around the beginning of the Miocene.