Identification of a Resistance Gene bls1 to Bacterial Leaf Streak in Wild Rice Oryza rufipogon Griff.

Bacterial leaf streak (BLS) of rice, caused by Xanthomonas oryzae pv. oryzicola (Xoc) is a worldwide destructive disease. Development of resistant varieties is considered to be one of the most effective and eco-friendly ways to control the disease. However, only a few genes/QTLs having resistance to BLS have been identified in rice until now. In the present study, we have identified and primarily mapped a BLS-resistance gene, bls1, from a rice line DP3, derived from the wild rice species Oryza rufipogon Griff. A BC₂F₂ (9311/DP3//9311) population was constructed to map BLS-resistance gene in the rice line DP3. The segregation of the resistant and susceptible plants in BC₂F₂ in 1:3 ratio (χ²=0.009, χ²_{0.05, 1}=3.84, P>0.05), suggested that a recessive gene confers BLS resistance in DP3. In bulked segregant analysis (BSA), two SSR markers RM8116 and RM584 were identified to be polymorphic in resistant and susceptible DNA bulks. For further mapping the resistance gene, six polymorphic markers around the target region were applied to analyze the genotypes of the BC₂F₂ individuals. As a result, the BLS-resistant gene, designated as bls1, was mapped in a 4.0-cM region flanked by RM587 and RM510 on chromosome 6.     

Identification and Molecular Mapping of the RsDmR Locus Conferring Resistance to Downy Mildew at Seedling Stage in Radish (Raphanus sativus L.)

Downy mildew (DM), caused by the fungus Peronospora parasitica, is a destructive disease of radish (Raphanus sativus L.) worldwide. Host resistance has been considered as an attractive and environmentally friendly approach to control the disease. However, the genetic mechanisms of resistance in radish to the pathogen remain unknown. To determine the inheritance of resistance to DM, F₁, F₂ and BC₁F₁ populations derived from reciprocal crosses between a resistant line NAU-dhp08 and a susceptible line NAU-qtbjq-06 were evaluated for their responses to DM at seedling stage. All F₁ hybrid plants showed high resistance to DM and maternal effect was not detected. The segregation for resistant to susceptible individuals statistically fitted a 3:1 ratio in two F₂ populations (F_2(SR) and F_2(RS)), and 1:1 ratio in two BC₁F₁ populations, indicating that resistance to DM at seedling stage in radish was controlled by a single dominant locus designated as RsDmR. A total of 1972 primer pairs (1036 SRAP, 628 RAPD, 126 RGA, 110 EST-SSR and 72 ISSR) were screened, and 36 were polymorphic between the resistant and susceptible bulks, and consequently used for genotyping individuals in the F₂ population. Three markers (Em9/ga24₃₇₀, NAUISSR826₇₀₀ and Me7/em10₄₀₀) linked to the RsDmR locus within a 10.0 cM distance were identified using bulked segregant analysis (BSA). The SRAP marker Em9/ga24₃₇₀ was the most tightly linked one with a distance of 2.3 cM to RsDmR. These markers tightly linked to the RsDmR locus would facilitate marker-assisted selection and resistance gene pyramiding in radish breeding programs.     

African Cassava Whitefly,Bemisia tabaci,Resistance in African and South American Cassava Genotypes

The whitefly, Bemisia tabaci, is a major pest of cassava, particularly in Africa where it is responsible both for the transmission of plant viruses and, increasingly, for direct damage due to feeding by high populations. To date, there have been no practical solutions to combat this emerging problem, due to the inability of the subsistence farmers that grow cassava to afford expensive inputs such as insecticides. A programme of research was carried out linking institutes in Africa, the UK and South America, to identify possible resistance sources in cassava to the whitefly, Bemisia tabaci. The South American genotype MEcu 72 and several Ugandan cassava landraces including Ofumba Chai, Nabwire 1 and Mercury showed good levels of resistance to B. tabaci. Field and screen-house experiments showed that all of the improved, high-yielding cassava mosaic disease (CMD) resistant cassava genotypes assessed were highly susceptible to B. tabaci and supported high populations of all life stages. These data support the hypothesis that the continuing high populations of cassava B. tabaci in Uganda are due, in part, to the widespread adoption of CMD-resistant cassava varieties during the CMD pandemic. They also show that the whitefly, Aleurotrachelus socialis, resistance present in the South American cassava genotypes could have broader applicability in the Old World.     

