Lysigenous Aerenchyma Formation in Arabidopsis Is Controlled by LESION SIMULATING DISEASE1

Abstract

Aerenchyma tissues form gas-conducting tubes that provide roots with oxygen under hypoxic conditions. Although aerenchyma have received considerable attention in Zea mays, the signaling events and genes controlling aerenchyma induction remain elusive. Here, we show that Arabidopsis thaliana hypocotyls form lysigenous aerenchyma in response to hypoxia and that this process involves H 2 O 2 and ethylene signaling. By studying Arabidopsis mutants that are deregulated for excess light acclimation, cell death, and defense responses, we find that the formation of lysigenous aerenchyma depends on the plant defense regulators LESION SIMULATING DISEASE1 (LSD1), ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1), and PHYTOALEXIN DEFICIENT4 (PAD4) that operate upstream of ethylene and reactive oxygen species production. The obtained results indicate that programmed cell death of lysigenous aerenchyma in hypocotyls occurs in a similar but independent manner from the foliar programmed cell death. Thus, the induction of aerenchyma is subject to a genetic and tissue-specific program. The data lead us to conclude that the balanced activities of LSD1, EDS1, and PAD4 regulate lysigenous aerenchyma formation in response to hypoxia.

Waterproofing Crops: Effective Flooding Survival Strategies

“…This arises after several days of waterlogging and enhances the aeration of roots and nodules necessary for growth and nitrogen fixation, respectively (Shimamura et al, 2010). The single cell layer cortex of Arabidopsis does not form aerenchyma, but waterlogging may promote the formation of lacunae in secondary xylem of the hypocotyl of mature rosettes (Mühlenbock et al, 2007), which could facilitate gas exchange.…”

Unraveling the Tapestry of Networks Involving Reactive Oxygen Species in Plants

“…H 2 O 2 together with ethylene has been demonstrated to be involved in the hypoxia-induced lysigenous aerenchyma formation in Arabidopsis. Interestingly, this cell death event involves early rootto-shoot signaling and shoot regulatory feedback on a root-specific redox regulation (Mü hlenbock et al, 2007), emphasizing the interplay between ROS and redox.…”

The Heat-Inducible Transcription Factor HsfA2 Enhances Anoxia Tolerance in Arabidopsis

“…The aqueous phase was then used for the analyses. H 2 O 2 abundance was quantified according to Guilbault et al (1967) and the subsequent modification by Muhlenbock et al (2007), in a reaction volume of 3 mL containing 50 mM HEPES, pH 7.5, 50 mM homovanilic acid, 4 mM peroxidase, and an aliquot of extract. Fluorescence was then measured at 425 nm after excitation at 315 nm, 30 min after the beginning of the reaction.…”