水稻矮化基因WLD1的图位克隆

水稻(Oryza sativa)矮化是与光合效率及产量等密切相关的重要农艺性状。发掘更多的水稻矮秆资源,不仅能够进一步加深对水稻株高分子遗传机制的认识,而且还能为水稻新品种培育提供新的种质资源。在水稻T-DNA插入突变体库中筛选到1个矮化、宽叶小粒突变体(wld1)。经图位克隆将WLD1基因定位在第5号染色体长臂,位于分子标记In Del37与InDel48之间,基因编号为LOC_Os05g32270,属于AP2转录因子家族。该基因第6外显子处胸腺嘧啶缺失,造成转录提前终止。石蜡切片观察结果显示,茎部第2节间横向细胞数目增加,而纵向细胞数目未变。RT-PCR检测结果表明,LOC_Os05g32270在突变体wld1中不表达,造成功能缺失。该基因与已报道的水稻OsSMOS1(SMALL ORGAN SIZE1)为等位基因。水稻突变体wld1的矮秆遗传效应可直接应用于育种中。该研究结果进一步明确了突变体wld1的表型特征与遗传基础,为解析其参与的信号途径提供参考。     

大田增强UV-B辐射对元阳梯田地方水稻茎秆性状和倒伏指数的影响

大田原位种植元阳梯田2个地方水稻品种——白脚老粳和月亮谷,研究2年不同强度(0、2.5、5.0和7.5 kJ·m^-2)UV-B辐射对水稻穗下第1至第4节的茎秆性状(节间长、茎秆粗和茎壁厚)和倒伏指数的影响.结果表明: 增强UV-B辐射对水稻茎秆的节间长和茎秆粗没有显著影响,但导致茎壁厚度显著减小,其中,7.5 kJ·m^-2 UV-B辐射对水稻穗下第4节茎秆茎壁厚度的影响较大,降幅为11.6%～19.6%;增强UV-B辐射导致水稻茎秆的倒伏指数增加,增大水稻倒伏的风险,水稻穗下第4节茎秆倒伏指数最大,并大于倒伏临界值(200);水稻穗下第4节、第3节和第2节茎秆的倒伏指数与茎壁厚度呈显著负相关.表明增强UV-B辐射显著减小元阳梯田水稻茎秆的茎壁厚是增加其倒伏风险的主要原因.
     

Natural alleles of a uridine 5ʹ-diphospho-glucosyltransferase gene responsible for differential endosperm development between upland rice and paddy rice

Traditional upland rice generally exhibits insufficient grains resulting from abnormal endosperm development compared to paddy rice. However, the underlying molecular mechanism of this trait is poorly understood. Here, we cloned the uridine 5ʹ-diphospho (UDP)-glucosyltransferase gene EDR1 (Endosperm Development in Rice) responsible for differential endosperm development between upland rice and paddy rice by performing quantitative trait loci analysis and map-based cloning. EDR1 was highly expressed in developing seeds during grain filling. Natural variations in EDR1 significantly reduced the UDP-glucosyltransferase activity of EDR1^YZN compared to EDR1^YD1, resulting in abnormal endosperm development in the near-isogenic line, accompanied by insufficient grains and changes in grain quality. By analyzing the distribution of the two alleles EDR1^YD1 and EDR1^YZN among diverse paddy rice and upland rice varieties, we discovered that EDR1 was conserved in upland rice, but segregated in paddy rice. Further analyses of grain chalkiness in the alleles of EDR1^YD1 and EDR1^YZN varieties indicated that rice varieties harboring EDR1^YZN and EDR1^YD1 preferentially showed high chalkiness, and low chalkiness, respectively. Taken together, these results suggest that the UDP-glucosyltransferase gene EDR1 is an important determinant controlling differential endosperm development between upland rice and paddy rice.     

