<Emphasis Type="Italic">Withania somnifera</Emphasis> (Linn.) Dunal: a review of chemical and pharmacological diversity

Withania somnifera Dunal, is a commonly used herb in Indian Ayurvedic medicine system. Due to its pharmacological value and an inexhaustible source of novel biologically active compounds, it has been a great interest for researchers. The plant is known to possess anti-inflammatory, antitumor, antistress, antioxidant, immunomodulatory and hemopoetic properties. Various withanolides, steroidal lactones, have been isolated from W. somnifera and were known to have high therapeutic value. Based on the differences in the substitution patterns of withanolides the species has been classified into various chemotypes. So far, three different chemotypes have been identified, which have been further classified into ecotypes based on the contents of withanolides. Present review summarizes the phytochemical variability and pharmacological advances reported in literature.     

Callus induction and plantlet regeneration in <Emphasis Type="Italic">Withania somnifera</Emphasis> (L.) dunal

Summary Callus induction was observed from hypocotyl, root, and cotyledonary leaf segments, grown on Murashige and Skoog (MS) medium supplemented with various concentrations and combinations of 2,4-dichlorophenoxyacetic acid (2,4-D) and kinetin (KN). Maximum callusing (100%) was obtained from root and cotyledonary leaf segments grown on MS medium supplemented with a combination of 2 mg l⁻¹ (9.1 μM) 2,4-D and 0.2 mg l⁻¹ (0.9 μM) KN. The calluses, when subcultured in the same medium, showed profuse callusing. However, these calluses remained recalcitrant to regenerate regardless of the quality and combinations of plant growth regulators in the nutrient pool. When hypocotyl segments were used as explants, callus induction was noticed in 91% of cultures which showed shoot regeneration on MS medium supplemented with 2 mg l⁻¹ 2,4-D and 0.2 mg l⁻¹ KN. These shoots were transferred to fresh medium containing various concentrations and combinations of 6-benzyladenine (BA) and N⁶-(2-isopentenyl)adenosine (2-iP). Maximum shoot multiplication was observed after 60 d of the second subculture on MS medium containing 2 mg l⁻¹ (8.9 μM) BA. These shoots were rooted best (87%) on MS medium containing 2 mg l⁻¹ (9.9 μM) indole-3-butyric acid (IBA). The plantlets were transferred to the field after acclimatization and showed 60% survival.     

Genotype independent and efficient <Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated genetic transformation of the medicinal plant <Emphasis Type="Italic">Withania somnifera</Emphasis> Dunal

Withania somnifera one of the most reputed Indian medicinal plant has been extensively used in traditional and modern medicines as active constituents. A high frequency genotype and chemotype independent Agrobacterium-mediated transformation protocol has been developed for W. somnifera by optimizing several factors which influence T-DNA delivery. Leaf and node explants of Withania chemotype was transformed with A. tumefaciens strain GV3101 harboring pIG121Hm plasmid containing the gusA gene encoding β-glucuronidase (GUS) as a reporter gene and the hptII and the nptII gene as selection markers. Various factors affecting transformation efficiency were optimized; as 2 days preconditioning of explants on MS basal supplemented with TDZ 1 μM, Agrobacterium density at OD₆₀₀ 0.4 with inclusion of 100 μM acetosyringone (As) for 20 min co-inoculation duration with 48 h of co-cultivation period at 22 °C using node explants was found optimal to improved the number of GUS foci per responding explant from 36?±?13.2 to 277.6?±?22.0, as determined by histochemical GUS assay. The PCR and Southern blot results showed the genomic integration of transgene in Withania genome. On average basis 11 T₀ transgenic plants were generated from 100 co-cultivated node explants, representing 10.6 % transformation frequency. Our results demonstrate high frequency, efficient and rapid transformation system for further genetic manipulation in Withania for producing engineered transgenic Withania shoots within very short duration of 3 months.     

