Extreme temperature events associated with climate change have led to significant declines in rice production, particularly when they occur during reproductive growth stages. However, existing models lack the ability to capture the distinct effects of sustained versus episodic low-temperature stress. In this study, a two-year temperature-controlled experiment was conducted with two temperature levels to compare the impacts of individual and combined low-temperature stress at booting (BS), flowering (FS), and combined (BS + FS) stages on rice yield and its components. Low-temperature stress occurring at booting and combined stages significantly reduced spikelet fertility in the upper spike and grain number in the lower spike, whereas it showed a stronger effect on the spikelet fertility in the lower spike at flowering stage. Under the same cooling degree-days (CDD), continuous low temperature at 12 degrees C for 8 days at booting caused the largest yield loss (55.3 %), compared with 15.5 % at flowering and 39.3 % under the combined treatment, suggesting that low-temperature stress exerts different cumulative effects across booting and flowering stages. We refined the ORYZA yield formation algorithms using these experimental insights, enabling the model to account for both intermittent low-temperature events and combined stress across booting and flowering stages, thereby better reflecting the conditions observed in rice production. The improved model substantially enhanced simulation accuracy (RMSE reduced from 7.18 to 2.05 g plant-1; D index increased from 0.72 to 0.93), and was further validated against historical low-temperature events at multiple sites in Northeast China. This improvement enhances the reliability of rice yield predictions under field low-temperature scenarios, thereby supporting climate risk assessment and cold-tolerance breeding.

ABSTRACT Under increasing climate variability and the expansion of rice cultivation into marginal cold‐prone environments, low temperature has become a major constraint on yield stability and sustainable rice production. Rice is particularly vulnerable to transient cold stress during reproductive development, and cold injury at the booting stage often causes severe and irreversible yield losses. Improving booting‐stage cold tolerance through genetic approaches is therefore essential for safeguarding food security in high‐latitude rice‐growing regions. In this study, we developed a recombinant inbred line (RIL) population of 144 lines derived from a cross between the highly cold‐tolerant landrace Lijiangxintuanheigu (LTH) and the northern elite japonica cultivar Shennong 265 (SN265) to dissect the genetic basis of booting‐stage cold tolerance. Using spikelet sterility as the primary indicator, we conducted quantitative trait locus (QTL) mapping under controlled cold‐stress conditions across two consecutive years. In total, nine QTLs associated with spikelet sterility were identified on chromosomes 2, 3, 4, 6, 7, and 11, each explaining 10.56%–32.49% of the phenotypic variance. Among these loci, a major‐effect QTL on chromosome 2, designated qCTB2, was consistently detected across years and mapping methods and was subsequently validated using near‐isogenic lines derived from a residual heterozygous line. Interaction‐effect analysis revealed strong additive and complementary effects between qCTB2 and other favorable loci, highlighting its central role in pyramiding‐based breeding strategies. Comparative mapping and sequence comparison indicated that qCTB2 is unlikely to be allelic to the known cold‐tolerance‐related gene LGS1, suggesting that qCTB2 likely represents an independent locus contributing to booting‐stage cold tolerance. Overall, this study identifies a robust major‐effect locus, qCTB2, and demonstrates its additive and complementary interactions with other loci, providing a practical genetic framework for pyramiding‐based improvement of booting‐stage cold tolerance and yield stability in high‐latitude rice production systems under increasing climate variability.

The increasing frequency and intensity of low-temperature events in temperate and cold rice production regions threatens rice yields under climate change. While process-based crop models can project climate impacts on rice yield, their accuracy under low-temperature conditions has not been well evaluated. Our 6 year chamber experiments revealed that low temperatures reduce spikelet fertility from panicle initiation to flowering, grain number per spike during panicle development, and grain weight during grain filling. We examined the algorithms of spikelet fertility response to temperature used in crop models. The results showed that simulation performance is poor for crop yields if the same function was used at different growth stages outside the booting stage. Indeed, we replaced the algorithm for the spikelet fertility parameter of the ORYZA model and developed the function of estimated grain number per spike and grain weight. After that, the algorithm with improved equations was applied to 10 rice growth models. New functions considered the harmful effects of low temperatures on rice yield at different stages. In addition, the threshold temperatures of cold tolerance were set for different rice varieties. The improved algorithm enhances the ability of the models to simulate rice yields under climate change, providing a more reliable tool for adapting rice production to future climatic challenges.