Benzo(a)pyrene diolepoxide adducts to albumin in workers exposed to polycyclic aromatic hydrocarbons: association with specific CYP1A1, GSTM1, GSTP1 and EHPX genotypes

We investigated whether the presence of (+)-anti-benzo(a)pyrene diolepoxide adducts to serum albumin (BPDE-SA) among workers exposed to benzo(a)pyrene (BaP) and unexposed reference controls was influenced by genetic polymorphisms of cytochrome P4501A1 (CYP1A1), microsomal epoxide hydrolase (EHPX), glutathione S-transferases M1 (GSTM1) and P1 (GSTP1), all involved in BaP metabolism. Exposed workers had significantly higher levels of adducts (0.124 ± 0.02 fmol BPTmg^-1 SA, mean ± SE) and a higher proportion of detectable adducts (40.3%) than controls (0.051 ± 0.01 fmol BPT mg^-1 SA; 16.1%) (p = 0:014 and p = 0:012). Smoking increased adduct levels only in occupationally exposed workers with the GSTM1 deletion (GSTM1 null) (p = 0:034).

Smokers from the exposed group had higher adduct levels when they were CYP1A1 *1/*1 wild-type rather than heterozygous and homozygous for the variant alleles (CYP1A1 *1/*2 plus *2/*2) (p = 0:01). The dependence of BPDE-SA adduct levels and frequency on the CYP1A1 *1/*1 genotype was most pronounced in GSTM1-deficient smokers. Exposed workers with GSTM1 null/GSTP1 variant alleles had fewer detectable adducts than those with the GSTM1 null/GSTP1*A wild-type allele, supporting for the first time the recent in vitro finding that GSTP1 variants may be more effective in the detoxification of BPDE than the wild-type allele. Logistic regression analysis indicated that occupational exposure, wild-type CYP1A1*1/*1 allele and the combination of GSTM1 null genotype+EHPX genotypes associated with predicted low enzyme activity were significant predictors of BPDE-SA adducts. Though our findings should be viewed with caution because of the relatively limited size of the population analysed, the interaction between these polymorphic enzymes and BPDE-SA adducts seems to be specific for high exposure and might have an impact on the quantitative risk estimates for exposure to polycyclic aromatic hydrocarbons.     

Enantioselective microbial reduction of 3,5-dioxo-6-(benzyloxy) hexanoic acid, ethyl ester

The key chiral intermediate 3,5-dihydroxy-6-(benzyloxy) hexanoic acid, ethyl ester 2a, was made by the stereoselective microbial reduction of 3,5-dioxo-6-(benzyloxy) hexanoic acid, ethyl ester 1. Among various microbial cultures evaluated, cell suspensions of Acinetobacter calcoaceticus SC 13876 reduced 1 to 2a. The reaction yield of 85% and optical purity of 97% was obtained using glycerol-grown cells. The substrate was used at 2 g l⁻¹ and cells were used at 20% (w/v, wet cells) concentrations. The optimum pH for the reduction of 1 to 2a was 5.5 and the optimum temperature was 32°C. Cell extracts of A. calcoaceticus SC 13876 in the presence of NAD⁺, glucose, and glucose dehydrogenase reduced 1 to the corresponding monohydroxy compounds 3 and 4 [3-hydroxy-5-oxo-6-(benzyloxy) hexanoic acid ethyl ester 3, and 5-hydroxy-3-oxo-6-(benzyloxy) hexanoic acid ethyl ester 4]. Both 3 and 4 were further reduced to 2a by cell extracts. Reaction yield of 92% and optical purity of 99% were obtained when the reaction was carried out in a 1-l batch using cell extracts. The substrate was used at 10 g l⁻¹. Product 2a was isolated from the reaction mixture in 72% overall yield. The GC and HPLC area % purity of the isolated product was 99% and the optical purity was 99.5%. The reductase which converted 1 to 2a was purified about 200-fold from cell extracts of A. calcoaceticus SC 13876. The purified enzyme gave a single protein band on SDS-PAGE corresponding to 35,000 daltons.     

