Strigolactone biosynthesis is evolutionarily conserved, regulated by phosphate starvation and contributes to resistance against phytopathogenic fungi in a moss, Physcomitrella patens
Strigolactone biosynthesis is evolutionarily conserved, regulated by phosphate starvation and contributes to resistance against phytopathogenic fungi in a moss, Physcomitrella patens
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DOI：
10.1111/nph.14506
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发表时间：
2017-10-01
期刊：
影响因子：
9.4
通讯作者：
Al-Babili, Salim
中科院分区：
文献类型：
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作者：
Decker, Eva L.;Alder, Adrian;Al-Babili, Salim
在种子植物中，独脚金内酯（SL）调节建筑和诱导菌根共生响应环境线索。SL由类胡萝卜素裂解双加氧酶（CCD）7和8从9-顺式-β-胡萝卜素的组合活性形成，导致被细胞色素P450（进化枝711;拟南芥中的MAX 1）转化为各种SL的己内酯。由于小立碗藓具有CCD 7和CCD 8的同源物，但缺乏MAX 1，因此我们研究了PpCCD 7和PpCCD 8是否一起形成carlactone，以及这些酶的缺失如何影响生长和与环境的相互作用。我们研究了PpCCD 7和PpCCD 8的体外酶活性，通过高效液相色谱（HPLC）和LC-MS鉴定了形成的产物，我们将PpCCD 7和PpCCD 8分别定义为立体特异性的9-cis-CCD和己内酯合酶。Delta CCD 7和Delta CCD 8系显示增强的茎丝生长，这通过添加SL类似物GR 24或己内酯是可逆的。野生型（WT）分泌物诱导列当种子萌发。磷酸盐饥饿后，这种活性增加，并取消在两个突变体的渗出物。我们的研究揭示了SL生物合成、SL功能及其受生物和非生物因素调控的深层进化保守性。
In seed plants, strigolactones (SLs) regulate architecture and induce mycorrhizal symbiosis in response to environmental cues. SLs are formed by combined activity of the carotenoid cleavage dioxygenases (CCDs) 7 and 8 from 9-cis-beta-carotene, leading to carlactone that is converted by cytochromes P450 (clade 711; MAX1 in Arabidopsis) into various SLs. As Physcomitrella patens possesses CCD7 and CCD8 homologs but lacks MAX1, we investigated if PpCCD7 together with PpCCD8 form carlactone and how deletion of these enzymes influences growth and interactions with the environment.We investigated the enzymatic activity of PpCCD7 and PpCCD8 in vitro, identified the formed products by high performance liquid chromatography (HPLC) and LC-MS, and generated and analysed Lambda CCD7 and Lambda CCD8 mutants.We defined enzymatic activity of PpCCD7 as a stereospecific 9-cis-CCD and PpCCD8 as a carlactone synthase. Delta CCD7 and Delta CCD8 lines showed enhanced caulonema growth, which was revertible by adding the SL analogue GR24 or carlactone. Wild-type (WT) exudates induced seed germination in Orobanche ramosa. This activity was increased upon phosphate starvation and abolished in exudates of both mutants. Furthermore, both mutants showed increased susceptibility to phytopathogenic fungi.Our study reveals the deep evolutionary conservation of SL biosynthesis, SL function, and its regulation by biotic and abiotic cues.