氮肥用量和播期对优良食味粳稻直链淀粉含量的影响

以直链淀粉含量不同的半糯粳稻新品种(系)为材料,设置高氮(450kg/hm~2)、中氮(300kg/hm~2)、低氮(150kg/hm~2)和不施肥(CK)4个氮肥水平,分期播种并进行短日照处理,研究了氮肥用量和播期对优良食味粳稻直链淀粉含量的影响。结果表明,氮肥用量对优良食味粳稻的直链淀粉含量有显著影响,随着氮肥用量的增加,直链淀粉含量有降低的趋势,两年均以高氮处理的直链淀粉含量最低。播期对优良食味粳稻的直链淀粉含量也有显著影响,随播期的推迟,直链淀粉含量呈降低趋势,这主要与抽穗后6~15d的温度有关,高温可使直链淀粉含量提高。短日照处理的结果也证实了这一点。     

空气中CO2浓度升高条件下水稻抽穗期的QTL定位

以65个水稻染色体片段置换系(chromosome segment substitution lines,CSSLs)为材料,对比分析了正常大气CO2浓度（对照）和开放式空气CO2浓度升高（free air CO2 enrichment,FACE,大气CO2浓度增加200 μmol/mol）下水稻抽穗期的变化,并定位了相关QTL(quantitative trait loci)。供试株系的抽穗期对CO2浓度升高表现为提早、延迟和不变等3种响应,抽穗期两极变化最大的株系为AI46（提前11 d）和AI63（延迟6 d）。两种条件下,共检测到9个控制抽穗期的QTL,分布在第3、4、6、7、8、10和11染色体上。其中位于第6和第8染色体上的 qHD6 4和 qHD8 4在两种CO2浓度下都检测到,但在FACE下的贡献率均显著增大;而 qHD3A 3和 qHD11A 7只在正常条件下检测到, qHD4F 4、 qHD10F 4和 qHD11F 4则只在FACE下检测到。 暗示控制水稻抽穗期的基因表达易受环境CO2浓度的影响。     

Delay of heading date as an index of water stress in rainfed rice in mini-watersheds in Northeast Thailand

Drought is recognized as a primary constraint for rainfed rice production. In this study, the spatial distribution of heading date of rainfed rice and its relation to field water conditions were investigated for 2 years in mini-watersheds called Nong in Northeast Thailand, in order to clarify the toposequential variation in the degree of water stress of rice. Although the difference in the relative field elevation in the mini-watersheds was only a few meters, the water availability in terms of standing water and soil moisture markedly decreased with ascending elevation. Rice cultivars, KDML 105 and RD 6, the two dominant genotypes in Northeast Thailand, reached the heading stage at nearly the same day in the absence of water stress, independent of transplanting or seeding date under customary management. As the water availability decreased with ascending field elevation, the heading date of rice was markedly delayed. The delay seemed to be related to the cumulative water stress before heading of rice. The rice harvest index and yield at farmers’ fields decreased linearly with the delay of heading. The observed toposequential distribution of heading date indicated that quite severe water stress was imposed in the uppermost fields of the mini-watersheds, while practically no water stress occurred in the lower fields, at least in the lower half of the mini-watersheds. These results suggest that the delay of heading is a good index for rice water stress in rice in Northeast Thailand and can be applicable to field classification with respect to drought risk.     

水稻开花时间基因OsDTH10的过表达分析

开花时间(抽穗期)是农作物一个重要的农艺性状,与农作物的产量息息相关。调节农作物的开花抽穗时间是提高农作物产量的一条重要途径。为了揭示水稻开花时间基因OsDTH10在水稻抽穗期调控中的功能,利用反向遗传学方法构建了水稻OsDTH10基因过量表达载体,获得转基因植株,分析目的基因在过量表达条件下的功能。结果表明,过量表达OsDTH10导致水稻的抽穗期推迟;RT-PCR检测结果表明OsDTH10的表达量在晚抽穗的转基因株系中明显提高,但在没有表型的转基因株系及野生型中表达量较低,说明晚抽穗的表型是由于OsDTH10过量表达所致。组织特异性表达结果表明OsDTH10在植物的不同器官中都有表达,但在水稻的茎、叶鞘中表达量较高。分析OsDTH10在不同叶龄叶片中的表达,结果表明OsDTH10在未完全展开的剑叶叶片及倒2叶中的表达量较高,但在下部较老的倒3叶及倒4叶中的表达量下降。另外,分析OsDTH10在不同光周期条件下的昼夜节律性表达,结果表明无论在短日照还是长日照条件下,OsDTH10都在白天(光期)有表达高峰,在夜晚(暗期)表达降低,表明OsDTH10可能涉及光周期调控通路调节水稻的抽穗期。     