Identification of the resistance gene to powdery mildew in Chinese wheat landrace Baiyouyantiao

Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is one of the most damaging diseases to wheat in the world. The cultivation of resistant varieties of wheat is essential for controlling the powdery mildew epidemic. Wheat landraces are important resources of resistance to many diseases. Mapping powdery mildew resistance genes from wheat landraces will promote the development of new varieties with disease resistance. The Chinese wheat landrace Baiyouyantiao possesses characteristic of disease resistance to powdery mildew. To identify the resistance gene in this landrace, Baiyouyantiao was crossed with the susceptible cultivar Jingshuang 16 and seedlings of parents and F₁, BC₁, F₂, and F_2:3 were tested with Bgt isolate E09. The genetic results showed that the resistance of Baiyouyantiao to E09 was controlled by a single recessive gene, tentatively designated PmBYYT. An Illumina wheat 90K single-nucleotide polymorphism (SNP) array was applied to screen polymorphisms between F₂-resistant and F₂-susceptible DNA bulks for identifying the chromosomal location of PmBYYT. A high percentage of polymorphic SNPs between the resistant and susceptible DNA bulks was found on chromosome 7B, indicating that PmBYYT may be located on this chromosome. A genetic linkage map of PmBYYT consisting of two simple sequence repeat markers and eight SNP markers was developed. The two flanking markers were SNP markers W7BL-8 and W7BL-15, with genetic distances of 3 and 2.9 cM, respectively. The results of this study demonstrated the rapid characterization of a wheat disease resistance gene and SNP marker development using the 90K SNP assay. The flanking markers of gene PmBYYT will benefit marker-assisted selection (MAS) and map-based cloning in breeding wheat cultivars with powdery mildew resistance.     

芥蓝BC_3代Ogura CMS育性恢复材料的创制及Rfo基因传递和背景分析

【目的】创制Ogura细胞质不育(Ogura CMS)的恢复系是利用Ogura CMS种质资源的有效途径。本研究基于已获得的BC2代育性恢复单株15Q23,继续用芥蓝进行回交,通过分析育性恢复基因Rfo的传递效率,及BC3代Rfo阳性株的遗传背景、育性表现、结实性和倍性,从而加速甘蓝类蔬菜Ogura CMS恢复材料的创制,获得甘蓝类蔬菜Ogura CMS恢复系。【方法】以BC2代育性较好的单株15Q23为父本,Ogura CMS芥蓝15Y102为母本进一步回交,利用Rfo特异分子标记对所有回交后代进行筛选,计算BC3代Rfo传递效率,并调查BC3代Rfo阳性单株的形态特征、育性恢复情况、结实性、倍性;选取遗传背景近于芥蓝、结实较好的重点单株继续回交获得BC4代,分析BC4代Rfo传递效率和阳性单株倍性。【结果】在开花的不同时期,单株15Q23花粉活力差异明显,以不同时期的花粉进行回交的结实性也存在极显著差异(P0.01),平均结实率为0.07粒/授粉花蕾(7%)。利用Rfo特异标记对获得的BC3代单株进行苗期筛选,结果表明,Rfo可稳定传递,遗传背景分析结果表明,BC3代单株与芥蓝15Y102遗传相似系数在0.81—0.92,遗传背景比BC2代单株15Q23(0.73)更近于芥蓝,形态标记聚类结果与遗传背景标记聚类结果一致。形态观察发现,BC3单株形态特征都近于芥蓝,但生长势较亲本芥蓝更强;倍性鉴定结果表明,多数BC3后代接近于四倍体。开花后观察34个BC3后代单株的育性,有Rfo标记的单株育性均得到恢复。但不同单株间花粉活力存在差异,单株16Q1-4、16Q1-7、16Q1-10在整个花期花粉活力一直在75%以上。利用亲本芥蓝对花粉活力较好的Rfo阳性单株(花粉活力50%)进行回交,以单株16Q1-4和单株16Q1-10当父本时结实性最好,结实率分别为15%和9%,显著高于BC2代阳性单株15Q23(7%,P0.05)。BC4代单株中Rfo可以稳定传递,Rfo传递效率接近33%;对以16Q1-4为父本回交获得的24株阳性株进行倍性检测,不同单株间倍性差异较大,其中3株的荧光峰值和亲本芥蓝相近,倍性近于芥蓝。【结论】利用芥蓝对种间杂交六倍体Rfo阳性株进行第3、第4代回交,Rfo可稳定传递,成功获得了遗传背景、形态特征近于亲本芥蓝,结实性较BC2代单株15Q23显著提升的BC3代Ogura CMS育性恢复材料16Q1-4和16Q1-10。     

