Role of symbiotic auxotrophy in the Rhizobium-legume symbioses.
Role of symbiotic auxotrophy in the Rhizobium-legume symbioses.
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DOI：
10.1371/journal.pone.0013933
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发表时间：
2010-11-11
期刊：
影响因子：
3.7
通讯作者：
Poole P
中科院分区：
文献类型：
--
作者：
Prell J;Bourdès A;Kumar S;Lodwig E;Hosie A;Kinghorn S;White J;Poole P
豆科根瘤菌不能通过两种主要氨基酸ABC转运复合物AapJQMP和BraDEFGC转运支链氨基酸的蚕豆突变体在接种到豌豆（Pisumsativum）植物上时产生氮饥饿表型。在不确定的豌豆根瘤中的拟杆菌具有减少的丰度和较低的染色体数目。它们减少支链氨基酸生物合成途径的转录，并依赖于宿主的提供。这被称为“共生营养缺陷型”。在AapQ中确定了一个重要的溶质特异性区域，并且在该区域中改变P144 D将支链氨基酸转运降低到非常低的速率。携带P144 D的菌株在豌豆上仍然完全有效地固定N2，表明R.豆科植物蚕豆支持野生型固氮速率。支链氨基酸运输的重要性，然后在其他豆类根瘤菌共生。一个aap bra突变体R.豆科植物菜豆也表现出氮饥饿症状时，接种在法国豆（菜豆vulgaris），植物生产有限的结节。该表型与豌豆上观察到的表型不同，并伴随着根瘤数量减少和每个根瘤的固氮作用。然而，苜蓿中华根瘤菌2011的aap bra双突变体在苜蓿上没有表现出表型。共生营养缺陷型发生在有限豌豆和无限豆根瘤证明其重要性的类细菌的形成和根瘤功能的豆类与不同的发展计划。然而，只有少量的支链氨基酸的需要和共生营养缺陷型没有发生在苜蓿中华根瘤菌-苜蓿共生条件下测量。aap bra突变体接种在不同豆科植物上的共生表型的对比可能反映了氨基酸有效性、共生营养缺陷型和根瘤发育程序的变化。
Rhizobium leguminosarum bv. viciae mutants unable to transport branched-chain amino acids via the two main amino acid ABC transport complexes AapJQMP and BraDEFGC produce a nitrogen starvation phenotype when inoculated on pea (Pisum sativum) plants. Bacteroids in indeterminate pea nodules have reduced abundance and a lower chromosome number. They reduce transcription of pathways for branched-chain amino acid biosynthesis and become dependent on their provision by the host. This has been called “symbiotic auxotrophy”. A region important in solute specificity was identified in AapQ and changing P144D in this region reduced branched-chain amino acid transport to a very low rate. Strains carrying P144D were still fully effective for N2 fixation on peas demonstrating that a low rate of branched amino acid transport in R. leguminosarum bv. viciae supports wild-type rates of nitrogen fixation. The importance of branched-chain amino acid transport was then examined in other legume-Rhizobium symbioses. An aap bra mutant of R. leguminosarum bv. phaseoli also showed nitrogen starvation symptoms when inoculated on French bean (Phaseolus vulgaris), a plant producing determinate nodules. The phenotype is different from that observed on pea and is accompanied by reduced nodule numbers and nitrogen fixation per nodule. However, an aap bra double mutant of Sinorhizobium meliloti 2011 showed no phenotype on alfalfa (Medicago sativa). Symbiotic auxotrophy occurs in both determinate pea and indeterminate bean nodules demonstrating its importance for bacteroid formation and nodule function in legumes with different developmental programmes. However, only small quantities of branched chain amino acids are needed and symbiotic auxotrophy did not occur in the Sinorhizobium meliloti-alfalfa symbiosis under the conditions measured. The contrasting symbiotic phenotypes of aap bra mutants inoculated on different legumes probably reflects altered timing of amino acid availability, development of symbiotic auxotrophy and nodule developmental programmes.
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影响因子：
3.2
作者：
Karunakaran, R.;Ramachandran, V. K.;Poole, P. S.
通讯作者：
Poole, P. S.
DOI：
10.1073/pnas.0600912103
发表时间：
2006-03-28
影响因子：
11.1
作者：
Mergaert, P;Uchiumi, T;Kondorosi, E
通讯作者：
Kondorosi, E
DOI：
10.1073/pnas.0407269101
发表时间：
2004-11-23
影响因子：
11.1
作者：
Barnett, MJ;Tolman, CJ;Long, SR
通讯作者：
Long, SR
影响因子：
3.5
作者：
FELLAY, R;FREY, J;KRISCH, H
通讯作者：
KRISCH, H
DOI：
10.1099/00221287-87-2-343
发表时间：
1975-01-01
期刊：
JOURNAL OF GENERAL MICROBIOLOGY
影响因子：
--
作者：
JOHNSTON, AWB;BERINGER, JE
通讯作者：
BERINGER, JE