Laguerre Gisèle, Depret Géraldine, Bourion Virginie, Duc Gérard
INRA, UMR1229 Microbiologie du Sol et de l'Environnement, BP 86510, F-21065 Dijon Cedex, France.
Present address: USC1242 INRA, Symbioses Tropicales et Méditerranéennes, Campus de Baillarguet, TA A-82/J, F-34398 Montpellier Cedex 5, France.
New Phytol. 2007;176(3):680-690. doi: 10.1111/j.1469-8137.2007.02212.x. Epub 2007 Sep 5.
The variability of the developmental responses of two contrasting cultivars of pea (Pisum sativum) was studied in relation to the genetic diversity of their nitrogen-fixing symbiont Rhizobium leguminosarum bv. viciae. A sample of 42 strains of pea rhizobia was chosen to represent 17 genotypes predominating in indigenous rhizobial populations, the genotypes being defined by the combination of haplotypes characterized with rDNA intergenic spacer and nodD gene regions as markers. We found contrasting effects of the bacterial genotype, especially the nod gene type, on the development of nodules, roots and shoots. A bacterial nod gene type was identified that induced very large, branched nodules, smaller nodule numbers, high nodule biomass, but reduced root and aerial part development. The plants associated with this genotype accumulated less N in shoots, but N concentration in leaves was not affected. The results suggest that the plant could not control nodule development sustaining the energy demand for nodule functioning and its optimal growth. The molecular and physiological mechanisms that may be involved are discussed.
研究了两种对比鲜明的豌豆（Pisum sativum）品种发育反应的变异性，及其与固氮共生菌豌豆根瘤菌（Rhizobium leguminosarum bv. viciae）遗传多样性的关系。选取了42株豌豆根瘤菌样本，以代表本地根瘤菌种群中占主导地位的17种基因型，这些基因型通过以rDNA基因间隔区和nodD基因区域为标记所表征的单倍型组合来定义。我们发现细菌基因型，尤其是nod基因类型，对根瘤、根和地上部的发育有不同的影响。鉴定出一种细菌nod基因类型，它能诱导出非常大的分支根瘤、较少的根瘤数量、较高的根瘤生物量，但会减少根和地上部的发育。与该基因型相关的植株地上部积累的氮较少，但叶片中的氮浓度不受影响。结果表明，植物无法控制根瘤发育以维持根瘤功能及其最佳生长所需的能量需求。文中讨论了可能涉及的分子和生理机制。