Climate change has increased the trend in the intensity of global extreme weather events, including chilling. Nitrogen is one of the most essential nutrients for rice growth and development. Chilling will limit the uptake and translocation of nitrogen and the formation of grain protein in rice plants. The experiment conducted in the climate chamber with chilling stress applied at the grain filling stage revealed different effects on protein concentration in aboveground organs and caused asymmetry in grain protein contents (GPC) and grain protein yield (GPY). Chilling stress applied during the grain filling stage reduced the accumulation rate of rice grain protein by inhibiting the nitrogen uptake and the translocation from vegetative organs to grains, which resulted in a 35 % decrease in grain nitrogen accumulation and a 92 % increase in vegetative organs during grain filling. Consequently, the average nitrogen harvest index is reduced by 12 %. Nitrogen accumulation was severely affected when cooling degree days (CDD) >= 70 degrees C days. As the chilling intensity increased, the decrease of GPY was more significant than that of GPC. Moreover, we improved the grain temperature-nitrogen uptake function under chilling stress based on the relationship between CDD and the reduction in rice grains. By comparing the improved function and the modules in the existing crop model using the datasets from open field and artificial control experiments, we demonstrated that the current research on quantifying rice nitrogen uptake at extreme temperature stress needed further improvement. The effects of environmental stress on grain nitrogen accumulation are complex. Future studies should pay more attention to the ability of extreme temperature stress to affect nitrogen accumulation in various rice organs.

Salt–alkaline stress is one of the most stressful occurrences, causing negative effects on plant development and agricultural yield. Identifying and utilizing genes that affect alkaline tolerance is an excellent approach to accelerate breeding processes and meet the needs for remediating saline–alkaline soil. Here, we employed a mapping population of 176 recombinant inbred lines (RILs) produced from a cross between alkali-tolerant Longdao5 and alkali-sensitive Zhongyouzao8 to identify the quantitative trait loci (QTLs) determining alkali tolerance at the seedling stage. For the evaluation of alkali tolerance, the recovered seedling’s average alkali tolerance index (ATI), root number (RN), root length (RL), seedling dry weight (SW), root dry weight (RW), and seedling height (SH) were assessed, together with their relative alkaline damage rate. Under alkaline stress, the ATI was substantially negative connected with the root number, seedling height, seedling dry weight, and root dry weight; however, it was considerably positive correlated with the relative alkaline damage rate of the root number and root dry weight. A total of 13 QTLs for the root number, root length, seedling height, seedling dry weight, root dry weight, and alkali tolerance index under alkaline stress were identified, which were distributed across chromosomes 1, 2, 3, 4, 5, 7, and 8. All of these QTLs formed two QTL clusters for alkali tolerance on chromosome 5 and chromosome 7, designated AT5 and AT7, respectively. Nine QTLs were identified for the relative alkaline damage rate of the root number, root length, seedling height, seedling dry weight, and root dry weight under alkali stress. These QTLs were located on chromosome 2, 4, 6, 7, 8, 9, and 12. In conclusion, these findings further strengthen our knowledge about rice’s genetic mechanisms for alkaline tolerance. This research offers clues to accelerate breeding programs for new alkaline-tolerance rice varieties.