早花基因（FT）介导的烟草快速回交改良研究

【目的】针对常规回交育种周期较长的问题,以烟草为模式植物,探索快速回交改良作物的有效方法。【方法】以对TMV免疫的烤烟品种Fc8作为抗性供体亲本,以综合性状优良但感TMV的中烟100为受体亲本进行回交改良及种质创新。首先从拟南芥中克隆早花FT,将其连接到植物表达载体P22上,并转入农杆菌中,采用叶盘法转化烟草Fc8,创建含FT的Fc8阳性植株。阳性植株分别与中烟100杂交,根据F₁后代群体中早花基因的分离比例,鉴定筛选含单拷贝FT的阳性植株。接下来,从含单拷贝FT的阳性植株的F₁群体中选择早花植株,与中烟100回交,根据回交分离群体中FT早花基因与TMV抗性N基因的分离比例,筛选FT与N基因不连锁的阳性植株。选择该阳性植株与中烟100连续回交。在每一回交分离世代中,选择早花且含有TMV抗性标记的植株连续回交,当后代遗传背景大部分与中烟100相近,并保留TMV抗性时选择非早花且含N基因标记的植株,鉴定无FT、Ubi启动子、Nos终止子和Hyg筛选标记等转基因元件后,连续自交纯化,筛选改良的创新种质。【结果】通过转基因技术共获得8株含FT的Fc8阳性植株,经鉴定获得一个含单拷贝FT,且FT和TMV抗性N基因不连锁的Fc8植株。用该植株作为TMV抗性的供体亲本回交改良中烟100,一年多时间已回交加代到BC₄F₁,比常规回交育种时间缩短450-500 d。早花基因在杂交、回交各世代均能稳定表达,早花植株在苗龄50-60 d现蕾开花,早花植株现蕾开花时,一般有3-4片叶,株高平均约35 cm,同期非早花植株高约27 cm,仍然处于营养生长阶段。非早花植株在苗龄130-140 d现蕾开花,平均株高约120 cm,叶片数18-20片。FT能使植株花期提前70-90 d,缩短世代周期约一半时间;早花加代结合TMV分子标记筛选得到了BC₁、BC₂、BC₃代TMV抗性烟草新种质。【结论】借助FT介导的早花及抗TMV基因分子标记,能有效地缩短烟草TMV抗性回交育种周期、加快回交育种进程,虽利用转基因技术但可获得不含有任何转基因元件的创新种质。     

Genetics and fitness costs of resistance to flupyradifurone in Bemisia tabaci from China

Flupyradifurone is a promising new insecticide used for controlling Bemisia tabaci during vegetable production. In this study, we assessed the fitness costs and mode of inheritance associated with resistance to flupyradifurone in B. tabaci by comparing the susceptible strain (MED-S) to one field-evolved flupyradifurone-resistant strain (WH-R, with 199-fold resistance) and one laboratory-selected flupyradifurone-resistant strain (FLU-SEL, with 124-fold resistance). Progenies of reciprocal crosses between WH-R and MED-S (F_1A, F_1B, and pooled F₁), and between FLU-SEL and MED-S (F_1C, F_1D, and pooled F₁’), showed varying degrees of dominance, indicating that resistance to flupyradifurone in WH-R was autosomal and incompletely dominant, yet in FLU-SEL it was autosomal and incompletely recessive. Furthermore, the development of resistance to flupyradifurone occurred at the expense of fitness costs for the resistant populations. Compared to the MED-S strain, WH-R showed a relative fitness of 0.50 with significantly prolonged developmental durations and reduced survival rates of the nymphal and pseudopupal stages, as well as decreased fecundity and hatchability. Similarly, FLU-SEL showed a relative fitness of 0.65 and also demonstrated prolonged developmental durations and reduced survival rates of nymphs and pseudopupae, as well as decreased hatchability in comparison with the MED-S strain. However, no significant differences in fecundity were observed between MED-S and FLU-SEL. The present study provides useful knowledge for formulating pest management strategies in the field, which will allow growers to slow the development of resistance to flupyradifurone and to sustainably control B. tabaci.     

