Clarification of the mechanisms of growth response to cultivation methods in rice plants with genome information

为分析深水灌溉在QTL水平上对秋光（温带粳稻）与IRAT109（热带粳稻）杂交的回交自交系群体分蘖数（TN）、茎粗（CT）和穗粒数（SPP）的影响，于2004年和2005年在宫城大学实验农场进行了标准灌溉和深水灌溉两种不同灌溉方式下的TN、CT、籽粒产量（YD）及其构成因素的研究。双因素方差分析显示，几乎所有性状都存在显著的灌溉基因型相互作用。在全氮和穗数（PN）的qtl中，部分qtl与灌溉存在交互作用，如两种不同灌溉方式LOD评分差异较大或相对参数LOD评分较高的qtl（标准灌溉与深水灌溉条件下各参数的比值）。此外，CT和SPP的qtl与它们共定位，在相对参数上具有相反的作用。说明深水灌溉对分蘖抑制、CT增大和SPP增加之间存在因果关系。1个与灌溉相互作用的CT QTL与TN QTL不对应，说明深水灌溉直接增大CT（=不仅通过抑制分蘖）的机制也存在。在QTL水平上考察产量形成，12号染色体上PN的QTL与一年内YD的大效应QTL相对应，说明PN在QTL水平上对YD有较强的调控作用。但其对YD的影响被SPP的相反作用所抵消，因此在其他年份未检测到YD的QTL。PN与SPP在QTL水平上的代偿机制的不适应性决定了YD的QTL表达模式。

To analyze the effect of deep water irrigation on tiller number (TN), culm thickness (CT) and spikelet number per panicle (SPP) at QTL level, TN, CT, grain yield (YD) and its components of backcross inbred population from the cross between Akihikari (temperate japonica) and IRAT109 (tropical japonica) were investigated under two different water regimes (the standard irrigation and the deep-water irrigation) at the experimental farm of the Miyagi University in 2004 and 2005.Two-way ANOVA revealed significant genotype-by-irrigation interactions for almost all traits. Among QTLs for TN and panicle number (PN), some QTLs interacted with irrigation (QTLs with great difference in LOD score between two different water regimes or high LOD score in relative parameter [the ratio of the parameters under the standard irrigation and the deep-water irrigation]).In addition, QTLs for CT and SPP were co-localized with them and had an opposite effect in relative parameter. This suggests the causal relationship between tiller suppression, enlargement of CT and increment of SPP by deep water irrigation. One QTL for CT interacting with irrigation was not corresponded to any QTLs for TN, suggesting the mechanism that deep water irrigation enlarges CT directly (=not only through tiller suppression) also exists. Examining the yield formation at QTL level, QTL for PN on chromosome 12 corresponded to large-effect QTL for YD in a year, suggesting that PN strongly regulates YD at QTL level. But its effect on YD was cancelled out by the opposite effect of SPP, thus QTL for YD is not detected in the other year. The unsuitability of compensatory mechanism at QTL level between PN and SPP determines the expression pattern of QTL for YD.