An efficient <Emphasis Type="Italic">Agrobacterium rhizogenes</Emphasis>-mediated transformation protocol of <Emphasis Type="Italic">Withania somnifera</Emphasis>

This is the first report on Agrobacterium rhizogenes-mediated transformation of Withania somnifera for expression of a foreign gene in hairy roots. We transformed leaf and shoot tip explants using binary vector having gusA as a reporter gene and nptII as a selectable marker gene. To improve the transformation efficiency, acetosyringone (AS) was added in three stages, Agrobacterium liquid culture, Agrobacterium infection and co-culture of explants with Agrobacterium. The addition of 75 μM AS to Agrobacterium liquid culture was found to be optimum for induction of vir genes. Moreover, the gusA gene expression in hairy roots was found to be best when the leaves and shoot tips were sonicated for 10 and 20s, respectively. Based on transformation efficiency, the Agrobacterium infection for 60 and 120 min was found to be suitable for leaves and shoot tips, respectively. Amongst the various culture media tested, MS basal medium was found to be best in hairy roots. The transformation efficiency of the improved protocol was recorded 66.5 and 59.5?% in the case of leaf and shoot tip explants, respectively. When compared with other protocols the transformation efficiency of this improved protocol was found to be 2.5 fold higher for leaves and 3.7 fold more for shoot tips. Southern blot analyses confirmed 1–2 copies of the gusA transgene in the lines W1-W4, while 1–4 transgene copies were detected in the line W5 generated by the improved protocol. Thus, we have established a robust and efficient A. rhizogenes mediated expression of transgene (s) in hairy roots of W. somnifera.     

High-efficient <Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated <Emphasis Type="Italic">in planta</Emphasis> transformation in black gram (<Emphasis Type="Italic">Vigna mungo</Emphasis> (L.) Hepper)

In vitro culture and genetic transformation of black gram are difficult due to its recalcitrant nature. Establishment of gene transfer procedure is a prerequisite to develop transgenic plants of black gram in a shorter period. Therefore, genetic transformation was performed to optimize the factors influencing transformation efficiency through Agrobacterium tumefaciens-mediated in planta transformation using EHA 105 strain harbouring reporter gene, bar, and selectable marker, gfp-gus, in sprouted half-seed explants of black gram. Several parameters, such as co-cultivation, acetosyringone concentration, exposure time to sonication, and vacuum infiltration influencing in planta transformation, have been evaluated in this study. The half-seed explants when sonicated for 3 min and vacuum infiltered for 2 min at 100 mm of Hg in the presence of A. tumefaciens (pCAMBIA1304– bar) suspensions and incubated for 3 days co-cultivation in MS medium with 100 µM acetosyringone showed maximum transformation efficiency (46 %). The putative transformants were selected by inoculating co-cultivated seeds in BASTA^® (4 mg l^?1) containing MS medium followed by BASTA^® foliar spray on 15-day-old black gram plants (35 mg l^?1) in green house, and the transgene integration was confirmed by biochemical assay (GUS), Polymerase chain reaction, Dot-blot, and Southern hybridisation analyses.     

Chondroprotective potential of root extracts of <Emphasis Type="Italic">Withania somnifera</Emphasis> in osteoarthritis

This is the first report describing two novel chondroprotective activities of aqueous extracts of Withania somnifera root powder. First, these extracts had a statistically significant, short-term chondroprotective effect on damaged human osteoarthritic cartilage matrix in 50% of the patients tested. Second, these extracts caused a significant and reproducible inhibition of the gelatinase activity of collagenase type 2 enzyme in vitro.     

Withanolide production by <Emphasis Type="Italic">in vitro</Emphasis> cultures of <Emphasis Type="Italic">Withania somnifera</Emphasis> and its association with differentiation

Withanolides-steroidal lactones, isolated from various Solanaceous plants have received considerable attention due to their potential biological activities. Five selected withanolides (withanone, withaferin A, withanolide A, withanolide B, withanolide E) were identified by HPLC-UV (DAD) — positive ion electrospray ionization mass spectroscopy in Withania somnifera (L.) Dunal cv. WSR plants and tissues cultured in vitro at different developmental phases. Cultures were established from five explants on Murashige and Skoog’s medium supplemented with different plant growth regulators. Results suggest that production of withanolides is closely associated with morphological differentiation.     

A modified <Emphasis Type="Italic">in planta</Emphasis> method of <Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated transformation enhances the transformation efficiency in safflower (<Emphasis Type="Italic">Carthamus tinctorius</Emphasis> L.)