分子标记辅助甜瓜抗蔓枯病基因的聚合及品种改良

【目的】蔓枯病（gummy stem blight）是一种真菌性土传病害,是危害甜瓜生产的严重病害之一,其存在生理小种的分化,品种即使仅携带单个抗病基因,仍会导致甜瓜抗性逐步降低甚至丢失。建立甜瓜抗蔓枯病聚合育种的分子标记辅助选择体系,选育抗性高且不再分离的聚合抗源自交系和品质优良且高抗甜瓜蔓枯病的改良白皮脆品种（品系）,为甜瓜优质、抗病和高产育种提供一种简单、快捷的选择方法和重要的中间材料。【方法】利用5份甜瓜单一抗源材料PI140471、PI157082、PI511890、PI482398和PI420145两两杂交获得8份聚合抗源（082-471、082-890、082-398、145-471、145-082、145-890、145-398和890-398）。利用3个不同浓度的蔓枯病病菌孢子液（5×10⁵个/mL、5×10⁷个/mL、5×10⁹个/mL）对8份聚合抗源的F₁植株幼苗进行接种鉴定。结合春、秋两季的接种鉴定结果,筛选得到2份聚合后抗性显著提高的基因组合145-471和145-398。一方面,以145-471和145-398为材料,利用苗期梯度接种鉴定、分子标记辅助选择以及农艺性状观察,对其自交后代进行逐代筛选至F₇。另一方面,选用组合PI420145和PI140471以及PI420145和PI482398作为蔓枯病抗性基因的供体亲本,综合性状优良的感病甜瓜品种‘白皮脆’为抗性基因受体亲本。先分别单向回交5代,在单个基因回交转移时,利用分子标记检测结合农艺性状观察对回交后代进行筛选。当回交后代的遗传背景得到一定程度恢复后,再将2个方向的回交后代进行杂交,后自交3代稳定。【结果】聚合抗源对不同浓度的蔓枯病菌均表现为抗,而单一抗源对不同浓度蔓枯病菌表现出选择性抗性且抗性水平低于聚合抗源。SSR标记CMCT505和CMTA170a在PI140471和PI482398上可分别扩增出189 bp和121 bp的特异性片段,SCAR标记SGSB₁₈₀₀可以在PI420145上扩增出1 800 bp的特异性片段,而145-471（145-398）的聚合单株可以同时扩增出189 bp和1 800 bp（121 bp和1 800 bp）两条特异片段。聚合抗源145-471（或145-398）的自交F₇世代以及改良白皮脆BC₅F₄世代群体的分子标记鉴定结果显示,各单株已经成功聚合了Gsb-1和Gsb-6（或Gsb-4和Gsb-6）两个抗病基因,抗性不再有分离且农艺性状稳定一致。初步建立了甜瓜抗蔓枯病聚合育种的分子标记辅助选择体系,获得了两份表现高抗且抗性不再分离的聚合抗源自交系F₇和2个以优质品种‘白皮脆’为受体亲本的改良白皮脆BC₅F₄品种（系）。改良白皮脆BC₅F₄世代表现为高抗甜瓜蔓枯病,且在单果质量、果形指数、果实脆度、果肉质地、果肉厚度和可溶性固形物含量等农艺性状方面与白皮脆并无显著差异。【结论】创建的3个分子标记CMCT505、CMTA170a和SGSB₁₈₀₀对抗病基因Gsb-1、Gsb-4和Gsb-6的选择具有较高的准确性。初步建立了甜瓜抗蔓枯病聚合育种的分子标记辅助选择体系,为甜瓜优质、抗病和高产育种提供了一种简单、快捷的选择方法,将大大提高育种的效率。改良‘白皮脆’作为抗病育种的新材料,为甜瓜抗病品种的选育和抗病基因进一步聚合提供了材料。     

Development of Insect-Resistant Hybrid Rice by Introgressing the Bt Gene from Bt Rice Huahui 1 into 11-32A/B,a Widely Used Cytogenic Male Sterile System

