SummaryVitamin-A deficiency (VAD) is a major malnutrition problem in South Asia, where indica rice is the staple food. Indica-type rice varieties feed more than 2 billion people. Hence, we introduced a combination of transgenes using the biolistic system of transformation enabling biosynthesis of provitamin A in the endosperm of several indica rice cultivars adapted to diverse ecosystems of different countries. The rice seed-specific glutelin promoter (Gt-1 P) was used to drive the expression of phytoene synthase ( psy ), while lycopene β -cyclase ( lcy ) and phytoene desaturase ( crtI ), fused to the transit peptide sequence of the pea-Rubisco small subunit, were driven by the constitutive cauliflower mosaic virus promoter (CaMV35S P). Transgenic plants were recovered through selection with either CaMV35S P driven hph (hygromycin phosphotransferase) gene or cestrum yellow leaf curling virus promoter (CMP) driven pmi (phophomannose isomerase) gene.

A single Agrobacterium strain harbouring two binary plasmids was successfully used for the first time to develop a marker-free transgenic rice of improved nutritional value. Sixty-eight T0 co-transformants were obtained in three indica rice cultivars--two popular high-yielding Bangladeshi varieties (BR28 and BR29), and one high-iron rice cultivar (IR68144). Marker-free lines were obtained from 14 out of 24 selected co-transformants screened in the T1 generation. The accumulation of total carotenoids in polished T2 rice seeds of the primary transgenic VPBR29-17-37 reached levels of up to 3.0 microg/g, with the level of beta-carotene reaching 1.8 microg/g. In the cultivars BR28 and IR68144, total carotenoid levels in the transformants reached 2.0 microg/g of polished rice seeds. The levels of lutein and other carotenoids in the seeds were also significantly enhanced. T1 plants obtained from primary transgenics with simple gene-integration patterns tended to have a lower carotenoid content than the original parental lines. This study describes the development of marker-free transgenic rice lines containing high levels of carotenoids, and addresses the relationship between the rearrangement of transgenes and the presence of metabolic end products in transgenic rice.

SummaryWe have developed near-isogenic introgression lines (NIILs) of an elite indica rice cultivar

Fluorescent lamps (artificial light) and sunlight were used as lighting source in present study to identify feasibility of using sunlight in plant tissue culture laboratory. In vitro regenerated nodal segments of the cardinal variety of potato (Solanum tuberosum L.) were inoculated in MS medium without any growth regulator for shoot and root development. After 30 days of culture in an average temperature at 21.94±0.21°C, relative humidity 39.35±0.75%, various morphological responses i.e. plantlet height, diameter of plantlet, number of nodes per plantlet, inter node distance, number of leaves per plantlet, fresh and dry weight of plantlets , number of root, length of root, growth rate etc. were recorded. The average light intensity at sunlight and artificial treatment was observed at 4805.5±326.54 lux and 3484±84.44 lux, respectively. All the growth factors performed better result in sunlight treatment than those of artificial one except average number of nodes and leaves. The average height of plantlet at sunlight was 53.33±3.32 mm which was greater than that of artificial light 51.67±2.15 mm. Fresh weight and dry weight are two important morphological factors for plantlet and in case of fresh weight that was always greater 0.49±0.097 in sunlighted plantlet and 0.21±0.026 in artificial one. In case of dry weight the average weight 0.08±0.016 was greater in sunlighted plantlet than that of 0.03±0.004 in artificial one. Number of roots, root length and growth rate of the plantlets observed higher in sunlighted plantlets compared to artificial light. Moreover, the sunlighted plantlets were healthier, vigorous and strong which helped plants to establish in net house easily. Considering the cost of electricity consumption, from a laboratory area of 20.47 m 2 BD Taka 63% could be saved in each month by using sunlight. As low cost options of energy saving in tissue culture laboratory using sunlight would be feasible and environmentally friendly technology for commercial point of view in Bangladesh.

This study was conducted to estimate heterosis for the yield and yield contributing traits of 32 cross combinations involving 12 diverse lines of some Bangladeshi tomato genotypes considering line x tester mating fashion at the experimental field of Sher-e-Bangla Agricultural University, Dhaka in 2016-2017 and 2017-2018 winter season. The experiment was designed in a Randomized Complete Block Design (RCBD) with three replications. The analysis of variance (ANOVA) showed highly significant difference for all the characters suggesting the presence of genetic variability among the studied materials. Four cross combinations (L1xT1, L3xT2, L3xT3, L5xT1) showed desirable negative significant heterosis for days to first flowering in both relative heterosis (RH) and heterobeltiosis (HB) ranged from -2.56% to -19.05%, respectively. Highest positive significant heterosis in both RH and HB was observed in four crosses L4xT4 (63.48% and 48.25%), L5xT2 (46.77% and 46.27%), L5xT4 (62.58% and 34.78%) and L8xT3 (37.39% and 35.12%) for individual fruit weight (g), while six crosses L1xT2, L1xT4, L3xT2, L4xT4, L5xT4 and L6xT1 exhibited highest positive significant heterosis for yield per plant (kg) in both HB and RH ranged from 16.09% to 88.46% respectively. Heterotic hybrids with maximum number of studied desirable yield contributing traits (8) of both RH and HB were identified only two crosses L1xT2 and L4xT4. Progressive Agriculture 30 (2): 179-185, 2019