一株溶植酸磷类芽孢杆菌的分离筛选及对水稻幼苗的促生作用

采用溶磷平板筛选和重金属耐性复筛相结合,从薇甘菊根际分离到一株兼具多重金属抗性的溶磷细菌(编号为ZLT11),16S rRNA 基因序列分析显示,该菌株属于类芽孢杆菌。菌株对植酸钙和植酸的溶磷量分别为84.10和73.84 mg·L^-1,其在30 ℃、初始pH为9.0时对植酸钙的溶磷量最高,达95.66 mg·L^-1。菌株ZLT11能耐受≤400 mg·L^-1 Pb ²⁺、≤100 mg·L^-1 Cd ²⁺及≤40 mg·L^-1 Hg ²⁺,当添加植酸钙为磷源时,接种菌株ZLT11使水稻幼苗平均根长、根数、苗高和总生物量较对照幼苗分别增加106.7%、76.6%、49.0%和46.3%。菌株ZLT11还能显著促进水稻幼苗在Cd胁迫下的生长。     

不同氮水平下不同种稗草对水稻产量形成的影响

以‘南粳9108’(粳稻)为材料,自移栽至成熟期分别与无芒稗、西来稗和光头稗共培养,以无稗草共培为对照,观察不同种类共培稗草在不同施氮水平下(0、120、240、360 kg N·hm^-2)对水稻产量形成的影响.结果表明:相同氮肥水平下,不同种稗草株高表现为西来稗>无芒稗>光头稗,生育期由长到短为无芒稗>西来稗>光头稗.随着氮肥施用量的增加,不同种稗草的生物量在240 kg N·hm^-2下达到最大值,然后降低,无芒稗和西来稗的生物量均显著高于光头稗.在0 kg N·hm^-2下,不同种稗草对水稻产量无显著影响;在120 kg N·hm^-2下,无芒稗和光头稗处理水稻产量与无稗草处理差异不显著,但西来稗处理产量较无稗草处理显著降低;在240 kg N·hm^-2下,无芒稗、西来稗和光头稗处理显著减产;在360 kg N·hm^-2下,无芒稗和西来稗处理产量较无稗草处理显著降低,光头稗处理与无稗草处理差异不显著.稗草和氮肥对水稻产量形成具有明显的互作效应.120 kg N·hm^-2下,西来稗处理显著降低了水稻灌浆期剑叶硝酸还原酶活性、光合速率和根系氧化力以及成熟期氮积累量和干物质量,其他稗草处理与对照差异不显著;在240和360 kg N·hm^-2下,无芒稗和西来稗处理降低了水稻上述指标;在0 kg N·hm^-2下,各处理的上述指标差异不显著.回归分析表明,稗草表型对水稻产量的影响由大到小的顺序为生物量、株高、生育期和分蘖数,推测稗草较大的生物量造成水稻剑叶光合速率、硝酸还原酶活性、根系氧化力、氮积累量和干物质积累量降低,影响了水稻的生长发育,造成水稻减产.     

水稻品种中抗褐飞虱抗原次生物质的分析

借助高效液相色谱(HPLC)技术,研究了130份对褐飞虱生物型Ⅱ具有不同抗性水平的水稻样品(26个品种)中13个次生物质含量(峰面积)的差异;运用主成分分析和多元回归分析,建立了水稻品种抗性级别的预测模型:Y=3.4593-0.02491X₁+0.08475X₂-0.04227X₈+0.1174X₁₂.结果表明,水稻的抗性水平与峰面积值之间极显著相关(r²=0.84,P<0.01),峰1、峰2、峰8、峰12对应的次生化合物是影响水稻对褐飞虱生物型Ⅱ抗性水平的主要抗原次生化合物;水稻品种中起抗虫作用的抗原次生物质不止一种,而是几种的组合,而且它们对水稻抗虫性的贡献权重是不完全相同的.     

Creation of aromatic maize by CRISPR/Cas

Aroma is an important quality parameter for breeding in rice (Oryza sativa). For example, the aromatic rice varieties basmati and jasmine rice, with a popcorn-like scent, are popular worldwide and routinely command a price premium. 2-acetyl-1-pyrroline (2AP) is a key flavor compound among over 200 volatiles identified in fragrant rice. A naturally fragrant germplasm exists in multiple plant species besides rice, which all exhibit lower activity of BETAINE ALDEHYDE DEHYDROGENASE 2 (BADH2). However, no equivalent aromatic germplasm has been described in maize (Zea mays). Here, we characterized the two maize BADH2 homologs, ZmBADH2a and ZmBADH2b. We generated zmbadh2a and zmbadh2b single mutants and the zmbadh2a-zmbadh2b double mutant by CRISPR/Cas in four inbred lines. A popcorn-like scent was only noticeable in seeds from the double mutant, but not from either single mutant or in wild type. In agreement, we only detected 2AP in fresh kernels and dried mature seeds from the double mutant, which accumulated between 0.028 and 0.723 mg/kg 2AP. These results suggest that ZmBADH2a and ZmBADH2b redundantly participate in 2AP biosynthesis in maize, and represent the creation of the world's first aromatic maize by simultaneous genome editing of the two BADH2 genes.     