Huahui 1 is an elite transgenic male sterile restorer line of wild rice abortive-type that expresses a Bacillus thuringiensis （Bt） δ-endotoxin and provides effective and economic control oflepidopteran insects. To exploit Huahui 1 to develop a new Bt rice, the insertion site of the Bt gene was determined by thermal asymmetric interlaced PCR （TAIL-PCR）. Bt was located in the promoter region ofLOC. Os10g10360, approximately 5.35 Mb from the telomere of the short arm of chromosome 10. For the first time, a Bt cytoplasmic male sterile （CMS） system was developed by introgressing Bt from Huahui 1. The recipient CMS system used consisted of Indonesia paddy rice-type II-32B （maintainer line） and II-32A （male sterile line）. Marker-assisted selection was used to increase selection efficiency in the backcrossing program. In BC5F1, the Bt plant 85015-8 was selected for further analyses, as it had the highest SSR marker homozygosity. In addition, the linkage drag of the foreign Bt gene in 85015-8 was minimized to 8.01-11.46 Mb. The foreign Bt gene was then delivered from 85015-8 into II-32A. The resultant Bt II-32A and Bt II-32B lines were both resistant to lepidopteran in field trials, and agronomic traits were not disturbed. The maintainability of II-32B, and the male sterility and general combining ability of II-32A, were not affected by the Bt introgression. This study demonstrates a simple and fast approach to develop Bt hybrid rice.     

Breeding of CMS maintainer lines through anther culture assisted by high-resolution melting-based markers

The integrated use of molecular marker-assisted selection (MAS) and anther culture has potential to significantly increase efficiency in plant breeding; however, reports on this kind of practical use are very limited. In the present study, we report the development of cytoplasmic male sterile (CMS) maintainers with aroma, disease resistance and red-brown hulls, as an example of integration of MAS and anther culture in rice breeding. A high-resolution melting (HRM)-based functional molecular marker was developed for the red-brown hull trait caused by a unique mutation (rbh1) in OsCAD2. Functional molecular markers for genes of rice blast resistance (Pi2), aroma (fgr) and red-brown hull (rbh1) were used for precise genotyping of individual plants in the BC₁ and BC₂F₂ populations derived from a cross between CMS maintainers Huaxiang B (pi2–/rbh1–/fgr–) and Rong 3B (Pi2+/RBH1+/Fgr+). A total of 89 doubled haploid (DH) lines were generated from selected BC₂F₂ plants (Pi2+/rbh1–/fgr–) by anther culture. Seven DH lines were subsequently selected as the potential new CMS maintainers based on their overall performance and high resistance to blast. Our study demonstrated that integration of MAS and anther culture significantly accelerated the development of CMS maintainers with multiple stacked genes.     

我国小麦农家品种白老芒麦的抗条锈性遗传分析

以感病材料铭贤169作母本,白老芒麦作父本配制杂交组合,获得杂种F1代种子;F1代植株自交获得F2代种子,以F1代作为父本与铭贤169回交获得BC1代种子。对亲本、F1代、F2代和BC1代植株接种鉴定,根据F1代、BC1代的抗性表现和F2代的抗感分离情况推知白老芒麦(甘地806)对CYSu-XI的抗病性是由一对显性基因和两对隐性基因的互补作用控制。     

河八王杂交种F1、BC1及其亲本DNA甲基化水平和模式变化

为分析河八王及后代基因组DNA甲基化水平和遗传模式变化,以河八王及其后代F_1和BC_1为材料,采用甲基化敏感扩增多态性技术(Methylation sensitive amplification polymorphism,MSAP)结合毛细管电泳技术(Capillary electrophoresis,CE)分析亲本及后代基因组DNA甲基化水平和遗传模式变化规律。结果表明:母本‘GT05-3256’的MSAP比率是59.6%,父本‘GXN1’则是60.5%,其杂交种F_1的MSAP比率是56.4%～59.0%,均低于双亲;BC_1的母本‘YC94-46’的MSAP比率是59.4%,父本‘T6-3’则是59.0%,BC_1MSAP比率是56.9%～69.8%,整体平均为62.8%,平均值高于双亲。BC_1世代总甲基化水平略高于F_1世代水平。F_1和BC_1基因组CCGG位点发生甲基化的方式整体上以内部胞嘧啶双链甲基化为主。在F_1和BC_1中均检测到70种甲基化类型,并进一步分为A、B、C、D和E等5大类,其中A类是亲本向杂交种的甲基化遗传类型;B类是去甲基化类型,表示杂交种相应于其亲本的甲基化减弱;C类是过或超甲基化类型,表示杂交种相应于其亲本的甲基化增强;D类是次甲基化类型,杂交后代甲基化水平比双亲均要低;E类为不定类型。结果显示,B、C、D、E是杂交种的甲基化变异类型;F_1的甲基化遗传类型(A类)比例明显低于BC_1,但变异类型B、C、D、E高于BC_1;杂交形成F_1和BC_1过程中,基因组DNA普遍发生了超甲基化修饰。     

