Genetic suppressors of the Lotus japonicus har1-1 hypernodulation phenotype.

Lotus japonicus har1 mutants respond to inoculation with Mesorhizobium loti by forming an excessive number of nodules due to genetic lesions in the HAR1 autoregulatory receptor kinase gene. In order to expand the repertoire of mutants available for the genetic dissection of the root nodule symbiosis (RNS), a screen for suppressors of the L. japonicus har1-1 hypernodulation phenotype was performed.

Genetic supressors of Lotus japonicus har1-1 hypernodulation show altered interactions with Glomus intraradices.

Mutant lines of Lotus japonicus (Regel) Larsen that show defects in nodulation as well as in mycorrhiza formation are valuable resources for studying the events required for the establishment of functional symbioses. In this study, 11 mutant lines derived from a screen for genetic suppressors of har1-1 hypernodulation were assessed quantitatively for their ability to form arbuscular mycorrhizal (AM) symbiosis. The presence of extraradical mycelia, appressoria, intraradical hyphae, arbuscules and vesicles were scored.

Morphological alterations of pea (Pisum sativum cv. Sparkle) arbuscular mycorrhizas as a result of exogenous ethylene treatment.

Little is known about the role of phytohormones in the formation of arbuscular mycorrhizas (AM). Although the involvement of ethylene in AM formation is unclear, it is considered very important for several aspects of plant growth and development. The effect of a suspected inhibitory level of ethylene was investigated to help elucidate its role in regulating the formation of AM.