RID1 sets rice heading date by balancing its binding with SLR1 and SDG722

Rice(Oryza sativa) is a major crop that feeds billions of people, and its yield is strongly influenced by flowering time(heading date). Loss of RICE INDETERMINATE1(RID1) function causes plants not to flower; thus, RID1 is considered a master switch among flowering-related genes. However, it remains unclear whether other proteins function together with RID1 to regulate rice floral transition.Here, we revealed that the chromatin accessibilityand H3 K9 ac, H3 K4 me3, and H3 K36 me3 levels at Headin...     

紫云英配施化肥对水稻氮素吸收利用和紫云英氮在水稻-土壤体系分配、残留的影响

明确紫云英配施化肥条件下水稻对氮素吸收利用和紫云英氮在水稻-土壤体系的吸收利用、分配及残留规律,能够为豫南稻区合理施肥提供依据。本研究利用原状土柱模拟和¹⁵N示踪技术,研究等氮条件下不施肥(CK)、化肥+22500 kg·hm^-2紫云英(FM1)、化肥+30000 kg·hm^-2紫云英(FM2)、化肥+37500 kg·hm^-2紫云英(FM3)、化肥+22500 kg·hm^-2紫云英+石灰(FM1+CaO)、化肥+30000 kg·hm^-2紫云英+石灰(FM2+CaO)、化肥+37500 kg·hm^-2紫云英+石灰(FM3+CaO)对水稻氮素吸收利用、水稻-土壤体系氮素养分平衡和紫云英矿化分解的氮在水稻各部位吸收利用、分配及残留的影响。结果表明: 与CK相比,施肥显著提高了稻谷氮吸收量、稻秆氮吸收量和氮素表观损失量、氮素盈余量。稻谷氮吸收量、稻秆氮吸收量和水稻氮利用率随紫云英翻压量增加呈先升高后降低趋势,氮素表观损失量和氮素盈余量随紫云英翻压量增加呈先降低后上升趋势,均以翻压30000 kg·hm^-2紫云英配施化肥处理效果较好。增施石灰可提高水稻稻谷氮吸收量、稻秆氮吸收量和水稻氮利用率,降低氮素表观损失量和氮素盈余量,以FM2+CaO处理效果最好。各施肥处理水稻吸收的氮来源于紫云英的比例为6.3%～13.2%,来源于土壤和肥料的比例为86.8%～93.7%;水稻对紫云英氮的当季利用率为23.8%～33.6%,水稻各部位对紫云英氮的利用率表现为籽粒>茎叶>根;紫云英氮在土壤中的残留率为37.6%～62.4%,损失率为7.8%～38.6%。综合考虑水稻氮素吸收利用、水稻-土壤体系氮素养分平衡和紫云英氮在水稻中的分配状况,该研究区以FM2+CaO处理为最优。     

Engineering broad-spectrum disease-resistant rice by editing multiple susceptibility genes

Rice blast and bacterial blight are important diseases of rice (Oryza sativa) caused by the fungus Magnaporthe oryzae and the bacterium Xanthomonas oryzae pv. oryzae (Xoo), respectively. Breeding rice varieties for broad-spectrum resistance is considered the most effective and sustainable approach to controlling both diseases. Although dominant resistance genes have been extensively used in rice breeding and production, generating disease-resistant varieties by altering susceptibility (S) genes that facilitate pathogen compatibility remains unexplored. Here, using CRISPR/Cas9 technology, we generated loss-of-function mutants of the S genes Pi21 and Bsr-d1 and showed that they had increased resistance to M. oryzae. We also generated a knockout mutant of the S gene Xa5 that showed increased resistance to Xoo. Remarkably, a triple mutant of all three S genes had significantly enhanced resistance to both M. oryzae and Xoo. Moreover, the triple mutant was comparable to the wild type in regard to key agronomic traits, including plant height, effective panicle number per plant, grain number per panicle, seed setting rate, and thousand-grain weight. These results demonstrate that the simultaneous editing of multiple S genes is a powerful strategy for generating new rice varieties with broad-spectrum resistance.     

