Minal Mhatre

A Study of Antioxidant Properties of Some Varieties of Grapes (Vitis vinifera L.)

Grapes (Vitis vinifera L.) are a major fruit crop in the world. Grapes seem to confer health benefits due to their antioxidant activity. We have evaluated the antioxidant potential of 11 grapes varieties from India and nearby Asian countries. The assays employed involve different levels of antioxidant action like ferric reducing antioxidant power, radical scavenging by 1,1-diphenyl-2-picrylhydrazyl, ferrylmyoglobin/2,2′-azobis-3-ethylbenzthiazoline-6-sulfonic acid, oxygen radical absorbance capacity (ORAC), and inhibition of lipid peroxidation. The total phenolic and flavonoids contents were also estimated. Our study indicates that cv. Mango is the most potent followed by Sharad Seedless. Ethanolic extracts were found to be more effective than aqueous extracts. Cv. Sharad Seedless, Mango, and Manikchaman also had high ORAC values. Their HPLC analysis showed the presence of various antioxidant polyphenols. In conclusion our studies identified some varieties of grapes with high antioxidant activities and showed that their high antioxidant potential may be due to their phenolic and flavonoid contents.

Regeneration of plants from the culture of leaves and axillary buds in mulberry (Morus indica L.)

Stem segments, axillary buds and leaves excised from established shoot cultures of Morus indica were soaked in MS liquid medium containing benzyladenine (0.5, 1, 2 mg/1) and were cultured subsequently on semi solid medium of the same composition. Numerous shoot buds differentiated from leaf and axillary buds but stem segments were unresponsive. The shoot buds on isolation and culture developed into plantlets. Callus tissues which developed at the base of the leaf explant upon subculture also differentiated numerous shoot buds.

Induction of somatic embryogenesis and plantlets in tendrils of Vitis vinifera L.

Abstract Somatic embryogenesis was observed in callus initiated from tendril explants of Vitis vinifera L. cvs. Thompson, Sonaka and Tas-e-Ganesh on Emershad and Ramming medium supplemented with 1 µm 6-benzylaminopurine. Low-frequency conversion to shoots was obtained in the third and fourth subculture on the same medium. Emerging shoots subsequently formed complete plantlets on liquid rooting medium containing 1 µm indole-3-acetic acid. The possible use of tendrils as a novel explant for somatic embryogenesis in grape is discussed.

Micropropagation of Vitis vinifera L: towards an improved protocol

Abstract Nodal explants bearing a single axillary bud, from three cultivars of cultivated grape, viz., ‘Thompson seedless’, ‘Sonaka’ and ‘Tas-e-Ganesh’, were used to initiate shoot cultures on G16 medium containing adenine sulphate, monobasic sodium phosphate, BAP and NAA. Each shoot, developed from an axillary bud, produced a tuft of multiple shoots on a medium containing BAP, calcium pantothenate, monobasic sodium phosphate and IBA. Subculture of the tuft of multiple shoots to an ‘elongation medium’ resulted in distinct individual shoots. Rooting of shoots and plantlet formation was achieved on IAA-containing liquid medium. A culture procedure for enhanced multiple shoot production and the recovery of complete plants is described. The use of this protocol for the commercial exploitation of cultivated grape is discussed.

Plantlet regeneration via somatic embryogenesis in anther callus of Vitis latifolia L.

Abstract Anthers of Vitis latifolia L. (wild grape) cultured on Nitsch and Nitsch medium supplemented with 20 μM 2,4-D and 9 μM BAP produced callus after 4–6 weeks. Subculture of callus onto Nitsch and Nitsch medium containing 10 μM NAA produced somatic embryos within 6 weeks. On growth regulator-free Nitsch and Nitsch basal medium somatic embryos converted to plantlets in 6–8 weeks. One gram of callus produced more than 400 somatic embryos with 13.7% being converted to complete plantlets, which were subsequently established in soil. Regenerated plants were found to have mixoploid populations of cells, 2n = 38 and n = 19.

Somaclonal variation in micropropagated dormant axillary buds of pineapple (Ananas comosus L., Merr.)

Summary Dormant axillary buds excised from crowns of pineapple (Ananas comosus L., Merr.) cultured on growth regulator free Nitsch medium sprouted after 8–10 d. Sprouted buds produced multiple shoots (7–10 shoots per bud) upon transfer to solidified Murashige and Skoog medium supplemented with 9.67 μM NAA, 9.84 μM IBA and 9.29 μM KIN. Each isolated shoot upon subculture to liquid medium of the same composition further proliferated to form more multiple shoots (60–65 shoots) and were maintained on a gyratory shaker (90–100 rpm). In vitro grown shoots were rooted on White medium supplemented with 0.54 μM NAA and 1.97 μM IBA. In vitro plantlets were established in cups with soilrite and hardened for four weeks. Phenotypic variants such as albinos, white streaked shoots and shoots with elongated internodes were observed in in vitro cultures. Approximately 520 in vitro produced plantlets were established in the field and these plants exhibit somaclonal variation. Thirty-eight plants were found to be yellowish, spineless with anthocyanin streaks and three were anthocyanin rich, spined plants.

