抗感白粉病青稞的内生真菌群落差异分析

种子内生微生物组与种子的健康发育有着密切的关系。本研究收集对白粉病抗病和易感共11个品种的青稞种子,利用扩增子测序技术对内生真菌的群落、丰度和多样性进行研究。从不同品种的青稞种子中共鉴定4个门、17个纲、35个目、66个科、107个属的内生真菌,其中子囊菌门Ascomycota、担子菌门Basidiomycota和被孢菌门Mortierellomycota是优势菌门;链格孢属Alternaria、微座孢属Microdochium、亚隔孢壳属Didymella、镰刀菌属Fusarium和球腔菌属Mycosphaerella为优势菌属。根据生物信息学注释结果,在鉴定到的107个属中,抗病品种的青稞种子中特有的属有20个,感病品种的青稞种子中特有的属有50个;通过对两组样本的分析,发现感病品种中真菌物种多样性高于抗病品种。本研究通过扩增子测序技术初步确定了青稞抗、感白粉病两组样品中的真菌群落结构和优势菌群,为进一步研究青稞内携真菌与抗/感病的关系提供了基础,从内生菌的角度为青稞白粉病的防控提供新的策略。     

钙调素结合蛋白参与调控植物逆境胁迫的研究进展

Ca²⁺是植物体内重要的第二信使,当植物受到各种环境刺激时,细胞内的Ca²⁺浓度瞬间产生变化,并被Ca²⁺信号效应器识别,通过与下游的靶蛋白结合并调节其活性,参与调控植物各种生理活动。钙调素结合蛋白以依赖Ca²⁺或不依赖Ca²⁺的方式结合钙调素。对目前已经鉴定的植物钙调素结合蛋白结构特点进行了综述,并着重介绍了钙调素结合蛋白是如何参与调节植物对生物胁迫和非生物胁迫的反应,为提高作物抗病抗逆能力研究提供理论基础。     

酸雨对三峡库区4种植物幼苗光合生理及根际土壤的影响北大核心CSCD

近年来酸雨的酸性和频率越来越高,酸雨类型逐渐由硫酸型向硫酸-硝酸混合型及硝酸型转变。该研究以两年生马尾松、杉木、青冈和毛竹幼苗为试验材料,通过4个月的盆栽实验对幼苗进行硫酸型(SAR)、硝酸型(NAR)和混合型(MAR)酸雨及其各自3个酸雨浓度(pH 2.5、pH 3.5、pH 4.5)的处理,并以pH 5.7的蒸馏水为对照组,对植物的净光合速率、叶绿素含量、树种株高变化量以及植物根际土壤pH值和交换性盐基离子含量进行测定,以探究植物幼苗对模拟酸雨的敏感性及抗性特征,为酸雨受灾区的植被建设和抗酸树种的培育提供参考数据。结果表明:(1)不同浓度及类型酸雨在一定程度上能够抑制植物的净光合速率、阻碍叶绿素的合成,即酸雨浓度越高,植物净光合速率越低,叶绿素含量越少。(2)低浓度酸雨能够促进植物株高的增长,但随着酸雨浓度的增大,植物株高增长量受到严重抑制,且马尾松和青冈的表现最为明显。(3)植物根际土壤在低浓度酸雨胁迫下能够有效释放出盐基离子中和酸根离子从而降低酸雨的毒害,但随着酸雨浓度的增大,盐基离子含量不断衰减,土壤pH值逐渐减小。(4)杉木、马尾松、毛竹、青冈的平均隶属度值在不同酸雨类型作用下的表现不尽相同,总体上杉木对硫酸型和混合型酸雨的抗性最强,而毛竹能耐受硝酸型及混合型酸雨,青冈相比其他3种树种对酸雨的抗性最弱。研究发现,马尾松对硝酸型酸雨最敏感,且受胁迫的pH阈值为2.5~3.5,但对硫酸型酸雨表现出明显的抗性;杉木对3种类型酸雨的抗性较其他3种树种要强,毛竹抵抗硝酸型酸雨能力强于其他2种酸雨,而青冈对硝酸型酸雨的抵抗力强于其他2种酸雨且是抗酸能力最弱的树种,毛竹、杉木及青冈受酸雨胁迫的pH阈值为3.5~4.5;4种植物对酸雨的综合抵抗能力表现为杉木>毛竹>马尾松>青冈。     

