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Seed morphology of 19 species of Chlorophytum (Asparagaceae) collected from different regions of India were studied. The seeds are diverse in shape, size, color, weight, surface architectural pattern, and hilum characters. These characters are used for preparation of key for identification of the taxa. The study reveals that morphology of seed clearly distinguishes Chlorophytum kolhapurense from C. bharuchae, C. gothanense from C. borivilianum, and C. belgaumense from C. arundinaceum, all of them showing similar vegetative and floral traits. Morphometric analyses have also been carried out to find out the phenotypic similarities among the investigated species. Seed traits show phenetic affinities between Chlorophytum glaucoides and C. tuberosum, and between C. comosum and C. nilgheriensis which are quite dissimilar in floral morphology. The same observations are found in C. laxum, C. nepalense, and C. borivilianum. In contrast, seed characters show close affinities between C. glaucum and C. indicum, and between C. filipendulum subsp. amaniens and C. heynei, these traits are strongly correlated with other morphological and cytological characters. The results highlight the taxonomic significance of the seed morphological features in the investigated species of Chlorophytum, and their phenetic interrelationships.

A new species, Commelina badamica from the sandstone plateaus of Badami, Karnataka, India is described and illustrated. C. badamica is similar to C. clavata and C. diffusa, but differs in indefinite habit; linear–narrowly lanceolate leaves; puberulous or velutinous to tomentose spathes; clawless petals; velutinous ovary; radiately tri-lobed stigma; one capsule per spathe and trapezoidal, ventrally truncate seeds.

Asymbiotic seed germination of Eulophia nuda Lindl. was observed on Knudson C medium. About 90% seeds germinated within 8-10 weeks and formed green protocorms in 11-12 weeks. Effect of BA and IBA was studied on plantlet development from protocorms. BA shows the best results with respect to number and length of shoots. Maximum number (6.45±1.36) and length (3.90±0.99) was observed on MS medium supplemented with 4.44μM.BA. Maximum root growth was also observed on same medium (4.8±0.99 number of roots and 1.43±0.13cm length). The regenerated plantlets were successfully acclimatized and transferred to earthen pots. The results presented here show that in vitro seed germination and plantlet development in Eulophia nuda Lindl., an endangered orchid, can be achieved at a higher rate by this method.Int J Appl Sci Biotechnol, Vol 3(2): 243-247 DOI: http://dx.doi.org/10.3126/ijasbt.v3i2.12476

An in vitro micropropagation system has been developed for the Ceropegia anjanerica Malpure et al., a rare endemic plant species having ornamental as well as medicinal potential but a limited reproductive capacity. Axillary bud explants were cultured on Murashige and Skoog medium supplemented with 6-Benzylaminopurine, Thidiazuron and 6-Furfurylaminopurine along with combination of Indole-3-Butyric Acid. Although all concentrations showed multiple shoot formation, the best results (8.0 ± 0.5) were achieved with MS + 6-Benzylaminopurine (8.87 µM) + 6-Furfurylaminopurine (18.58 µM). Half strength Murashige and Skoog medium fortified with Indole-3-Acetic Acid (8.56 µM) showed good rooting response (4.0 ± 0.7). Well grown plantlets hardened, acclimatized and established in greenhouse exhibited 78 % survival.

The genus Cyanotis D. Don in India is taxonomically revised. Thirteen taxa of Cyanotis have been recognized with their updated nomenclature. Detailed descriptions, illustrations and geographical distribution have been provided. Cyanotis glabrescens (C. fasciculata var. glabrescens) and C. axillaris var. cucullata (Cyanotis cucullata) are new combinations and status proposed, notes on the complex of C. arachnoidea, C. burmaniana and C. tuberosa have been given, while some taxa warranting typifications have been lectotypified.

An annotated enumeration of Amischotolype (Commelinaceae) in India including one endemic species is given with description, illustrations and key. In addition, notes on the occurrence of genus Porandra in India is provided.

A new species of Hubbardia Bor from the northern Western Ghats is described and illustrated. The new species differs from H. heptaneuron by its glumes with long tubercle-based hairs and two stamens in the fertile floret.

