低温胁迫下野生马齿苋转录组分析

Transcriptome changes induced by low temperature stress in wild Portulaca oleracea

【目的】探讨马齿苋低温胁迫的机制,对低温胁迫下野生马齿苋转录本差异进行分析。【方法】马齿苋幼苗采用低温(白天10℃、14 h,晚上5℃、10 h)和适温(白天30℃、14 h,晚上25℃、10 h)处理14 d后,利用二代(RNA-Seq)和三代(Iso-Seq)转录组测序技术探讨适温处理和低温胁迫处理马齿苋的转录本差异。【结果】每个样本平均获得的干净片段为45397055,平均GC含量为47.48%,平均Q20和Q30分别为97.7%和93.29%。适温和低温胁迫相比共有26621个差异表达基因(DEGs),上调的DEGs为12045个,下调的DEGs为14576个。GO分析发现适温和低温胁迫相比,马齿苋上调对各种光反应、叶绿素合成和光保护的基因数目显著高于其下调的基因数,而下调丙酮酸磷酸双激酶活性、金属离子转运、调节碳水化合物代谢过程和光系统反应中心I等方面基因的数目显著高于上调的基因数目;KEGG富集差异分析表明蛋白酶体、真核生物核糖体生物发生、昼夜近似节律、萜类主链生物合成及苯环氨基酸生物合成等富集丰富。【结论】GO分析暗示低温胁迫下,马齿苋明显增加了丙酮酸磷酸双激酶活性基因数目,该酶催化CO_(2)受体磷酸烯醇式丙酮酸的再生,从而增加CO_(2)受体的含量;但明显下调了对各种光反应、叶绿素合成的基因数目,暗示低温胁迫显著影响了马齿苋的光合作用。该研究结果可为马齿苋低温胁迫的分子机制研究提供参考。

【Objective】The present paper aimed investigate the response mechanism of Purslane(Portulaca oleracea L.)under low temperature stress,transcriptomic analyses were conducted.【Method】The seedlings of P.oleracea were cultured at low temperature(10℃and 14 hours in the daytime,5℃and 10 hours at night)and suitable temperature(30℃and 14 hours in the daytime,25℃and 10 hours at night)for 14 days.The different transcripts of P.oleracea between suitable temperature and low temperature stress treatment were screened and analyzed by the second(RNA sequencing,RNA-Seq)and third(isoform sequencing,Iso-Seq)generation transcriptome sequencing techniques.【Result】The average clean reads per each sample was 45397055,the average GC content per each sample was 47.48%,and the average Q20 and Q30 per each sample were 97.7%and 93.29%respectively.26621 differentially expressed genes(DEGs)were identified compared to low temperature stress,including 12045 up-regulated DEGs and 14576 down-regulated DEGs.GO functional classification and enrichment analysis showed that under low temperature stress,the number of up-regulated genes in cellular response to various lights,chlorophyll synthesis and light protection were significantly higher than that of down-regulated genes,while the number of down-regulated genes in pyruvatephosphate double kinase activity,metal ion transport,regulating carbohydrate metabolism and photosystem response center I were significantly more than that of up-regulated genes;KEGG pathway analysis indicated that DEGs significantly enriched in proteasome,eukaryotic ribosomal biogenesis,the circadian approximate rhythm,terpene main chain biosynthesis and other pathways.【Conclusion】According to the analysis of GO,it is suggested that the number of genes for pyruvatephosphate double kinase,which catalyzed the phosphoenolpyruvate regeneration of CO_(2)receptor,was significantly increased under low temperature stress,and thereby the content of CO_(2)receptor was increased.However,the number of genes for various light responses and chlorophyll synthesis was significantly reduced.It was indicated that photosynthesis of P.oleracea was significantly affected under low temperature stress.The results would provide reference for the molecular mechanism of P.oleracea under low temperature stress.