Abstract:

To address the breeding bottlenecks, specifically the prominent homogenization of japonica rice varieties, narrow genetic base, and the difficulty in synergistically improving yield and quality in Heilongjiang Province—this study utilized 676 japonica rice accessions from cold regions (comprising 485 germplasm resources and 191 major cultivars). Leveraging the RICE40 breeding chip and phenotypic identification data from four representative ecological sites (Wuchang, Minzhu, Jiamusi, and Heihe), we systematically investigated the regulatory effects of indica introgression on trait evolution, yield formation, and quality characteristics in cold region japonica rice. The results indicated a significant increasing trend in the proportion of indica ancestry in cold region japonica rice over successive breeding eras, with the major cultivar population exhibiting a significantly higher indicaproportion than the germplasm resource population. Indica introgression segments were unevenly distributed across all 12 rice chromosomes, with high-frequency introgressed segments predominantly enriched on chromosomes 2, 3, 5, 6, 9, 10, and 12. Correlation analysis revealed that indica ancestry was significantly positively correlated with spikelet number per panicle, panicle weight, and plant height, effectively enhancing yield potential. However, it also led to a significant decrease in head milled rice rate and taste value, alongside a significant increase in grain protein content. Furthermore, 164 related functional genes were identified. Notably, superior indica genes for disease resistance (Pii/HIT7/pi5-1) and yield enhancement (GW8/OsSPL16) underwent strong artificial selection in the major cultivar population. The frequency of GW8/OsSPL16 in the major cultivated population (16.2%) was significantly higher than that in the germplasm resourse population (1.2%), whereas Pii/HIT7/pi5-1 maintained a stably high allele fequency of 19.0% in both populations. These findings provide crucial theoretical insights and core gene resources for broadening the genetic background of cold region japonica rice and advancing molecular precision design breeding via inter-subspecific hybridization.

Key words: cold region japonica rice, indica ancestry, RICE40 breeding chip, yield traits, taste quality, functional genes

摘要：

针对黑龙江省粳稻品种同质化突出、遗传基础狭窄、产量与品质协同改良难度大的育种瓶颈，本研究以676份寒地粳稻材料（含485份种质资源、191份主栽品种）为试验材料，依托RICE40水稻育种芯片，结合485份种质材料在五常、民主、佳木斯、黑河4个典型生态区的表型鉴定数据，系统探究了籼型血缘渗入对寒地粳稻性状演化、产量形成及品质特性的调控规律。结果表明，寒地粳稻籼型血缘比例随育种年代推移呈显著上升趋势，且主栽群体籼型血缘比例极显著高于资源群体；籼型血缘区段在水稻12条染色体上呈不均匀分布，高频渗入区段主要富集于第2、3、5、6、9、10、12号染色体。相关性分析显示，籼型血缘与粳稻穗粒数、穗质量及株高呈显著正相关，可有效提升品种单产潜力，但会显著降低整精米率与食味值，同时显著提高籽粒蛋白质含量。本研究共鉴定获得164个相关功能基因，其中抗病优异籼型基因Pii/HIT7/pi5-1、增产优异籼型基因GW8/OsSPL16在主栽群体中经受强烈人工选择，GW8/OsSPL16在主栽群体中的频率（16.2%）显著高于在资源群体中的频率（1.2%），Pii/HIT7/pi5-1在两群体中均保持19.0%的稳定高频分布。本研究结果可为利用籼粳亚种间杂交拓宽寒地粳稻遗传背景、开展分子精准设计育种提供重要理论依据与核心基因资源。

关键词: 寒地粳稻, 籼型血缘, RICE40育种芯片, 产量性状, 食味品质, 功能基因