Model averaging for genome‐enabled prediction with reproducing kernel Hilbert spaces: a case study with pig litter size and wheat yield

Predictive ability of yet‐to‐be observed litter size (pig) grain yield (wheat) records of several reproducing kernel Hilbert spaces (RKHS) regression models combining different number of Gaussian or t kernels was evaluated. Predictive performance was assessed as the average (over 50 replicates) predictive correlation in the testing set. Predictions from these models were combined using three different types of model averaging: (i) mean of predicted phenotypes obtained in each model, (ii) weighted average using mean squared error as weight or (iii) using the marginal likelihood as weight. (ii) and (iii) were obtained in a validation set with 5% of the data. Phenotypes consisted of 2598, 1604 and 1879 average litter size records from three commercial pig lines and wheat grain yield of 599 lines evaluated in four macro‐environments. SNPs from the PorcineSNP60 BeadChip and 1447 DArT markers were used as predictors for the pig and wheat data analyses, respectively. Gaussian and univariate t kernels led to same predictive performance. Multikernel RKHS regression models overcame shortcomings of single kernel models (increasing the predictive correlation of RKHS models by 0.05 where 3 Gaussian or t kernels were fitted in the RKHS models simultaneously). None of the proposed averaging strategies improved the predictive correlations attained with single models using multiple kernel fitting.     

大白菜突变体库的构建及M2叶片表型变异的研究

 利用不同浓度甲基磺酸乙酯（EMS）诱变大白菜自交系‘A03’种子,根据M₁代植株发芽率、成活率、育性及M₂代成活率,筛选出适宜的EMS诱变浓度为0.4%。采取EMS种子诱变1次、EMS种子诱变2次及EMS花蕾诱变结合小孢子培养的方法构建了含有4 253个家系及相应自交M₂代种子的大白菜突变体库。在该突变体库M₂群体中分别对苗期6 404株幼苗及莲座期7 756个单株的叶片性状进行了形态学调查,总的表型变异频率高达37.62%和26.33%。     

Sensitive detection of the c‐KIT c.1430G>T mutation by mutant‐specific polymerase chain reaction in feline mast cell tumours

Here, we describe the establishment of mutant‐specific polymerase chain reaction (PCR) for detection of a c‐KIT c.1430G>T mutation in feline mast cell tumours. Several mutations in feline c‐KIT have been identified, with the c.1430G>T mutation accounting for a significant portion of feline mast cell tumour mutations. The c.1430G>T mutation in c‐KIT exon 9 was detected in 15.7% (11 of 70) of samples by mutant‐specific PCR but in only 7.1% (5 of 70) by PCR–restriction fragment length polymorphism (RFLP) in the genomic DNA isolated from 70 formalin‐fixed paraffin‐embedded sections or cells collected by fine needle aspiration. Mutant‐specific PCR showed remarkably higher detection rate than did PCR–RFLP. DNA sequence analysis did not always yield identical results to those of mutant‐specific PCR, suggesting heterogeneity of tumour cells. Mutant‐specific PCR is a valid and efficient screening tool for detection of the c‐KIT c.1430G>T point mutation in feline mast cell tumours compared with PCR–RFLP and sequencing analysis.     

Use of advanced recombinant lines to study the impact and potential of mutations affecting starch synthesis in barley

The effects on barley starch and grain properties of four starch synthesis mutations were studied during the introgression of the mutations from diverse backgrounds into an elite variety. The lys5f (ADPglucose transporter), wax (granule-bound starch synthase), isa1 (debranching enzyme isoamylase 1) and sex6 (starch synthase IIa) mutations were introgressed into NFC Tipple to give mutant and wild-type BC₂F₄ families with different genomic contributions of the donor parent. Comparison of starch and grain properties between the donor parents, the BC₂F₄ families and NFC Tipple allowed the effects of the mutations to be distinguished from genetic background effects. The wax and sex6 mutations had marked effects on starch properties regardless of genetic background. The sex6 mutation conditioned low grain weight and starch content, but the wax mutation did not. The lys5 mutation conditioned low grain weight and starch content, but exceptionally high β-glucan contents. The isa1 mutation promotes synthesis of soluble α-glucan (phytoglycogen). Its introgression into NFC Tipple increased grain weight and total α-glucan content relative to the donor parent, but reduced the ratio of phytoglycogen to starch. This study shows that introgression of mutations into a common, commercial background provides new insights that could not be gained from the donor parent.     

干热风对冬小麦灌浆速率和千粒重的影响

为定量分析冬小麦灌浆不同时期出现的干热风对小麦产量形成带来的危害,利用郑州农业气象试验站连续两个年度的干热风人工控制试验数据,结合前期作物观测资料,研究了干热风对冬小麦籽粒灌浆速率及千粒重的影响。结果表明,干热风导致冬小麦灌浆速率不同程度下降,不同时期干热风的降幅表现为灌浆中期灌浆后期灌浆前期,重度干热风轻度干热风。随着干热风后冬小麦的自身修复和后续灌浆进程,最终千粒重不同程度降低,降低幅度最大的是灌浆后期重度干热风,千粒重降低5.4g,降幅达14.5%;其次为灌浆中期重度和轻度干热风,千粒重分别降低9.7%和4.8%;再次为灌浆后期轻度干热风;而灌浆前期干热风对千粒重影响不显著。     