Dissecting the genetic basis of heavy panicle hybrid rice uncovered <Emphasis Type="Italic">Gn1a</Emphasis> and <Emphasis Type="Italic">GS3</Emphasis> as key genes

Key message

Shuhui498 (R498) is an elite parent of heavy panicle hybrid rice by pyramiding the rare gn1a and null gs3 alleles. This finding reveals the genetic basis and great potential application in future breeding of R498.

Abstract

The heavy panicle trait, defined as 5 g or more of grain weight per panicle, is one of the target traits in super-high-yield rice breeding programs. The use of heavy panicle-type hybrid rice has been shown to be a successful strategy for super-high-yield breeding programs, particularly under the environmental conditions of high humidity and deficient solar radiation in southwestern China. However, the genetic components of the heavy panicle trait in hybrid rice remain elusive. Here, we report that the combination of loss-of-function mutations in Grain number 1a (Gn1a) and Grain Size 3 (GS3) is responsible for the heavy panicle phenotype of the elite hybrid rice restorer line Shuhui498 (R498). The null gn1a allele is the determinant factor for heavy panicles through increased grain number, while gs3 is associated with grain size and weight. R498 pyramided the two major null alleles, resulting in heavy panicles with a high grain number and large grains. Clustering analysis revealed that the null gn1a^R498 allele is a rare haplotype which has been innovatively utilized in R498, underscoring the great potential of R498 for breeding purposes. Our research thus sheds light on the distinct genetic compositions of heavy panicle-type rice and may potentially facilitate super-high-yield rice breeding.

     

寒地不同熟性品种水稻产量对CO2浓度和温度升高响应的模拟

选择黑龙江省作为研究区域,根据主栽水稻生育期内所需积温选取3个代表性品种,重点分析增温和大气CO₂肥效作用对不同熟性品种水稻产量的影响.采用2013年的逐日气象资料及开顶式气室(OTC)(3个CO₂浓度:390、450和550 μmol·mol^-1)试验资料对品种的遗传参数进行调试;然后采用经验证的CERES-Rice作物模型分别模拟了3个CO₂浓度水平下,伴随温度升高1、2、3和4 ℃时早、中、晚熟品种水稻产量.结果表明: 随CO₂浓度升高,不同品种水稻产量均上升;随温度升高,早熟品种产量持续下降,中、晚熟品种产量先上升再下降.若不考虑CO₂肥效作用,除了中熟和晚熟品种在增温1 ℃时会有3.1%和0.27%的小幅增产外,其余均表现为减产,其中早熟品种减产幅度最大,增温4 ℃时减产高达57.7%,而中熟和晚熟品种减产10%左右.若考虑CO₂肥效作用,450 μmol·mol^-1 CO₂浓度下,中熟和晚熟品种在增温2 ℃时仍增产0.75%和3.2%;550 μmol·mol^-1 CO₂浓度下,中熟品种在增温3 ℃时仍增产4.5%,晚熟品种在增温4 ℃时仍增产0.39%.而无论是否考虑CO₂肥效作用,早熟品种在增温作用下均表现大幅度减产.与不考虑CO₂肥效相比,大气CO₂肥效作用有效提高了水稻产量,但CO₂肥效对增产的贡献率在不同品种间差异不明显,且贡献率均小于10%.     

