Harnessing the hidden genetic diversity for improving multiple abiotic stress tolerance in rice (Oryza sativa L.).

To develop superior rice varieties with improved yield in most rainfed areas of Asia/Africa, we started an introgression-breeding program for simultaneously improving yield and tolerances of multiple abiotic stresses. Using eight BC1 populations derived from a widely adaptable recipient and eight donors plus three rounds of phenotypic selection, we developed 496 introgression lines (ILs) with significantly higher yield under drought, salt and/or non-stress conditions in 5 years. Six new varieties were released in the Philippines and Pakistan and many more are being evaluated in multi-location yield trials for releasing in several countries. Marker-facilitated genetic characterization revealed three interesting aspects of the breeding procedure: (1) the donor introgression pattern in specific BC populations was characteristic; (2) introgression frequency in different genomic regions varied considerably, resulting primarily from strong selection for the target traits; and (3) significantly lower heterozygosity was observed in BC progenies selected for drought and salinity tolerance. Applying strong phenotypic selection under abiotic stresses in early segregating generations has major advantages for not only improving multiple abiotic stress tolerance but also achieving quicker homozygosity in early generations. This breeding procedure can be easily adopted by small breeding programs in developing countries to develop high-yielding varieties tolerant of abiotic stresses. The large set of trait-specific ILs can be used for genetic mapping of genes/QTL that affect target and non-target traits and for efficient varietal development by designed QTL pyramiding and genomics-based recurrent selection in our Green Super Rice breeding technology.

[Factors associated with retention in a community-based methadone maintenance treatment among drug users in Urumqi, Xinjiang Uigur Autonomous Region].

OBJECTIVE: To explore the factors associated with retention in a community-based methadone maintenance treatment(MMT) among drug users in Urumqi. METHODS: With national MMT guideline( drift) for heroine addicted drug users, local heroine-dependent people were admitted to community-based MMT program affiliated to Xinjiang Uigur Autonomous Region Center for Mental Health. Data on outpatients' social-demo characteristics, baseline behaviors on drug use and daily stabilized dose of drugs were entered to MMT database. RESULTS: Up to 10, Feb. , 2006,353 persons withdrew MMT treatment among 709 heroin dependant drug users. Between 11, Aug., 2005 and 10, Feb., 2006, with median duration as 77 days, cumulative drop-out rate of 90 days and 180 days after first dose of MMT were 73.8% among 455 and 99.4% among 355 drug users, respectively. The incidence of drop-outs was 29.8 per 100 person-month. The median length of stay (days) in MMT was 68.0 (95% CI: 59.0- 78.0). Correlates of retention were found as: Being Uigur(HR = 1.35;95% CI :1.09-1.67), duration of drug use (HR =0.74; 95% CI:0.55-0.99) and stabilized dose(HR = 0.60;95% CI: 0.48-0.74) was found in multiple Cox proportional hazard regression model. CONCLUSION: Retention of MMT among drug users in Urumqi was low. Uigur people should be given individual counseling to help them increase the compliance rate. Within the ranges of clinic dosage, adjustment of the methadone dose on an individual base might serve as an appropriate approach to increase the effectiveness of the program.