Genome-Wide Analysis Reveals the Roles of lncRNA in Se accumulation and detoxification in alfalfa (Medicago sativa L.)

Medicago sativa L. is the most extensively cultivated and high biomass forage. Selenium is an essential microscale mineral for humans and animals and is a beneficial element for plants, which could increase yields under low concentration and have a poisoning effect under high concentration. LncRNA is involved in diverse biological processes such as flowering, photomorphogenesis, vernalization and stress response in the plants. To study the possible role of lncRNAs in Se accumulation and detoxification underlying alfalfa, we identified and analyzed lncRNAs in alfalfa leaves under 0 mg L-1, 100 mg L-1, 500 mg L-1 based on the degradome deep sequencing. We identified a total of 64,684 novel lncRNAs, from which 3155 were differentially expressed lncRNAs (DELs). The expression patterns of some lncRNAs can be significantly differentially expressed between high and low concentrations. The results of GO and KEGG analysis suggested that sulfate transporter and ABC transporter might be a contributor to Se accumulation in alfalfa. The jasmonic acid (JA) promoted by lipoxygenase and allene oxide synthase may play an important role in Se resistance. The high expression of some key genes of selenocompound metabolism may be beneficial to remove excess Se. The phenylpropanoid, flavonoid, isoflavonoid, and anthocyanidin biosynthesis and autophagy may alleviate the Se toxicity by scavenging reactive oxygen. The expression patterns of nine lncRNAs and their protein-coding genes were validated by qRT-PCR. The same expression pattern was observed between most lncRNAs and their target genes. This study has excavated potential lncRNAs and will give new insight and rich genetic resources to Se-enriched breeding. Research of 3 different selenite concentration in alfalfa leaf

紫花苜蓿（Medicago sativa L.）是目前种植范围最广、生物量最高的饲草作物。硒是人体与动物必需的微量矿物质，同时也是植物的有益元素：低浓度硒可提升作物产量，高浓度硒则会产生毒害作用。长链非编码RNA（long non-coding RNA，LncRNA）参与植物的开花调控、光形态建成、春化作用以及胁迫响应等多种生物学过程。为探究长链非编码RNA在紫花苜蓿硒积累与解毒过程中的潜在作用，本研究基于降解组深度测序（degradome deep sequencing）技术，对0 mg·L⁻¹、100 mg·L⁻¹、500 mg·L⁻¹三个亚硒酸盐浓度处理下的紫花苜蓿叶片中的长链非编码RNA进行了鉴定与分析。本研究共鉴定得到64684条新发现的长链非编码RNA，其中3155条为差异表达长链非编码RNA（differentially expressed lncRNAs，DELs）。部分长链非编码RNA的表达模式在高、低硒浓度处理组间存在显著差异。基因本体（Gene Ontology，GO）与京都基因与基因组百科全书（Kyoto Encyclopedia of Genes and Genomes，KEGG）富集分析结果显示，硫酸盐转运蛋白（sulfate transporter）与ABC转运蛋白（ABC transporter）可能参与调控紫花苜蓿的硒积累过程。脂氧合酶与丙二烯氧化物合酶介导的茉莉酸（jasmonic acid，JA）信号通路可能在紫花苜蓿硒抗性中发挥重要作用。硒化合物代谢通路中部分关键基因的高表达，有助于清除植物体内过量的硒。苯丙烷类、黄酮类、异黄酮类及花青素生物合成通路与细胞自噬过程，可通过清除活性氧来缓解硒毒害。本研究通过实时荧光定量聚合酶链式反应（quantitative real-time polymerase chain reaction，qRT-PCR）验证了9条长链非编码RNA及其对应的蛋白编码基因的表达模式，多数长链非编码RNA与其靶基因的表达趋势保持一致。本研究挖掘得到具有潜在研究价值的长链非编码RNA，可为富硒育种提供全新的研究视角与丰富的遗传资源。本研究针对3种不同亚硒酸盐浓度处理下的紫花苜蓿叶片展开了相关研究。