Identification and Fine Mapping of Heading Date Related Mutant Gene in Rice

A rice heading-date-related mutant was isolated from a 60 Co-γ-ray-induced mutation pool of Zhejing 22,a conventional japonica cultivar in Zhejiang Province,China.The mutant was characterized by a delayed heading date of almost 20 d longer than the wild type plant.Genetic analysis revealed that the mutation was controlled by a single nuclear-encoded recessive gene that was designed as HD(t)(heading date tentatively).To isolate the HD(t) gene,a map-based cloning approach was employed using 479 F 2 mutant individual plants derived from the cross between the hd(t) mutant(japonica) × Zhenshan 97(indica).Finally,the HD(t) gene was mapped to an approximate 53 kb region between the insertion and deletion(InDel) markers of 10-61W and 10-66W on chromosome 10.According to the genome sequence of Nipponbare,the target region contains 11 annotated genes.It is helpful for future cloning of HD(t) gene based on this fine mapping results.     

一个水稻类树稻突变体(leafy head 3)基因的精细定位

 从常规粳稻常优94后代中筛选到一份自然突变的抽穗期延迟的类树稻突变体lhd3（leafy head 3）。在短日照条件下,与野生型比较,lhd3突变体在生长后期,上部节间会继续长出叶片（一般为3片）和高位分蘖,类似于树的侧枝生长,抽穗期延迟,但基部分蘖数不受影响。经典遗传分析表明,lhd3与籼稻南京6号的F2群体中,正常植株与类树稻植株的分离比符合3∶1,说明此性状受单隐性基因控制。利用该群体进行图位克隆,将LHD3基因定位在水稻第1染色体短臂的两个新发展的STS标记wpla3和wpla25之间。再利用5个新发展的STS和CAPS标记,最终将该基因精细定位在WX6和CAPS1两个标记之间,物理距离约为60 kb。通过水稻基因组注释系统共预测到10个开放阅读框（ORF）。对该基因的进一步克隆将有助于阐明水稻生育期和叶原基发育调控机理。     

Quantitative Trait Loci for Heading Date and Their Relationship with Genetic Control of Yield Traits in Rice (Oryza sativa)

Grain yield and heading date are key factors determining the commercial potential of a rice variety. Mapping of quantitative trait loci (QTLs) in rice has been advanced from primary mapping to gene cloning, and heading date and yield traits have always attracted the greatest attention. In this review, genomic distribution of QTLs for heading date detected in populations derived from intra-specific crosses of Asian cultivated rice (Oryza sativa) was summarized, and their relationship with the genetic control of yield traits was analyzed. The information could be useful in the identification of QTLs for heading date and yield traits that are promising for the improvement of rice varieties.     

轮回422与籼稻杂交F1抽穗期超亲遗传分析

 分析了偏粳型广亲和品种轮回422与籼稻品种南京11、I188025（具有簇生小穗标记基因Cl）杂交F₁～F₃及BC₁在不同日长条件下的抽穗期表现。长日照试验表明，F₁超亲迟熟（超亲优势率达49%）主要受两对互补基因控制。短日照试验结果证明，杂种超亲迟熟主要由其强感光性引起的，上述互补基因属于感光性基因．通过互补测验和连锁分析证明，两籼稻亲本所携互补基因为等位关系，此基因与6号染色体上的Cl基因连锁，重组率为27.78%±1.82%。根据试验结果可以认为，感光性基因的互补作用是造成籼粳杂种一代生育期超亲迟熟的主要遗传原因。     

水稻光温敏核不育系的光温特性及其熟期性模型研究

对8个熟期性不同的水稻光温敏核不育系在三亚、贵阳、武汉、南京4地各4 a的分期播种熟期性资料及同期的温度和日长资料进行了分析.结果表明,不同熟期类型不育系的感光性和感温性强弱均为晚籼(粳)＞中籼＞早籼;大部分不育系在中温条件(24～28℃)下的感光性强于在低、高温条件下的感光性;各不育系短日下的感温级低于或等于长日下的感温级;短日高温生育期的表现与常规水稻一致,即中籼＞早籼＞晚籼(粳).选配了各不育系的熟期性模型,早籼和中籼不育系可以用温度线性或非线性模型表达,但晚籼(粳)不育系以用光温综合模型表达为宜.     

