Liu Touming, Zhu Siyuan, Tang Qingming, Tang Shouwei
Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changsha 410205, China.
Gene. 2015 Mar 1;558(1):131-7. doi: 10.1016/j.gene.2014.12.057. Epub 2014 Dec 27.
Cadmium (Cd) contamination in agricultural soils has become a major environmental problem in China. Ramie, a fiber crop, has frequently been proposed for use as a phytoremediation crop for the restoration of Cd-contaminated farmlands. However, high levels of Cd can greatly inhibit stem growth in ramie, which reduces its economic value as a crop. To understand the potential mechanisms behind this phenomenon, the ramie genes involved in the Cd stress response were identified using Illumina pair-end sequencing on two Cd-stressed plants (CdS1 and CdS2) and two control plants (CO1 and CO2). Approximately 48.7, 51.6, 41.2, and 47.1 million clean sequence reads were generated from the libraries of CO1, CO2, CdS1, and CdS2, respectively, and de novo assembled to yield 56,932 non-redundant unigenes. A total of 26,686 (46.9%) genes were annotated for their function. Comparison of gene expression levels in CO and CdS ramie revealed 155 differentially expressed genes (DEGs) between treatment and control conditions. Sixteen DEGs were further analyzed for expression differences by using real-time quantitative PCR (qRT-PCR). Among these 16 DEGs, 2 genes encoding GA2-oxidase (a major enzyme for deactivating bioactive gibberellins [GAs]) showed markedly up-regulated expression in Cd stressed ramie. This might be responsible for the growth inhibition of Cd-stressed ramie. Pathway enrichment analysis revealed that the cutin, suberine and wax biosynthesis pathway was markedly enriched by DEGs. The discovery of these Cd stress-responsive genes and pathways will be helpful in further understanding the mechanism of Cd-stress response and improving Cd stress tolerance in ramie.
农业土壤中的镉(Cd)污染已成为中国一个主要的环境问题。苎麻作为一种纤维作物,常被提议用作修复镉污染农田的植物修复作物。然而,高浓度的镉会极大地抑制苎麻茎的生长,从而降低其作为作物的经济价值。为了解这一现象背后的潜在机制,利用Illumina双末端测序技术,对两株镉胁迫植株(CdS1和CdS2)和两株对照植株(CO1和CO2)进行分析,鉴定出参与镉胁迫反应的苎麻基因。分别从CO1、CO2、CdS1和CdS2的文库中产生了约4870万、5160万、4120万和4710万个干净的序列读数,并进行了从头组装,得到56932个非冗余单基因。共有26686个(46.9%)基因被注释了功能。比较CO和CdS苎麻中的基因表达水平,发现处理组和对照组之间有155个差异表达基因(DEG)。通过实时定量PCR(qRT-PCR)进一步分析了16个DEG的表达差异。在这16个DEG中,有2个编码GA2-氧化酶(一种使生物活性赤霉素[GAs]失活的主要酶)的基因在镉胁迫的苎麻中表达明显上调。这可能是镉胁迫苎麻生长受抑制的原因。通路富集分析表明,角质、木栓质和蜡质生物合成通路被DEG显著富集。这些镉胁迫响应基因和通路的发现将有助于进一步了解镉胁迫反应的机制,并提高苎麻对镉胁迫的耐受性。