QTL mapping reveals a tight linkage between QTLs for grain weight and panicle spikelet number in rice.

BACKGROUND: A number of QTL studies reported that one genomic region was associated with several traits, indicating linkage and/or pleiotropic effects. The question of pleiotropy versus tight linkage in these studies should be solved using a large-size population combined with high-density mapping. For example, if each of the 2 parents has a TGW-increasing or SPP-increasing QTL that is tightly linked, complementary combination of the 2 beneficial QTLs by using molecular markers could produce higher yields compared to the 2 parents. However, a pleiotropic QTL with opposite effects on the SPP and 1,000-grain weight (TGW) is complicated and challenging in terms of its application to rice improvement. RESULTS: In this study, using a series of BC5F4 nearly isogenic lines (NILs) that were derived from a cross between the Korean japonica cultivar Hwayeongbyeo and Oryza rufipogon, we demonstrated that 2 QTLs, qSPP5 for spikelets per panicle (SPP) and qTGW5 for grain weight (TGW), are tightly linked on chromosome 5. Alleles from the O. rufipogon parent increased the SPP and decreased TGW in the Hwayeongbyeo background. qSPP5 was located within a 803-kb interval between the simple sequence repeat (SSR) markers INDEL3 and RM18076. Based on the map position, qTGW5 seemed to be the same gene as qSW5, which controls grain morphology. The additive effect of the O. rufipogon allele at qSPP5 was 10-15 SPP, and 33.0% of the phenotypic variance could be explained by the segregation of the SSR marker RM18058. Yield trials with BC5F4 NILs showed that lines that contained a homozygous O. rufipogon introgression at the qSPP5 region out-yielded sibling NILs that contained Hwayeongbyeo DNA by 15.3% and out-yielded the Hwayeongbyeo parent by 7.3%. CONCLUSION: Based on the finding that the O. rufipogon allele for the SPP was beneficial in the japonica and indica cultivar backgrounds, the qSPP5 allele could be valuable for improving rice yields. In addition, the NIL populations and molecular markers are useful for cloning qSPP5.

[Effects of different ecological conditions on grain quality and RVA profile of japonica rice from Yunnan of China and Korea].

Taking sixteen japonica rice varieties from Yunnan of China and Korea growing at three locations with different altitudes in Yunnan Plateau as test materials, this paper studied the effects of different ecological conditions on their grain quality, including brown rice length (BRL), brown rice width (BRW), length-width ratio (L/W), chalky rate (CR), whiteness (WH), amylose content (AC), protein content (PC), and alkali digestion value (ADV), and their starch RVA profile, including peak viscosity (PKV), hot viscosity (HTV), final viscosity (FLV), breakdown viscosity (BDV), setback viscosity (SBV), consistence viscosity( CTV), peak time (PeT), and pasting temperature (PaT). Of all the test parameters, SBV had the largest coefficient of variation. The coefficients of variation of BRL, CR, AC, PC, ADV, FLV, SBV, and PeT of Yunnan varieties were higher than those of Korean varieties, while the BRW, L/W, WH, PKV, HTV, BDV, CTV, and PaT of Korean varieties had higher coefficients of variation than those of Yunnan varieties. With increasing altitude, the BRL, BRW, L/W, WH, AC, ADV, FLV, and CTV of Yunnan varieties, and the BRL, BRW, WH, PC, PKV, HTV and BDV of Korean varieties decreased significantly, while the CR, PC, HTV, and PeT of Yunnan varieties, and the L/W, AC, ADV, SBV and CTV of Korean varieties increased significantly. The CR of Korean varieties had no obvious change. The PKV, BDV, and PaT of Yunnan varieties and the PaT of Korean varieties increased after an initial decrease, whereas the SBV of Yunnan varieties and the FLV and PeT of Korean varieties were in reverse.

Reform Microbiology Experiment Teaching Methods, Enhance the Students’ Comprehensive Abilities / 微生物学通报

In order to cultivate the students’ abilities of thinking and practicing and enhance their comprehensive abilities in microbiology experiment, the authors try to search for some new teaching ways and assessment methods in microbiology experimental teaching and also attempt to make some improvement in the textbook and adjustment in teaching schedule so as to develop the students into specialized talents.