TDK1 is a popular rice variety from the Lao PDR. Originally developed for irrigated conditions, this variety suffers a high decline in yield under drought conditions. Studies have identified three quantitative trait loci (QTLs) for grain yield under drought conditions, qDTY3.1 , qDTY6.1 , and qDTY6.2 , that show a high effect in the background of this variety. We report here the pyramiding of these three QTLs with SUB1 that provides 2-3 weeks of tolerance to complete submergence, with the aim to develop drought- and submergence-tolerant near-isogenic lines (NILs) of TDK1. We used a tandem approach that combined marker-assisted backcross breeding with phenotypic selection to develop NILs with high yield under drought stress and non-stress conditions and preferred grain quality. The effect of different QTL combinations on yield and yield-related traits under drought stress and non-stress conditions is also reported. Our results show qDTY3.1 to be the largest and most consistent QTL affecting yield under drought conditions, followed by qDTY6.1 and qDTY6.2 , respectively. QTL class analysis also showed that lines with a combination of qDTY3.1 and qDTY6.1 consistently showed a higher tolerance to drought than those in which one of these QTLs was missing. In countries such as Lao PDR, where large areas under rice cultivation suffer vegetative-stage submergence and reproductive-stage drought, these lines could ensure yield stability. These lines can also serve as valuable genetic material to be used for further breeding of high-yielding, drought- and submergence-tolerant varieties in local breeding programs.

中文翻译：

---

结合水稻的耐旱性和耐淹性：标记辅助育种和QTL组合效应。


TDK1 是老挝人民民主共和国的流行水稻品种。该品种最初是为灌溉条件而开发的，但在干旱条件下产量会大幅下降。研究已经确定了干旱条件下谷物产量的三个数量性状基因座（QTL）：qDTY3.1、qDTY6.1和qDTY6.2，它们在该品种的背景下表现出很高的效果。我们在这里报告了这三个 QTL 与 SUB1 的金字塔化，提供 2-3 周的完全淹没耐受性，目的是开发 TDK1 的耐旱和耐淹没近等基因系 (NIL)。我们采用串联方法，将标记辅助回交育种与表型选择相结合，开发在干旱胁迫和非胁迫条件下具有高产量和优选谷物品质的 NIL。还报道了干旱胁迫和非胁迫条件下不同QTL组合对产量和产量相关性状的影响。我们的结果显示，qDTY3.1 是干旱条件下影响产量最大且最一致的 QTL，其次是 qDTY6.1 和 qDTY6.2。 QTL类别分析还表明，具有qDTY3.1和qDTY6.1组合的品系始终表现出比其中一个QTL缺失的品系更高的干旱耐受性。在老挝人民民主共和国等国家，大面积水稻种植遭受营养阶段淹没和生殖阶段干旱，这些品系可以确保产量稳定。这些品系还可以作为宝贵的遗传材料，用于在当地育种计划中进一步培育高产、耐旱和耐淹的品种。