Comparative Transcriptome Profiling of the Maize Primary, Crown and Seminal Root in Response to Salinity Stress

Soil salinity is a major constraint to crop growth and yield. The primary and lateral roots of Arabidopsis thaliana are known to respond differentially to a number of environmental stresses, including salinity. Although the maize root system as a whole is known to be sensitive to salinity, whether or not different structural root systems show differential growth responses to salinity stress has not yet been investigated. The maize primary root (PR) was more tolerant of salinity stress than either the crown root (CR) or the seminal root (SR). To understand the molecular mechanism of these differential growth responses, RNA-Seq analysis was conducted on cDNA prepared from the PR, CR and SR of plants either non-stressed or exposed to 100 mM NaCl for 24 h. A set of 444 genes were shown to be regulated by salinity stress, and the transcription pattern of a number of genes associated with the plant salinity stress response differed markedly between the various types of root. The pattern of transcription of the salinity-regulated genes was shown to be very diverse in the various root types. The differential transcription of these genes such as transcription factors, and the accumulation of compatible solutes such as soluble sugars probably underlie the differential growth responses to salinity stress of the three types of roots in maize.土壤盐度是限制作物生长与产量的主要逆境因子之一。已有研究表明，拟南芥（Arabidopsis thaliana）的初生根与侧根对包括盐胁迫在内的多种环境胁迫存在差异化响应。尽管整体玉米根系对盐胁迫敏感，但不同结构根系是否会对盐胁迫产生差异化生长响应，目前仍未得到系统研究。相较于冠根（crown root, CR）与胚根（seminal root, SR），玉米初生根（primary root, PR）对盐胁迫的耐受性更强。为解析此类差异化生长响应的分子机制，本研究对未受胁迫或经100 mM氯化钠（NaCl）处理24小时的玉米初生根、冠根及胚根的互补脱氧核糖核酸（cDNA）进行了RNA测序（RNA-Seq）分析。研究共鉴定出444个受盐胁迫调控的基因，且不同根系中与植物盐胁迫响应相关的基因转录模式存在显著差异。不同根系中盐调控基因的转录模式呈现出高度多样性。包括转录因子在内的此类基因的差异化转录，以及可溶性糖等相容性溶质的积累，可能是玉米三类根系对盐胁迫产生差异化生长响应的分子基础。