Ethylene works as a possible regulator for the rootlet elongation and transcription of genes for phosphorus acquisition in cluster roots of Lupinus albus L.
Ethylene works as a possible regulator for the rootlet elongation and transcription of genes for phosphorus acquisition in cluster roots of Lupinus albus L.
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DOI：
10.1080/00380768.2022.2050662
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发表时间：
2022-03
影响因子：
2
通讯作者：
Hirotsuna Yamada;S. Nishida;J. Wasaki
中科院分区：
文献类型：
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作者：
Hirotsuna Yamada;S. Nishida;J. Wasaki
摘要白露平（Lupinus albus L.）是一种耐缺磷植物。它们在缺磷条件下形成独特形态的根，即所谓的丛枝根。CRs通过扩大根表面积和磷的动员活动来促进磷的吸收。先前的研究表明，几种激素功能参与了CR的形成。乙烯是植物对低磷胁迫下根构型和磷吸收的重要调控因子。然而，对乙烯对CR形态发生的影响了解还不够。本研究的重点是乙烯对CR形态和磷获取基因表达的影响。首先，对公开RNA-Seq数据的重新分析表明，乙烯合成基因的表达在CR成熟过程中被诱导。然后，将乙烯合成抑制剂CoCl2和乙烯前体ACC应用于无磷水培培养中形成的CR，为期10天。测定根系CR形态、磷获取相关基因转录水平和柠檬酸盐浓度。结果表明，在CR中，根的伸长以Co2+浓度依赖性的方式促进，表明乙烯是阻止根伸长的主要原因。在acc处理的未成熟CR中，酸性磷酸酶、磷酸盐转运体、柠檬酸合成酶和一种可能的柠檬酸转运体的mRNA积累量增加，表明乙烯诱导了P获取基因的转录。根系中柠檬酸盐浓度的变化趋势与柠檬酸合酶的表达趋势相似，说明乙烯积累促进了柠檬酸盐的合成。阻止根茎伸长和调控P获取基因表达的作用被认为是乙烯的独立功能。由此得出结论，乙烯可能是CRs中根茎伸长和P获取基因转录的调节剂，但还需要进一步研究来阐明阻止根茎伸长和转录调控的分子机制。
ABSTRACT White lupin (Lupinus albus L.) plants are tolerant plants under phosphorus (P)deficiency. They form unique morphological roots, so-called cluster roots (CRs) under P deficiency. CRs contribute to P absorption by the expansion of the root surface area and P mobilization activities. Previous research has implied the involvement of several hormonal functions in CR formation. Ethylene is a key regulator responsible for the modification of root architecture and P acquisition in response to low P in plants. However, understanding the effect of ethylene on CR morphogenesis is not enough. Here, the focus was on the effects of ethylene on CR morphology and gene expression for P acquisition. First, a reanalysis of public RNA-Seq data indicated that the gene expression for ethylene synthesis was induced during CR maturation. In turn, the 10-days application of an ethylene synthesis inhibitor, CoCl2, and an ethylene precursor, ACC, to CR formed in hydroponic culture without P was performed. CR morphology, transcript levels of the genes related to P acquisition, and citrate concentration in roots were determined. The results indicated that the elongation of rootlets in CR was promoted in a Co2+ concentration-dependent manner, suggesting that ethylene is responsible for the arrest of rootlet elongation. mRNA accumulation for acid phosphatases, phosphate transporters, citrate synthases, and a putative citrate transporter increased in ACC-treated immature CR, suggesting that ethylene induces the transcription of genes for P acquisition. Additionally, the trend of citrate concentration in roots among treatments was similar to that in the expression of citrate synthases, supporting that ethylene accumulation promotes citrate synthesis. The roles of the arrest of rootlet elongation and regulation of gene expressions for P acquisition are considered independent functions of ethylene. It was concluded that ethylene works as a possible regulator for the rootlet elongation and transcription of genes for P acquisition in CRs, although further studies are required to elucidate the molecular mechanisms of the arrest of rootlet elongation and transcriptional regulation.