秸秆生物炭对砂姜黑土有机磷组分含量的影响

研究秸秆生物炭对砂姜黑土有机磷组分及分配的影响,对剖析土壤磷循环机制和农田磷管理有重要意义。依托砂姜黑土定位试验,分析不施肥（CK）、常规施肥（NPK）、化肥与6.0、12、36和48 t·hm^-2小麦秸秆生物炭一次性增施（BC₆、BC₁₂、BC₃₆和BC₄₈）6个处理对作物产量、土壤理化性质及有机磷组分的影响。结果表明,与NPK处理相比,增施秸秆生物炭均可保障小麦和玉米产量,并显著增加（P < 0.05）土壤有机碳、全氮和pH,提升土壤肥力和缓解土壤酸化;砂姜黑土有机磷以中等活性有机磷为主（37.4%～45.4%）,其分配比例因秸秆生物炭施用量的不同而呈现差异。BC₆、BC₁₂、BC₃₆和BC₄₈处理土壤活性有机磷含量分别为11.4、10.7、9.2和9.3 mg·kg^-1,分别较NPK处理下降8.8%、14.4%、26.4%和25.6%,差异显著（P＜0.05）,且土壤活性有机磷含量与生物炭施用量呈显著线性负相关（R² = 0.881 6,P＜0.05）。增施秸秆生物炭处理（BC₆、BC₁₂、BC₃₆和BC₄₈）土壤活性有机磷所占比例较NPK处理均显著降低（P＜0.05）,这说明增施秸秆生物炭除了可有效提升土壤肥力水平、缓解土壤酸化之外,还可有效降低土壤有机磷活性,增强有机磷稳定性,保障作物产量,其中以一次性增施36 t·hm^-2效果最好,宜在砂姜黑土区广泛应用。     

Resistance of barley varieties to Heterodera avenae in the Qinghai–Tibet Plateau,China

The cereal cyst nematode, Heterodera avenae, is one of the most economically important pathogens impacting the worldwide production of cereals and is widely distributed in more than 16 regions in China. The present study used the numbers of nematodes inside the plant roots to evaluate the resistance/susceptibility of different subpopulations of barley Hordeum vulgare (QH2R, QH6R and TB2R) to H. avenae under field and pot conditions. Nematode development in two highly resistant varieties was also evaluated by in vivo experiment and microscopic observation. Analyses of 186 selected varieties showed the numbers of susceptible varieties identified with the number of females/cysts per plant (NFP) method were significantly higher than those identified with the Pf/Pi ratio (PPR) method, which indicated that the NFP method rather than the PPR method is more reliable to evaluate the resistance of barley. The field and pot experiment results indicated that the QH2R subpopulation had lower females/cysts numbers than QH6R and TB2R subpopulations, and eight HR varieties (Sunong 7617, Sunong 7635, Dongyuan 87-14, Rudong 14-46, Rudong 87-57, Rudong 87-8-45, Rudong 88-14-2, and Rudong 88-67-1) were identified in QH2R, with the NFP numbers below 4.2. Further microscopic observation of nematode development suggested that H. avenae often penetrated less into highly resistant varieties (Sunong 7635 and Dongyuan 87-14) and more frequently failed to develop into females than the susceptible barleys. The promising resistant varieties identified in the present research might be helpful for breeders to develop CCN-resistant cultivars and control H. avenae populations effectively at low costs.     

甘蔗与河八王杂交BC1对黑穗病的抗性鉴定与初步评价

为研究甘蔗与河八王杂交BC1品系(SNBC1)对黑穗病的抗性水平,以广西蔗区甘蔗黑穗病混合孢子粉为接种源,利用人工浸渍接种与自然感病相结合的方法,对河八王BC1、黑穗病鉴定对照品种及亲本共38个材料进行黑穗病抗性鉴定。通过观测发病潜伏期、持续发病期、接种发病率、自然发病率这4个病情参数,结合对照品种的抗性表现,评价参试品系的抗性,并通过系统聚类分析验证。结果表明4个病情参数之间的相关性达极显著水平:SNBC1品系中:未发病品系7个,占18.42%;高抗(HR)的品系15个,占39.47%;抗(R)品系3个,占7.89%;中感(MS)品系有3个,占7.89%;感(S)品系有2个,占5.26%。系统聚类分析结果与SNBC1材料的抗性表现一致。     

