Mühlenbock P, Plaszczyca M, Plaszczyca M, Mellerowicz E, Karpinski S
Lysigenous aerenchyma formation in Arabidopsis is controlled by LESION SIMULATING DISEASE1
The Plant Cell: 2007 19:3819-3830

Aerenchyma tissues form gas-conducting tubes that provide rootswith oxygen under hypoxic conditions. Although aerenchyma havereceived considerable attention in Zea mays, the signaling eventsand genes controlling aerenchyma induction remain elusive. Here,we show that Arabidopsis thaliana hypocotyls form lysigenousaerenchyma in response to hypoxia and that this process involvesH2O2 and ethylene signaling. By studying Arabidopsis mutantsthat are deregulated for excess light acclimation, cell death,and defense responses, we find that the formation of lysigenousaerenchyma depends on the plant defense regulators LESION SIMULATINGDISEASE1 (LSD1), ENHANCED DISEASE SUSCEPIBILITY1 (EDS1), andPHYTOALEXIN DEFICIENT4 (PAD4) that operate upstream of ethyleneand reactive oxygen species production. The obtained resultsindicate that programmed cell death of lysigenous aerenchymain hypocotyls occurs in a similar but independent manner fromthe foliar programmed cell death. Thus, the induction of aerenchymais subject to a genetic and tissue-specific program. The datalead us to conclude that the balanced activities of LSD1, EDS1,and PAD4 regulate lysigenous aerenchyma formation in responseto hypoxia.

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