Evaluation of the antioxidant activity of non-transformed and transformed pineapple: A comparative study

Pineapple has several beneficial properties including antioxidant activity. We investigated the antioxidant effect of different extracts of non-transformed (S) and transformed pineapple (with the magainin gene construct, [TS], for disease resistance). They were examined using 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging, oxygen radical absorbance capacity (ORAC) and lipid peroxidation assays besides phenolic and flavonoid contents. HPLC analysis was carried out to identify the possible components responsible for the differences observed. The present study indicates that the ORAC values of extracts range from 9.5 to 26.4, similar to or higher than those for some fruits and vegetables. The HPLC analysis shows that the main compounds present are ascorbic acid, quercetin, flavone-3-ols, flavones, cinnamic acids. The TS core Et. extract exhibited slightly higher concentration of ascorbic acid and considerably higher concentration of flavon-3-ols. Our study, in general, indicates that the transformation event has caused only marginal difference in antioxidant activity. Moreover the TS samples showed more antioxidant activity in some aspects and also exhibit more flavonoid content. It appears that plant cell transformation has only caused minor and favourable changes in the overall chemical composition. Thus the TS pineapple variety may have potential applications in human health like its non-transformed counterpart.

Cloning and molecular characterization of a putative bZIP transcription factor VvbZIP23 from Vitis vinifera

The proteins harboring bZIP domains comprise a large family and play key roles in many cellular processes, one of them being tolerance to biotic and abiotic stresses in plants. In the present study, we characterize a putative bZIP transcription factor from Vitis vinifera namely VvbZIP23. Our studies revealed that a GFP fusion of VvbZIP23 is localized in the nucleus showing VvbZIP23 codes for a nuclear localized protein. VvbZIP23 identified by in silico approaches from grapevine DNA databases available in the public domain NCBI is present in a single copy in the grapevine genome as shown by Southern blot analysis. Expression of VvbZIP23 is induced by a wide spectrum of abiotic stresses, including drought, salt, and cold. Exogenous application of signaling chemicals like abscisic acid, methyl viologen, salicylic acid, jasmonic acid, and ethephon also induced expression of VvbZIP23. This shows that VvbZIP23 is involved in regulating a number of stress responses in V. vinifera. The 5′ proximal region of VvbZIP23 contains many cis-acting elements, which show induction of VvbZIP23 expression in multiple stress responses. Transcripts of VvbZIP23 were found in many parts of the grapevine plant with the highest expression detected in leaves. Further in silico analysis shows that the open reading frame of VvbZIP23 is 822 bp long and codes for a 273 amino acid long protein having a characteristic bZIP domain in its N-terminal end. Overexpression of VvbZIP23-GFP fusion protein in grapevine callus leads to enhanced transcript levels of genes, homologues of which are reported to be important in regulating many stress conditions.

Plant Regeneration in Protoplast Cultures of Tylophora indica

Protoplasts isolated from callus tissue derived from freshly cultured stem segments of Tylophora indica (Asclepiadaceae) rapidly divided and resulted in callus. Subsequent embryoid/ shoot bud differentiation in callus was observed on MS medium supplemented with auxins and cytokinins. The embryoids/shoot buds on transfer to appropriate basal medium without growth substances grew into plantlets. Protoplasts isolated from callus tissue maintained for over five years showed divisions and subsequent callus formation but failed to regenerate plants.

Bioencapsulation of Somatic Embryos in Woody Plants

Application of synthetic seed technology in the field of micropropagtion, storage and transport has been well recognized in several agronomically important crops and woody species. Despite the spurt in synthetic seed research in the recent past, there is need for more studies mainly on the physiological and biochemical aspects of synthetic seeds, especially the factors affecting their germination and subsequent plant growth in the soil (Redenbaugh, 1990, 1993). Establishment of an efficient somatic embryogenesis system is a major prerequisite for a successful program on synthetic seeds. However, this has not been achieved very well in several important woody plants. Long life cycle, extended juvenility, poor and inconsistent seed yield and constraints in establishment of in vitro cultures are some of the major hurdles for woody plant species. It is always desirable to raise cultures from mature plants with known features and desired traits but explants from mature trees exhibit recalcitrance under aseptic conditions and therefore most studies on tree tissue culture use seedling parts. However in this, efficacy of progeny is not known.