Although rhizobia that establish a nitrogen-fixing symbiosis with legumes are also known to promote growth in non-legumes, studies on rhizobial associations with wheat roots are scarce. We searched for Rhizobium leguminosarum symbiovar viciae (Rlv) strains naturally competent to endophytically colonize wheat roots. We isolated 20 strains from surface-sterilized wheat roots and found a low diversity of Rlv compared to that observed in the Rlv species complex. We tested the ability of a subset of these Rlv for wheat root colonization when co-inoculated with other Rlv. Only a few strains, including those isolated from wheat roots, and one strain isolated from pea nodules, were efficient in colonizing roots in co-inoculation conditions, while all the strains tested in single strain inoculation conditions were found to colonize the surface and interior of roots. Furthermore, Rlv strains isolated from wheat roots were able to stimulate root development and early arbuscular mycorrhizal fungi colonization. These responses were strain and host genotype dependent. Our results suggest that wheat can be an alternative host for Rlv; nevertheless, there is a strong competition between Rlv strains for wheat root colonization. In addition, we showed that Rlv are endophytic wheat root bacteria with potential ability to modify wheat development.

中文翻译：

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Rhizobium leguminosarum symbiovar viciae 菌株是天然的小麦内生菌，可以刺激根系发育

虽然与豆科植物建立固氮共生关系的根瘤菌也能促进非豆科植物的生长，但关于根瘤菌与小麦根系的研究很少。我们搜索了豆科根瘤菌symbiovar viciae ( Rlv ) 菌株，这些菌株天然具有内生定植小麦根系的能力。我们从表面灭菌的小麦根中分离出 20 个菌株，发现与在Rlv物种复合体中观察到的相比，Rlv的多样性较低。我们测试了这些Rlv的一个子集在与其他Rlv共同接种时对小麦根系定殖的能力. 只有少数菌株，包括从小麦根中分离的菌株和从豌豆根瘤中分离的菌株，在共接种条件下能有效地在根部定殖，而在单菌株接种条件下测试的所有菌株都被发现在根的表面和内部定植。根。此外，从小麦根部分离的Rlv菌株能够刺激根部发育和早期丛枝菌根真菌定植。这些反应依赖于菌株和宿主基因型。我们的结果表明小麦可以作为Rlv的替代宿主；尽管如此， Rlv菌株之间在小麦根系定植方面存在着激烈的竞争。此外，我们证明了Rlv是内生小麦根细菌，具有改变小麦发育的潜在能力。