Factors affecting in vitro propagation were evaluated for Ceropegia attenuata Hook., an endemic and endangered plant having ornamental potential but a limited reproductive capacity. Rapid shoot multiplication from nodal explants was established using varying concentrations of cytokinins and auxins either alone or in combinations. The highest frequency of shoot induction was achieved when nodal explants were inoculated on Murashige and Skoog (MS) medium supplemented with 13.31 μM 6-benzylaminopurine with a mean of 12.9 ± 0.5 shoots per explant. High concentrations of TDZ (6.81–11.35 μM) and KN (6.78–11.61 μM) resulted in stunted and vitrified shoots. Factors implicated in the promotion of floral transition of the C. attenuata have been identified which are 4-amino-3, 5, 6-trichloropicolinic acid (picloram), 6-benzylaminopurine, sucrose and photoperiod. The highest frequency of flowering (100%) was obtained when axillary shoot explants were transferred to MS medium supplemented with picloram (4.14 μM) within 4 weeks of culture. Transfer of in vitro regenerated shoots to half strength MS medium with 2.46 μM indole-3-butyric acid (IBA) showed maximum root induction. The in vitro grown plantlets were successfully acclimatized in the glasshouse with 85% of survival and showed normal development. The developed protocol provided a simple, cost-effective approach for the conservation of endangered plant C. attenuata for replenishing its declining populations.

Mucuna laticifera, a new species of Fabaceae from Sikkim state of India is described and illustrated here. It can be distinguished from its closely related species by the presence of a watery latex, uniformly green to pale yellow corolla, glabrous standard and wings and parallel pod margins.

Callisia is a tortuous genus reported to show a wide range of chromosome counts. Present paper reports an unusual chromosome number 2n = 18 for C. fragrans, a number that is so far not known, not only in C. fragrans but also for the entire genus Callisia. The variable chromosome number and varied karyotype architecture is indicative of the fact that the genome of the genus Callisia may be still unstable and in constant evolution.

An efficient protocol was developed for the rapid in vitro multiplication of an endemic and critically endangered medicinal herb, Ceropegia noorjahaniae Ans., via enhanced axillary bud proliferation from nodal explants. The effects of phytohormones [6-benzylaminopurine (BAP), kinetin (Kin) thidiazuron (TDZ), indole-3-acetic acid (IAA), indole-3-butyric acid (IBA) or α-naphthalene acetic acid (NAA)] on in vitro regeneration were investigated. The highest number of shoots (18.3 ± 1.3), maximum shoot length (10.1 ± 0.8 cm) and the highest response of shoot induction (95 %) were recorded on MS medium supplemented with 2.0 mg/l BAP. Rooting was best achieved on half-strength MS medium augmented with IBA (1.0 mg/l). Half-strength MS medium supplemented with BAP (4 mg/l) and sucrose (5 %, w/v) produced an average of 5.6 flower buds per microshoots with highest (90 %) flower bud induction response. The plantlets regenerated in vitro with well-developed shoot and roots were successfully established in pots containing sterile sand and coco peat (1:1) and grown in a greenhouse with 85 % survival rate. The regenerated plants did not show any detectable morphological variation. The developed method can be successfully employed for large-scale multiplication and conservation of C. noorjahaniae.

Murdannia saddlepeakensis (Commelinaceae), a new species from the Andaman and Nicobar Islands, India, is described and illustrated. The new species is remarkable for its narrowly linear leaves, two fertile stamens, single seeded locule and scorbiculate seeds.

SHMT (serine hydoxymethyltransferase), a type I pyridoxal 5'-phosphate-dependent enzyme, catalyses the conversion of L-serine and THF (tetrahydrofolate) into glycine and 5,10 -methylene THE SHMT also catalyses several THF-independent side reactions such as cleavage of P-hydroxy amino acids, trans-amination, racemization and decarboxylation. In the present study, the residues Asn(341), Tyr(60) and Phe(351), which are likely to influence THF binding, were mutated to alanine, alanine and glycine respectively, to elucidate the role of these residues in THF-dependent and -independent reactions catalysed by SHMT. The N341A and Y60A bsSHMT (Bacillus stearothermophilus SHMT) mutants were inactive for the THF-dependent activity, while the mutations had no effect on THF-independent activity. However, mutation of Phe(351) to glycine did not have any effect oil either of the activities. The crystal structures of the glycine binary complexes of the mutants showed that N341A bsSHMT forms an external aldimine as in bsSHMT, whereas Y60A and F351G bsSHMTs exist as a Mixture of internal/external aldimine and gem-diamine forms. Crystal structures of all of the three Mutants obtained in the presence of L-allo-threonine were similar to the respective glycine binary complexes. The structure of the ternary complex of F351G bsSHMT with glycine and FTHF (5-formyl THF) showed that the monoglutamate side chain of FTHF is ordered in both the subunits of the asymmetric unit, unlike in the wild-type bsSHMT. The present studies demonstrate that the residues Asn(341) and Tyr(60) are pivotal for the binding of THF/FTHF, whereas Phe(351) is responsible for the asymmetric binding of FTHF in the two subunits of the dimer.