Rice direct seeding has the significant potential to save labor and water, conserve environmental resources, and reduce greenhouse gas emissions tremendously. Therefore, rice direct seeding is becoming the major cultivation technology applied to rice production in many countries. Identifying and utilizing genes controlling mesocotyl elongation is an effective approach to accelerate breeding procedures and meet the requirements for direct-seeded rice (DSR) production. This study used a permanent mapping population with 144 recombinant inbred lines (RILs) and 2828 bin-markers to detect quantitative trait loci (QTLs) associated with mesocotyl length in 2019 and 2020. The mesocotyl lengths of the rice RILs and their parents, Lijiangxintuanheigu (LTH) and Shennong 265 (SN265), were measured in a growth chamber at 30°C in a dark environment. A total of 16 QTLs for mesocotyl length were identified on chromosomes 1(2), 2(4), 3(2), 4, 5, 6, 7, 9, 11(2), and 12. Seven of these QTLs, including qML1a, qML1b, qML2d, qML3a, qML3b, qML5, and qML11b, were reproducibly detected in both years via the interval mapping method. The major QTL, qML3a, was reidentified in two years via the composite interval mapping method. A total of 10 to 413 annotated genes for each QTL were identified in their smallest genetic intervals of 37.69 kb to 2.78 Mb, respectively. Thirteen predicted genes within a relatively small genetic interval (88.18 kb) of the major mesocotyl elongation QTL, qML3a, were more thoroughly analyzed. Finally, the coding DNA sequence variations among SN265, LTH, and Nipponbare indicated that the LOC_Os03g50550 gene was the strongest candidate gene for the qML3a QTL controlling the mesocotyl elongation. This LOC_Os03g50550 gene encodes a mitogen-activated protein kinase. Relative gene expression analysis using qRT-RCR further revealed that the expression levels of the LOC_Os03g50550 gene in the mesocotyl of LTH were significantly lower than in the mesocotyl of SN265. In conclusion, these results further strengthen our knowledge about rice's genetic mechanisms of mesocotyl elongation. This investigation's discoveries will help to accelerate breeding programs for new DSR variety development.

Lodging is one of the main limiting factors affecting rice production. It can damage the canopy structure, decrease the leaf photosynthesis rate and increase the population humidity. These undesirable factors could induce fungal diseases, cause spike germination, and then affect the quality and the yield of grain. This paper reviewed the research status of the evaluation methods of rice lodging and inducing causes, the relationship between lodging resistance and the physical and chemical properties of the stem, and the identification and functional study of lodging resistance genes. We compared the characteristics of different rice lodging evaluation methods, analyzed the effects of plant type, field managements including nitrogen fertilizer management, planting density and planting methods, and environmental factors including the gale, rainstorm, and ozone on lodging, summarized the effects of the physical properties and chemical components of stems including cellulose content, lignin content and the number of vascular bundle on lodging, concluded the regulation mechanism of dwarf related genes and cellulose synthesis related genes involved in lodging resistance in rice. In addition, we prospect the future research on lodging resistance and put forward some research suggestions:（1） Innovating and optimizing the evaluation system of rice lodging;（2） Identifying new lodging resistance genes and strengthening the mechanism research of rice lodging resistance;（3） Breeding lodging resistance rice varieties;（4） According to the factors of varieties, cultivation conditions and climate environment, formulating the comprehensive response measures of lodging.

Rice breeders are now developing new varieties with semi-high or even high plant height to further increase the grain yield, and the problem of lodging has re-appeared. We identified a major quantitative trait locus (QTL), qSCM4, for resistance to lodging by using an F2 segregant population and a recombinant self-incompatible line population from the cross between Shennong265 (SN265) and Lijiangxintuanheigu (LTH) after multiple years and multiple environments. Then, the residual heterozygous derived segregant population which consisted of 1781 individual plants, and the BC3F2 segregant population which consisted of 3216 individual plants, were used to shorten the physical interval of qSCM4 to 58.5 kb including 11 genes. DNA sequencing revealed the most likely candidate gene for qSCM4 was Os04g0615000, which encoded a functional protein with structural domains of serine and cysteine. There were 13 DNA sequence changes in LTH compared to SN265 in this gene, including a fragment deletion, two base changes in the 3′ UTR region, six base changes in the exons, and four base changes in the introns. A near-isogenic line carrying qSCM4 showed that it improved the lodging resistance through increasing stem thickness by 25.3% and increasing stem folding resistance by 20.3%. Furthermore, it was also discovered that qSCM4 enhanced the primary branch per panicle by 16.7%, secondary branch by per panicle 9.9%, and grain number per panicle by 14.7%. All the above results will give us a valuable genetic resource for concurrently boosting culm strength and lodging resistance, and they will also provide a basis for further research on the lodging resistance mechanism of rice.

