A rice serine carboxypeptidase-like gene OsBISCPL1 is involved in regulation of defense responses against biotic and oxidative stress

Serine carboxypeptidase-like proteins (SCPLs) comprise a large family of protein hydrolyzing enzymes that play roles in multiple cellular processes. During the course of study aimed at elucidating the molecular basis of induced immunity in rice, a gene, OsBISCPL1, encoding a putative SCPL, was isolated and identified. OsBISCPL1 contains a conserved peptidase S10 domain, serine active site and a signal peptide at N-terminus. OsBISCPL1 is expressed ubiquitously in rice, including roots, stems, leaves and spikes. Expression of OsBISCPL1 in leaves was significantly up-regulated after treatments with benzothiadiazole, salicylic acid, jasmonic acid and 1-amino cyclopropane-1-carboxylic acid, and also up-regulated in incompatible interactions between rice and the blast fungus, Magnaporthe grisea. Transgenic Arabidopsis plants with constitutive expression of OsBISCPL1 were generated and disease resistance assays indicated that the OsBISCPL1-overexpressing plants showed an enhanced disease resistance against Pseudomonas syringae pv. tomato and Alternaria brassicicola. Expression levels of defense-related genes, e.g. PR1, PR2, PR5 and PDF1.2, were constitutively up-regulated in transgenic plants as compared with those in wild-type plants. Furthermore, the OsBISCPL1-overexpressing plants also showed an increased tolerance to oxidative stress and up-regulated expression of oxidative stress-related genes. The results suggest that the OsBISCPL1 may be involved in regulation of defense responses against pathogen infection and oxidative stress.     

Heterologous expression of <Emphasis Type="Italic">Arabidopsis</Emphasis><Emphasis Type="Italic">NPR1</Emphasis> (<Emphasis Type="Italic">AtNPR1</Emphasis>) enhances oxidative stress tolerance in transgenic tobacco plants

In Arabidopsis, NPR1 (non-expressor of pathogenesis related genes 1, AtNPR1) functions downstream of salicylic acid (SA) and modulates the SA mediated systemic acquired resistance. It is also involved in a cross talk with the jasmonate pathway that is essential for resistance against herbivores and necrotrophic pathogens. Overexpression of AtNPR1 in transgenic plants resulted in enhanced disease resistance. Recently, tobacco transgenic plants expressing AtNPR1 were shown to be tolerant to the early instars of Spodoptera litura (Meur et al., Physiol Plant 133:765–775, 2008). In this communication, we show that the heterologous expression of AtNPR1 in tobacco has also enhanced the oxidative stress tolerance. The transgenic plants exhibited enhanced tolerance to the treatment with methyl viologen. This tolerance was associated with the constitutive upregulation of PR1, PR2 (glucanase), PR5 (thaumatin like protein), ascorbate peroxidase (APX) and Cu²⁺/Zn²⁺ superoxide dismutase (SOD). This is the first demonstration of the novel function of heterologous expression of AtNPR1 in oxidative stress tolerance in transgenic tobacco.     

Differential activation of defense-related genes in susceptible and resistant pepper cultivars infected with Phytophthora capsici

This study investigated the expression pattern of genes encoding for a basic PR-1 protein, a basic beta-1,3-glucanase, a peroxidase, and a sesquiterpene cyclase involved in defense responses in three pepper cultivars with different levels of resistance to Phytophthora capsici. All genes were up-regulated in infected stems of the pepper cultivars, with expression being detected 8h post-inoculation. mRNA levels of these genes increased markedly by 24h post-inoculation, and maximal induction levels were observed for the PR-1 and sesquiterpene cyclase genes. PR-1, peroxidase, and sesquiterpene genes were always expressed at higher levels in resistant cultivars than in the susceptible cultivar, although up-regulation was observed in both, suggesting that the differences between these pepper genotypes in susceptibility and resistance are a matter of the timing and magnitude of the defense response.     

水杨酸诱导下蝙蝠蛾拟青霉转录组分析及虫草酸代谢途径关键酶基因挖掘

【目的】虫草酸是虫草中重要的活性成分之一,但其低含量极大地限制了其工业应用。水杨酸(salicylic acid, SA)是一种非生物诱导子,可以显著提高蝙蝠蛾拟青霉中虫草酸的合成,但蝙蝠蛾拟青霉虫草酸代谢途径及其对水杨酸的响应尚不明确。本研究旨在获得蝙蝠蛾拟青霉响应SA处理的转录组学信息,挖掘蝙蝠蛾拟青霉中虫草酸代谢途径关键酶基因。【方法】采用SA诱导培养蝙蝠蛾拟青霉,8 h后选取诱导和未诱导的菌丝进行转录组高通量测序分析。【结果】测序最终获得40.37 Gb的clean data,拼接得到20 317条unigene,平均长度为1 357.13 bp,功能注释共获得13 592条unigene。差异基因分析共筛选出差异基因2 574个,其中有1 135个上调,1 439个下调。KEGG富集分析表明,差异基因主要富集于细胞周期、减数分裂、半乳糖代谢、DNA复制、糖醇脂类生物合成、甘油脂类代谢等KEGG通路中。进一步分析得到与虫草酸代谢相关的基因13条,其中参与虫草酸生物合成的基因glk、gpi、gla、mpi、fbp、mtld在SA处理后表达量上调,而涉及虫草酸消耗的基因mdh在SA...     

