摘要
利用cDNA-AFLP技术对海滨锦葵幼苗盐胁迫下叶片和根部的基因差异表达模式进行分析和比较,并对部分盐胁迫应答的转录衍生片段进行了回收、测序和功能推测,以从转录水平分析海滨锦葵的耐盐分子机制。结果显示:(1)盐胁迫下海滨锦葵幼苗叶片和根部的基因差异表达多以量的变化为主,包括盐胁迫下基因表达上调、下调或随盐处理浓度高低和胁迫时间长短而波动的差异表达模式;只有少量基因的差异表达表现出质的变化,如盐胁迫下基因沉默或诱导表达;(2)仅在盐胁迫处理2h的海滨锦葵幼苗根部,基因的差异表达以质的变化为主的类型比例略高于量的变化类型比例;(3)盐胁迫应答基因在不同组织中上调、下调、诱导或沉默的比例随胁迫处理时段而动态变化,在刚胁迫时基因表达的差异加剧,而后随胁迫处理时段的延长而渐趋稳定。结果预示,从基因表达水平探讨植物的耐盐分子机理,尽管有一定的规律可循,但由于不同组织对盐胁迫的应答是动态变化的过程,海滨锦葵不同组织在盐胁迫不同阶段的基因时、空、序表达特征并没有固定的程式。对部分盐胁迫下上调或诱导表达的转录衍生片段(Trivially distributed file system,TDFs)进行的序列分析和功能推测表明,苗期海滨锦葵在盐胁迫下应答基因至少涉及3类:(1)离子平衡重建或减少胁迫损伤相关基因(特别是运转蛋白类);(2)恢复盐胁迫下植物生长和发育相关基因:如参与能量合成和激素调节途径相关基因等;(3)信号转导相关基因及功能未确定的新基因。文章并对盐胁迫应答基因的差异表达模式与海滨锦葵的耐盐性关系进行了讨论。
Kosteletzkya virginica L. Presl. is an obligate wetland species indigenous to southeastern US. Its niche in salt marsh foretells its high salinity tolerance, cDNA-AFLP technique was used to identify the gene transcriptional profiles of leaves and roots from K. virginica seedlings under salt stress in order to clarify the molecular architecture of stress tolerance in the dicot halophyte. Expression analysis over time intervals and under various salt stresses in leaves or roots showed that the quantitatively expressed pattern （in which genes were quantitatively upor down-regulated under salt stress or fluctuate with different NaC1 concentrations） was more prevalent than the qualitatively expressed pattern （in which genes were in- duced or silenced under salt stress） in K. virginica seedlings under salt stress. The qualitative pattern was appreciably more predominant than the quantitative one only in roots when exposed to salt stress for 2 h. Although each expression pattern was observed in leaves as well as in roots, the percentage of genes （i.e., up-/down-regulated or induced/silenced under salt stress） was dynamically changeable under salt stress at different time intervals. All these results indicated that there was no established formula of gene expression patterns in deciphering the sophisticated mechanism of plant salinity tolerance, considering that plants undergo a series of dynamically physiological and metabolic pathways in sensing and response to salt stress for different tissues and during different stages of stress. A number of Trivially distributed file system （TDFs） up-regulated or induced under salt stress from leaves and roots were sequenced, and the sequences were blasted against the NCBI non-redundant protein database using translated nucleotide query （Blastx）. The TDFs from K. virginica seedlings involved in sensing and response to salt stress can be classified at least into three groups according to their putative functions： （1） genes for re-establishing ionic homeostasis or preventing from damage （specially genes for transporter）; （2） genes for resuming plant growth and development under salt stress, such as key enzymes involved in energy synthesis or hormone regulatory pathway; （3） genes for signal transduction and so on. The relationship of expression patterns of these TDFs with the molecular mechanism of salt tolerance in K. virginica was discussed.
出处
《遗传》
CAS
CSCD
北大核心
2008年第7期941-950,共10页
Hereditas（Beijing)
基金
“十一五”国家科技支撑项目(编号:2006BAD09A04,2006BAD09A08)资助~~