Molecular Mapping of Two Novel Stripe Rust Resistant Genes YrTp1 and YrTp2 in A-3 Derived from Triticum aestivum × Thinopyrum ponticum

Loss of variety resistance to stripe rust (Puccinia striiformis Westend f. sp.tritici) is an important factor causing massive periodical epidemic of rust in wheat production. Creation and development of new races of rust pathogen have led to serious crisis of resistance loss in widely planted varieties. This has quickened the search for new resistance resources. Molecular marker could facilitate the identification of the location of novel genes. A line A-3 with high resistance (immune) to currently epidemic yellow rust races (CY29, 31, 32) was screened out in offspring of Triticum aestivum × Thinopyrum ponticum. Segregation in F₂ and BC₁ populations indicated that the resistance was controlled by two independent genes: one dominant and one recessive. SSR markers were employed to map the two resistant genes in the F₂ and BC₁ populations. A marker WMC477-_167bp located on 2BS was linked to the dominant gene with genetic distance of 0.4 cM. Another marker WMC364-_{208 bp} located on 7BS was linked to the recessive-resistant gene with genetic distance of 5.8 cM. The two genes identified in this paper might be two novel stripe rust resistant genes, which were temporarily designated as YrTp1 and YrTp2, respectively. The tightly linking markers facilitate transfer of the two resistant genes into the new varieties to control epidemic of yellow rust.     

SSR标记辅助回交选育抗草甘膦油菜新品系的研究

为快速培育抗除草剂草甘膦的油菜新品系,以含草甘膦氧化还原酶基因gox的转基因抗草甘膦材料C9为供体亲本,以优良甘蓝型冬油菜Gr-1、Gr-2为轮回亲本,以回交转育为基本方法,利用gox基因的PCR检测和喷除草剂2种方法对回交后代进行前景选择,并利用SSR分子标记进行背景辅助选择,将抗草甘膦基因gox导入Gr-1、Gr-2中,在BC3选育得到遗传背景回复率大于96%的抗草甘膦油菜新品系。     

分子连锁分析探讨家蚕高抗BmNPV品系的抗性遗传基础

【目的】家蚕核型多角体病毒(Bombyx mori nucleopolyhedrovirus,BmNPV)所引发的血液型脓病是一种传染性强的蚕病,极大地影响蚕业生产。本研究旨在定位对BmNPV高抗的家蚕品系中控制其抗性的基因,进而解析其抗性遗传机制,为培育抗性素材和品系提供理论支持。【方法】以BmNPV高抗家蚕品系99R和较感品系Dazao-N为亲本,配制连锁分析(BC_1F)和定位分析(BC_1M)回交群体。首先对两个亲本品系进行浓度梯度添毒,统计感病死亡的家蚕头数,运用SPSS 17.0软件,计算其半致死剂量(LD_(50)),在此基础上确定BC_1分离群体的攻毒剂量,并通过单头定量攻毒,选取感病个体作为连锁定位分析材料;利用筛选得到的覆盖家蚕全套常染色体的多态性标记进行分型,并通过T检验计算各标记与抗性的连锁显著性水平(P值),筛选出与抗性相连锁的标记。在这些标记所在的染色体上加密标记,检测各标记在定位分析群体中的基因型,定位抗性基因。【结果】LD_(50)(99R)=2.92×10~6个多角体/头,LD_(50)(Dazao-N)=9.78×10~5个多角体/头,基于双亲的半致死剂量,选择介于两者之间且略高于其均值的剂量——2×10~6个多角体/头作为BC_1分离群体的攻毒剂量;先后于2014年秋季和2015年春季处理并检测连锁分析群体,前后两次所进行的连锁分析结果有较大差异,其中第一次找到Chr22上的多态性标记S2205与99R抗性连锁,而第二次的连锁分析显示标记S2205与抗性不连锁,也没有找到其他的连锁关系。通过与前人对BmNPV抗性的连锁定位分析结果进行对比,发现连锁定位分析结果的不可重复性是一个普遍的问题。AY380833是GenBank中已公布的在家蚕高抗品系NB和871C中与其抗性位点紧密连锁的分子标记,本研究调查发现其与99R和871C的抗性位点均不连锁。【结论】分子连锁分析结果证明,家蚕对BmNPV的抗性在不同抗性品系中遗传基础有很大的差异性,同一品系可能具有多个抗性位点;家蚕对BmNPV的抗性是一种复杂性状,在符合"质量-数量性状"结论的同时,其数量性状特征突出。     

