ミャンマー連邦シャン州北部およびカチン州における稲遺伝資源の探索収集

Myanmar is a country having a large genetic diversity of crop genetic resources. But through the introduction of improved varieties, local varieties so called landraces are now on the verge of extinction. It is a critical stage to explore, collect and conserve domestic plant genetic resources in the country for future utilization. Thus a joint rice exploration program of MAFF Genebank project and Myanmar Seed Bank was carried out in the Northern Shan State and Kachin State of Myanmar from November 16 to December 15,2000. Of the lowland rice varieties collected, 80 percent were improved varieties introduced from foreign countries in the past 3～5 years. However some landraces suitable for the eating habitat of local people or local agro-ecological conditions such as alkali soil are still remained. On the other hand, most of the upland rice varieties were landraces although improved varieties have been gradually introduced. A total of 104 varieties including landraces, improved varieties and wild rices were collected. In the landraces, a big variation was observed on grain shape, grain color, plant type, tolerance to cool weather and resistance to pests and diseases

Studies on the effects of calorie restriction on the gene expression in Brachionus plicatilis

報告番号: 甲25839 ; 学位授与年月日: 2010-03-24 ; 学位の種別: 課程博士 ; 学位の種類: 博士(農学) ; 学位記番号: 博農第3539号 ; 研究科・専攻: 農学生命科学研究科水圏生物科学専

シオミズツボワムシの遺伝子発現に及ぼすカロリー制限の影響に関する研究

University of Tokyo (東京大学

Identification of genes differentially expressed by calorie restriction in the rotifer (Brachionus plicatilis)

A monogonont rotifer Brachionus plicatilis has been widely used as a model organism for physiological, ecological studies and for ecotoxicology. Because of the availability of parthenogenetic mode of reproduction as well as its versatility to be used as live food in aquaculture, the population dynamic studies using the rotifer have become more important and acquired the priority over those using other species. Although many studies have been conducted to identify environmental factors that influence rotifer populations, the molecular mechanisms involved still remain to be elucidated. In this study, gene(s) differentially expressed by calorie restriction in the rotifer was analyzed, where a calorie-restricted group was fed 3h day-1 and a well-fed group fed ad libitum. A subtracted cDNA library from the calorie-restricted rotifer was con-structed using suppression subtractive hybridization (SSH). One hundred sixty-three expressed sequence tags (ESTs) were identiWed, which included 109 putative genes with a high identity to known genes in the publicly available database as well as 54 unknown ESTs. After assembling, a total of 38 different genes were obtained among 109 ESTs. Further validation of expression by semi-quantitative reverse transcription-PCR showed that 29 out of the 38 genes obtained by SSH were up regulated by calorie restriction

Characterization of Myanmar Paw San Hmwe Accessions Using Functional Genetic Markers

Paw San Hmwe (PSM) rice has been cultivated in many areas of Myanmar for a long time. Strong aroma, good taste and its elongation during cooking are the key characteristics of PSM rice. Thirty-one PSM accessions were genotypically characterized, and their physical grain and cooking quality traits were studied. We used specific gene markers associated with aroma, apparent amylose content (AAC) and alkali spreading value to determine the alleles carried by different PSM accessions. The results revealed that six PSM accessions (PSM10, PSM12, PSM13, PSM21, PSM22 and PSM30) had a 3-bp insertion in Os2AP gene. Gel consistency (GC) allele was predominant among the PSM accessions for gelatinization temperature (GT), however, the phenotype observed was between low and intermediate GT because of the combination of the GC allele with the presence of low GT allele at heterozygous state from the other loci of the SSIIa gene. Intermediate to high AAC was observed among the PSM accessions corresponding to the haplotype identified for the single nucleotide polymorphism G/T and the (CT)n repeat in the Wx gene. The characterization and grouping data of PSM accessions posted benefits to Myanmar seed banks, and our results will help in maintaining the integrity of PSM rice variety

Molecular Breeding for Improving Productivity of Oryza sativa L. cv. Pusa 44 under Reproductive Stage Drought Stress through Introgression of a Major QTL, qDTY12.1

Increasing rice production is quintessential to the task of sustaining global food security, as a majority of the global population is dependent on rice as its staple dietary cereal. Among the various constraints affecting rice production, reproductive stage drought stress (RSDS) is a major challenge, due to its direct impact on grain yield. Several quantitative trait loci (QTLs) conferring RSDS tolerance have been identified in rice, and qDTY12.1 is one of the major QTLs reported. We report the successful introgression of qDTY12.1 into Pusa 44, a drought sensitive mega rice variety of the northwestern Indian plains. Marker-assisted backcross breeding (MABB) was adopted to transfer qDTY12.1 into Pusa 44 in three backcrosses followed by four generations of pedigree selection, leading to development of improved near isogenic lines (NILs). Having a recurrent parent genome (RPG) recovery ranging from 94.7–98.7%, the improved NILs performed 6.5 times better than Pusa 44 under RSDS, coupled with high yield under normal irrigated conditions. The MABB program has been modified so as to defer background selection until BC3F4 to accelerate generational advancements. Deploying phenotypic selection alone in the early backcross generations could help in the successful recovery of RPG. In addition, the grain quality could be recovered in the improved NILs, leading to superior selections. Owing to their improved adaptation to drought, the release of improved NILs for regions prone to intermittent drought can help enhance rice productivity and production