大蒜气生鳞茎形态发生及其碳水化合物和内源激素含量以及相关基因表达的变化特征

以大蒜品种‘二水早’(早熟)、‘麻江红蒜’(中晚熟)和‘徐州白’(晚熟)为材料,采用石蜡切片技术结合显微观察探讨气生鳞茎形成过程中植株茎尖和花序轴形态变化,并测定了‘麻江红蒜’气生鳞茎形成过程中可溶性糖、蔗糖、淀粉和内源激素含量及相关基因表达变化,明确不同熟期各品种大蒜气生鳞茎形成进程和形态解剖学特征,以及碳水化合物和内源激素与大蒜气生鳞茎形成的关系,以探讨大蒜气生鳞茎分化的生理机制。结果表明:(1)依据茎尖生长点和花序轴的形态解剖特征,将气生鳞茎形成进程划分为启动期、气生鳞茎原基分化期(包括保护叶原基、贮藏叶原基分化)、气生鳞茎膨大期和气生鳞茎成熟期等4个时期;3个品种气生鳞茎在相同发育时期的形态解剖学特征相同,但分化时间不同,其分化顺序与大蒜品种成熟期表现一致;当总苞叶叶尖露出叶鞘,花器官原基分化时,花序轴周围分生组织区域产生小突起,标志着气生鳞茎原基分化的开始;外层保护叶由白色转为紫色时气生鳞茎进入成熟期。(2)气生鳞茎开始膨大后,其可溶性糖和蔗糖含量均显著降低,淀粉含量显著升高;ZR含量在启动期显著升高;IAA和MeJA含量在气生鳞茎原基分化期维持在较高水平,但IAA含量随着气生鳞茎膨大显著降低,并在成熟期降至最低。(3)果聚糖代谢相关基因1-SST、1-FEH分别在膨大初期、膨大中期表达量显著升高;细胞壁转移酶基因CWI相对表达量在气生鳞茎原基分化期显著升高;蔗糖信号转导基因T6P和生长素信号转导的关键转录因子ARF1相对表达量均在气生鳞茎分化期显著升高;茉莉酸信号调控途径中的负调控因子JAZ相对表达量在大蒜气生鳞茎原基分化期和膨大初期均维持一个较低水平。研究认为,大量可溶性糖及ZR在茎尖积累,可以启动气生鳞茎原基分化,促进气生鳞茎形态发生;高浓度IAA和MeJA可促进气生鳞茎原基分化;气生鳞茎膨大消耗可溶性糖,且低浓度IAA有利于气生鳞茎膨大;成熟的气生鳞茎积累大量淀粉。     

茉莉酸类与植物地下贮藏器官的形成

茉莉酸类化合物（茉莉酸及其衍生物）可能参与了马铃薯,薯蓣,菊芋的块茎,甘薯的块根以及洋葱,大蒜的鳞茎形成,JA及MeJA均可诱导离体下马铃薯块茎的形成和马铃薯髓部细胞的膨大,JA诱导细胞膨大是由于蔗糖积累导致渗透压增加以及细胞壁结构变化,从而使其伸展性增加,纤维素的合成起了重要作用,细胞骨架也是JA诱导细胞膨大所必需的,但迄今为止,尚未确定块茎形成的直接诱导物。     

兰州百合组培鳞茎发育研究

该研究以兰州百合商品种球鳞片为外植体材料,通过组织培养诱导丛生芽萌发及高频增殖,再以丛生芽为材料诱导其发育形成小鳞茎,调节培养基对小鳞茎进行膨大发育培养,最终形成促进兰州百合组培鳞茎膨大发育的“三步”组培培养技术路线;对发育过程中形成的丛生芽、小鳞茎及膨大鳞茎进行淀粉含量测定与生长特征参数统计,分析各步培养对鳞茎形成发育过程中淀粉含量与形态变化的影响。结果表明：所建立的“三步”培养方案培育出的组培鳞茎直径、重量与鳞片数分别为1.66 cm、2.48 g和26.33片,有效地促进了鳞茎的膨大,并能诱导鳞茎主茎杆的形成发育;在培养进程中其淀粉含量呈现逐步增加的趋势,这表明与鳞茎膨大发育正相关,同时鳞茎大小、重量及鳞片数三者也表现为正相关性;当鳞茎所含鳞片数在26片以上时,其生长点易发育形成主茎杆。该文研究了兰州百合组培鳞茎的形成与膨大发育技术,所研发的“三步”培养组成的鳞茎膨大发育组培技术有效地促进了鳞茎的膨大发育,而膨大发育的鳞茎能有效地缩短田间生长周期,从时间上提高百合生产量,同时为实现兰州百合膨大的鳞茎种球规模化生产提供技术支撑。     