Initial material for breeding of fiber flax under conditions of the Volga-Vyatka region

Sixty two cultivar samples of fiber flax of various ecological-and-geographic origin were studied for basic economically valuable traits (straw and seed productivity, fiber content and its quality) in 2014–2016 under conditions of the Volga-Vyatka region (Kirov oblast). The best genotypes were identified in terms of a set of traits: Flax of Heilonjiang no. 7 and no. 10; Heiya 11, 13 and 14; Huanguang 2 (China); Belinka (the Netherlands); and AP₅ (Russia). Straw yield depends on the stem technical length (r = 0.71–0.76). Cultivar samples having high fiber contents (28.7–34.5%) are identified: Mirazh, Tverskoi, AP₅, AP₆, Pskovskii-93, Dobrynya, Nord, Peresvet (Russia), B-179 (Lithuania), and Merilin (the Netherlands). High fiber durability is characteristic of samples Soglasie (Belarus)—20.3 kgf; Er-27 (Russia)—18.5 kgf; and B-179 (Lithuania)— 17.8 kgf.     

抗除草剂转基因油菜与野芥菜的抗性回交3代子3代的适合度

【目的】抗除草剂转基因油菜(Brassica napus,AACC,2n=38)的抗性基因一旦成功漂移到近缘杂草中,将会给农田杂草防除带来很大的困难。转基因油菜的近缘杂草野芥菜(wild B.juncea,AABB,2n=36)广泛分布于中国西部地区并沿长江流域扩散,因此有必要深入研究抗除草剂转基因油菜与野芥菜回交后代的适合度,为抗性基因是否能成功漂移到近缘杂草中提供试验依据。【方法】在田间以不同密度(低密度为15株/区,高密度为30株/区)单种和混种(野芥菜与回交后代以4﹕1、3﹕2、1﹕1比例混种)野芥菜及抗性回交3代子3代(抗草甘膦转基因油菜及抗草丁膦转基因油菜与野芥菜的抗性正反回交3代子3代分别表示为BC_3mF_4R、BC3p F4R和BC_3mF_4L、BC_3pF_4L,m表示以野芥菜为母本的回交后代,p表示以野芥菜为父本的回交后代),测定抗性正反回交3代子3代的营养生长(株高、茎粗、一次分枝数、地上部单株干生物量)和生殖生长(单株有效角果数、单株种子质量、角果长、每角果饱粒数)的适合度成分,并比较供试回交后代的总适合度与野芥菜的差异。【结果】在单种条件下,BC_3mF_4R和BC_3pF_4R的各适合度成分及总适合度均与野芥菜无显著差异;尽管在高密度下BC_3mF_4L和BC3p F4L的茎粗、地上部单株干生物量和单株有效角果数显著低于野芥菜,但BC_3mF_4L和BC_3pF_4L的总适合度仍与野芥菜无显著差异;因此,在单种条件下,抗草甘膦或抗草丁膦的回交3代子3代在低密度和高密度均具有与野芥菜相当的总适合度。当回交后代与野芥菜混种时,在低密度3种比例混种下,抗草甘膦和抗草丁膦的回交3代子3代的总适合度与野芥菜无显著差异;在高密度3种比例混种下,BC_3 F_4R与野芥菜的各适合度成分及总适合度无显著差异,但BC_3 F_4L的株高、茎粗、一次分枝数、地上部单株干生物量、单株有效角果数、单株种子质量及总适合度均显著低于野芥菜。相关性分析结果表明,BC_3 F_4的各适合度成分仅与种植密度相关。【结论】抗草甘膦或抗草丁膦的正反回交3代子3代都具有在野外生存定植的可能性,且抗草甘膦的回交3代子3代比抗草丁膦的回交3代子3代的可能性更大。因此,在防范转基因油菜的基因逃逸时不仅要防范转基因油菜与近缘杂草的初始杂交,而且要防范杂交后代与近缘杂草的不断回交,以免产生适合度较高的回交后代。