小麦—中间偃麦草抗条锈衍生系的分子细胞遗传学研究

应用缺体回交法,以部分阿勃缺体为母本,中4为父本,培育出1个对目前条锈病优势小种和新小种高抗至免疫的小麦－－中间偃麦草衍生系N9025－3－3－2－1－1。研究表明,该选系在形态学和细胞学上已经基本稳定,染色体构型为2n=42=21“,抗病性来自中间偃麦草（Thinopyron intermedium）。以中间偃麦草DNA为探针,对N9025－3－3－2－1－1进行基因组原位杂交分析结果证明,它为小麦－中间偃麦草异代换－易位系。     

芝麻病毒病害研究：Ⅱ.芝麻黄花叶病病原鉴定

继对芝麻矮化坏死病源研究之后,又对普遍发生的芝麻黄花叶病害分离物(YMo—I)进行了系统鉴定。该分离物普遍存在于各芝麻主产区,普通年份发病率为1～5％。YMo—I侵染芝麻引起叶片褪绿及黄绿相间花叶。摩擦接种能够侵染4科12种(品种)植物。局部侵染苋色藜、昆诺藜;系统侵染大豆、花生、望江南、克氏烟等。该病毒能够由桃蚜、花生蚜、大豆蚜以非持久性方式进行传播。ELISA检测其病株种子带毒率为0.5％,但尚未发现种生病苗。病毒在组织汁液中存活期3天;钝化温度55～60℃,稀释限点4×10~(-3)。提纯病毒为弯曲线状粒体,大小约为13×730nm。并有极易凝聚的趋势。病组织中诱导大量典型PVY第一亚组的风轮形和卷筒状细胞质内含体和少数多边形结晶核内含体。血清学上该病毒与花生条纹病毒(PStV)、西瓜花叶病毒—2(MMV—2)密切相关,与花生斑驳病毒、大豆花叶病毒弱相关;与芜菁花叶病毒不相关。但它不侵染WMV—2的寄主—黄瓜,并且该病害田间的发生流行与芝麻、花生的间作方式以及PStV在花生田间的流行密切相关。根据上述结果,YMo—I分离株被鉴定为花生条纹病毒的一芝麻分离株。     

水稻条纹叶枯病抗性位点的检测和效应分析

利用111个家系组成的热研2号（Oryza sativa subsp．japonica‘Reyan2’）／Milyang23（Oryza sativa subsp．indica‘Milyang23’）重组自交系（recombinant inbred lines,RIL）群体（F7）,采用重病区田间自然接种方法,以病情指数作为条纹叶枯病的表型值,鉴定了2个亲本及111个RIL家系对条纹叶枯病的抗性。使用QTL Cartographer软件复合区间作图法,对水稻（Oryza sativa）条纹叶枯病抗性基因进行了QTL分析。结果检测到2个抗水稻条纹叶枯病的QTL,分别位于第2和第11染色体上,其中第11染色体上的QTL贡献率为19．58％,表明这是一个主效的QTL,该QTL及其附近的分子标记,可以用于水稻条纹叶枯病抗性分子标记辅助育种。     

小麦条锈菌主要结构中糖基种类的细胞化学定位研究

用8种植物凝集素探针对小麦条锈菌主要结构中的糖基种类进行了细胞化学定位。电镜观察结果表明在菌丝和吸器母细胞壁中存在有α-葡萄糖或α-甘露糖、乙酰胺基葡萄糖、α-半乳糖、α-乙酰半乳糖、岩藻糖和β-连结的糖基,而隔膜中仅含α-葡萄糖或甘露糖和乙酰胺基葡萄糖基;在吸器颈壁中分布有α-葡萄糖或α-甘露糖;尽管吸器体壁中仅含乙酰胺基葡萄糖,而在吸器外间质中存在有半乳糖,乙酰半乳糖,α-葡萄糖或甘露糖等糖基。以上结果表明不同结构所含糖基种类并非一致。     

Hijacking of the nucleolar protein fibrillarin by TGB1 is required for cell‐to‐cell movement of Barley stripe mosaic virus

Barley stripe mosaic virus (BSMV) Triple Gene Block1 (TGB1) is a multifunctional movement protein with RNA‐binding, ATPase and helicase activities which mainly localizes to the plasmodesmata (PD) in infected cells. Here, we show that TGB1 localizes to the nucleus and the nucleolus, as well as the cytoplasm, and that TGB1 nuclear‐cytoplasmic trafficking is required for BSMV cell‐to‐cell movement. Prediction analyses and laser scanning confocal microscopy (LSCM) experiments verified that TGB1 possesses a nucleolar localization signal (NoLS) (amino acids 95–104) and a nuclear localization signal (NLS) (amino acids 227–238). NoLS mutations reduced BSMV cell‐to‐cell movement significantly, whereas NLS mutations almost completely abolished movement. Furthermore, neither the NoLS nor NLS mutant viruses could infect Nicotiana benthamiana systemically, although the NoLS mutant virus was able to establish systemic infections of barley. Protein interaction experiments demonstrated that TGB1 interacts directly with the glycine–arginine‐rich (GAR) domain of the nucleolar protein fibrillarin (Fib2). Moreover, in BSMV‐infected cells, Fib2 accumulation increased by about 60%–70% and co‐localized with TGB1 in the plasmodesmata. In addition, BSMV cell‐to‐cell movement in fib2 knockdown transgenic plants was reduced to less than one‐third of that of non‐transgenic plants. Fib2 also co‐localized with both TGB1 and BSMV RNA, which are the main components of the ribonucleoprotein (RNP) movement complex. Collectively, these results show that TGB1–Fib2 interactions play a direct role in cell‐to‐cell movement, and we propose that Fib2 is hijacked by BSMV TGB1 to form a BSMV RNP which functions in cell‐to‐cell movement.     

