A doubled haploid （DH） population, which consists of 120 lines derived from anther culture of a typical indica and japonica hybrid‘CJ06＇/‘TNI＇, was used in this study. Ligule lengths of flag leaf were investigated for quantitative trait loci （QTL） mapping using the DH population. Five QTLs （qLL-2, qLL.4, qLL-6, qLL-IO and qLL-12） controlling the ligule length （LL） were detected on chromosomes 2, 4, 6, 10 and 12, with the variances explained 11.4%, 13.6%, 27.8%, 22.1% and 11.0%, respectively. Using four known genes of ZmGL1, ZmGL2, ZmGL3 and ZmGL4 in maize from the MaizeGDB, their homologs in rice were aligned and integrated into the existing simple sequence repeats linkage map by in silico mapping. A ZmLG1 homolog gene, OsLG1 encoding a squamosa promoter binding protein, was located between the markers RM255 and RM280, which is just identical to the interval of qLL.4 on the long arm of chromosome 4. The results are beneficial to dissection of the ligule molecular mechanism and the study of cereal evolution.
Dali ZengJiang HuGuojun DongJian LiuLongjun ZengGuangheng ZhangLongbiao GuoYihua ZhouQian Qian
A mutant of panicle differentiation in rice called non-panicle （nop） was discovered in the progeny of a cross between 93-11 and Nipponbare. The mutant exhibits normal plant morphology but has apparently few tillers. The most striking change in nop is that its panicle differentiation is blocked, with masses of fluffy bract nodes generate from the positions where rachis branches normally develop in wild-type plants. Genetic analysis suggests that nop is controlled by a single recessive gene, which is temporarily named Nop（t）. Based on its mutant phenotype, Nop（t） represents a key gene controlling the initiation of inflorescence differentiation, By using simple sequence repeat markers and sequence tagged site markers, Nop（t） gene was fine mapped in a 102-kb interval on the long arm of chromosome 6. These results will facilitate the positional cloning and functional studies of the gene.
This paper introduces Vietnam's climate condition,main rice production regions and analyses the expansion of rice planting area,rice cropping system during the last decades.The result from the change of rice production,planting area,yield,and rice trade indicates that the economic reforms in Vietnam from 1986 have contributed to a spectacular rise in rice production and exports.However,there are still problems and opportunities for rice production and export in Vietnam.The paper suggests that Vietnam should make the most use of the advanced international rice cultivars and technology to improve irrigation and water conservancy facilities to benefit rice farmer and consolidate Vietnam to be the major exporter of rice in the world market.
The extraction of DNA is often the most time consuming and laborious step in high-throughput molecular genetic analysis and marker assisted selection （MAS） programs. A simple method for preparation of rice genomic DNA was developed. A small amount （1~50 mg） of leaf tissue of rice seedling, 500 pL of extraction buffer, and one steel bead were put into a 2-mL microcentrifuge tube. After vigorously mashing for 2 min, 5 μL of supernatant was directly applied to PCR amplification. Otherwise, the supematant was precipitated with two times volume of ethanol to obtain high quality genomic DNA. This method is simple, rapid, low cost, and reliable for PCR analysis. One person can manipulate as many as 96 samples for PCR in 10 min. It is especially suitable for genotyping of large number of samples.
A double haploid （DH） population, which consists of 120 lines derived from anther culture of a typical indica and japonica hybrid ‘CJ06＇/‘TNI＇, was used to investigate the genetic basis for rice leaffolder resistance. Using a constructed molecular linkage map, five QTLs for rolled leaves were detected on chromosomes 1, 2, 3, 4, and 8. The positive alleles from C J06 on chromosomes 3, 4, and 8 increased the resistance to rice leaffolder, and the alleles from TN1 on chromosomes 1 and 2 also enhanced resistance to leaffolder. The interactions between QTLs were identified and tested, and four conditional interactions were acquired for resistance to rice leaffolder. These loci were located on chromosomes 2, 9, 10, and 11, respectively. QTL pyramiding indicated that the positive alleles affect resistance to leaffolder. The prospective application of this data in rice breeding was also discussed.
