蓝光对真菌的调控作用及研究进展

蓝光是环境中的重要信号因子,可影响微生物特别是真菌的生理周期、形态变化、基因表达,进而影响微生物的代谢活动。在国外,蓝光对微生物的影响研究是一个热点问题,并进行了较深入的研究,已在真菌中发现了一些蓝光受体因子。主要综述了蓝光对真菌影响的一些研究进展。     

蓝光诱导促进黑曲霉产糖化酶的研究

考察了蓝光对黑曲霉产糖化酶的影响并采用扫描电镜观察蓝光下黑曲霉形态发育过程,结果表明,与黑暗对照组相比,蓝光处理使菌丝粗壮,孢囊增大,分生孢子发育提前,黑曲霉糖化酶活力增加,孢子发育和产糖化酶的进程有一定的对应性。黑曲霉在黑暗下生长至36h时,经蓝光诱导糖化酶产量提高更为明显,提示了黑曲霉存在一个对蓝光反应产生最适光感应的发育阶段,对于光调节黑曲霉产糖化酶来说,蓝光诱导的光强由弱到强,比持续蓝光培养或采用较高光强诱导效果更好,表明黑曲霉产糖化酶存在一种光适应机制,能够感应和适应光强度变化,调节其自身代谢。从抑制性扣除杂交实验和蓝光光强变化对差异基因表达的分析来看,糖化酶基因以及呼吸链中部分氧化还原酶基因在蓝光诱导下表达皆有增强,蓝光信号转导影响了核基因编码的线粒体呼吸链相关酶基因表达水平,交替氧化酶可能参与了蓝光信号途径,影响了黑曲霉产糖化酶和孢子发育。研究结果可为在现有水平上应用蓝光调节提高糖化酶产量找到新的技术突破口和提供新思路。     

花生疮痂病菌蓝光受体EaWC 1基因克隆及生物信息学分析

光是真菌感知和适应环境的重要信息载体,调控多种生理生化过程。痂囊腔菌素(Elsinochromes,ESC)是花生疮痂病菌重要的毒力因子,蓝光对其具有正调控作用,为了进一步揭示光调控ESC机制,开展了花生疮痂病菌蓝光受体基因EaWC 1克隆、生物信息学分析和表达模式研究。结果表明,蓝光受体基因EaWC 1全长为3 261bp,具有一个完整的开放阅读框,编码长度为1 086个氨基酸的蛋白质,相对分子质量11.95 kD,理论等电点为8.81,具有核定位信号,为稳定亲水性蛋白。qPCR定量分析表明,EaWC 1基因表达受到蓝光诱导,其表达模式与ESC毒素含量呈显著正相关。研究结果对于阐明花生疮痂病菌蓝光受体生物功能,揭示ESC毒素生物合成光调控机制和调控网络奠定了理论基础。     

蓝光受体下游信号转导组分的研究进展

为了全面了解蓝光受体信号转导组分及其调节机制的研究进展,着重地阐述了蓝光受体的信号转导组分中的Ca~(2 )、蛋白质的可逆磷酸化、阴离子通道和G蛋白,以及植物如何通过多条信号转导途径调节其形态和发育的变化以适应环境的变化等。     

海洋真菌灰绿曲霉蓝光感应基因Agwc1的克隆、鉴定与序列分析

蓝光感应系统在不同的光感应过程中都起到十分关键的作用,这些生理过程包括无性/有性发育,昼夜节律钟,次级代谢产物的生成等.为了对蓝光感应系统作进一步的研究,通过简并引物PCR 和基因组走读方法得到了海洋真菌灰绿曲霉蓝光调节受体基因Agwc1,并通过多种生物信息学方法对其核苷酸和蛋白质序列进行了分析.Agwc1 基因全长2 724 bp,包含3个内含子,编码852 个氨基酸,蛋白质分子量是96 kD,等电点为8.17,很有可能定位于细胞核中,通过序列比对与系统进化树分析,发现AgWC1 蛋白与其他物种中的WC-1 蛋白有很高的同源性.在本研究中成功鉴定了Agwc1 基因,这是国际上首次在海洋丝状真菌领域鉴定光感应基因,并且AgWC1 很有可能在灰绿曲霉蓝光感应系统中发挥重要功能.     

