【作者】 关春景； 张彦妮；

【Author】 Chun-jing Guan;Yan-ni Zhang;College of Landscape Architecture, Northeast Forestry University;

【机构】 东北林业大学园林学院；

【摘要】 细叶百合(Liliumpumilum)花瓣反卷鲜红色,具有较高观赏价值,非常耐寒,且耐干旱、耐盐碱,是百合抗性育种的重要的亲本。在本研究中,在细叶百合低温解除休眠的转录组测序结果中筛选出21个NAC基因并命名为LpNAC1-LpNAC21。对21个NAC基因进行生物信息学分析,大多数Lp NAC基因含有NAM结构域,Lp NAC蛋白氨基酸数在51-890之间,分子量5966.5-100080.4Da之间,Lp NAC蛋白质二级结构主要以无规则卷曲构成,α-螺旋、β-转角则散布于整个蛋白质中,跨膜结构域预测显示LpNAC19和LpNAC20具有单个跨膜结构域,系统发育树分析表明LpNAC蛋白与拟南芥NAC蛋白一起被分为七个不同的组(命名为NACa至NACg)。通过PlantTFDB进一步预测LpNAC基因在细叶百合中的功能,结果显示细叶百合NAC基因都具有转录调控的功能,同时还具有响应非生物胁迫、参与花发育、果实成熟和参与脱落酸信号转导等功能。用200mM NaCl(盐胁迫),20%PEG6000(干旱胁迫),150μm ABA和2℃(冷胁迫)对细叶百合幼苗处理,处理时间为0h、1h、3h、6h、12h、24h和48h。进行实时RT-PCR分析确定了NAC基因的相对表达量。结果显示细叶百合的NAC基因受到NaCl,PEG,冷和ABA胁迫在叶、鳞茎或根中被诱导表达。在四组胁迫条件下LpNAC9和LpNAC17在根中被诱导并高度表达。响应于胁迫(NaCl, PEG,冷和ABA)基因LpNAC5、LpNAC10、LpNAC19和LpNAC20在鳞茎中表达水平比对照高2出倍以上。在叶片中LpNAC2、LpNAC8、LpNAC17和LpNAC20在Na Cl,PEG,2℃和ABA处理条件下表达水平均为上调表达。LpNAC2、LpNAC10、LpNAC17和LpNAC20的表达水平在盐,干旱,低温和ABA处理下,在根、球茎和叶片中高度表达,表明它们可能在非生物胁迫反应中发挥作用并可能依赖于ABA应激信号通路。尤其是在鳞茎中,LpNAC5在NaCl,PEG,冷和ABA胁迫下高度表达。然而,在根和叶中,LpNAC5的表达水平在胁迫的所有时间点下调或没有显着变化。这表明LpNAC5可能参与了鳞茎的发育。我们目前分析了不同胁迫条件下21个细叶百合NAC基因的综合表达模式。结果表明它们在非生物胁迫和依赖ABA胁迫信号传导途径中起作用。这项研究报道了细叶百合中NAC基因家族,阐明了细叶百合中NAC基因在非生物胁迫中的作用,为分子育种提高植物抗逆性提供候选基因。更多还原

【Abstract】 L. pumilum, is striking due to its graceful flowers and bright red color, and it has a high ornamental value. L. Pumilum is highly tolerant to abiotic stresses, such as cold, drought,salt and alkalinity. These characteristics make the species a suitable source for investigating stress tolerance mechanisms. In the present study, there were 21 NAC genes filtered from the transcriptome sequencing results of L. pumilum cryogenic dormancy and named LpNAC1-LpNAC21. Bioinformatic analysis of 21 NAC genes showed that most NAC genes contained the complete NAM domain. The amino acid number of NAC proteins were between 51-890 and the molecular weight were 5966.5-100080.4 Da. The protein structure of the LpNAC protein, which was mainly composed of an irregular curl, α-helix, β-angle, was scattered throughout the protein. The transmembrane domain prediction shows that LpNAC19 and LpNAC20 have a single transmembrane domain. All LpNAC proteins were divided into seven different groups(named NACa to NACg) along with Arabidopsis NAC proteins. The PlantTFDB further predicted the function of LpNAC genes showed that NAC genes had the function of transcriptional regulation, as well as being involved in flower development, fruit maturation and abscisic acid signal transduction in response to abiotic stresses. Then, the seedlings were treated with one of the following solutions and treatment time: 200 m M/L NaCl(salt stress); 20%PEG6000(drought stress); 150μΜ ABA; or low temperature(2 °C) for 1,3, 6, 12, 24 and 48 h.the relative abundance of the LpNAC genes was determined by calculating the CT values of the real-time RT-PCR analysis under normal growth conditions. The LpNACs genes were clearly enhanced by NaCl, PEG, cold and ABA stresses, either in the leaves, bulbs or roots. In the roots LpNAC9 and LpNAC17 were highly expressed by all the stresses. In the bulbs, the expression of LpNAC5, LpNAC10, LpNAC19 and LpNAC20 increased to more than 2-fold greater than the control in response to stress(NaCl, PEG, cold and ABA). In the leaves, LpNAC2, LpNAC8,LpNAC17 and LpNAC20 were up-regulated by the NaCl, PEG, cold and ABA treatment. The expressions of LpNAC2, LpNAC10, LpNAC17 and LpNAC20 were highly induced in the roots,bulbs and leaves under the high salinity, drought, cold and ABA treatment, indicating that they may play roles in the response to abiotic stress and were closely regulated by the ABA dependent stress signaling pathway. ABA is a plant hormone that plays a diverse role in responding to various environmental stimuli. In particular, in the bulbs, LpNAC5 was highly involved under the NaCl, PEG, cold and ABA stress. However, in the roots and leaves, the expression of LpNAC5was down-regulated or did not markedly change at all the time points of stress. This suggested that LpNAC5 might be involved in bulb development. Our current analysis of the comprehensive expression patterns of 21 LpNACs genes in L. pumilum under different stress conditions provides novel information to determine their tissue specific expression in response to abiotic stress. The results indicate that they play a role in the abiotic stress tolerance and ABA-dependent stresssignaling pathways. This study report of the NAC gene family in L. pumilum and elucidates the roles of NACs in abiotic stress tolerance and contributes to the selection of candidate genes for using molecular breeding to improve plant stress tolerance.更多还原