Correlation and Regressive Model Between Spikelet Fertilized Rate and Temperature in Inter-Subspecific Hybrid Rice

To study the sensitivity of inter-subspecific hybrid rice to climatic conditions, the spikelet fertilized rate (SFR) of four types of rice including indica-japonica hybrid, intermediate hybrid, indica and japonica were analyzed during 2000-2004. The inter-subspecific hybrids showed lower SFR, and much higher fluctuation under various climatic conditions than indica and japonica rice, showing the inter-subspecific hybrids were sensitive to ecological conditions. Among 12 climatic factors, the key factor affecting rice SFR was temperature, with the most significant factor being the average temperature of the seven days around panicle flowering (T7). A regressive equation of SFR-temperature by T7, and a comprehensive synthetic model by four important temperature indices were put forward. The optimum temperature for inter-subspecific hybrids was estimated to be 26.1-26.6℃, and lower limit of safe temperature to be 22.5-23.3℃ for panicle flowering, showing higher by averagely 0.5℃ and 1.7℃, respectively, to be compared with indica and japonica rice. This suggested that inter-subspecific hybrids require proper climatic conditions. During panicle flowering, the suitable daily average temperature was 23.3-29.0℃, with the fittest one at 26.1-26.6℃. For an application example, optimum heading season for inter-subspecific hybrids in key rice growing areas in China was as same as common pure lines, while inferior limit for safe date of heading was about a ten-day period earlier than those of common pure lines.     

玉米和狗尾草光周期敏感性的比较研究

光周期是影响植物生长发育的关键因素之一。玉米和狗尾草都是短日照禾本科植物,且都具有光周期敏感性。对玉米和狗尾草的光周期敏感性比较研究,探索易于研究的狗尾草光周期敏感性机理,借以解析玉米光周期敏感性反应的机理。以玉米自交系CML288、黄早四和狗尾草自交系A10为材料,研究在长日照、短日照和在不同生育时期长短日照相互挪移处理下的光周期反应。结果表明,玉米和狗尾草在长日照条件下都表现出营养生长旺盛和生育期延迟,二者在长日照条件下的光周期敏感阶段都比短日照条件下的光周期敏感阶段长;玉米在进入光周期敏感期之前有一段时间的光周期钝感期,而狗尾草从发芽出苗就直接进入光周期敏感期。两个光周期敏感程度不同的玉米自交系比较,光周期敏感自交系CML288比光周期相对不敏感自交系黄早四的光周期敏感阶段长。     

Photosynthetic Characteristics of Flag Leaves in Rice White Stripe Mutant 6001 During Senescence Process

Physiological, biochemical and electron microscopy analyses were used to investigate the photosynthetic performance of flag leaves in rice white stripe mutant 6001 during the senescence process. Results showed that the chlorophyll content at the heading and milk-ripe stages in rice mutant 6001 were about 34.78% and 3.00% less than those in wild type 6028, respectively. However, the chlorophyll content at the fully-ripe stage in rice mutant 6001 was higher than that in wild type 6028. At the heading stage, the net photosynthetic rate （Pn） in rice mutant 6001 was lower than that in wild type 6028. Rice mutant 6001 also exhibited a significantly slower decrease rate of Pn than wild type 6028 during the senescence progress, especially at the later stage. Furthermore, Ca2~-ATPase, Mg~~-ATPase and photophosphorylation activities exhibited the similar trends as the Po. During the senescence process, the 68 kDa polypeptide concentrations in the thylakoid membrane proteins exhibited a significant change, which was one of the critical factors that contributed to the observed change in photosynthesis. We also observed that the chloroplasts of rice mutant 6001 exhibited higher integrity than those of wild type 6028, and the chloroplast membrane of rice mutant 6001 disintegrated more slow during the senescence process. In general, rice mutant 6001 had a relatively slower senescence rate than wild type 6028, and exhibited anti-senescence properties.     

水稻OsENO2-2基因过表达对水稻抽穗期的影响

【目的】 OsENO2-2是OsENO2通过可变剪切产生的短转录本,其cDNA序列从粳稻中花11中分离获得。本研究的主要目的是初步分析OsENO2-2在水稻抽穗期调控中的作用。【方法】 构建了OsENO2-2的超量表达载体,获得转基因植株,通过对表型的观察和统计,分析目的基因在过量表达条件下的功能,并利用反向遗传学方法验证该基因的功能。【结果】 OsENO2-2过量表达导致水稻在长日照条件下的抽穗期推迟,而短日照条件下抽穗期无明显变化。通过qRT-PCR方法对水稻开花关键基因的检测发现,在长日照条件下,RFT1的表达量在超表达材料中显著下调,其他开花重要基因表达量在野生型和超表达材料中没有显著变化;而在短日照条件下,所有检测基因的表达量在野生型和超表达材料中均没有显著变化。【结论】 在长日照条件下,OsENO2-2主要通过调控RFT1基因的表达来调控水稻抽穗期。     