不同波长光源对新蚜虫疠霉产孢能力的影响及霉菌蓝光受体基因的克隆和表达分析

光在调控真菌的多种生理过程中发挥着重要作用。为探究光照对新蚜虫疠霉Pandora neoaphidis产孢的影响,本文研究了不同波长光源(蓝光、绿光、白光、红光、黄光)和无光黑暗条件对新蚜虫疠霉分生孢子弹射能力的影响,通过cDNA末端的快速扩增(RACE)对新蚜虫疠霉的蓝光受体蛋白基因pnwc-1进行克隆并对其进行生物信息学分析,利用qRT-PCR对蓝光光源不同照射时长下pnwc-1的表达量进行了定量分析。结果表明,蓝色光源(波长460–465nm)照射后的新蚜虫疠霉菌丝产生的分生孢子数量显著高于其他波长光源,排序为:蓝光>绿光>白光>红光>黄光>无光。另外,分析克隆获得的全长为2 423bp的pnwc-1基因发现,其编码的蛋白具有蓝光受体蛋白典型的保守结构域,同源比对结果显示新蚜虫疠霉与接合菌门真菌归为一类但相对独立。qRT-PCR的定量分析结果表明随着照射时长增加,蓝光处理能显著提高pnwc-1的表达量,而且pnwc-1的相对表达量与累积产孢量存在正相关(R2=0.9798)。本研究为后续蓝光及其受体基因功能的深入研究提供了实验基础,并促进以新蚜虫疠霉为代表的虫霉目真菌在害虫生物防治中的应用。     

拟南芥蓝光受体CRY2的功能及其介导的光形态建成

植物具备一套复杂的由两种蓝光受体和多种信号转导下游组分组成的蓝光感应系统,通过感受光照强度、光的方向和光周期,调节自身对蓝光的应答.蓝光反应的有效波长是蓝光和近紫外光(320～400nm),故蓝光受体也叫蓝光/近紫外光受体.CRY2(Cryptochromes,CRY)是一个核蛋白,在转录水平受蓝光的调节,它的作用是增加拟南芥对蓝光的敏感性.植物蓝光调节的反应主要有向光性、抑制幼茎伸长、叶绿体迁移、刺激气孔张开和调节基因表达等.对植物蓝光反应突变体分子生物学研究进展进行了综述,对蓝光受体及信号转导下游组分在植物发育中的作用及蓝光诱发植物作出反应的分子机制进行了探讨.     

植物蓝光反应突变体分子生物学研究

植物具备一套复杂的由3种蓝光受体和多种信号转导下游组分组成的蓝光感应系统,通过感受光照强度、光的方向和光周期,调节自身对蓝光的应答。本文综述了植物蓝光反应突变体分子生物学研究进展,探讨蓝光受体及信号转导下游组分在植物发育中的作用及蓝光诱发植物作出反应的分子机制。     

蓝光光照对蛹虫草子实体生长和主要活性成分的影响

光作为一种重要的环境因子,可影响真菌的生长发育、生理周期、形态变化及次级代谢产物的产生,对于蛹虫草而言,光照还是其子实体生长发育的必要条件。选择2株不同来源的蛹虫草菌株,研究了自然光照和蓝光光照条件下,其子实体生长、抗氧化酶活性和主要活性成分的变化。结果表明蓝光光照对于蛹虫草子实体产量没有明显的促进和抑制作用。自然光照条件下成熟子实体的超氧化物歧化酶(superoxide dismutase,SOD)活性显著高于蓝光光照,过氧化氢酶(catalase,CAT)活性没有明显差别,而过氧化物酶(peroxidase,POD)活性则表现出菌株差异。子实体主要活性成分方面,腺苷、甘露醇含量不受蓝光影响,类胡萝卜素在蓝光光照条件下含量极显著高于自然光光照,蓝光对子实体、虫草素、粗多糖含量的影响则存在菌株差异。研究为蛹虫草子实体的栽培条件优化,提高蛹虫草子实体质量提供依据。     

植物蓝光反应突变体分子生物学研究

植物具备一套复杂的由3种蓝光受体和多种信号转导下游组分组成的蓝光感应系统,通过感受光照强度、光的方向和光周期,调节自身对蓝光的应答.本文综述了植物蓝光反应突变体分子生物学研究进展,探讨蓝光受体及信号转导下游组分在植物发育中的作用及蓝光诱发植物作出反应的分子机制.     