优化子叶节转化法培育大豆MtDREB2A转基因植株

将正交因素试验与GUS基因组织化学染色等技术相结合, 优化大豆(Glycine max)品种东农50遗传转化体系, 导入抗旱关键基因MtDREB2A。结果表明, 大豆种子表面消毒, NaClO溶液法与Cl₂气熏蒸法的去污染率分别达到98.67%和93.33%。子叶节法转GUS基因组织化学染色率(68.33%)显著高于下胚轴法(14.00%)和胚尖法(0.67%) (P<0.05)。种子萌发5天, 农杆菌(Agrobacterium tumefaciens)培养温度25°C, OD₆₀₀=0.9, 共培养5天的转GUS基因子叶节最高达72.00%; 恢复培养5天, 草丁膦(3 mg·L^-1)、头孢噻肟钠(200 mg·L^-1)和羧苄青霉素(300 mg·L^-1)筛选诱导分化的转GUS基因不定芽最多为3.33%; 优化的大豆遗传转化体系转化效率为1.11%。转MtDREB2A基因大豆东农50植株根系更加密集, 主根长度和侧根数量均显著高于对照(P<0.05), 证实MtDREB2A基因具有促进大豆根系生长的作用, 为利用该基因进行大豆抗旱育种奠定了坚实的基础并提供了理论依据。     

微微型藻华爆发海域硅酸盐与叶绿素a分布特征研究

以南戴河近岸海域为研究对象,分析了该海域2009年5~10月份硅酸盐和叶绿素a的时空分布特征,并初步探讨了它们与微微型藻华的关系。结果表明:整个调查期间该海域硅酸盐平均含量为0.67±0.31 mg·L^-1,叶绿素a平均含量为2.06±1.16 ug·L^-1;其平面分布呈现近岸高、远岸低的特点;硅酸盐平均含量9月最高、5月最低;叶绿素a平均含量在8~9月高、5~6月低;微微藻赤潮期间海域硅酸盐和叶绿素a平均含量明显高于未发生微微藻赤潮的2008年同期。叶绿素a与硅酸盐浓度呈现出正相关关系,在微微藻赤潮爆发期间尤为显著,可能是因为微微型浮游植物大量生长抑制了硅藻等消耗硅酸盐藻类的正常生长繁殖所致。     

ZmFBL41 Chang7-2: 玉米抗纹枯病的关键利器

由真菌Rhizoctonia solani引起的纹枯病严重危害玉米(Zea mays)和水稻(Oryza sativa)等作物的安全生产。R. solani的宿主范围广且抗源少, 加之相关的抗性机制研究有限, 导致纹枯病的危害长期得不到有效控制。近期, 中国科学家通过对318份玉米自交系进行全基因组关联分析, 筛选到1个与纹枯病抗性相关的、编码F-box结构域蛋白的候选基因ZmFBL41 (GRMZM2G109140)。ZmFBL41蛋白是SCF (SKP1-Cullin-F-box) E3泛素连接酶复合体的一员, 能介导复合体对肉桂醇脱氢酶ZmCAD的降解, 从而降低木质素的积累, 使玉米易感纹枯病。玉米抗病自交系Chang7-2中, 蛋白ZmFBL41 ^Chang7-2因2个关键氨基酸的变异, 不能结合并降解底物ZmCAD, 使木质素含量增加, 从而提高玉米对纹枯病的抗性。该研究率先揭示了SCF复合体可通过降解肉桂醇脱氢酶来调控植物免疫反应的新型分子机制, 为提高玉米及其它作物对纹枯病的抗性提供了重要理论依据和基因资源。     

A recent retrotransposon insertion of J caused E6 locus facilitating soybean adaptation into low latitude

Soybean (Glycine max) is an important legume crop that was domesticated in temperate regions. Soybean varieties from these regions generally mature early and exhibit extremely low yield when grown under inductive short-day (SD) conditions at low latitudes. The long-juvenile (LJ) trait, which is characterized by delayed flowering and maturity, and improved yield under SD conditions, allowed the cultivation of soybean to expand to lower latitudes. Two major loci control the LJ trait: J and E6. In the current study, positional cloning, sequence analysis, and transgenic complementation confirmed that E6 is a novel allele of J, the ortholog of Arabidopsis thaliana EARLY FLOWERING 3 (ELF3). The mutant allele e6^PG, which carries a Ty1/Copia-like retrotransposon insertion, does not suppress the legume-specific flowering repressor E1, allowing E1 to inhibit Flowering Locus T (FT) expression and thus delaying flowering and increasing yields under SD conditions. The e6^PG allele is a rare allele that has not been incorporated into modern breeding programs. The dysfunction of J might have greatly facilitated the adaptation of soybean to low latitudes. Our findings increase our understanding of the molecular mechanisms underlying the LJ trait and provide valuable resources for soybean breeding.