水稻花器官发育基因DPS2的鉴定和精细定位

【目的】鉴定和克隆花器官发育相关基因,为进一步研究水稻花发育的分子机制奠定基础。【方法】在大田常规种植条件下比较了突变体dps2 (Defective pistil and stamens 2)和野生型春江06的主要农艺性状及花器官形态特征差异;扫描电镜及石蜡切片观察花药结构并用染色法观察花粉和胚囊的育性;利用图位克隆方法进行基因精细定位;qRT-PCR分析了花发育相关基因在野生型和突变体中的表达水平。【结果】dps2突变体抽穗期变长,不能正常扬花,雄蕊和雌蕊皱缩且花药和柱头数目增多;进一步研究发现,dps2突变体花药腔室塌陷,内无可见小孢子,即使部分花药形成腔室,花粉粒也无淀粉积累呈干瘪状。此外,突变体胚囊育性也受到影响;遗传分析表明该突变性状受一对隐性核基因控制,该基因位于第4染色体短臂上91.2 kb的区间内,区间内未见花器官发育相关基因的报道。qRT-PCR检测发现,水稻ABCDE模型中的B类、C类和E类基因的表达在突变体中显著升高。【结论】dps2突变体的雄蕊及雌蕊均发育异常,最终导致完全不育,推测DPS2可能在水稻第3轮雄蕊发育和第4轮雌蕊发育调控中发挥重要作用。     

Dissection of Genetic Mechanism of Abnormal Heading in Hybrid Rice

Abnormal heading in hybrid rice production has caused great economic loss in recent years,but the genetic basis of this phenomenon remains elusive.In this study,we developed four testcross populations using 38 introgression lines(ILs)from Shuhui 527(SH527)/Fuhui 838(FH838)//SH527population as male parents and four male sterile lines(MSLs;namely II-32A,Xieqingzao A,Gang 46A and Jin 23A)as female parents.Progeny testing allowed us to identify 55 abnormal heading combinations in Hefei,but had late heading date in Hangzhou and Guangzhou of China.By one-and two-way analysis of variance,a total of 21 QTLs and 31 pairs of epistatic QTLs associated with photosensitivity were identified in the four populations,respectively.Genotypic analysis showed that the IL parent of most abnormal heading combinations showed some introgressions at markers RM331 and RM3395 on chromosome 8(strongly associated with the known genes OsHAP3H/DTH8/Ghd8/LHD1)of donor FH838alleles,and these two markers were also identified as affecting photosensitivity.The observation that the recipient parent(SH527),donor parent(FH838),their testcross combinations with four MSLs,and the IL parents of abnormal heading combinations had normal heading date in Hefei suggested that OsHAP3H/DTH8/Ghd8/LHD1 showed no independent regulation on abnormal heading in the abnormal heading combinations.It is noteworthy that complex epistasis among RM331 or RM3395 with other loci,including dominant×additive,additive×dominant,and dominant×dominant epistases,were identified only in the four testcross populations of the current study,but not in the SH527/FH838//SH527 population,suggesting the cause of abnormal heading in abnormal heading combinations in Hefei and delayed heading in Hangzhou and Guangzhou.     

叶面喷施亚硒酸钠对再生稻产量及品质的影响

【目的】以叶面喷施的形式研究硒对再生稻产量及品质的影响,旨在为再生稻优质、高产栽培技术提供依据。【方法】试验于2016年在湖北省洪湖市沙口镇进行,以丰两优香1号为试验材料,Na_2SeO_3为供硒源;设置0、5.625和11.250 g/hm~2三个硒肥施用量,始穗期、齐穗期和始+齐穗期三个施硒时期进行叶面喷施。【结果】叶面喷施Na_2SeO_3的处理再生稻产量均高于对照组,始穗期喷施Na_2SeO_3处理的再生稻产量与对照相比虽然有提升但并不显著;齐穗期施用5.625 g/hm~2、11.250 g/hm~2 Na_2SeO_3处理分别增产2.59%和5.50%,始穗期+齐穗期施用5.625 g/hm~2、11.250 g/hm~2 Na_2SeO_3处理分别增产4.83%和7.08%;始穗期与齐穗期均喷施11.250 g/hm~2 Na_2SeO_3处理产量最高,为5533 kg/hm~2,叶面施用Na_2SeO_3能增加再生稻每穗粒数、实粒数和结实率。齐穗期施用11.250g/hm~2 Na_2SeO_3的再生稻稻米整精米率最高,且显著高于对照组,最高值为61.37%;齐穗期施用11.250 g/hm~2Na_2SeO_3的再生稻稻米垩白粒率最低,且显著低对照组,最低值为9.37%。【结论】研究表明,施用Na_2SeO_3能提升再生稻产量,改善再生稻米品质,提升再生稻整精米率,降低垩白率。始穗期与齐穗期均喷施11.250 g/hm~2Na_2SeO_3再生稻产量达到最高;齐穗期施用11.250 g/hm~2 Na_2SeO_3再生稻品质最优。     