Blue light (470 nm) effectively inhibits bacterial and fungal growth

Blue light (470 nm) LED antimicrobial properties were studied alone against bacteria and with or without the food grade photosensitizer, erythrosine (ERY) against filamentous fungi. Leuconostoc mesenteroides (LM), Bacillus atrophaeus (BA) or Pseudomonas aeruginosa (PA) aliquots were exposed on nutrient agar plates to Array 1 (AR1, 0·2 mW cm^?2) or Array 2 (AR2, 80 mW cm^?2), which emitted impure or pure blue light (0–300 J cm^?2), respectively. Inoculated control (room light only) plates were incubated (48 h) and colonies enumerated. The antifungal properties of blue light combined with ERY (11·4 and 22·8 μmol l^?1) on Penicillium digitatum (PD) and Fusarium graminearum (FG) conidia were determined. Conidial controls consisted of: no light, room light‐treated conidia and ERY plus room light. Light‐treated (ERY + blue light) conidial samples were exposed only to AR2 (0–100 J cm^?2), aliquots spread on potato dextrose agar plates, incubated (48 h, 30°C) and colonies counted. Blue light alone significantly reduced bacterial and FG viability. Combined with ERY, it significantly reduced PD viability. Blue light is lethal to bacteria and filamentous fungi although effectiveness is dependent on light purity, energy levels and microbial genus.

Significance and Impact of the Study

Light from two arrays of different blue LEDs significantly reduced bacterial (Leuconostoc mesenteroides, Bacillus atrophaeus and Pseudomonas aeruginosa) viabilities. Significant in vitro viability loss was observed for the filamentous fungi, Penicillium digitatum and Fusarium graminearum when exposed to pure blue light only plus a photosensitizer. F. graminearum viability was significantly reduced by blue light alone. Results suggest that (i) the amount of significant loss in bacterial viability observed for blue light that is pure or with traces of other wavelengths is genus dependent and (ii) depending on fungal genera, pure blue light is fungicidal with or without a photosensitizer.     

LOVe across kingdoms: Blue light perception vital for growth and development in plant–fungal interactions

Blue light plays an important role in the growth and development of fungi. Environmental cues enable plant pathogenic fungi to synchronise essential metabolic pathways to that of their hosts to gain a competitive advantage. Phylogenetic analysis of the LOV domain present in blue light receptors across all three kingdoms suggests that these receptors in fungal lineages have undergone convergent evolution to use the same domain for control and regulation of similar cellular and metabolic processes. In this review, the genetic basis of blue light photoperception in fungi, and the functions it regulates, will be discussed. Furthermore, the evolution of the light sensing domain and its role in pathogenesis is hypothesised concluding with how knowledge of conserved LOV domains may be exploited for fungal disease control in crop plants.     

VIVID is a flavoprotein and serves as a fungal blue light photoreceptor for photoadaptation

Blue light regulates many physiological and developmental processes in fungi. Most of the blue light responses in the ascomycete Neurospora crassa are dependent on the two blue light regulatory proteins White Collar (WC)-1 and -2. WC-1 has recently been shown to be the first fungal blue light photoreceptor. In the present study, we characterize the Neurospora protein VIVID. VIVID shows a partial sequence similarity with plant blue light photoreceptors. In addition, we found that VIVID non-covalently binds a flavin chromophore. Upon illumination with blue light, VIVID undergoes a photocycle indicative of the formation of a flavin-cysteinyl adduct. VVD is localized in the cytoplasm and is only present after light induction. A loss-of-function vvd mutant was insensitive to increases in light intensities. Furthermore, mutational analysis of the photoactive cysteine indicated that the formation of a flavin-cysteinyl adduct is essential for VIVID functions in vivo. Our results show that VIVID is a second fungal blue light photoreceptor which enables Neurospora to perceive and respond to daily changes in light intensity.     