Plant transformation has emerged as an important tool to integrate foreign genes in the plant genome to modify the plants for desired traits. Though many techniques of plant transformation are available; getting single copy transgenic events and cost associated remains a big challenge. Thus Agrobacterium-mediated transformation remains the method of choice due to multiple advantages. In the present work a tissue culture free protocol of Agrobacterium-mediated transformation was optimized in safflower, an oil seed crop recalcitrant to transformation. As a proof of concept we selected pCAMBIA2300 gene cassette containing Arabidopsis specific delta 15 desaturase (FAD3) downstream to truncated seed specific promoter beta-conglycinin and optimized tissue culture free protocol of Agrobacterium-mediated transformation using embryos as explants. Addition of silwet L-77, sonication treatment, vacuum infiltration in infection medium and use of paper wicks in co-cultivation period increased the transformation efficiency to 19.3%. Further, success in transformation was confirmed via product accumulation in 21 independent transgenic events wherein oil in transformed seeds showed significant accumulation of alpha-linolenic acid (ALA; 18:3; n3) which is generated from linoleic acid (LA; 18:2; n3) in a FAD3 catalyzed reaction. The present protocol can be utilized to produce transgenic safflower with different desired characters.     

Ectopic expression of cucumber (<Emphasis Type="Italic">Cucumis sativus</Emphasis> L.) <Emphasis Type="Italic">CsTIR</Emphasis>/<Emphasis Type="Italic">AFB</Emphasis> genes enhance salt tolerance in transgenic <Emphasis Type="Italic">Arabidopsis</Emphasis>

Auxin receptors TIR1/AFBs play an essential role in a series of signaling network cascades. These F-box proteins have also been identified to participate in different stress responses via the auxin signaling pathway in Arabidopsis. Cucumber (Cucumis sativus L.) is one of the most important crops worldwide, which is also a model plant for research. In the study herein, two cucumber homologous auxin receptor F-box genes CsTIR and CsAFB were cloned and studied for the first time. The deduced amino acid sequences showed a 78% identity between CsTIR and AtTIR1 and 76% between CsAFB and AtAFB2. All these proteins share similar characteristics of an F-box domain near the N-terminus, and several Leucine-rich repeat regions in the middle. Arabidopsis plants ectopically overexpressing CsTIR or CsAFB were obtained and verified. Shorter primary roots and more lateral roots were found in these transgenic lines with auxin signaling amplified. Results showed that expression of CsTIR/AFB genes in Arabidopsis could lead to higher seeds germination rates and plant survival rates than wild-type under salt stress. The enhanced salt tolerance in transgenic plants is probably caused by maintaining root growth and controlling water loss in seedlings, and by stabilizing life-sustaining substances as well as accumulating endogenous osmoregulation substances. We proposed that CsTIR/AFB-involved auxin signal regulation might trigger auxin mediated stress adaptation response and enhance the plant salt stress resistance by osmoregulation.     

Lignin modification <Emphasis Type="Italic">in planta</Emphasis> for valorization

Lignocellulose polysaccharides are encrusted by lignin, which has long been considered an obstacle for efficient use of polysaccharides during processes such as pulping and bioethanol fermentation. Hence, numerous transgenic plant lines with reduced lignin contents have been generated, leading to more efficient enzymatic saccharification and forage digestion. However, lignin is also a potential feedstock for aromatic products and an important direct-combustion fuel, or a by-product fuel in polysaccharide utilization such as pulping and bioethanol production. For aromatic feedstock production, the complicated structure of lignin along with its occlusion within polysaccharide matrices makes lignin utilization intractable. To alleviate these difficulties, simplification of the lignin structure is an important breeding objective for future high-value utilization of lignin. In addition, higher lignin contents are beneficial for increasing heating values of lignocellulose, because lignin has much larger heating values than polysaccharides, cellulose and hemicelluloses. Structural modification of lignin may also be effective in increasing heating values of lignocellulose biomass, because the heating value of p-hydroxyphenyl lignin is highest, followed by those of guaiacyl lignin and of syringyl lignin in this order. Herein, recent developments for augmenting lignin contents and for lignin structural modifications, to improve its utilization by metabolic engineering, are outlined.     

Factors affecting <Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated transformation in <Emphasis Type="Italic">Hybanthus</Emphasis><Emphasis Type="Italic">enneaspermus</Emphasis> (L.) F. Muell.