Genetic analyses of heading date of Japonica rice cultivars from Northeast China

Northeast regions of China (38–55°N latitude) play an important role in Japonica rice planting. Heading dates of 10 Japonica rice cultivars native to the Northeast of China were investigated and their sensitivities to photoperiod and temperature were analyzed. The results showed that these Japonica rice cultivars were insensitive to photoperiod but strongly sensitive to temperature, i.e. a high temperature can markedly shorten the heading date. Genetic analyses were conducted on these 10 cultivars using a set of heading date tester lines. All these Japonica cultivars carried a dominant early heading gene Ef-1, and most of these cultivars carried the photoperiod insensitivity allele e₁, and two types of alleles were presented at the Se-1 locus, including recessive photoperiod insensitivity gene Se-1^e and dominant strong photoperiod-sensitivity (PS) gene Se-1ⁿ. The PS of these cultivars carrying E₁ or Se-1ⁿ can be repressed or weakened by Ef-1 and the recessive allele hd2 they carried. These results provided a reasonable explanation to the adaptability of Japonica rice to the high latitude environment of the Northeast China, and could be useful for breeding new cultivars well adapted to the high latitude regions and expanding the rice cultivation range.     

Genetic Analysis and Gene Mapping of Light Brown Spotted Leaf Mutant in Rice

A light brown spotted-leaf mutant of rice was isolated from an ethane methyl sulfonate (EMS)- induced IR64 mutant bank. The mutant, designated as lbsl1 (light brown spotted-leaf 1), displayed light brown spot in the whole growth period from the first leaf to the flag leaf under natural summer field conditions. Agronomic traits including plant height, growth duration, number of filled grains per panicle, seed-setting rate and 1000-grain weight of the mutant were significantly affected. Genetic analysis showed that the mutation was controlled by a single recessive gene, tentatively named lbsl1(t), which was mapped to the short arm of chromosome 6. By developing simple sequence repeat (SSR) markers, the gene was finally delimited to an interval of 130 kb between markers RM586 and RM588. The lbsl1(t) gene is likely a novel rice spotted-leaf gene since no other similar genes have been identified near the chromosomal region. The genetic data and recombination populations provided will facilitate further fine-mapping and cloning of the gene.     

Isolation of a novel mutant gene for soil-surface rooting in rice (Oryza sativa L.)

Background

Root system architecture is an important trait affecting the uptake of nutrients and water by crops. Shallower root systems preferentially take up nutrients from the topsoil and help avoid unfavorable environments in deeper soil layers. We have found a soil-surface rooting mutant from an M₂ population that was regenerated from seed calli of a japonica rice cultivar, Nipponbare. In this study, we examined the genetic and physiological characteristics of this mutant.

Results

The primary roots of the mutant showed no gravitropic response from the seedling stage on, whereas the gravitropic response of the shoots was normal. Segregation analyses by using an F₂ population derived from a cross between the soil-surface rooting mutant and wild-type Nipponbare indicated that the trait was controlled by a single recessive gene, designated as sor1. Fine mapping by using an F₂ population derived from a cross between the mutant and an indica rice cultivar, Kasalath, revealed that sor1 was located within a 136-kb region between the simple sequence repeat markers RM16254 and 2935-6 on the terminal region of the short arm of chromosome 4, where 13 putative open reading frames (ORFs) were found. We sequenced these ORFs and detected a 33-bp deletion in one of them, Os04g0101800. Transgenic plants of the mutant transformed with the genomic fragment carrying the Os04g0101800 sequence from Nipponbare showed normal gravitropic responses and no soil-surface rooting.

Conclusion

These results suggest that sor1, a rice mutant causing soil-surface rooting and altered root gravitropic response, is allelic to Os04g0101800, and that a 33-bp deletion in the coding region of this gene causes the mutant phenotypes.