Establishment of a functional symbiosis between the cyanobacterium Nostoc punctiforme and the bryophyte Anthoceros punctatus requires genes involved in nitrogen control and initiation of heterocyst differentiation.
Establishment of a functional symbiosis between the cyanobacterium Nostoc punctiforme and the bryophyte Anthoceros punctatus requires genes involved in nitrogen control and initiation of heterocyst differentiation.
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蓝藻发菜和苔藓植物 Anhoceros punctatus 之间功能共生的建立需要参与氮控制和异形囊分化启动的基因。
DOI：
10.1099/00221287-148-1-315
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发表时间：
2002
期刊：
影响因子：
1.5
通讯作者：
J. Meeks
中科院分区：
文献类型：
--
作者：
Francis C. Y. Wong;J. Meeks
三个突变株（ntcA，hetR，hetF）的蓝藻Nostoc punctiforme无法区分异形胞的特点，并检查他们的能力，形成一个共生协会的brandelte花点。以前未知的N. punctiforme hetR突变体包括耐冷动丝的分化，而ntcA突变体的营养细胞随机裂解，产生短的细丝，以下铵剥夺。hetF和hetR突变株感染A. punctatus与野生型N. punctiforme，但不支持植物伴侣的生长。这些结果证实了A.通过藻殖体导致联合体的建立的punctatus在生理学上与功能性固氮联合体的发育解偶联。它们还表明，HetR和HetF下游的异形胞调控元件是自由生活和共生异形胞分化和固氮酶表达所必需的。在全局氮调节因子ntcA中具有突变的菌株不感染A。punctatus，尽管其能够以低频率分化藻殖体。当与ntcA的一个或多个拷贝互补时，突变株感染A. punctatus以与野生型相似的频率，并在不存在结合氮的情况下支持植物伴侣的生长。这些结果建立了一个连接之间的存在的功能性拷贝的ntcA和hormogonium分化的幅度，和形成的hormogonia的行为。
Three mutant strains (ntcA, hetR, hetF) of the cyanobacterium Nostoc punctiforme unable to differentiate heterocysts were characterized and examined for their ability to form a symbiotic association with the bryophyte Anthoceros punctatus. Previously unknown characteristics of the N. punctiforme hetR mutant include differentiation of chilling-resistant akinetes, while vegetative cells of the ntcA mutant randomly lysed, yielding short filaments, following ammonium deprivation. Strains with mutations in hetF and hetR infected A. punctatus with similar frequency to that of wild-type N. punctiforme but did not support growth of the plant partner. These results confirm that the infection of A. punctatus by hormogonia leading to the establishment of an association is physiologically uncoupled from the development of a functional diazotrophic association. They also indicate that heterocyst regulatory elements downstream from HetR and HetF are required in both free-living and symbiotic heterocyst differentiation and nitrogenase expression. A strain with a mutation in the global nitrogen regulator ntcA did not infect A. punctatus despite its ability to differentiate hormogonia at a low frequency. When complemented with one or more copies of ntcA, the mutant strain infected A. punctatus at a similar frequency as the wild-type and supported growth of the plant partner in the absence of combined nitrogen. These results established a connection between the presence of a functional copy of ntcA and the magnitude of hormogonium differentiation, and the behaviour of the formed hormogonia.
DOI：
10.1073/pnas.89.12.5655
发表时间：
1992-06-15
影响因子：
11.1
作者：
LIANG, J;SCAPPINO, L;HASELKORN, R
通讯作者：
HASELKORN, R