水稻半矮杆突变体‘双辐矮糯’的农艺性状与遗传分析

倒伏是影响水稻（Oryza sativa L.）生产的重要因素,半矮杆是协调高产和抗倒性的理想资源。前期通过辐射诱变‘湘辐糯1号’获得了半矮杆突变体‘双辐矮糯’。本研究分析了‘双辐矮糯’的茎节配置特点、基本农艺性状及其遗传规律。结果表明：‘双辐矮糯’株高较‘湘辐糯1号’（133.13 cm）降低了24.88 cm,穗、第1节和第2节长度显著缩短,降幅分别达到18.10%、23.06%和19.13%,而第3、4、5节长度缩短程度不明显,表明其株高突变基因主要控制穗和高位茎节的伸长。‘双辐矮糯’的单株有效穗为10.4个,是‘湘辐糯1号’（5.2个）的2.04倍,其强分蘖能力确保了在每穗总粒数下降20.24%和千粒重下降7.51%情况下单株产量仍表现出25.26%的增长。品质分析发现,‘双辐矮糯’的粒长、粒宽、长宽比等外观品质指标及直链淀粉含量、胶稠度等食味品质指标与‘湘辐糯1号’无显著差异,说明‘双辐矮糯’株高的下降未对外观品质与食味品质产生不利影响。遗传分析发现,48对SSR标记在‘双辐矮糯’与‘湘辐糯1号’间扩增出了完全一致的基因型,二者遗传背景相似度达到了100.00%,证实了‘双辐矮糯’是源于‘湘辐糯1号’的真实变异。利用‘双辐矮糯’与‘湘辐糯1号’构建了2个正反交F₂群体,分析发现群体中半矮杆植株与野生型植株理论分离比符合1∶3,表明半矮杆性状受一个隐性细胞核基因控制。本研究明确了‘双辐矮糯’的株高表型和遗传特点,为深入挖掘其育种价值奠定基础。     

吉林省玉米穗期害虫种类及发生情况分析

吉林省是玉米生产大省,为明确吉林省玉米穗期害虫种类、分布及发生情况,2013～2016年对吉林省9个地市,42个县(市/区),累计409个地点的玉米穗期害虫进行系统调查,为玉米穗期害虫的监测预警和制定合理防治策略提供科学依据。调查发现,吉林省玉米穗期有27种有害生物,隶属于3个纲,7个目,18个科。亚洲玉米螟、双斑长跗萤叶甲、叶螨和蚜虫的有虫田率均在80%以上,百株虫量和危害级别较高,是吉林省玉米的主要害虫。美洲黍潜叶蝇、古毒蛾、大青叶蝉、梨剑纹夜蛾、赤角盲蝽、白星花金龟等有虫田率在20%以下,且百株虫量<1头,尚未玉米生产造成威胁。此外,迁飞性害虫黏虫也是玉米穗期重要害虫,棉铃虫是潜在的玉米穗期重要害虫。     

大豆脂肪酸脱氢酶GmFAD3C-1基因的克隆及功能分析

研究通过对大豆脂肪酸脱氢酶GmFAD3家族中4个关键酶基因序列进行比对,与对照JN18相比,大豆低亚麻酸突变体MT72中GmFAD3C-1基因在起始密码子后+966bp处存在一个碱基位点的缺失（G→?）,产生移码突变,导致氨基酸序列上产生较大变化（该突变基因命名为gmfad3c-1）。构建GmFAD3C-1基因超表达及CRISPR/Cas9编辑载体,利用花粉管通道法获得T₂转化植株。脂肪酸脱氢酶酶活测定结果显示,超表达植株T₂籽粒中,酶活与对照相比上升47.62%~78.85%,编辑载体T₂籽粒中,酶活与对照相比下降25.67%~47.11%。脂肪酸相对含量测定的结果进一步表明,GmFAD3C-1基因的表达与植株亚麻酸含量密切相关。     

人泛素结合酶UbcH5c活性突变体的构建·纯化以及催化活性研究

[目的]构建人泛素结合酶UbcH5c的活性位点突变体S22R和F62A,同时分析这2种突变体蛋白与野生型蛋白在泛素化反应中的活性差异。[方法]通过点突变(Site-Directed Mutagenesis)的方法构建2种突变体质粒,利用0.5 mmol/L IPTG分别诱导2种突变体蛋白在大肠杆菌中进行表达;将菌体超声破碎后,依次利用阳离子交换层析法对UbcH5c突变蛋白进行分离纯化,最后利用体外泛素化酶促反应结合蛋白免疫印迹杂交的方法分析野生型UbcH5c与其活性突变体UbcH5c S22R和UbcH5c F62A在泛素化修饰上的差异。[结果]人泛素结合酶UbcH5c的2个突变体蛋白S22R、F62A的泛素化修饰程度明显弱于野生型蛋白。[结论]突变体S22R和F62A突变均不同程度的改变了人泛素结合酶UbcH5c与泛素分子之间的结合活性,即2个突变的位点中第62位苯丙氨酸残基及第22位丝氨酸残基均是UbcH5c结合泛素的关键位点,而且后者对于UbcH5c结合泛素活性的影响更大。