Identification and Expression Analyses of the Nitrate Transporter Gene (NRT2) Family Among Skeletonema species (Bacillariophyceae)
Identification and Expression Analyses of the Nitrate Transporter Gene (NRT2) Family Among Skeletonema species (Bacillariophyceae)
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DOI：
10.1111/jpy.12896
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发表时间：
2019-08-24
影响因子：
2.9
通讯作者：
Rynearson, Tatiana A.
中科院分区：
文献类型：
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作者：
Kang, Lee-Kuo;Rynearson, Tatiana A.
高亲和力硝酸盐转运蛋白被认为是硅藻吸收硝酸盐的主要转运系统。在硅藻属双丝藻中，从作为海洋微生物真核生物转录组测序项目的一部分产生的转录组中新鉴定了三种形式的编码高亲和力硝酸盐转运蛋白（NRT 2）的基因。为了研究NRT 2在不同氮环境下的表达，在硝酸盐充足，铵充足和硝酸盐限制条件下进行了实验室实验，使用三种生态上重要的螺旋藻物种：S. dohrnii，S. menzelii和S.马里诺伊。为每种NRT 2形式和物种开发引物，并进行Q-RT-PCR。对于每一种NRT 2形式，三种螺旋藻物种具有相似的转录模式。NRT 2：1的转录水平显着升高氮限制条件下，但强烈抑制铵的存在下。NRT 2：2的转录水平也被铵抑制，但在硝酸盐充足和氮限制的条件下增加了5- 10倍。最后，NRT 2：3的转录水平在各种氮条件下没有显著变化，并且表现得更像组成型表达基因。基于观察到的NRT 2形式之间的转录变异，我们提出了一个修正的模型描述硝酸盐吸收动力学调节的多种形式的硝酸盐转运蛋白基因在不同的氮条件下，在螺旋藻。不同物种之间的差异NRT 2转录反应表明，物种特异性的适应策略存在于该属内，以科普环境变化。
High-affinity nitrate transporters are considered to be the major transporter system for nitrate uptake in diatoms. In the diatom genus Skeletonema, three forms of genes encoding high-affinity nitrate transporters (NRT2) were newly identified from transcriptomes generated as part of the marine microbial eukaryote transcriptome sequencing project. To examine the expression of each form of NRT2 under different nitrogen environments, laboratory experiments were conducted under nitrate-sufficient, ammonium-sufficient, and nitrate-limited conditions using three ecologically important Skeletonema species: S. dohrnii, S. menzelii, and S. marinoi. Primers were developed for each NRT2 form and species and Q-RT-PCR was performed. For each NRT2 form, the three Skeletonema species had similar transcriptional patterns. The transcript levels of NRT2:1 were significantly elevated under nitrogen-limited conditions, but strongly repressed in the presence of ammonium. The transcript levels of NRT2:2 were also repressed by ammonium, but increased 5- to 10-fold under nitrate-sufficient and nitrogen-limited conditions. Finally, the transcript levels of NRT2:3 did not vary significantly under various nitrogen conditions, and behaved more like a constitutively expressed gene. Based on the observed transcript variation among NRT2 forms, we propose a revised model describing nitrate uptake kinetics regulated by multiple forms of nitrate transporter genes in response to various nitrogen conditions in Skeletonema. The differential NRT2 transcriptional responses among species suggest that species-specific adaptive strategies exist within this genus to cope with environmental changes.