Research Progress on Adaptive Survival Relationship Between Small Colony Variants and Bacteria

Small colony variants (SCVs) have been shown to be part of the regular growth cycle, which are highly dynamic or stable and can be selected during various harsh conditions. The features of SCVs include slow growth, colony morphology irregular and biochemical characteristics abnormal, making the separation and identification of SCVs into trouble. SCVs can cause chronic persistent infection, but not lead to strong immune response to host. Furthermore, SCVs are serious resistant to antibacterials normally. In this paper, we introduce the phenotype classification of SCVs, the relationship with the host's immune response and the effects of antibacterials on SCVs, which will provide theoretical support for further research of SCVs.     

面向作物表型分析的大豆植株叶片语义重建

为解决三维扫描仪、多视图数据获取的三维点云因缺少语义信息导致难以从点云上判别植株器官部位问题,提出一种二维先验语义嵌入的大豆植株叶片三维语义建模方法：首先,基于Mask R-CNN模型对大豆叶片进行语义分割;然后,对分割结果和多视图数据进行立体重建融合学习,实现大豆植株叶片二维语义到三维叶片点云迁移,获得植株叶片点云语义信息,进而建立植株叶片三维语义模型。通过多组盆栽大豆植株试验对该模型进行验证,提取叶长和叶宽与人工实测数据进行对比分析,叶长和叶宽均方误差分别为2.53和1.52 mm,决定系数分别为0.97和0.89。结果表明,该方法能够便捷、精准地构建植株叶片三维语义模型。     

Purebreeding of Red Maasai and crossbreeding with Dorper sheep in different environments in Kenya

The aim of this article was to study opportunities for improvement of the indigenous and threatened Red Maasai sheep (RM) in Kenya, by comparing purebreeding with crossbreeding with Dorper sheep (D) as a terminal breed, in two different environments (Env. A and a harsher Env. B), assuming different levels of genotype‐by‐environment interaction (G × E). Breeding goals differed between environments and breeds. Four scenarios of nucleus breeding schemes were stochastically simulated, with the nucleus in Env. A. Overall, results showed an increase in carcass weight produced per ewe by more than 10% over 15 years. Genetic gain in carcass weight was 0.17 genetic SD/year (0.2 kg/year) across scenarios for RM in the less harsh Env. A. For survival and milk yield, the gain was lower (0.04–0.05 genetic SD/year). With stronger G × E, the gain in the commercial tier for RM in the harsher Env. B became increasingly lower. Selection of females also within the commercial tier gave slightly higher genetic gain. The scenario with purebreeding of RM and a subnucleus in Env. B gave the highest total income and quantity of meat. However, quantity of meat in Env. A increased slightly from having crossbreeding with D, whereas that in Env. B decreased. A simple and well‐designed nucleus breeding programme would increase the genetic potential of RM. Crossbreeding of RM with D is not recommended for harsh environmental conditions due to the large breed differences expected in that environment.     

华癸中慢生根瘤菌7653R MCHK_8182基因的共生固氮功能

根据华癸中慢生根瘤菌7653R全局转录组分析结果,获得在共生固氮阶段显著上调表达的基因MCHK_8182;设计重叠延伸PCR引物,构建MCHK_8182双交换突变重组质粒载体;通过三亲本杂交,将突变载体导入7653R;在蔗糖压力培养下进行筛选,最终获得MCHK_8182双交换突变株。PCR及测序验证双交换突变株构建成功。植物盆栽试验结果显示,与7653R野生型接种的植株相比,MCHK_8182突变菌株接种的植株根瘤数减少,但固氮酶活未见明显差异。     

植物响应淹水胁迫的研究进展

淹水胁迫是影响植物分布与生长发育的重要因素,植物耐涝性研究是提高作物耐涝性以应对日益严峻的极端气候及规模化生产管理的关键。为了合理开展植物耐涝性研究,深入挖掘不同植物响应淹水胁迫的调控机理,本文归纳了淹水胁迫对植物生长发育的影响,总结了植物响应淹水胁迫的调节机制,并详细分析了淹水胁迫对植物表型性状、生物量、光合作用、活性氧离子积累、糖含量和生物膜的影响,以及乙烯信号分子、活性氧清除机制、渗透调节、形态调节、分子和代谢调控在植物响应淹水胁迫中的调节机制。最后,通过总结,提出了合理开发外源调节物质提高作物耐涝性值得进一步的深入研究。     