Serine hydroxymethyltransferase (SHMT) from Bacillus stearothermophilus (bsSHMT) is a pyridoxal 5'-phosphate-dependent enzyme that catalyses the conversion of l-serine and tetrahydrofolate to glycine and 5,10-methylene tetrahydrofolate. In addition, the enzyme catalyses the tetrahydrofolate-independent cleavage of 3-hydroxy amino acids and transamination. In this article, we have examined the mechanism of the tetrahydrofolate-independent cleavage of 3-hydroxy amino acids by SHMT. The three-dimensional structure and biochemical properties of Y51F and Y61A bsSHMTs and their complexes with substrates, especially l-allo-Thr, show that the cleavage of 3-hydroxy amino acids could proceed via Cα proton abstraction rather than hydroxyl proton removal. Both mutations result in a complete loss of tetrahydrofolate-dependent and tetrahydrofolate-independent activities. The mutation of Y51 to F strongly affects the binding of pyridoxal 5'-phosphate, possibly as a consequence of a change in the orientation of the phenyl ring in Y51F bsSHMT. The mutant enzyme could be completely reconstituted with pyridoxal 5'-phosphate. However, there was an alteration in the λmax value of the internal aldimine (396 nm), a decrease in the rate of reduction with NaCNBH3 and a loss of the intermediate in the interaction with methoxyamine (MA). The mutation of Y61 to A results in the loss of interaction with Cα and Cβ of the substrates. X-Ray structure and visible CD studies show that the mutant is capable of forming an external aldimine. However, the formation of the quinonoid intermediate is hindered. It is suggested that Y61 is involved in the abstraction of the Cα proton from 3-hydroxy amino acids. A new mechanism for the cleavage of 3-hydroxy amino acids via Cα proton abstraction by SHMT is proposed.

Acetylornithine aminotransferase (AcOAT) is one of the key enzymes involved in arginine metabolism and catalyzes the conversion of N-acetylglutamate semialdehyde to N-acetylornithine (AcOrn) in the presence of $_L$-glutamate. It belongs to the Type I subgroup II family of pyridoxal $5^{\prime}$-phosphate (PLP) dependent enzymes. E. coli biosynthetic AcOAT (eAcOAT) also catalyzes the conversion of N-succinyl-$_L$-2-amino-6-oxopimelate to N-succinyl-$_{L,L}$-diaminopimelate, one of the steps in lysine biosynthesis. In view of the critical role of AcOAT in lysine and arginine biosynthesis, structural studies were initiated on the enzyme from S. typhimurium (sAcOAT). The $K_m$ and $k_{cat}/K_m$ values determined with the purified sAcOAT suggested that the enzyme had much higher affinity for AcOrn than for ornithine (Orn) and was more efficient than eAcOAT. sAcOAT was inhibited by gabaculine (Gcn) with an inhibition constant $(K_i)$ of $7\mu M$ and a second-order rate constant $(k_2)$ of 0.16 $mM^{-1} s^{-1}$. sAcOAT, crystallized in the unliganded form and in the presence of Gcn or $_L$-glutamate, diffracted to a maximum resolution of $1.90 \AA$ and contained a dimer in the asymmetric unit. The structure of unliganded sAcOAT showed significant electron density for PLP in only one of the subunits (subunit A). The asymmetry in PLP binding could be attributed to the ordering of the loop $L_{\alpha k-\beta m}$ in only one subunit (subunit B; the loop from subunit B comes close to the phosphate group of PLP in subunit A). Structural and spectral studies of sAcOAT with Gcn suggested that the enzyme might have a low affinity for PLP-Gcn complex. Comparison of sAcOAT with T. thermophilus AcOAT and human ornithine aminotransferase suggested that the higher specificity of sAcOAT towards AcOrn may not be due to specific changes in the active site residues but could result from minor conformational changes in some of them. This is the first structural report of AcOAT from a mesophilic organism and could serve as a basis for drug design as the enzyme is important for bacterial cell wall biosynthesis.