中国食用向日葵育种国产化历程及研究进展

中国食用向日葵育种近40年来取得了巨大成就,实现了从自留农家种、选育常规品种、引进国外杂交种以及培育国产杂交种4 次品种更新。中国向日葵种植面积基本保持在59万hm²左右,种植区主要集中在北方10个省区,其中内蒙古自治区种植面积约占全国总面积的四分之三,其次是新疆。中国以食用向日葵种植为主,约占总面积的95%以上,是世界上食用向日葵主要生产国。食用向日葵主要用于休闲嗑食,除高产外,商品外观品质(粒型、色泽、口感等)仍将是当今主要育种目标。另外,向日葵生产区因长期连作种植,病原菌、列当等生物逆境因素与向日葵发生协同进化,加之食用向日葵遗传背景狭窄,病虫草害日趋严重。该文通过对中国食用向日葵育种历程进行回顾,尤其对国内外有关向日葵抗病育种研究进展进行综述,为解析食用向日葵抗性育种机制以及前瞻性抗性品种储备提供重要的理论与技术支持,以推动食用向日葵产业的高效优质发展。     

生物炭对土壤中抗生素抗性基因的阻控潜力及机制研究进展

土壤中抗生素抗性基因(ARGs)污染是全世界面临的重大环境和健康挑战,开发有效技术以减少其负面影响对维护土壤和人类健康至关重要。生物炭具有高碳含量、大表面积、良好的吸附性能和经济优势,可能是一种非常合适的阻控材料。其对ARGs的阻控作用可能归因于以下3种机制: 1) 吸附某些污染物,如抗生素和重金属,减弱ARGs的共选择性压力;2) 通过改变土壤理化特性影响微生物种群结构,从而限制细菌之间ARGs的水平转移;3) 通过吸附或破坏质粒、转座子、整合子等水平转移载体,直接减弱基因水平转移能力。但生物炭对ARGs的阻控效果取决于生物炭的物料来源、热解工艺和添加水平等。此外,生物炭的老化可能会降低其阻控ARGs的效果。生物炭的内源性污染物,如多环芳烃和重金属,也可能导致环境中特定抗生素抗性细菌的富集或诱导水平基因转移。在后续研究中,应根据土壤环境选择合适的生物炭种类,并采取生物炭老化控制措施,以进一步提高生物炭对ARGs的阻控作用。     

三种裸子植物木质部结构与功能对不同生境的适应

生境异质性是影响植物生长发育的重要因素。植物木质部水力系统是土壤-植物-大气连续体的主要通路, 直接影响植物的基本行为和功能, 同时也反映了植物对环境变化的适应性。为对比天目山3种裸子植物枝条木质部水力功能、机械和解剖结构性状在不同生境(自然生境与人工生境)的差异, 揭示裸子植物对不同生境的适应机制, 该研究以金钱松(Pseudolarix amabilis)、杉木(Cunninghamia lanceolata)和雪松(Cedrus deodara)为研究对象, 测定枝木质部导水率、栓塞抗性(导水率损失50%时的水势)、机械以及解剖结构性状。结果发现: 1)人工生境植株比自然生境植株水力效率弱, 但栓塞抗性强。2)自然生境雪松木质部导水系统存在效率-安全权衡; 不论自然还是人工生境杉木、金钱松木质部导水系统均无效率-安全权衡。3)人工生境雪松和金钱松木质部存在机械-安全权衡。相比人工生境, 土壤水分有效性低的自然生境中, 植物采用增大纹孔膜直径来提高水力效率, 此外, 还可通过增加木材密度、扩大管胞直径来避免栓塞带来的威胁。     

Carbon Monoxide： A Novel Antioxidant Against Oxidative Stress in Wheat Seedling Leaves

