特种稻种质资源研究进展与展望

我国从20世纪80年代开始广泛关注特种稻种质资源研究.至今以丰富的特种稻种质资源为基础,积极开展特种稻特殊性状遗传分析的同时,将常规育种与生物技术相结合,创新黑米、红米、软米、巨胚米、甜米等一系列特种稻新种质,并在水稻育种和生产上提供应用,为增加稻农收入做出了积极贡献.广泛开展特种稻资源的特殊性状鉴定和评价,筛选具有独特特性的优异种质资源,并进行基因型检测与遗传多样性分析和核心种质构建;将多个特殊性状相聚合,创新赖氨酸、微量元素、维生素等含量较高,黄酮、花青3-葡萄糖苷、生物碱等生理活性物质含量较高的水稻种质是今后我国特种稻资源研究的重要内容.     

海南具C4、C3解剖特征的禾本科植物

为了充分认识海南地区现有禾本科植物的光合途径类型,为该地区禾本科植物的种质资源学、生理生态学研究提供可靠的资料,通过调查并收集整理海南禾本科牧草种质资源,以C3、C4植物在解剖结构上的差异为基础,利用石蜡制片技术鉴定海南禾本科植物光合途径的类型。结果表明,在224份研究材料中,有189种禾草属于C4光合类型,35种禾草属于C3光合类型,分别占禾草种数的84%和16%,说明该区域禾草以高光效的C4类型为主。     

转玉米PEPC基因水稻中有限的C4光合微循环及其生理作用

用转PEPC基因水稻(Oryza sativa L. subsp.japonica Kitaake)和原种水稻Kitaake为材料,研究了不同基因型水稻叶片中的C4光合微循环及其功能.通过测定与光合C4途径有关的关键酶,如磷酸烯醇式丙酮酸羧化酶(PEPC)、NADP -苹果酸酶(NADP -ME)、NADP -苹果酸脱氢酶(NADP -MDH)和丙酮酸磷酸双激酶(PPDK),说明原种水稻叶片中具有完整的C4光合酶体系;用外源OAA或MA饲喂叶切片或叶绿体后明显增加光合速率,证明原种水稻中具有一个有限的光合C4微循环.将玉米的PEPC基因导入原种水稻后,可大幅度提高光合C4微循环的速率.测定不同基因型的CO2交换速率,看出水稻中C4光合微循环的增强有提高净光合速率(Pn)和降低光呼吸速率/净光合速率(Pr/Pn)比值的作用.叶绿素荧光特性分析表明,C4光合微循环的增强伴随着PSⅡ电子传递效率(Fv/Fm)和光化学猝灭(qP)的增加以及非光化学猝灭(qN)的降低;这些结果为通过基因工程手段提高作物光合效率的遗传育种提供了科学根据.     

转玉米PEPC基因水稻中有限的C4光合微循环及其生理作用

用转PEPC基因水稻(OryzasativaL.subsp.japonicaKitaake)和原种水稻Kitaake为材料,研究了不同基因型水稻叶片中的C4光合微循环及其功能。通过测定与光合C4途径有关的关键酶,如磷酸烯醇式丙酮酸羧化酶(PEPC)、NADP -苹果酸酶(NADP -ME)、NADP -苹果酸脱氢酶(NADP -MDH)和丙酮酸磷酸双激酶(PPDK),说明原种水稻叶片中具有完整的C4光合酶体系;用外源OAA或MA饲喂叶切片或叶绿体后明显增加光合速率,证明原种水稻中具有一个有限的光合C4微循环。将玉米的PEPC基因导入原种水稻后,可大幅度提高光合C4微循环的速率。测定不同基因型的CO2交换速率,看出水稻中C4光合微循环的增强有提高净光合速率(Pn)和降低光呼吸速率/净光合速率(Pr/Pn)比值的作用。叶绿素荧光特性分析表明,C4光合微循环的增强伴随着PSⅡ电子传递效率(Fv/Fm)和光化学猝灭(qP)的增加以及非光化学猝灭(qN)的降低;这些结果为通过基因工程手段提高作物光合效率的遗传育种提供了科学根据。     

转PEPC基因水稻具有初级CO2浓缩机制的生理特点

以原种粳稻Kitaake为对照, 研究了转玉米PEPC基因水稻的PEPC的高表达和碳同化特性的关系. 结果显示: 与原种相比, 转PEPC基因水稻气孔导度和光合速率显著增加, 经统计分析, 气孔导度的增加与光合速率的增加并无相关性. 而在高光强下, 与CO2浓缩有关的PEPC, CA酶蛋白的表达显著增加. 因此在大气CO2浓度下可显著增加光合能力(50%); 无CO2条件下, 可减少叶内CO2释放量, 从而降低了CO2补偿点. 用专一的抑制剂DCDP处理, 证明转PEPC基因水稻叶内PEPC的高表达与碳同化能力的提高和Fv/Fm的稳定性有关. 用14C示踪20 s, 转PEPC基因水稻14C较多的分配在C4光合原初产物天冬氨酸中, 意味着叶内存在着一定的C4光合代谢途径. 上述结果说明, 用代谢工程可以在叶内构建初级的CO2浓缩机制, 为转基因的高光效育种技术提供了生理依据.     