Early-matured aromatic japonica rice from the Northeast is the most popular rice commodity in the Chinese market. The Qigeng10 (QG10) was one of the varieties with the largest planting area in this region in recent years. It was an early-matured japonica rice variety with a lot of superior traits such as semi-dwarf, lodging resistance, long grain, aromatic and good quality. Therefore, a high-quality assembly of Qigeng10 genome is critical and useful for japonica research and breeding. In this study, we produced a high-precision QG10 chromosome-level genome by using a combination of Nanopore and Hi-C platforms. Finally, we assembled the QG10 genome into 77 contigs with an N50 length of 11.80 Mb in 27 scaffolds with an N50 length of 30.55 Mb. The assembled genome size was 378.31Mb with 65 contigs and constituted approximately 99.59% of the 12 chromosomes. We identified a total of 1,080,819 SNPs and 682,392 InDels between QG10 and Nipponbare. We also annotated 57,599 genes by the Ab initio method, homology-based technique, and RNA-seq. Based on the assembled genome sequence, we detected the sequence variation in a total of 63 cloned genes involved in grain yield, grain size, disease tolerance, lodging resistance, fragrance, and many other important traits. Finally, we identified five elite alleles (qTGW2Nipponbare, qTGW3Nanyangzhan, GW5IR24, GW6Suyunuo, and qGW8Basmati385) controlling long grain size, four elite alleles (COLD1Nipponbare, bZIP73Nipponbare, CTB4aKunmingxiaobaigu, and CTB2Kunmingxiaobaigu) controlling cold tolerance, three non-functional alleles (DTH7Kitaake, Ghd7Hejiang19, and Hd1Longgeng31) for early heading, two resistant alleles (PiaAkihikari and Pid4Digu) for rice blast, a resistant allele STV11Kasalath for rice stripe virus, an NRT1.1BIR24 allele for higher nitrate absorption activity, an elite allele SCM3Chugoku117 for stronger culms, and the typical aromatic gene badh2-E2 for fragrance in QG10. These results not only help us to better elucidate the genetic mechanisms underlying excellent agronomic traits in QG10 but also have wide-ranging implications for genomics-assisted breeding in early-matured fragrant japonica rice.

Chilling is the main limiting factor for rice production in high-altitude and high-latitude regions. Many studies have reported the impacts of chilling on leaf photosynthesis and biomass accumulation, but few of them explored the response of photosynthesis to chilling at different growth stages of rice and whether the decrease of photosynthesis at each stage is caused by stomatal or non-stomatal limiting factor. In order to achieve high grain yield for rice, it is critical to understand how chilling affects leaf photosynthesis and plant growth. In this study, we conducted a two-year field experiment (in 2018 and 2019) to investigate the effects of chilling at booting, flowering, and grain filling stages on leaf photosynthesis, plant growth, and grain yield for a japonica rice cultivar (Songjing6). At each target growth stage, the treatment included four chilling temperatures (12, 15, 18, and 21 ?, respectively) and four chilling durations (2, 4, 6, and 8 days, respectively). The results showed that rice photosynthesis gradually decreased as the chilling temperature was decreasing and the chilling duration was increasing. The net photosynthetic rate decreased the most at the booting stage, followed by the flowering stage, and the grain filling stage. Compared with the chilling treatment at 2 days, the chilling treatment at 12, 15, and 18? for 4, 6, and 8 days reduced net photosynthetic rate by 15.1-36.1 %, 18.7-27.2 %, and 15.2-17.2 % at the booting, flowering, and grain filling stages, respectively. The chilling-induced decrease in net photosynthetic rate was mainly attributed to stomatal limiting factor at the booting and flowering stages but non-stomatal limiting factor at the grain filling stage. During the chilling treatment, the available light for rice plants was reduced and the rice plants were impaired in their ability to use weak light. The decrease in photosynthesis lead to reduced leaf source capacity and crop growth rate, hence the reduced aboveground biomass and increased source and sink increment ratio, and ultimately decreased the grain yield for rice. Our results indicate that maintaining efficient photosynthetic functioning at the booting and flowering stages is the key to combat chilling stress for rice.

利用盐腺将植株地上部分携带的过量盐分排出体外,是耐盐植物适应土壤盐碱化的重要机制之一.大量的国内外研究表明,耐盐禾本科植物中存在典型的盐腺结构.为探明禾本科作物的耐盐碱机制,从而改良其耐盐碱功能,本文概述了禾本科植物盐腺的形态和结构、禾本科植物典型双细胞型盐腺的排盐机制、双细胞型盐腺向体外排出离子的功能特点,以及影响盐腺排盐能力的因素,并对今后深入开展盐腺的研究进行了展望.盐腺的抗逆功能可以提高禾本科植物的抗盐性和抗重金属性,平衡作物体内的离子和重金属含量,最终能够提高作物的产量和品质.禾本科植株盐腺对光合作用和病虫害抵抗作用的机理将成为未来研究的热点.

