Two field experiments were conducted to ascertain the potential of micropropagation technique for faster production of seed cane by using tissue culture plants raised through apical meristem culture in first generation (TC 0) followed by clonal propagation through cane setts in next generation (TC1). About 18, 520 plants, produced from a single shoot through micropropagation, were required at row to row and plant to plant spacing of 90 and 60 cm, respectively as compared to 88 quintal of cane seed in conventional methods for planting in an area of one hectare. Multiplication ratio was 100-150 times using tissue culture plants as compared to 11-12 using conventional cane setts, leading to drastic reduction in seed cane requirement. The TC 1 exhibited superiority over vegetatively propagated conventional crop for millable canes and stalk yield by 17 and 10.4 per cent, respectively. Though the single cane weight and cane diameter (non-significantly) were slightly lesser in TC1 as compared to conventional crop, this did not distress its potential as seed crop. The incidence of Ratoon Stunting Disease (RSD) and Leaf Scald Disease (LSD) was very low in TC 1 crop as compared to conventional crop. The findings established the potential of tissue culture technique for the production of quality seed free of pests and pathogens in the existing varieties and rapid multiplication of newly released varieties for quick adoption by the growers.

Somatic embryogenesis and plantlet formation were obtained from callus and cell suspension cultures of 40-year- old Himalayan Poplar (Populus ciliata Wall ex Royle). Callus and cell suspensions were obtained by transfer of inoculum of semiorganized leaf cultures, which were maintained on Murashige and Skoog (MS) medium supplemented with benzylaminopurine (BAP), to MS with 2,4-dichlorophenoxyacetic acid (2,4-D). Reduction of 2,4-D concentration during subsequent subculture of cell suspensions resulted in the formation of embryoids. These embryoids developed further only after being transferred to agar-based MS medium supplemented with BAP and naphthalene acetic acid. Loss of embryogenic potential was observed in cell suspensions after 6 subcultures. However, callus cultures retained the embryogenic potential even after repeated subcultures for more than a year. Plantlets could be successfully hardened and grown in natural outdoor conditions.

No abstract

A widespread leaf deformity disease of mentha (mint), accompanied by whiteflies, the vectors of begomoviruses, was observed in Punjab in the last few years. The presence of begomovirus was indicated by DNA dot-blot analysis using the conserved coat protein and replicationassociated protein genes of another begomovirus, Sri Lankan cassava mosaic virus (SLCMV). A DNA fragment (2.0 kb), representing a partial genomic DNA of a begomovirus, amplified from the symptomatic mentha leaves was used to design end-primers and further amplify an additional 0.9 kb fragment, representing the remaining portion of the resident viral DNA. The two sequences, assembled together (2.7 kb), showed that they represented the complete sequence of an isolate of Tomato leaf curl Karnataka virus (ToLCKV) DNA. Using universal betasatellite primers, a 1.4 kb fragment was amplified from the same sample. This cloned DNA fragment showed complete sequence identity with the previously reported Cotton leaf curl Multan betasatellite (CLCuMB). Majority of the symptomatic mentha leaf samples, collected from four districts of Punjab, showed cross-hybridization in DNA dot-blot using cloned SLCMV and CLCuMB DNA, indicating the presence of one or more begomoviruses related to SLCMV and the betasatellite, CLCuMB. The begomovirus and betasatellite could be mechanically transmitted to Nicotiana benthamiana. Whitefly transmission of the resident begomovirus could also be demonstrated on mentha. The evidence indicates the association of ToLCKV and CLCuMB, a hitherto new combination of a begomovirus and a betasatellite associated with a leaf deformity disease in mentha in Punjab.

No abstract