Molecular characterization of marker-free transgenic lines of indica rice that accumulate carotenoids in seed endosperm.

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.

Current developments in plant biotechnology for genetic improvement: the case of rice (Oryza sativa L.).

As the World's population is expanding rapidly, all possible techniques for crop improvement must be utilized to meet the food demands of the next century. Although conventional breeding techniques have considerably increased the productivity of modern crops, the application of advanced molecular technologies could speed up further crop improvement. Use of biotechnology, such as the various tissue-culture methods and gene-transfer techniques now available, could significantly shorten the breeding process, and overcome some of the substantial agronomic and environmental problems that have not been solved using conventional methods. The present review discusses biotechnological developments in the genetic improvement of rice, the principal food for more than a third of the World's population.

Field performance of anther-culture-derived lines from F1 crosses of Indica rices under saline and nonsaline conditions.

Field experiments were conducted to evaluate and compare the yield and agronomic characteristics of anther-culture-derived (AC) lines in rice and the parents under saline and nonsaline soil conditions. The yield stability of two entries was also evaluated by comparing their performance under two distinct nonsaline soil environments. The test entries were planted in randomized complete block design with four replications at each test location. Data were collected on grain yield, yield components, and agronomic characteristics. This study demonstrates that through anther culture, it is possible to produce homozygous diploid lines in a short time. The possibility of regenerating recombinants with desirable characteristics such as good plant type and salinity tolerance, higher yield, and increased resistance to pests and diseases from both the parents is high.

Anther culture in rice: IV. The effect of abscisic acid on plant regeneration.

The effect of abscisic acid (ABA) on plant regeneration in anther-derived calli of rice Oryza sativa L. varieties Taipei 177, Taipei 309 and Fujisaka 5 was studied.ABA at concentrations up to 4×10(-6) M stimulated fresh weight increase in Taipei 309 and Fujisaka 5 while higher concentrations effected corresponding weight decreases in the three varieties tested. Relatively high ABA concentrations resulted in decreased callus size and production of more compact and whitish calli. ABA increased the frequency of calli producing green plants in Taipei 309 and the average green plant regeneration in all varieties tested.