Abstract
The infection thread (IT) is a plant-derived structure that is developed upon infection of root nodule bacteria. There are several Lotus japonicus mutants in which IT development is aborted. Among them, cyclops showed root hair curling and bacterial colonization, but IT initiation was mostly aborted. Concomitantly, nodule development was suppressed at the bump stage. Cyclops encodes a nuclear protein, which interacts with CCaMK. Interestingly, spontaneous nodule formation triggered by a gain-of-function CCaMK did not require CYCLOPS, indicating that the primary function of CYCLOPS is to initiate IT in epidermis. In alb1 mutant, IT was initiated but never penetrating into cortical layers. In some cases, abnormal IT could be observed in a developed nodule (Type II nodule), which aberrantly released bacteria into infected cells. We cloned the gene, encoding LRR-RK. Expression of Alb1 was induced by infection, and confined as a patchy pattern in epidermis.