Serine hydroxymethyltransferase (SHMT) belongs to the alpha-family of pyridoxal 5'-phosphate-dependent enzymes and catalyzes the reversible conversion of L-Ser and etrahydrofolate to Gly and 5,10-methylene tetrahydrofolate. 5,10-Methylene tetrahydrofolate serves as a source of one-carbon fragment in many biological processes. SHMT also catalyzes the tetrahydrofolate-independent conversion of L-allo-Thr to Gly and acetaldehyde. The crystal structure of Bacillus stearothermophilus SHMT (bsSHMT) suggested that E53 interacts with the substrate, L-Ser and etrahydrofolate. To elucidate the role of E53, it was mutated to Q and structural and biochemical studies were carried out with the mutant enzyme. The internal aldimine structure of E53QbsSHMT was similar to that of the except for significant changes at Q53, Y60 and Y61. The wild-type enzyme, carboxyl of Gly and side chain of L-Ser were in two conformations in the respective external aldimine structures. The mutant enzyme was completely inactive for tetrahydrofolate-depen dent cleavage of L-Ser, whereas there was a 1.5-fold increase in the rate of tetrahydrofolate-independent reaction with L-allo-Thr. The results obtained from these studies suggest that E53 plays an essential role in tetrahydrofolate/5-formyl tetrahydrofolate binding and in the proper positioning of C beta of L-Ser for direct attack by N5 of tetrahydrofolate. Most interestingly, the structure of the complex obtained by cocrystallization of E53QbsSHMT with Gly and 5-formyl tetrahydrofolate revealed the gem-diamine form of pyridoxal 5'-phosphate bound to Gly and active site Lys. However, density for 5-formyl tetrahydrofolate was not observed. Gly carboxylate was in a single conformation, whereas pyridoxal 5'-phosphate had two distinct conformations. The differences between the structures of this complex and Gly external aldimine suggest that the changes induced by initial binding of 5-formyl tetrahydrofolate are retained even though 5-formyl tetrahydrofolate is absent in the final structure. Spectral studies carried out with this mutant enzyme also suggest that 5-formyl tetrahydrofolate binds to the E53QbsSHMT-Gly complex forming a quinonoid intermediate and falls off within 4 h of dialysis, leaving behind the mutant enzyme in the gemdiamine form. This is the first report to provide direct evidence for enzyme memory based on the crystal structure of enzyme complexes.

In the course of revising the family Commelinaceae in India, it has been found that no type was indicated in the protologue of Streptolirion volubile Edgew. Thus, it warrants typification under execute Art. 9.2 of the International Code of Nomenclature (McNeill & al. 2012). Though not cited explicitly in the protologue, we consider Edgeworth’s own material collected in 1844 from the Indian Himalaya and annotated by him to constitute original material and therefore appropriate for typification. We herein designate a specimen at Kew that unequivocally agrees with the protologue as lectotype.

Acetylornithine aminotransferase (AcOAT) is a type I pyridoxal 5\prime-phosphate-dependent enzyme catalyzing the conversion of N-acetylglutamic semialdehyde to N-acetylornithine in the presence of \alpha-ketoglutarate, a step involved in arginine metabolism. In Escherichia coli, the biosynthetic AcOAT also catalyzes the conversion of N-succinyl-L-2-amino-6-oxopimelate to N-succinyl-L,L-diaminopimelate, one of the steps in lysine biosynthesis. It is closely related to ornithine aminotransferase. AcOATwas cloned from Salmonella typhimurium and E. coli, overexpressed in E. coli and purified using Ni–NTA affinity column chromatography. The enzymes crystallized in the presence of gabaculine. Crystals of E. coli AcOAT (eAcOAT) only diffracted X-rays to 3.5\AA and were twinned. The crystals of S. typhimurium AcOAT (sAcOAT) diffracted to 1.9 \AA and had a dimer in the asymmetric unit. The structure of sAcOAT was solved by the molecular-replacement method.