核桃JrNPR1基因的克隆与抗病响应潜力

病程相关基因非表达子NPR1（Nonexpressor of pathogenesis-related gene 1）基因,在植物抗病过程中起核心调控作用。核桃（Juglans regia）是我国乡村振兴的重要经济油料树种,其生长和产量严重受病虫害制约。为探索核桃抗病生理机制,筛选抗病基因,以‘香玲’核桃为试材,克隆获得JrNPR1基因,对其基本生物信息和病害响应进行分析,预测JrNPR1响应病害的功能。结果显示：JrNPR1基因开放读码框（ORF）长1 782 bp,包含593个氨基酸,理论等电点为6.40;与杨梅（Morella rubra）、蓖麻（Ricinus communis）等同源蛋白进行多序列比对,发现均有NPR1-like-C保守结构域,且JrNPR1与杨梅和欧洲栓皮栎（Quercus suber）等的同源蛋白具有较近的进化关系。其上游1 233 bp启动子中含有多种与植物抗病相关的顺式作用元件,如,WRKY71OS。在胶孢炭疽菌（Colletotrichum gloeosporioides）、矩圆黑盘孢菌（Melanconium oblongum）、黄单胞菌（Xanthomonas campestris）等病原处理下,JrNPR1被显著诱导,且其表达在水杨酸（Salicylic acid,SA）存在下高出单一病原处理的1.31~178.89倍。表明JrNPR1基因可能是抵抗核桃炭疽病、枝枯病、细菌性黑斑病的重要基因,且涉及SA信号通路。     

苹果TIPs亚家族成员的鉴定与干旱胁迫响应分析

【目的】鉴定并分析苹果液泡膜内在蛋白 (Tonoplast intrinsic proteins, TIP) 亚家族成员,探究该亚家族成员在苹果干旱胁迫下的表达模式。【方法】通过生物信息学方法对苹果MdTIPs全基因组进行鉴定,分析其家族成员的理化性质、基因结构、保守基序、顺式作用元件、系统进化树等,并结合实时荧光定量PCR (qRT-PCR) 对其在干旱胁迫下不同器官中的表达模式进行分析。【结果】在苹果基因组中,共检索得到了13个MdTIP基因,大部分成员亚细胞定位预测在质膜上,分布于10条染色体上,且每条染色体定位有1~3个成员;该基因家族成员的启动子区域包含多种响应激素和逆境胁迫的应答元件;qRT-PCR显示,MdTIPs亚家族成员在根中除MdTIP1;1外其余均都受上调表达,且MdTIP1;3和MdTIP1;4与对照相比,分别上调表达了5.27倍和5.69倍,推测是参与调控干旱胁迫的关键基因。【结论】初步鉴定并提供了MdTIPs亚家族成员信息,10个MdTIPs亚家族成员在根、茎、叶中差异表达,12个亚家族成员在根中高表达。结果为进一步研究苹果抗旱性基因资源的挖掘和利用提供了有价值的信息。     

Signalling molecules and blast pathogen attack activates rice OsPR1a and OsPR1b genes: A model illustrating components participating during defence/stress response

Recently the rice (Oryza sativa L.) OsPR1a and OsPR1b genes were primarily characterized against jasmonic acid, ethylene and protein phosphatase 2A inhibitors. The dicot PR1 are recognized as reliable marker genes in defence/stress responses, and we also propose OsPR1 as marker genes in rice, a model monocot crop genus. Therefore, to gain further insight into the expression/regulation of OsPR1 genes, we characterized their activation against signalling molecules such as salicylic acid (SA), abscisic acid (ABA) and hydrogen peroxide (H₂O₂), and the blast pathogen Magnaporthe grisea. Here, we report that SA and H₂O₂ strongly induced the mRNA level of both OsPR1 genes, whereas ABA was found to be moderately effective. These inductions were specific in nature and required a de novo synthesized protein factor. A potential interaction amongst the signalling molecules in modulating the expression of OsPR1 genes was observed. Moreover, a specific induction of OsPR1 expression in an incompatible versus compatible host-pathogen interaction was also found. Finally, based on our present and previous results, a model of OsPR1 expression/regulation has been proposed, which reveals their essential role in defence/stress responses in rice and use as potent gene markers.