• C R Bhatia

      Articles written in Proceedings – Plant Sciences

    • Genetic transformation of plants

      C R Bhatia Patricia Viegas Anjali Bhagwat Helena Mathews N K Notani

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      Current status of the molecular approaches for integrative genetic transformation of plants is reviewed.Agrobacterium-mediated and direct DNA transformation of protoplasts are considered. Elucidation of the molecular events in natural genetic transformation of plant cells in crown gall disease caused byAgrobacterium tumefaciens, has led to the development of T-DNA based vectors for introducing exogenous DNA into plant cells. Various strategies used for this are discussed. So far,Agrobacterium-mediated transformation has been most successful and widely used in dicotyledonous plants. Direct DNA transformation involves either DNA uptake by protoplasts or its mechanical delivery into the cell nucleus. Transformation of both monocotyledonous and dicotyledonous plant cells has been shown by this method. The genes transferred into plants from bacteria, other plant and animal species and various promoters used in chimeric gene constructs for the expression of such genes are listed. Organ specific expression and Mendelian inheritance of transferred genes have been demonstrated. Prospects of the transformation technique for the improvement of crop plants are examined. Gene transfers reported so far indicate that the immediate benefits will be in the development of cultivars carrying herbicide resistance or biocide gene(s). Identification, isolation and cloning of DNA sequences governing resistance to plant diseases or pests, and their introduction into improved cultivars could become possible in the future. Isolation, in vitro modification and re-introduction of the modified gene(s) back into the plant genome is yet another possibility for the future.

    • Screening for powdery mildew (Erysiphae polygoni DC.) resistance in mungbean (Vigna radiata (L.) Wilczek) using excised leaves

      K S Reddy S E Pawar C R Bhatia

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      A simple, reliable method for assessing powdery mildew reaction on excised mungbean leaves has been developed and used for screening germplasm accessions. Third trifoliate leaves from 21–25 day old field-grown plants were cultured in enamel trays filled with tap water at 21±1°C, 12 h/day photoperiod (4136 lux/m2 from incandescent and white fluorescent light). After 9–12 days such leaves showed rooting from petiole and substantial root growth followed. Excised leaves could be maintained upto 40 days. Leaves were sprayed with conidial suspension (3·5×106 conidia/ml) of a local isolate of powdery mildew fungus. In susceptible types, powdery mildew lesions appeared 8–10 days after inoculation, enlarged and coalesced to cover the entire leaf area in 20 days. Fifty five germplasm accessions were tested using this method; all except 7 RUM accessions were susceptible. These RUM accessions showed resistant reaction even after two reinoculations. They were also resistant in the field under natural powdery mildew infection.

    • Yield and oil content of doubled haploids of mustard (Brassica juncea (L.) Czern. and Coss.)

      V Abraham L George V T Srinivasan C R Bhatia

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      Progenies of androgenetic doubled haploid plants of mustard cv TM-4 in A4−A6 generations were evaluated for their seed yield and oil content. Eight progenies in the A5 generation out of the 97 (8%) A1 plants regenerated were equal in yield to the parent cultivar. The oil percentage in these doubled haploids were in the same range as that of the parent cultivar. The remaining androgenetic doubled haploids were statistically lower in yield. The data indicates that about 8% of thein vitro raised androgenetic plant progenies had no adverse effects on yield potential and point to the need for obtaining a large number of androgenetic doubled haploids to recover genotypes more productive than the better parent.

    • Seed coat and hypocotyl pigments in greengram and blackgram

      R N Pandey S E Pawar G J Chintalwar C R Bhatia

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      Three anthocyanins were found inVigna radiata (greengram) accessions with black seed coat, but were absent in cultivars having green seed coat.Vigna mungo (blackgram) had only one of them. The same 3 anthocyanins were found in cultivars with purple red hypocotyl ofVigna radiata accessions but were absent in the ones with green hypocotyls.Vigna mungo with purple red hypocotyls showed the presence of two anthocyanins. One common to both was identified as delphinidin-3-glucoside and the other is probably cyanidin-3-glucoside. Among the two accessions ofVigna radiata varsublobata examined, one was similar toVigna radiata accessions with black seed coat having delphinidin-3-glucoside and two other anthocyanins, while the other resembledVigna mungo having only delphinidin-3-glucoside in seed coat and both delphinidin and cyanidin-3-glucosides in hypocotyl. Chlorophyll content of the seed coats was in the following decreasing order: green, black, brown and yellow. Browning of the seed coat of cv TAP-7 after storage over a year was associated with reduction in chlorophyll content.

    • Inheritance of polypetalous corolla mutation in sesame

      G S S Murty C R Bhatia

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      A true breeding mutant having free corolla lobes, designated as polypetalous mutant was obtained in sesame (Sesamum indicum Linn.), after irradiating seeds of cv N62-32 with 1·6 kr fast neutrons. The inheritance pattern indicated that the polypetalous corolla is monogenic recessive to the gamopetalous corolla characteristic of sesame and the family Pedaliaceae. After crossing to another induced mutant having gamopetalous corolla with a band of pink coloured dots, a genetic stock with two recessive markers was isolated.

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