按照不完全双列杂交(NCII)设计,以6个恢复系为父本、3个不育系为母本共配制18个杂交粳稻组合,分析了产量相关性状的配合力及遗传参数.结果 表明,杂交组合的产量和结实率受母本的影响大于父本,每穗实粒数更多地依赖恢复系,穴穗数和千粒重则受双亲的共同影响.遗传分析表明,主要受基因加性效应影响的性状为穗实粒数,主要受非加性效应互作影响的性状包括产量和穴穗数,受基因加性效应和基因非加性效应共同控制的性状包括结实率和千粒重.黑龙江杂交粳稻组合产量及其相关性状受亲本一般配合力影响,但最终由其特殊配合力决定,且特殊配合力效应与亲本一般配合力效应具有相对独立性,因此,在选育高产杂交组合时,应首先选择一般配合力高的亲本,在此基础上,重点关注组合的特殊配合力.

在黑龙江稻区采集病样、分离病原菌的基础上,获得形态差异明显的20株水稻叶褐条斑病菌,利用ITS序列鉴定其均为Nigrospo?ra oryzae,由此推断Nigrospora oryzae为当地主要的水稻黑孢菌种群.此外,依据水稻叶褐条斑病的生物学特征,摸索了人工接种鉴定技术.该研究结果为抗水稻叶褐条斑病的遗传育种研究奠定基础.

大麻是黑龙江省重要的经济作物之一,年播种面积占全国一半左右.探明黑龙江省大麻种植面积、总产及单产变化趋势,解析气象环境因素对大麻产量的影响,对于黑龙江省大麻的科学区划布局和健康发展具有重要意义.本研究分析了黑龙江省2011-2019年大麻的播种面积、总产和单产的时空变化趋势,并探讨了大麻单产与主要气象因子间的关系.结果表明:黑龙江省大麻播种面积年均增长2 096.5 hm2,总产年均增长12 696.6 t,大麻种植区域主要分布在黑河市、绥化市、齐齐哈尔市、大庆市等区域,新增区域主要分布在齐齐哈尔市、哈尔滨市和牡丹江市.各地单产的变化幅度较大,变幅为58.2～10 178.6 kg·hm-2.黑河市、绥化市、大庆市等大麻传统主产区的单产高且稳定,一般为5 000～10 000 kg·hm-2.而新增区域的单产较低,哈尔滨市和齐齐哈尔地区的平均单产低于3 500 kg·hm-2,具有较大的提升空间.大麻单产与5-9月的≥10℃活动积温和5-9月的累计降水量呈正相关,与5-9月的太阳总辐射呈负相关,但未达到显著水平.现阶段不同区域的单位面积产量高低主要取决于栽培技术水平.

为促进黑龙江省农业科学院水稻相关知识产权成果的持续转化,以黑龙江省农业科学院为例,对其水稻相关知识产权保护的现状及存在的问题进行了剖析.黑龙江省农业科学院的水稻品种权主要来自于水稻研究所、耕作栽培研究所、绥化分院和生物技术研究所;发明专利主要来自耕作栽培研究所;实用新型专利主要来自水稻研究所和耕作栽培研究所.这些专利主要集中在耕作栽培相关技术和育种相关技术领域.进一步分析发现黑龙江省农业科学院知识产权工作存在品种保护意识不足和专利质量良莠不齐,缺乏有效转化的问题.同时针对上述问题提出了进一步加强知识产权工作的建议和对策.

