Echeverria Mariela, Scambato Agustina Azul, Sannazzaro Analía Inés, Maiale Santiago, Ruiz Oscar Adolfo, Menéndez Ana B
Unidad de Biotecnología 3, IIB-IINTECH/UNSAM-CONICET, Buenos Aires, Argentina.
Mycorrhiza. 2008 Sep;18(6-7):317-29. doi: 10.1007/s00572-008-0184-3. Epub 2008 Jul 25.
Our hypothesis is that Lotus glaber (a glycophytic species, highly tolerant to saline-alkaline soils) displays a plastic root phenotypic response to soil salinity that may be influenced by mycorrhizal and rhizobial microorganisms. Uninoculated plants and plants colonised by Glomus intraradices or Mesorhizobium loti were exposed to either 150 or 0 mM NaCl. General plant growth and root architectural parameters (morphology and topology) were measured and phenotypic plasticity determined at the end of the salt treatment period. Two genotypes differing in their salt tolerance capacity were used in this study. G. intraradices and M. loti reduced the total biomass of non-salinised, sensitive plants, but they did not affect that of corresponding tolerant ones. Root morphology of sensitive plants was greatly affected by salinity, whereas mycorrhiza establishment counteracted salinity effects. Under both saline conditions, the external link length and the internal link length of mycorrhizal salt-sensitive plants were higher than those of uninoculated control and rhizobial treatments. The topological trend (TT) was strongly influenced by genotype x symbiosis interaction. Under non-saline conditions, nodulated root systems of the sensitive plant genotype had a more herringbone architecture than corresponding uninoculated ones. At 150 mM NaCl, nodulated root systems of tolerant plants were more dichotomous and those of the corresponding sensitive genotype more herringbone in architecture. Notwithstanding the absence of a link between TTs and variations in plant growth, it is possible to predict a dissimilar adaptation of plants with different TTs. Root colonisation by either symbiotic microorganisms reduced the level of root phenotypic plasticity in the sensitive plant genotype. We conclude that root plasticity could be part of the general mechanism of L. glaber salt tolerance only in the case of non-symbiotic plants.
我们的假设是，光滑百脉根（一种对盐碱土具有高度耐受性的盐生植物）对土壤盐分表现出可塑性根系表型反应，这可能受菌根和根瘤菌微生物的影响。未接种的植株以及被根内球囊霉或百脉根中生根瘤菌定殖的植株分别暴露于150 mM或0 mM NaCl环境中。在盐处理期结束时，测定了植株的总体生长情况和根系结构参数（形态和拓扑结构），并确定了表型可塑性。本研究使用了两种耐盐能力不同的基因型。根内球囊霉和百脉根中生根瘤菌降低了非盐渍化敏感植株的总生物量，但对相应耐盐植株的总生物量没有影响。敏感植株的根系形态受盐分影响很大，而菌根的形成抵消了盐分的影响。在两种盐处理条件下，菌根盐敏感植株的外部连接长度和内部连接长度均高于未接种对照和根瘤菌处理的植株。拓扑趋势（TT）受基因型×共生相互作用的强烈影响。在非盐渍条件下，敏感植株基因型的结瘤根系比相应的未接种植株具有更明显的人字形结构。在150 mM NaCl条件下，耐盐植株的结瘤根系更倾向于二叉状，而相应敏感基因型植株的结瘤根系则更倾向于人字形结构。尽管TTs与植株生长变化之间没有关联，但仍有可能预测具有不同TTs的植株的不同适应性。两种共生微生物对根系的定殖均降低了敏感植株基因型根系表型可塑性水平。我们得出结论，只有在非共生植株的情况下，根系可塑性才可能是光滑百脉根耐盐的一般机制的一部分。