Light signaling in plants

Light signals have profound morphogenic effects on plant development. Signals perceived by the red/far‐red absorbing phytochrome family of photoreceptors and the blue/green/ UV‐A absorbing cryptochrome photoreceptor converge on a group of pleiotropic gene products defined by the COP/DET loci to control the pattern of development. The signaling pathway, although still undefined, includes several classic signaling molecules, such as G‐proteins, calcium, calmodulin, and cGMP. A separate signaling pathway is involved in the modulation of the phototropic response. Additional mutants have been identified that affect subsets of light signaling responses. This review provides an overview of our current understanding of the light signaling process, in particular recent genetic and biochemical advances.     

Effect of different light qualities on the ultrastructure, thylakoid membrane composition and assimilation metabolism of Chlorella fusca

Chlorella fusca (Shihira et Krauss) strain C-1.1.10 was grown under three different light qualities (red, white or blue light) in homocontinuous cultures. Under electron microscopy, blue light cultures showed enlarged cells, thinner cell walls and lower starch content than red light cells. Under blue light, the degree of stacking of the thylakoid membranes was significantly lower than under white or red light conditions. Changing the light from blue to red the ratio of exposed to appressed membranes was doubled. Compared to red light cells, blue light cells exhibited higher photosynthetic rates per chlorophyll molecule and contained less chlorophyll per dry weight. Blue light stimulated the content of soluble protein as well as that of soluble carbohydrates. The dry weight productivity per unit time was enhanced under blue light conditions. The thylakoid protein complexes which are generally assumed to be localized in the exposed membranes were found in higher concentrations under blue light than under red light. In blue light, both the Photosystem II/Photosystem I ratio and the ratio of light-harvesting chlorophyll protein to P-700 chlorophyll a -protein were lower than in red light. Blue light cells contained twice the concentration of cytochrome f , which correlates well with their higher photosynthetic capacity. When altering the light quality, the degree of change in the reaction center complexes was much lower than expected given the corresponding degree of change in the ratio of exposed to appressed membranes. These results are discussed in light of the question as to whether the variation in the stoichiometry of the laterally distributed complexes can be explained by changes in the degree of stacking alone.     

苔藓植物蓝光/紫外光-A 信号传导的研究

种子植物含有5个已分离的光受体和至少1个未鉴定的蓝光/紫外光-A受体。隐花色素(CRY1、CRY2和CRY3) 调节植物的生长发育,而向光蛋白(PHOT1和PHOT2) 调节植物对光的营养反应。黄素可以吸收蓝光和紫外光-A,是生色团。对这些光受体的结构和作用模式已了解很多。苔藓植物小立碗藓中含有2个已分离的隐花色素(CRY1a和CRY1b),负责调节侧枝形成和生长素代谢;有4个向光蛋白(PHOTA1,PHOTA2,PHOTB1,PHOTB2) 调节叶绿体的运动。苔藓细胞内蓝光/紫外光-A刺激引发的信号转导有Ca2+参与。     

The effect of blue light on energy levels in epidermal strips

Red light applied together with blue enhanced stomatal opening in epidermal strips of Commelina communis L. more than red light alone. In red light, stomatal opening was enhanced by exogenously applied ATP and was inhibited by 3-(3,4-dichlorophe-nyl)-l,l-dimethylurea (DCMU), while in the presence of blue light external ATP was almost without effect, and DCMU stimulated stomatal opening. Blue light increased the ATP levels in the epidermal strips. DCMU diminished the amount of ATP in both red light and red + blue light treatments, but did not abolish the stimulatory effect of blue light. Blue light also stimulated the respiration rate of the epidermal strips. Rotenone, which inhibited stomatal opening and respiration rate, abolished the effect of blue light in both processes. These results imply that blue light increases the ATP levels by stimulation of oxidative phosphorylation.