Agrobacterium tumefaciens-mediated transformation system was established for Hybanthus enneaspermus using leaf explants with the strain LBA4404 harbouring pCAMBIA 2301 carrying the nptII and gusA genes. Sensitivity of leaf explants to kanamycin was standardized (100 mg/l) for screening the transgenic plants. Transformation parameters (OD, virulence inducer, infection time, co-cultivation period, bactericidal antibiotics, etc.) influencing the gene transfer and integration were assessed in the present investigation. Fourteen-day pre-cultured explants were subjected with Agrobacterium strain LBA4404. Optimized parameters such as culture density of 0.5 OD₆₀₀, infection time of 6 min, AS concentration of 150 µM with 3 days co-cultivation revealed maximum transformation efficiency based on GUS expression assay. The presence of gusA in transgenics was confirmed by polymerase chain reaction and Southern blotting analysis. The present transformation experiment yielded 20 shoots/explant with higher transformation efficiency (28 %). The protocol could be used to introduce genes for trait improvement as well as for altering metabolic pathway for secondary metabolites production.     

<Emphasis Type="Italic">Agrobacterium-</Emphasis>mediated transformation of gypsophila (<Emphasis Type="Italic">Gypsophila paniculata</Emphasis> L.)

As a major contributor to the flower market, Gypsophila paniculata is an important target for the breeding of new varieties. However, gypsophila breeding is strongly hampered by the sterility of this species’ genotypes and the lack of a genetic-transformation procedure for this genus. Here we describe the establishment of a transformation procedure for gypsophila (Gypsophila paniculata L.) based on Agrobacterium inoculation of highly regenerative stem segments. The transformation procedure employs stem explants derived from GA₃-pretreated mother plants and a two-step selection scheme. The GA₃ treatment was crucial for obtaining high gene-transfer frequencies (75–90% GUS-expressing explants out of total inoculated explants), as shown using three different gypsophila varieties. An overall transformation efficiency of five GUS-expressing shoots per 100 stem explants was demonstrated for cv. Arbel. The applicability of the transformation system to gypsophila was further reinforced by the generation of transgenic plants expressing Agrobacterium rhizogenes rolC driven by a CaMV 35S promoter. Transgenic gypsophila plantlets exhibited extensive rooting and branching, traits that could be beneficial to the ornamental industry.     

<Emphasis Type="Italic">Ty</Emphasis>1<Emphasis Type="Italic">/copia</Emphasis>- and <Emphasis Type="Italic">Ty</Emphasis>3<Emphasis Type="Italic">/gypsy</Emphasis>-like DNA sequences in <Emphasis Type="Italic">Helianthus </Emphasis>species

Two repeated DNA sequences isolated from a partial genomic DNA library of Helianthus annuus, p HaS13 and p HaS211, were shown to represent portions of the int gene of a Ty3 /gypsy retroelement and of the RNase-Hgene of a Ty1 /copia retroelement, respectively. Southern blotting patterns obtained by hybridizing the two probes to BglII- or DraI-digested genomic DNA from different Helianthus species showed p HaS13 and p HaS211 were parts of dispersed repeats at least 8 and 7 kb in length, respectively, that were conserved in all species studied. Comparable hybridization patterns were obtained in all species with p HaS13. By contrast, the patterns obtained by hybridizing p HaS211 clearly differentiated annual species from perennials. The frequencies of p HaS13- and p HaS211-related sequences in different species were 4.3x10(4)-1.3x10(5) copies and 9.9x10(2)-8.1x10(3) copies per picogram of DNA, respectively. The frequency of p HaS13-related sequences varied widely within annual species, while no significant difference was observed among perennial species. Conversely, the frequency variation of p HaS211-related sequences was as large within annual species as within perennials. Sequences of both families were found to be dispersed along the length of all chromosomes in all species studied. However, Ty3 /gypsy-like sequences were localized preferentially at the centromeric regions, whereas Ty1/ copia-like sequences were less represented or absent around the centromeres and plentiful at the chromosome ends. These findings suggest that the two sequence families played a role in Helianthusgenome evolution and species divergence, evolved independently in the same genomic backgrounds and in annual or perennial species, and acquired different possible functions in the host genomes.     

Molecular Characterization and <Emphasis Type="Italic">in planta</Emphasis> Detection of <Emphasis Type="Italic">Sclerotinia sclerotiorum</Emphasis> Endopolygalacturonase Genes

Sclerotinia sclerotiorum, a plant pathogenic ascomycete, secretes multiple pectinolytic enzymes that facilitate penetration, colonization, and maceration of the plant tissues. Molecular analysis has previously revealed that the pectinolytic system of the fungus is organized as a multigene family, among which a subfamily of three members encoding for neutral endopolygalacturonase (endoPG) isoforms has been characterized. Here we describe the isolation and characterization of three additional endoPG-encoding genes (pg5, pg6, and pg7) that belong to distinct phylogenetic groups. Pairwise sequence comparison between the known endoPGs from S. sclerotiorum revealed 43% to 97% identity, and the genomic organization of the pectinolytic system showed a great similarity to that of the related necrotroph Botrytis cinerea. During plant pathogenesis, a sequential expression of the endoPG-encoding genes was shown.     