Carbon monoxide （CO）, an endogenous signaling molecule in animals, also provides potent cytoprotective effects including attenuation of lung lipid peroxidation induced by oxidant in the mouse. Our recent work demonstrated that 0.01 μmol/L hematin （a CO donor） treatment of wheat plants alleviated salt-induced oxidative damage in seedling leaves. In this report, we further discovered that hematin pretreatment （≤ 0.1 μmol/L） could delay wheat leaf chlorophyll loss mediated by further treatment of H202 and paraquat, two reactive oxygen species （ROS） sources, in dose-and even time-dependent manners. Also, compared with the control samples, seedling leaves pretreated with 0.01 or 0.1 μmol/L hematin for 24 h exhibited lower levels of H2O2 and lipid peroxidation, as well as higher contents of chlorophyll and activities of antioxidant enzymes. Such beneficial effects exerted by hematin were mimicked by the pretreatment of antioxidant butylated hydroxytoluene （BHT）, and differentially reversed when CO scavenger hemoglobin （Hb）, or CO specific synthetic inhibitor ZnPPIX was added, respectively. Taken together, the results presented In this paper directly illustrate for the first time that CO is able to strongly protect plants from oxidative damage caused by the overproduction of ROS, and strengthens the evidence that CO is a potent antioxidant in various abiotic and biotic stresses, as similar results have been shown in animal tissues.     

Changes in Unsaturated Levels of Fatty Acids in Thylakoid PSII Membrane Lipids During Chilling-induced Resistance in Rice

Temperature is one of the abiotic factors limiting growth and productivity of plants. In the present work, the effect of low non‐freezing temperature, as an inducer of “chilling resistance”, was studied in three cultivars of rice (Oryza sativa L.), japonica cv. 9516 (j‐9516), the two parental lines of superhigh‐yield hybrid rice between subspecies, Peiai/E32 (ji‐PE), and the traditional indica hybrid rice Shanyou 63 (i‐SY63). Leaves of chill‐treated rice showed chilling‐induced resistance, as an increase of their low‐temperature tolerance was measured using chlorophyll fluorescence measurements, revealing a change in photosystem II (PSII) efficiency. After 5 d of exposure to 11°C under low light (100 μmol m^‐2 s^‐1), levels of unsaturated fatty acids in PSII thylakoid membrane lipids decreased during the initial 1‐2 d, then increased slowly and reached 99.2%, 95.3% and 90.1% of the initial value (0 d) in j‐9516, ji‐PE and i‐SY63, respectively, on the fifth day. However, under medium light (600 μmol m^‐2 s^‐1), all cultivars experienced similar substantial photoinhibition, which approached steady state levels after a decline in levels of unsaturated fatty acids in PSII thylakoid membrane lipids to about 57.1%, 53.8% and 44.5% of the initial values (0 d) in j‐9516, ji‐PE and I‐SY63 on the fifth day. Under either chilling‐induced resistance (the former) or low temperature photoinhibition (the latter) conditions, the changes of other physiological parameters such as D1 protein contents, electron transport activities of PSII (ETA), F_v/F_m, xanthophyl cycle activities expressed by DES (deepoxide state) were consistent with that of levels of unsaturated fatty acids in PSII thylakoid membrane lipids. So there were negative correlations between saturated levels of fatty acids (16:1(3t), 16:0, 18:0), especially the 16:1(3t) fatty acid on thylakoid membrane and other physiological parameters, such as D1 protein contents, ETA and (A+Z)/(A+V+Z). A specific role of desaturation of fatty acids and the photoprotective pigments of the xanthophyl cycle, leading to an acclimation response in thylakoid membrane lipids may be involved. We conclude that chilling‐induced resistance is accelerated by the unsaturation of thylakoid membranes, and the ability of rice plants to cold‐harden can be enhanced by genetic engineering.     

球孢白僵菌Hog1 MAPK同源基因BbHog1的克隆及特征分析

根据几种丝状真菌Hog1 MAPK的保守氨基酸序列设计简并引物,从昆虫病原真菌球孢白僵菌中扩增出MAPK同源基因的部分片段,然后利用YADE法延伸该片段的上、下游邻接序列,获得MAPK编码基因的全长序列,命名为BbHog1。序列分析表明,该基因编码358个氨基酸的多肽,推测分子量为40.99kDa,等电点为5.49。BbHog1含有MAPK保守的蛋白激酶激活域(TGY),序列与粗糙脉孢霉os-2(AF297032)、烟曲霉OSM1(XM_747571)、隐球酵母HOG1(AF243531)和酿酒酵母Hog1(Z73285)等Hog1 MAPK高度同源,相似性分别为94%、89%、83%和80%。系统聚类结果表明,BbHog1与酵母Hog1 MAPK同源。Southern杂交表明,BbHog1在球孢白僵菌基因组中以单拷贝形式存在。Northern分析表明,BbHog1在高渗、亚高温和营养胁迫等条件下的表达明显升高。由此推测,BbHog1基因可能与球孢白僵菌对逆境胁迫的适应性调节密切相关。