基于1961-2019年松嫩平原盐碱地区域的13个气象站的逐日气象资料,分析了松嫩平原全年及水稻生长季内的平均气温、活动积温、昼夜温差、降水量和日照时数等农业气候资源的时空变化特征.结果表明,与第Ⅰ阶段(1961-1990年)相比,第Ⅱ阶段(1991-2019年)松嫩平原盐碱地区域的热量资源明显增加,年均气温升高了 1.1℃,年均气温的气候倾向率分布在0.23℃/10a～0.41℃/10a,5℃等值线向北推移了约2.2°.最冷月和最热月的平均气温分别增加了 1.4℃和0.7℃.水稻生长季内≥10℃的活动积温增加了 248.7℃·d,活动积温3000℃·d1等值线北移了约2.6°,昼夜温差降低了 0.6℃.年日照时数和生长季内日照时数均呈降低趋势,分别降低了 184.0和17.4h.以松花江为界,吉林省部分地区的降水量减少,黑龙江省部分地区的降水量略增加.该区域农业气候资源的整体变化特征表现为暖湿趋势,这必然会对该区域的盐碱地水稻生产产生一定的影响.

随着全球气候变暖,高温已成为威胁寒地水稻生产的主要气候因素之一.利用六角形开口玻璃房模拟日间增温,并用耐热高产品种龙稻21和热敏感优质品种龙稻18为试验材料,进行了不同生育时期的增温处理试验.结果表明,模拟增温设施能够实现日间平均1.2～2.6℃的增温效果.全生育期增温使龙稻21和龙稻18的产量分别提高7.4和4.5 t·hm-2,增产效应主要是通过增加生物量、有效穗数和每穗颖花数实现的.进一步分析不同生育时期增温对产量的影响发现,分蘖期、拔节期、抽穗期和灌浆期的增温使龙稻21的产量分别增加1.2、3.9、0.8和1.1 t·hm-2.拔节期、抽穗期和灌浆期的增温能使龙稻18的产量分别增加1.5、2.5和1.8 t·hm-2.孕穗期增温导致龙稻21和龙稻18的产量分别减少0.2和1.2 t·hm-2.各生育时期增产主要通过增加生物量、有效穗数和每穗颖花数实现.不同耐热品种对增温的响应不同,主要受结实率的影响.同时也发现,增温对千粒重存在负向作用.分蘖期和拔节期增温能够增加糙米率和精米率,而孕穗期、抽穗期和灌浆期的增温导致糙米率、精米率下降以及垩白米率、垩白度升高.增温对稻米食味值、蛋白质含量和直链淀粉含量的影响较小.未来如果高温出现在寒地水稻生育前期危害较弱,而且还有部分有利作用.但如果高温发生在孕穗期、抽穗期和灌浆期,对寒地优质稻谷的生产危害较大,应进一步加强对寒地水稻生育后期高温的研究和耐高温品种的选育.

The hereditary basis and identification of novel genes of heading date have significant implications for japonica rice improvement in northeast China, especially in Heilongjiang province. A re-sequenced recombinant inbred line (RIL) population derived from the cross between Lijiangxintuanheigu (LTH) and Shennong 265 (SN265) was used to detect the genetic basis for the RIL in 2017 and 2018. Fourteen heading date quantitative trait loci (QTLs), including nine in 2017 and thirteen in 2018, were detected with a linkage map containing 2,818 bin markers. They were distributed on chromosomes 3, 4, 6 and 9-11 with 9.34%-25.26% phenotypic variations. The QTLs qHD3a, qHD4a, qHD4b, qHD4c, qHD9b, qHD10, qHD11c and qHD11d were identified in both years. The qTRS1, qTRS3a (qHD3a), qTRS3b (qHD3b) and qTRS9 (qHD9a) alleles from LTH and the qTRS4 allele from SN265 were identified by controlling the temperature responsiveness in the RIL population. The explained phenotypic variation in these five QTLs varied from 14.52% to 26.31%. In order to accurately determine the difference in heading date under different temperature conditions, the RILs and two parents were grown in a phytotron. Four QTLs controlling temperature responsiveness were identified on chromosomes 3, 6 and 9, including qTRS3a (qHD3a), qTRS3b (qHD3b), qTRS6 and qTRS9 (qHD9a). In a different environment, qTRS3a (qHD3a), qTRS3b (qHD3b) and qTRS9 (qHD9a) were detected. A comparison of chromosomal locations between the QTLs detected in this study and heading date genes previously cloned indicated that DTH3, Hd16, RFL, HAF1, Ehd2 and RBS1 might be candidate genes for them. The four major heading date genes (Hd1, Ghd7, Ghd7.1 and Ghd8) affecting ecogeographical adaptation were sequenced between SN265 and LTH. SN265 carried a functional Hd1 haplotype, a weak functional Ghd7 haplotype, a weak functional Ghd7.1 haplotype and a weak functional Ghd8 haplotype. LTH also carried functional Hd1 haplotype, a weak functional Ghd7 haplotype, a non-functional Ghd7.1 haplotype and a non-functional Ghd8 haplotype. The combinations of the Hd1, Ghd7, Ghd7.1 and Ghd8 alleles in SN265 and LTH largely defined their short heading date under long-day conditions. The selection of heading date gene combinations with functional Hd1 alleles and non-functional alleles or weak functional alleles of Ghd7, Ghd7.1 and Ghd8 would be an effective way to improve japonica rice with proper heading days in Northeast China. The novel QTLs detected in this study could also become a valuable source for designing the appropriate heading date in Northeast China japonica rice.