The effect of polyamines on the efficiency of multiplication and rooting of <Emphasis Type="Italic">Withania somnifera</Emphasis> (L.) Dunal and content of some withanolides in obtained plants

An efficient mass multiplication protocol was developed for Withania somnifera (L.) Dunal from nodal explants of field-grown plants on Murashige and Skoog medium (MS) supplemented with 6-benzyladenine (BA) [1.5 mg L^−l], indole-3-acetic acid (IAA) [0.3 mg L^−l] and with the addition of polyamine, spermidine (20 mg L^−l) (shoot multiplication medium). A total of 46.4 shoots were obtained from nodal explants and they were elongated in the same medium in a culture duration of 6 weeks. The elongated shoots produced roots in MS medium fortified with putrescine (20 mg L^−l) after 4 weeks, and all the rooted plants were successfully hardened and acclimatized with a survival rate of 100%. An average of 276 shoots (46 × 6) was produced when at least six nodal explants obtained from each of the 46 in vitro grown shoots were cultured by microcutting method in the same shoot multiplication medium. On an average, 12,696 plants could be produced from all the shoots (276 × 46) by microcuttings in a period of 7 months. HPLC revealed a significant increase in the quantities of withanolide A, withanolide B, withaferin A and withanone in the leaves, stems, and roots of in vitro regenerated plants compared to the field-grown parent plants. Ploidy analysis using flow cytometry revealed genetic stability of in vitro regenerated plants. This protocol will be useful for scale-up production of withanolides on commercial scale.     

<Emphasis Type="Italic">S</Emphasis>-Allele characterization in self-incompatible pear (<Emphasis Type="Italic">Pyrus communis</Emphasis> L.)

Gametophytic self-incompatibility, a natural mechanism occurring in pear and other fruit-tree species, is usually controlled by the S-locus with allelic variants ( S1, S2, Sn). Recently, biochemical and molecular tools have determined the S-genotype of cultivars in various species. The present study determined the S-locus composition of ten European pear cultivars via S-PCR molecular assay, thereby obviating time-consuming fieldwork whose results are often ambiguous because of environmental effects. To verify the S-PCR assay, two putative S-allele DNA fragments of Japanese pear were isolated; their sequences proved to be identical to those reported in the databank. Six S-allele fragments of European pear were then sequenced. While field data confirmed the molecular results, fully and half-compatible field crosses were not distinguishable.     

Genetics and fine mapping of a yellow-green leaf gene (<Emphasis Type="Italic">ygl</Emphasis>-<Emphasis Type="Italic">1</Emphasis>) in cabbage (<Emphasis Type="Italic">Brassica oleracea</Emphasis> var. <Emphasis Type="Italic">capitata</Emphasis> L.)

Cabbage (Brassica oleracea var. capitata L.) is one of the most popular cultivated vegetables worldwide. Cabbage has rich phenotypic diversity, including plant height, head shape, head color, leaf shape and leaf color. Leaf color plays an important role in cabbage growth and development. At present, there are few reports on fine mapping of leaf color mutants in B. oleracea. In this study, a naturally occurring yellow-green leaf cabbage mutant (YL-1), derived from the self-pollinated progenies of the hybrid ‘Hosom’, was used for inheritance analysis and gene mapping. Segregation populations including F₂ and BC₁ were generated from the cross of two inbred lines, YL-1 and 01–20. Genetic analysis with the F₂ and BC₁ populations demonstrated that the yellow-green leaf color was controlled by a single recessive nuclear gene, ygl-1. Insertion–deletion (InDel) markers, designed based on the parental re-sequencing data, were used for the preliminary mapping with BSA (bulked segregant analysis) method. A genetic map constructed with 15 InDels indicated that ygl-1 was located on chromosome C01. The ygl-1 gene is flanked by InDel markers ID2 and M8, with genetic distances of 0.4 cM and 0.35 cM, respectively. The interval distance between two markers is 167 kb. Thus, it enables us to locate the ygl-1 gene for the first time in B. oleracea. This study lays the foundation for candidate gene prediction and ygl-1gene cloning.