甜菜对低氮胁迫的形态学响应机制

为了分析甜菜对低氮胁迫在形态学上的应答机制,本研究以甜菜种质资源‘780016B/12优’为研究对象,对缺氮(N 0 mmol/L)和低氮(N 1.5 mmol/L)条件下甜菜植株的形态和根系构型变化进行了深入分析。结果表明,甜菜遭受氮胁迫时,地上部生物量积累减少,地下部生物量积累增加,根冠比增加,叶面积减少,甜菜生长发育受到抑制。低氮胁迫7~14天后的根系面积、体积和根系分叉数增加量均大于对照(N 10 mmol/L)。氮胁迫下,甜菜的根系构型呈二分体状,且随着胁迫时间和缺氮程度的增加,地下生物量越大,这种状况表现的越为明显。因此可以推断,甜菜植株根系生物量的高低与根系构型有着密切的联系,甜菜通过改变根系比例和根系构型来获得氮素平衡。     

香蕉枯萎病菌内源报告基因细胞周期蛋白C1基因FocFCC1的鉴定及分析

本研究克隆鉴定了香蕉枯萎病菌4号生理小种（Foc4）的细胞周期蛋白C1（Fusarium Cyclin C1,FCC1）基因FocFCC1,采用Split-marker同源重组技术获得基因敲除突变体ΔFocFCC1,通过比较突变体和野生菌株在生长速度、产孢量和致病力等方面的差异,探索了FocFCC1基因缺失对香蕉枯萎病菌生物学功能的影响,并评估了FocFCC1作为枯萎菌内源报告基因的可行性。结果表明：与Foc4野生型菌株相比,ΔFocFCC1菌丝生长缓慢、菌丝畸形及产孢量减少,对巴西蕉苗的致病力明显减弱,推测FocFCC1基因在Foc4的生长发育、产孢及致病力等方面具有重要作用。以FocFCC1为靶标基因,评估了两种基因敲除重组方法介导的基因敲除效率,利用红色表型作为判断依据,挑取再生板上有红色表型的转化子进行PCR检测,Split-marker重组方法获得阳性转化子比例为91.7%,而多片段装配融合方法获得阳性转化子的比例为64%。ΔFocFCC1出现典型红色菌落,红色表型与PCR检测的FocFCC1阳性敲除转化子一一对应,FocFCC1基因敲除后红色表型肉眼容易分辨,可作为香蕉枯萎病菌内源报告基因探索新的遗传操作技术在该菌上应用的可行性。     

温度影响马铃薯块茎形成的研究进展

块茎是马铃薯的商品和营养繁殖器官,而温度是影响块茎形成最重要的环境因素之一。针对温度对马铃薯块茎诱导和起始、膨大和成熟生长发育阶段表型变化的影响,对光合特性、源库平衡和渗透调节物质等生理生化变化影响,对调控块茎形成的光周期、植物激素、sRNA和糖类物质通路的影响,以及马铃薯耐热性评价和遗传改良研究等方面进行了综述,以期为了解马铃薯块茎形成过程中温度调控机理和培育耐热马铃薯品种提供参考。     

青海省马铃薯黑胫病病原菌的鉴定

为明确引起青海省马铃薯黑胫病的病原菌,从青海省不同地区马铃薯黑胫病病样分离病原菌,研究病原菌的形态学特征、致病性、生理生化特性,并结合16S rRNA序列进行病原学鉴定。结果表明:引起马铃薯黑胫病的5个菌株均为黒腐果胶杆菌(Pectobacterium atrosepticum),来源不同的菌株接种马铃薯后致病力有差异;其中,3株强致病力菌株主要来自于乐都、湟中和大通,2株中等致病力菌株来自于民和和湟源。综上,黒腐果胶杆菌是引起青海省马铃薯黑胫病的病原菌。