Pair-rule patterning in the honeybee Apis mellifera: Expression of even-skipped combines traits known from beetles and fruitfly

 We have studied the binding pattern of antibody mAB 2B8 directed against even-skipped orthologous proteins (EVE) in honeybee embryos. Primary and secondary EVE stripes form in roughly anterior-to-posterior succession; there are 8 primary and 16 secondary stripes. The most posterior primary stripes appear only after the onset of gastrulation. The secondary stripes form by a splitting of primary stripes; they demarcate the parasegmental pattern. While these findings resemble EVE expression in long-germ beetles, the honeybee differs from both beetles and dipterans by two transient pair-rule traits in the parasegmental EVE pattern: the secondary stripes in head and thorax alternate in strength, yet out of register with the Drosophila pattern, and over the whole pattern the odd-numbered stripes vanish earlier than their even-numbered counterparts. As in Drosophila, however, the strong EVE stripes coincide with the weak engrailed (EN) stripes. These findings are taken to indicate that (1) honeybee and beetles share a conserved mode of EVE stripe formation whilst Drosophila has diverged in this respect, (2) honeybee and Drosophila have diverged from the beetles in specific pair-rule traits during the parasegmental expression of both EVE and EN, and (3) some of these traits differ in the register of segment pairing and thus may reflect regulatory divergences at the pair-rule level between dipterans and the honeybee.     

条形柄锈菌34号生理小种的分子标记

条形柄锈菌Puccinia striiformis f. sp. tritici 34号生理小种(CYR34)是目前我国毒性谱最宽、毒性最强的生理小种,对小麦生产和抗病品种选育造成了极大的影响。本研究采用RAPD-SCAR分子标记技术,从300条RAPD随机引物中筛选到CYR34的特异引物,通过特异性片段回收、克隆和测序(GenBank登录号为OL907303),依据序列设计出了S2008F34/S2008R34特异性引物,能够从CYR34及接种CYR34的小麦发病叶片总DNA中都扩增出417 bp的目标片段。采用该特异性引物检测2021年陕西渭南、咸阳和宝鸡地区小麦条锈菌CYR34的流行频率分别为8.6%、6.0%和10.8%。该项研究为小麦条锈菌CYR34号生理小种的快速检测提供了技术支撑。     

The cap-snatching frequency of a plant bunyavirus from nonsense mRNAs is low but is increased by silencing of UPF1 or SMG7

Bunyaviruses cleave host cellular mRNAs to acquire cap structures for their own mRNAs in a process called cap-snatching. How bunyaviruses interact with cellular mRNA surveillance pathways such as nonsense-mediated decay (NMD) during cap-snatching remains poorly understood, especially in plants. Rice stripe virus (RSV) is a plant bunyavirus threatening rice production in East Asia. Here, with a newly developed system allowing us to present defined mRNAs to RSV in Nicotiana benthamiana, we found that the frequency of RSV to target nonsense mRNAs (nsRNAs) during cap-snatching was much lower than its frequency to target normal mRNAs. The frequency of RSV to target nsRNAs was increased by virus-induced gene silencing of UPF1 or SMG7, each encoding a protein component involved in early steps of NMD (in an rdr6 RNAi background). Coincidently, RSV accumulation was increased in the UPF1- or SMG7-silenced plants. These data indicated that the frequency of RSV to target nsRNAs during cap-snatching is restricted by NMD. By restricting the frequency of RSV to target nsRNAs, NMD may impose a constraint to the overall cap-snatching efficiency of RSV. Besides a deeper understanding for the cap-snatching of RSV, these findings point to a novel role of NMD in plant–bunyavirus interactions.     

西科麦2028抗条锈性的遗传分析

西科麦2028是地理远缘小麦材料的杂交后代,具有突出的抗条锈病性能。为了解西科麦2028对小麦条锈病的抗性遗传规律,以西科麦2028和铭贤169的杂交群体为研究对象,采用我国目前小麦条锈菌流行小种CYR31、CYR32、CYR33、Su11-4对供试群体进行成株期接种,分析杂交后代的抗病性及分布情况。结果表明:西科麦2028对CYR31的抗病性由3对显性基因控制;对CYR32由2对显性和1对隐性基因控制;对CYR33由1对显性基因控制;对Su11-4由1对显性和1对隐性基因控制。