Pumpkin is one of the region’s main cashcrops in northeast China cultivated for its edible seed and sarcocarp. Gummy stem blight (GSB), caused by the main pathogenic fungus of Stagonosporopsis cucurbitacearum (Sc.) which was identified in our previous study, has hampered pumpkin industry development with the affection of its reduced biological yield and edible quality. To clear the plant immune response mechanisms against Sc. infection, RNA-seq technology was employed to sequence pumpkin leaf transcriptome, the total number of distinct differentially expressed genes (DEGs) between the treatments and control was 2351, 4892, 5285, 4698, and 4213 for 2, 6, 12, 24, and 96 h treatments, respectively. KEGG analysis results revealed 16 distinct significantly up-regulated DEGs associated with MAPK signaling and plant-pathogen interaction pathways that may actively participate in Sc. infection-associated processes, while other five DEGs exhibited significantly altered expression during GSB infection. An apyrase-like gene, Gene3360 (LOC111476496), with significantly different expression levels, was possessing an early-stage primary infection-based function, which was hypothesized an important role in the resistance of pumpkin to Sc. infection. This study further deepens our understanding of the mechanism and mechanism of pumpkin leaf resistance to fungal infection.

Among all cereals, rice is highly sensitive to cold stress, especially at the germination stage, which adversely impacts its germination ability, seed vigor, crop stand establishment, and, ultimately, grain yield. The dissection of novel quantitative trait loci (QTLs) or genes conferring a low-temperature germination (LTG) ability can significantly accelerate cold-tolerant rice breeding to ensure the wide application of rice cultivation through the direct seeding method. In this study, we identified 11 QTLs for LTG using 144 recombinant inbred lines (RILs) derived from a cross between a cold-tolerant variety, Lijiangxintuanheigu (LTH), and a cold-sensitive variety, Shennong265 (SN265). By resequencing two parents and RIL lines, a high-density bin map, including 2,828 bin markers, was constructed using 123,859 single-nucleotide polymorphisms (SNPs) between two parents. The total genetic distance corresponding to all 12 chromosome linkage maps was 2,840.12 cm. Adjacent markers were marked by an average genetic distance of 1.01 cm, corresponding to a 128.80 kb physical distance. Eight and three QTL alleles had positive effects inherited from LTH and SN265, respectively. Moreover, a pleiotropic QTL was identified for a higher number of erected panicles and a higher grain number on Chr-9 near the previously cloned DEP1 gene. Among the LTG QTLs, qLTG3 and qLTG7b were also located at relatively small genetic intervals that define two known LTG genes, qLTG3-1 and OsSAP16. Sequencing comparisons between the two parents demonstrated that LTH possesses qLTG3-1 and OsSAP16 genes, and SN-265 owns the DEP1 gene. These comparison results strengthen the accuracy and mapping resolution power of the bin map and population. Later, fine mapping was done for qLTG6 at 45.80 kb through four key homozygous recombinant lines derived from a population with 1569 segregating plants. Finally, LOC_Os06g01320 was identified as the most possible candidate gene for qLTG6, which contains a missense mutation and a 32-bp deletion/insertion at the promoter between the two parents. LTH was observed to have lower expression levels in comparison with SN265 and was commonly detected at low temperatures. In conclusion, these results strengthen our understanding of the impacts of cold temperature stress on seed vigor and germination abilities and help improve the mechanisms of rice breeding programs to breed cold-tolerant varieties.