兰州百合组培鳞茎发育研究（英文）

该研究以兰州百合商品种球鳞片为外植体材料,通过组织培养诱导丛生芽萌发及高频增殖,再以丛生芽为材料诱导其发育形成小鳞茎,调节培养基对小鳞茎进行膨大发育培养,最终形成促进兰州百合组培鳞茎膨大发育的"三步"组培培养技术路线;对发育过程中形成的丛生芽、小鳞茎及膨大鳞茎进行淀粉含量测定与生长特征参数统计,分析各步培养对鳞茎形成发育过程中淀粉含量与形态变化的影响。结果表明:所建立的"三步"培养方案培育出的组培鳞茎直径、重量与鳞片数分别为1.66 cm、2.48 g和26.33片,有效地促进了鳞茎的膨大,并能诱导鳞茎主茎杆的形成发育;在培养进程中其淀粉含量呈现逐步增加的趋势,这表明与鳞茎膨大发育正相关,同时鳞茎大小、重量及鳞片数三者也表现为正相关性;当鳞茎所含鳞片数在26片以上时,其生长点易发育形成主茎杆。该文研究了兰州百合组培鳞茎的形成与膨大发育技术,所研发的"三步"培养组成的鳞茎膨大发育组培技术有效地促进了鳞茎的膨大发育,而膨大发育的鳞茎能有效地缩短田间生长周期,从时间上提高百合生产量,同时为实现兰州百合膨大的鳞茎种球规模化生产提供技术支撑。     

茉莉酸类与植物地下贮藏器官的形成

茉莉酸类化合物(茉莉酸及其衍生物)可能参与了马铃薯、薯蓣、菊芋的块茎,甘薯的块根以及洋葱、大蒜的鳞茎形成。JA及MeJA均可诱导离体条件下马铃薯块茎的形成和马铃薯髓部细胞的膨大。JA诱导细胞膨大是由于蔗糖积累导致渗透压增加以及细胞壁结构变化,从而使其伸展性增加,纤维素的合成起了重要作用,细胞骨架也是JA诱导细胞膨大所必需的。但迄今为止,尚未确定块茎形成的直接诱导物。     

磷脂酶Dδ对拟南芥叶片衰老过程中内源ROS和激素含量的影响

活性氧（ROS）和植物激素是植物衰老过程中重要的内在或者外在的调控因子。我们发现,相对于离体诱导的衰老过程,在脱落酸（ABA）和乙烯（ethylene）促进的衰老过程中有较多的活性氧积累;在对拟南芥磷脂酶Dδ（PLDδ）缺失型突变体的研究中发现,与野生型相比,突变体在衰老过程中产生较少的活性氧。我们比较了上述两种基因型的离体叶片在离体、ABA和ethylene三种衰老处理下内源的ABA、茉莉酸甲酯（MeJA）、玉米素核苷（Zeatin Riboside, ZR）和吲哚乙酸（IAA）的含量变化,发现每一种激素对上述三种衰老处理的响应模式都很相似。在离体诱导的衰老中,两种基因型拟南芥的内源激素含量没有差异;而在ABA促进的衰老过程中,PLDδ缺失型突变体叶片中的MeJA的含量较低,ZR和IAA含量较高;在乙烯促进的衰老过程中,突变体中的ABA和MeJA的含量较低,ZR和IAA含量较高。上述内源激素的这种变化可能有助于延缓突变体的衰老。     

采后大蒜鳞茎的生理生化变化及其贮藏技术

采后大蒜鳞茎的生理生化变化及其贮藏技术刘淑娴,李月标,陈芳,张东林,蒋跃明（中国科学院华南植物研究所,广州５１０６５０）摘要大蒜鳞茎在室温下贮藏２个月后,胚芽开始生长．随着胚芽生长,呼吸速率、蛋白质和维生素Ｃ含量逐渐增高;而可溶性糖和干物质含量下降。...     

