植物干旱胁迫的信号通路及相关转录因子研究进展

植物对干旱环境的适应是一个复杂的生物学过程,涉及多条信号通路的交叉调控。其中,通过转录因子发挥的调控在植物的抗旱过程中起着至关重要的作用。目前参与植物干旱胁迫反应的转录因子主要有AP2/EREBP、MYB、NAC、bZIP和WRKY等。研究表明,单个转录因子可以激活或抑制大量下游靶基因的转录,而单一的靶基因又受到不同转录因子的调控,转录因子之间的串扰现象在植物干旱调控网络中普遍存在。该文总结了近年来国内外有关植物干旱胁迫响应中涉及的主要信号通路［ABA信号通路、Ca²⁺信号通路和促有丝裂原活化蛋白激酶(MAPKs)级联信号通路等］,并对以上5种转录因子的结构特点、分类以及它们对干旱胁迫的调控作用进行综述,同时对今后的研究方向进行了展望。     

小麦干旱诱导蛋白及相关基因研究进展

干旱胁迫条件下,小麦相关基因受到激活并表达产生干旱胁迫蛋白,主动适应干旱环境、维持个体存活和产量形成。介绍了小麦中一些干旱诱导蛋白及相关基因的研究进展,包括不同小麦品种、胁迫程度、发育阶段的差异性反应和共性特征、对主要干旱信号物质ABA和Ca²⁺的差异应答、以及新近发现的干旱诱导蛋白及相关基因的生物学特性及主要功能等。对于干旱诱导蛋白来说,研究手段和目标从过去以单向电泳技术为主、揭示蛋白条带的表达差异转到现在以双向电泳技术为主、以揭示蛋白质组中干旱诱导蛋白结构和功能的耦合。对于干旱诱导蛋白相关基因来说,研究内容主要包括功能基因和调控基因两大类,功能基因研究主要集中在LEA蛋白基因和透物质合成酶基因等几大类型上,而调控基因研究主要集中在转录因子和蛋白激酶等相关基因及其作用。对干旱诱导蛋白及相关基因在小麦栽培管理和产量育种中的应用前景展开了讨论。     

提高作物耐旱性的DREB转录因子研究进展

当植物受到干旱胁迫时就会感受到水分的变化,表达产生各种耐旱蛋白包括耐旱功能蛋白、转录因子和激酶,从而抵御干旱胁迫。目前已经明确的耐旱信号途径主要有4条：其中2条是ABA依赖的信号途径,另外2条是不依赖于ABA的信号途径。DREB转录因子是不依赖于ABA的信号途径中的一个重要的转录因子。由于DREB转录因子以及这一信号途径在各种植物中具有很高的保守性,研究这一信号途径对于改良作物的耐旱性以及了解植物抵御干旱的信号交叉联系具有重要意义。综述了近几年来在DREB基因的克隆、表达调控以及遗传转化方面的研究进展,并对未来的发展进行了展望。     

植物冷驯化的分子机理研究进展

植物冷驯化是一个非常复杂的过程,包括植物将感受到的低温信号转变成生化信号,以激活冷诱导基因的启动子,刺激特定的mRNA的转录,并在特定的组织中合成冷驯化蛋白.冷驯化蛋白通过增强膜脂流动性和阻止胞间冰晶形成等方式,以保护细胞免受低温伤害.冷驯化基因的表达以转录后调控为主,也有转录调控.某些冷诱导基因也可受ABA或其他环境胁迫(如高温、干旱、高盐、脱水等)诱导表达.     

水稻含有B-box锌指结构域的OsBBX25蛋白参与植物对非生物胁迫的响应

锌指蛋白在调控植物生长发育和应对逆境过程中发挥着重要作用.为进一步研究锌指类蛋白参与植物非生物胁迫响应的分子机制,对水稻(Oryza sativa)中一个编码含有B-box锌指结构域蛋白的OsBBX25基因进行了功能分析.OsBBX25受盐、干旱和ABA诱导表达.异源表达OsBBX25的转基因拟南芥(Arabidopsis thaliana)与野生型相比对盐和干旱的耐受性增强,且盐胁迫条件下转基因植物中KIN1、RD29A和COR15的表达上调,干旱胁迫下KIN1、RD29A和RD22的表达上调.外源施加ABA时,转基因植物的萌发率与野生型之间没有明显差异.OsBBX25可能作为转录调控的辅助因子调节胁迫应答相关基因的表达,进而参与植物对非生物胁迫的响应.     

干旱胁迫诱导下植物基因的表达与调控

干旱胁迫能够诱导植物表达大量的基因 ,研究这些基因的表达与调控 ,为植物抗旱的定向育种创造条件。本文系统介绍了在干旱胁迫条件下 ,植物体内渗透调节物质和可溶性糖合成有关的基因、离子和水分通道及Lea蛋白基因的表达 ,以及与这些基因表达相关的调控元件和因子 ,干旱胁迫信号转导等方面的最新研究进展。     

植物转录因子的研究进展

当植物感受干旱、低温和盐碱等非生物胁迫(abioticstress)时,能通过一系列的信号传递,激发转录因子,使其与顺式作用因子或其他转录因子相互作用,从而激活下游逆境相关基因的表达。     

液压信号与植物水分胁迫信号传递研究（综述）

植物根部受到干旱胁迫时,由茎部产生的液压信号使茎部作出反应.液压传递根到茎之间的水分胁迫信号.土壤干旱引起茎中场所产生液压反应,然后产生ABA信号,引起气孔关闭.在不同植物中,减弱液压反应,阻止干旱信号的长距离传导,气孔不能关闭.     

沙棘HrTCP转录因子家族鉴定及其干旱胁迫下的表达分析

TCP家族是植物特有的响应高盐、干旱等非生物胁迫的重要转录因子。该研究基于沙棘转录组数据,利用生物信息学与qRT-PCR对HrTCP转录因子家族进行鉴定,预测其家族成员的结构和功能,为解析TCP转录因子调控沙棘抵御干旱胁迫的作用机制奠定基础。结果表明:(1)获得了11个HrTCP转录因子成员,并命名为HrTCP2/4/7/8/11/13/15/17/18/19/20,编码氨基酸序列长度在218～590之间,蛋白质相对分子量为23.44～61.78 kD;亚细胞定位预测发现,除HrTCP13/17/18蛋白定位于细胞质,其余8个蛋白均定位于细胞核。(2)在干旱(15%PEG-6000)和高盐(200 mmol/L NaCl)胁迫后HrTCP4/7/19/20基因表达量呈不同程度上升趋势,其中HrTCP20表达量极显著高于对照,分别是对照的24倍与23倍。(3)外源激素脱落酸(0.1 mmol/L ABA)和茉莉酸甲酯(0.1 mmol/L MeJA)处理后,HrTCP7/19/20基因表达量也均呈上升趋势,其中,ABA诱导下HrTCP19基因表达量达到最高,是对照的16倍,而MeJA诱导下HrTCP20基因表达量上升最高,是对照的5倍。研究发现,HrTCPs转录因子家族成员可受干旱、高盐和激素诱导表达,进而调控沙棘对干旱胁迫的响应。     

干旱胁迫与ABA的信号转导

植物经历干旱胁迫时,ABA被普遍认为是一种干旱信号而传递干旱信息.在干旱信号ABA的转导过程中,从ABA的被感知到保卫细胞发生变化引起气孔关闭以及ABA诱导的基因表达都经历了复杂的变化.本文对ABA的信号转导过程进行了综述.     

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.