药用植物防风(Saposhnikovia divaricata)不同时期光合作用特性比较

通过对防风光合特性及光合有效辐射(PAR)、大气二氧化碳浓度(Ca)、气温(Ta)、叶温(Tl)和相对湿度(RH)等环境因子的同期观测,系统地研究了防风净光合速率(Pn)等在不同时期的日变化特征及其与环境因子之间的关系,为吉林省防风规范化种植提供理论依据.结果表明,不同时期防风净光合速率日变化均呈双峰型曲线,具有明显的光合"午休"现象.7月份防风光合速率中午降低主要由非气孔限制引起,8月份、9月份防风光合速率中午降低则主要由气孔限制引起,7月份高温低湿是限制防风Pn的主要环境因子.光合速率和蒸腾速率的不同步是引起水分利用效率变化的主要原因.光合有效辐射直接影响防风叶片的光合速率,从而影响防风有机物质的合成与转化,对防风生产力起到直接的限制作用.不同时期防风Pn与PAR呈显著正相关,不同时期防风叶片对不同环境因子的反映有所不同,环境因子中对Pn直接作用由大到小为7月份 Ta＞PAR＞Tl＞Ca＞RH,8月份为Tl＞PAR＞Ta＞RH＞Ca,9月份为Ta＞PAR＞Tl＞Ca＞RH.     

转PEPC基因水稻具有初级CO2浓缩机制生理特点

以原种粳稻Kitaake为对照, 研究了转玉米PEPC基因水稻的PEPC的高表达和碳同化特性的关系. 结果显示: 与原种相比, 转PEPC基因水稻气孔导度和光合速率显著增加, 经统计分析, 气孔导度的增加与光合速率的增加并无相关性. 而在高光强 下, 与CO₂浓缩有关的PEPC, CA酶蛋白的表达显著增加. 因此在大气CO₂浓度下可显著增加光合能力(50%); 无CO₂条件下, 可减少叶内CO₂释放量, 从而降低了CO₂补偿点. 用专一的抑制剂DCDP处理, 证明转PEPC基因水稻叶内PEPC的高表达与碳同化能力的提高和Fv/Fm的稳定性有关. 用14C示踪20 s, 转PEPC基因水稻14C较多的分配在C4光合原初产物天冬氨酸中, 意味着叶内存在着一定的C4光合代谢途径. 上述结果说明, 用代谢工程可以在叶内构建初级的CO₂浓缩机制, 为转基因的高光效育种技术提供了生理依据.     

重庆石灰岩地区木豆与十大功劳叶片气体交换的比较

对重庆石灰岩地区固氮植物木豆与非固氮植物十大功劳叶片气体交换进行了比较研究.结果表明木豆的日均净光合速率（Pn）、蒸腾速率（E）、气孔导度（Gs）和光能利用效率（LUE）均大于十大功劳,但两者的水分利用效率（WUE）没有差别.净光合速率在中午出现了较明显的光合＂午休＂现象.经分析木豆的光合午休主要由气孔因素引起,而十大功劳的光合午休现象以非气孔因素为主.同样,在季节变化中木豆的净光合速率（Pn）、蒸腾速率（E）、气孔导度（Gs）和光能利用效率（LUE）的季节均值也均大于十大功劳,但水分利用效率（WUE）却相反.木豆和十大功劳的叶绿素含量的季节变化与净光合速率季节变化趋势基本一致,木豆的叶绿素含量呈8月份高峰的单峰曲线,而十大功劳在8月份和10月份各有一高峰.木豆的叶绿素a/b的季节变化呈递减趋势,相反,十大功劳呈上升趋势.经分析,木豆和十大功劳的净光合速率的季节变化与叶绿素含量的季节变化相关联.木豆单位叶重的含氮量季节均值为37.6mg/g,明显高于十大功劳的14.8 mg/g,说明木豆的高固氮能力导致了木豆的高光合能力.但木豆的水分利用效率不如十大功劳,说明有高光合能力的固氮植物木豆在石灰岩地区的植被恢复中也存在其不适应的因素,但木豆是否真正适应干旱环境还需要进行全面的水分生理的研究.     

ABA、BA及DPI对高表达玉米C4pepc基因的水稻光合特性及叶绿素荧光特性的影响

为阐明水稻高表达玉米C4型磷酸烯醇式丙酮酸羧化酶基因(C4phosphoenolpyruvate carboxylase,C4pepc)出现高光效的分子机理,以盆栽转C4pepc水稻(PC)及野生型Kitaake(WT)为材料,花后7d茎吸入脱落酸(abscisic acid,ABA)、正丁醇(n-butanol,BA)及氯化二亚苯基碘(diphenyleneiodonium,DPI),考察其对叶片光合特性及酶活性等影响。结果表明:(1)与ABA处理不同,DPI和BA处理下PC的Pn均呈现先增加后下降的趋势,BA处理0.5h时Pn明显增加,原因主要是由于气孔导度的增加;(2)ABA、BA和DPI对Fv/Fm的影响不明显,与WT相比,PC的qP下降少;(3)BA处理后PC的PEPC活性降低了26%,而DPI处理则增加了48%。各处理并未对PEPC蛋白和基因的表达有影响。     

杏、李和杏李光合特性比较及优异种质筛选

利用Li-6400便携式光合测定系统对80份杏、李和杏李种质光合参数进行测定的结果表明,供试品种间光合特性差异较大。对80份种质进行聚类分析,根据光合速率将它们分为高、中、低3种光合速率类型,根据水分利用效率分为高、较高、中及低4种水分利用效率类型。杏中高光合速率类型占50%,高于李、杏李中该类型的频率;李和杏李则以中等光合速率为主,分别占55.2%和62.5%。杏和杏李中较高和中等水分利用效率类型较多,未发现高和低水分利用效率类型,而李的水分利用效率类型则分布广泛。综合考虑光合和水分指标,筛选出2个李品种澳得罗达、理查德早生,3个杏品种超仁、兰州大接杏和仰韶杏表现出高光效、较高水分利用效率,可用于今后的生产和育种实践。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

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.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.