Performance of Transgenic Chrysanthemum Harbouring Wasabi Defensin Gene for White Rust Disease Resistance

This study was intended to obtain white rust (Puccinia horiana) disease resistance Chrysanthemum transformed with wasabi defensin gene through mediation of Agrobacterium tumefaciens from three explant sources, i.e., leaf, lateral shoot bud, and internode. Observations were made on transformation efficiency, PCR analysis, in vitro and ex vitro disease resistance tests. Results showed that efficiency of transgenic callus and shoot regeneration was found both highest from lateral shoot buds (57.5% and 50.0%, respectively). PCR analysis showed that three putative transgenic plantlets from lateral shoot buds and one from leaf explant were putative transgenic carrying the wasabi, hpt, and nptII genes. Rooting test showed that the highest number of rooted plants was found in treatment of hygromycin (Hg) 25 mg L-1 (81%) and lowest was in treatment combination of kanamycin (Km) 50 mg L-1 + Hg 25 mg L-1 (25%). In vitro disease resistance test with sorus inoculation of P. horiana, directly on the leaves, resulted in 20 resistant plants out of 30 putative transgenic plants (66.67%). Ex vitro testing on adult plants of the same samples in a confined closed greenhouse (CGH) resulted in average of 80% transgenic Chrysanthemum plants were resistant, whereas in control plants caused white rust disease symptom

Comparison of cultivar identification methods of longkong, langsat and duku: Lansium spp.

DNA amplification (RAPD), sequencing (RAPD-based PCR) and quantification (flow cytometry) were tested for their ability to identify Lansium spp.; duku, langsat and longkong. The results revealed that all the techniques tested can be used successfully. It was clearly seen that DNA amplification and sequencing are cumbersome, expensive and time consuming. Flow cytometry is simple and quick to use, less labour intensive and accurate/repeatable and hence can be considered a practical alternative to the others. The data for measurement of DNA content showed that duku has the lowest DNA content while longkong has the highest DNA content and langsat was intermediate

Unreduced 3x gamete formation of allotriploid hybrid derived from the cross of Primula denticulata (4x) × P. rosea (2x) as a causal factor for producing pentaploid hybrids in the backcross with pollen of tetraploid P. denticulata

A triploid hybrid, which was obtained from interspecific crosses between tetraploidPrimula denticulata (2n = 4x = 44) and P. rosea (2n = 2x = 22), successfully produced 11plants by backcrossing with pollen of tetraploid P. denticulata. Analysis of ploidy level using flow cytometry and chromosome counting in the 11 BC_1 plants revealed that all progeny had much larger DNA contents and chromosome number than both parents. In this triploid-tetraploid (3x-4x) crossing, progeny was predominantly true or near pentaploid presumably produced by the fertilization between true or near triploid female gamete produced from triploid hybrid and diploid pollen of tetraploid P. denticulata. These results suggest that unreduced (3x) or near triploid female gametes were partially produced by single step meiosis, either FDR (first-division restitution) or SDR (second-divisionrestitution) process. The zygotes formed by the fertilization between true or near triploid egg produced by single step meiosis in triploid hybrid and diploid pollen produced by normal meiosis of tetraploid P. denticulata might be the only survivors in embryogenesis

A Histological Evaluation of Adventitious Bud Formation in Cotyledons in Crotalaria juncea L.

In Crotalaria juncea L., adventitious buds were formed in cotyledonary expiants cultured on 0.8% agar-solidified 1/2 MS basal medium containing B5 vitamins, 1.0 or 0.5 mg L–1 NAA, 5.0 or 10.0 mg L–1 BA and 3% sucrose. The frequency of adventitious bud formation was 30-45% in all combinations of NAA and BA. In histological observations, prominent mitotic figures were observed in several cells of the subepidermal palisade layers on the adaxial side of the expiants in contact with medium after 3 days of culture. Calli were formed within 6 days of culture. After 10 days of culture, numerous mature tracheary elements were produced at random in the proliferated regions, and cell divisions at the superficial region led to the formation of the meristematic structure. The shoot apex of the seedling produced numerous trichomes from superficial cells, but the adventitious bud formed on the cotyledon produced no trichomes. Initiation of the meristematic region in the expiant could be used as a target site for gene transfer experiments