Poulsen Katrine H, Nagy Réka, Gao Ling-Ling, Smith Sally E, Bucher Marcel, Smith F Andrew, Jakobsen Iver
Department of Biosystems, Risø National Laboratory, Roskilde, Denmark.
New Phytol. 2005 Nov;168(2):445-54. doi: 10.1111/j.1469-8137.2005.01523.x.
A Lycopersicon esculentum mutant (rmc) is resistant to colonization by most arbuscular mycorrhizal fungi (AMF), but one Glomus intraradices isolate (WFVAM 23) develops arbuscules and vesicles in the rmc cortex. It is unknown whether the symbiotic phosphate (Pi)-uptake pathway is operational in this interaction. Hyphal uptake of (32)Pi and expression of plant Pi transporter genes were investigated in the rmc mutant and its wild-type progenitor (76R) associated with three AMF. Hyphae transferred (32)Pi in all symbioses with 76R and in the rmc-G. intraradices WFVAM 23 symbiosis. The other AMF did not colonize rmc. The Pi transporter-encoding LePT1 and LePT2 were expressed constitutively or in P-starved roots, respectively. The mycorrhiza-inducible Pi transporters LePT3 and LePT4 were expressed only in plants with AMF colonization and symbiotic (32)Pi transfer. LePT3 and LePT4 transcripts were reliable markers for a functional mycorrhizal uptake pathway in rmc. Our novel approach to the physiology and molecular biology of P transport can be applied to other arbuscular-mycorrhizal symbioses, irrespective of the size of plant responses.
番茄（Lycopersicon esculentum）突变体（rmc）对大多数丛枝菌根真菌（AMF）的定殖具有抗性，但有一种根内球囊霉（Glomus intraradices）分离株（WFVAM 23）能在rmc皮层中形成丛枝和泡囊。尚不清楚共生磷酸盐（Pi）吸收途径在这种相互作用中是否起作用。研究了与三种AMF共生的rmc突变体及其野生型亲本（76R）中菌丝对（32）Pi的吸收和植物Pi转运蛋白基因的表达。在与76R的所有共生关系以及rmc-根内球囊霉WFVAM 23共生关系中，菌丝都能转运（32）Pi。其他AMF不能在rmc中定殖。编码Pi转运蛋白的LePT1和LePT2分别在组成型表达或在缺磷根中表达。菌根诱导型Pi转运蛋白LePT3和LePT4仅在有AMF定殖和共生（32）Pi转运的植物中表达。LePT3和LePT4转录本是rmc中功能性菌根吸收途径的可靠标记。我们对磷转运生理和分子生物学的新方法可应用于其他丛枝菌根共生关系，而不考虑植物反应的大小。
