Characterization of the Mt4 gene from Medicago truncatula
Characterization of the Mt4 gene from Medicago truncatula
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DOI：
10.1016/s0378-1119(98)00326-6
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发表时间：
1998-08-17
期刊：
影响因子：
3.5
通讯作者：
Harrison, MJ
中科院分区：
文献类型：
--
作者：
Burleigh, SM;Harrison, MJ
在此之前，我们从元宝紫花苜蓿中发现了一种磷酸盐饥饿诱导的基因MT4，它在根中的表达受磷肥和丛枝菌根真菌的侵染的影响而下调(Burleigh和Harison，1997)。在这里，我们介绍了对MT4的进一步研究。表达对外源磷肥高度敏感；在缺磷营养液中表达丰富，0.02或0.1 mM磷肥处理减少，1 mM或5 mM磷肥处理检测不到。对AM真菌侵染后MT4表达的时程实验表明，在未定植的根中，MT4的转录水平在生长的前三周增加，然后趋于平稳，而在被AM真菌Gloma versiforme侵染的根中，MT4的转录水平短暂上升，然后下降。虽然MT4基因只在根中表达，但在磷酸盐饥饿后的悬浮培养中也检测到了转录本。从元宝菇基因组文库中鉴定出一个含有MT4基因及其5‘端1133bp序列的基因组克隆。启动子区域含有一个保守的顺式元件，在酵母和番茄的磷酸盐饥饿诱导基因的启动子中发现。由于MT4是第一个被报道同时受磷酸盐真菌和菌根真菌独立调控的基因，该基因组克隆可能为分析这两个过程中涉及的信号转导途径提供了一个起点。(C)1998 Elsevier Science B.V.保留所有权利。
Previously we identified Mt4, a phosphate starvation inducible cDNA from Medicago truncatula which is down-regulated in roots in response to phosphate fertilization as well as colonization by arbuscular mycorrhizal (AM) fungi (Burleigh and Harrison, 1997). Here we present further studies of Mt4. Expression was highly sensitive to exogenous applications of phosphate fertilizer; transcripts were abundant in roots fertilized with nutrient solution lacking phosphate, reduced when fertilized with 0.02 or 0.1 mM phosphate and undetectable when fertilized with 1 or 5 mM phosphate. A time course experiment, to study the expression of Mt4 following colonization by AM fungi, revealed that Mt4 transcripts increased in uncolonized roots during the first three weeks of growth and then plateaued, while transcript levels in roots colonized with the AM fungus, Glomas versiforme, increased transiently and then decreased. Although the Mt4 gene is expressed exclusively in roots, transcripts were also detected in M. truncatula cell suspension cultures following phosphate starvation. A genomic clone containing the Mt4 gene and 1133 bp of the 5' flanking sequence was identified from a M. truncatula genomic library. The promoter region contains a conserved cis-element found in the promoters of phosphate starvation inducible genes of yeast and tomato. As Mt4 is the first cDNA reported to show independent regulation by both phosphate and mycorrhizal fungi, the genomic clone may provide a starting point from which to analyze the signal transduction pathways involved in these two processes. (C) 1998 Elsevier Science B.V. All rights reserved.