水杨酸对两个品种百合鳞茎膨大的作用及其与内源激素含量的关系

百合品种‘精粹’的鳞茎周径和鲜重随着叶面喷施水杨酸（SA）的浓度的增加而增加;品种‘普瑞头’鳞茎周径和鲜重也随着叶面喷施SA的浓度的变化而变化,其中以0．5mmol·L^-1SA的效应最明显。叶面喷施SA的百合鳞茎中ABA和GA3含量下降,IAA和ZR含量上升,鳞茎中（IAA＋GA3）／ABA、IAA／GA3比值均比未喷施SA的高,而IAA／ZR、GA3／ZR比值则比未喷施SA的低。显示鳞茎膨大与内源激素的含量相关。     

光敏素和激素对洋葱鳞茎形成的调控及其作用机制

介绍了光敏素和几种植物激素在洋葱鳞茎形成中的作用,以及激素通过对细胞微管的作用而影响叶鞘细胞膨大的机制,并讨论了今后应该加强的一些研究方面。     

百合鳞茎发育过程中淀粉合成相关酶基因的克隆及表达分析

该研究通过同源克隆技术克隆腺苷二磷酸葡萄糖焦磷酸化酶(AGPase)、颗粒结合淀粉合酶(GBSS)和可溶性淀粉合酶(SSS) 3类百合淀粉合成关键酶基因,分析这三类淀粉合成关键酶基因的表达变化,测定百合鳞茎膨大发育中淀粉含量变化。结果表明:(1) AGPase具有GlgC家族蛋白PLN02241蛋白结构特征及cl11394家族蛋白ADP_Glucose_PP与NTP_transferase结构域,获登录号KP751443; GBSS与SSS具有cl10013家族蛋白Glyco_transf_5,GT1_Glycogen_synthase_DULL1_like结构域,获登录号分别为KP751444、KP751445。(2)百合鳞茎形成与膨大发育过程中,淀粉含量呈现递增趋势,鳞茎盘开始分化茎杆时其淀粉含量最高,达到44.52%。鳞茎与叶片部位的三个淀粉合成相关酶基因表达量均逐渐增加;在鳞茎膨大后茎杆分化阶段,三个淀粉合成相关酶基因表达量达到最高,AGPase、GBSS、SSS在鳞片中的表达量分别为10.79,6.92和5.12,叶片中的表达量分别为6.79,5.22和4.41,鳞片中的表达量大幅度高于叶片;淀粉合成相关酶基因的表达量变化与淀粉含量、鳞茎的膨大发育成正相关。这为鳞茎的繁殖生产提供了可通过调节淀粉合成关键酶基因表达促进百合鳞茎膨大发育的思路。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Enterovirus 71 3C proteolytically processes the histone H3 N-terminal tail during infection

Highlights
1. The N-terminal tail of histone H3 is specifically cleaved during EV71 infection.
2. Viral protease 3C is identified as a protease responsible for proteolytically processing the N-terminal H3 tail.
3. Our finding reveals a new epigenetic regulatory mechanism for Enterovirus 71 in virus-host interactions.     

Detection of EBV and HHV6 in the Brain Tissue of Patients with Rasmussen’s Encephalitis

Rasmussen’s encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and 16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis, intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8⁺ T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8⁺ T cells are involved in the pathogenesis of RE.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).     

Development of a Novel Reverse Transcription Loop-Mediated Isothermal Amplification Method for Rapid Detection of SARS-CoV-2

In conclusion, the novel visual RT-LAMP assay is a simple, rapid, and sensitive approach for detection of SARS-CoV-2, and it is ready for application in primary care and community hospitals or health care centers, and even patients' own houses in response to the current SARS-CoV-2 epidemic because the assay does not require sophisticated equipment and skilled personnel. Furthermore, it is also ready to be used in fields for screening samples from wild animals and environments to facilitate the identification of potential intermediate hosts that mediate the cross-species transmission of SARS-CoV-2 from bats to humans.