Heading date, a complex quantitative trait, determines regional adaptability and is associated with grain yield and quality in rice. In this study, we characterized qHd2-1, a minor-effect quantitative locus (QTL) for promoting heading date (by 3–4 days) under long-day (LD) conditions, but not short-day (SD) conditions. The qHd2-1 locus was detected in single segment substitution line (SSSL) N22-1, which was developed using indica 9311 as the donor and japonica Nipponbare (NP) as the recipient. A set of substitution lines were developed from a segregating population derived from a cross between N22-1 and NP. Based on the genotypic identification and phenotypic evaluation of the target substitution lines, qHd2-1 was narrowed down to a 105-kb region between STS2-20 and STS2-22 on the short arm of chromosome 2. Furthermore, qHd2-1 was found to function by upregulating the florigen genes Hd3a and RFT1 during floral induction under LD conditions. Field tests showed that qHd2-1 promotion of heading date affects grain yield‑related agronomic traits, such as plant height, panicle number per plant, and flag leaf size, as well as thousand-grain weight and grain width. Taken together, these findings establish a foundation for cloning this minor-effect QTL involved in heading date, and qHd2-1 could be of great significance in rice breeding to allow the fine-tuning of heading date in rice cultivars.

抽穗期是一个复杂的数量性状，它决定区域的适应性，并与水稻的籽粒产量和品质有关。在这项研究中，我们对qHd2-1进行了表征，qHd2-1是次要的定量基因座（QTL），用于在长日（LD）条件下促进抽穗日期（3-4天），但在短日（SD）条件下不促进。所述qHd2-1在单个片段置换系（SSSL）N22-1，其使用开发检测轨迹籼稻9311作为供体和粳稻日本晴（NP）作为受体。从来自N22-1和NP之间杂交的分离种群中开发了一组替代系。基于目标替代品系qHd2-1的基因型鉴定和表型评估被缩小到染色体2。此外短臂STS2-20和STS2-22之间的105-kb的区域，qHd2-1被上调成花素基因发现功能Hd3a和RFT1 LD条件下花诱导期间。田间试验表明，qHd2-1抽穗期的提高会影响与产量相关的农艺性状，例如株高，单株穗数和剑叶大小以及千粒重和粒宽。综上所述，这些发现为克隆涉及抽穗期的次要效应QTL奠定了基础，而qHd2-1在水稻育种中具有重要意义，可以对水稻品种的抽穗期进行微调。