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.

[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.