The Aluminum (Al) and proton (H ) ions are major acid soil stress factors deleteriously affecting plant root growth and crop yield. In our preliminary studies, cotton seedlings (Gossypium hirsutum L.) displayed very sensitive phenotypes to Al and H rhizotoxicities. Based on previous Arabidopsis results, we aimed to characterize the Al stress responsive Sensitive to Proton rhizotoxicity 1 (GhSTOP1) transcription system in cotton by RNAi mediated down-regulation. With the help of seed embryo apex explants, we developed transgenic cotton plants overexpressing a GhSTOP1-RNAi cassette with NPTII selection. Kanamycin tolerant T1 seedlings were further considered for Al and H stress tolerance studies. Down-regulation of the GhSTOP1 displayed increased sensitivity to Al and proton rhizotoxicities and the root growth was significantly reduced in RNAi-lines. The expression profile of GhALMT1 (Aluminum-activated Malate Transporter 1), GhMATE (Multidrug and Toxic Compound Extrusion), GhALS3 (Aluminum Sensitive 3) and the key genes involved in the GABA shunt were downregulated in the transgenic RNAi lines. Additionally, the lateral root initiation process was delayed and the expression of GhNAC1 which is involved in lateral root initiation was also suppressed in transgenic lines. Besides, overexpression of GhSTOP1 in Arabidopsis accelerated root growth and AtMATE and AtALMT1 expression under Al stress conditions. These analyses indicate that the GhSTOP1 is necessary for the expression of several genes which are necessary for acid soil tolerance mechanisms and lateral root initiation. This article is protected by copyright. All rights reserved.
BackgroundVarious Panax ginseng cultivars exhibit a range of diversity for morphological and physiological traits. However, there are few studies on diversity of metabolic profiles and genetic background to understand the complex metabolic pathway in ginseng.MethodsTo understand the complex metabolic pathway and related genes in ginseng, we tried to conduct integrated analysis of primary metabolite profiles and related gene expression using five ginseng cultivars showing different morphology. We investigated primary metabolite profiles via gas chromatography–mass spectrometry (GC-MS) and analyzed transcriptomes by Illumina sequencing using adventitious roots grown under the same conditions to elucidate the differences in metabolism underlying such genetic diversity.ResultsGC-MS analysis revealed that primary metabolite profiling allowed us to classify the five cultivars into three independent groups and the grouping was also explained by eight major primary metabolites as biomarkers. We selected three cultivars (Chunpoong, Cheongsun, and Sunhyang) to represent each group and analyzed their transcriptomes. We inspected 100 unigenes involved in seven primary metabolite biosynthesis pathways and found that 21 unigenes encoding 15 enzymes were differentially expressed among the three cultivars. Integrated analysis of transcriptomes and metabolomes revealed that the ginseng cultivars differ in primary metabolites as well as in the putative genes involved in the complex process of primary metabolic pathways.ConclusionOur data derived from this integrated analysis provide insights into the underlying complexity of genes and metabolites that co-regulate flux through these pathways in ginseng.
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