A Novel Suppressor of Cell Death in Plants Encoded by the Lls1 Gene of Maize

The Lls1 (lethal leaf spot1) locus of maize is defined by a recessive mutation characterized by the initiation, in a developmentally programmed manner, of necrotic lesions that expand to kill leaves cell autonomously. The loss-of-function nature of all Lls1 mutants implies that the Lls1 gene is required to limit the spread of cell death in mature leaves. We have cloned the Lls1 gene by tagging with Mutator, a transposable element system in maize, and we show that it encodes a novel protein highly conserved in plants. Two consensus binding motifs of aromatic ring-hydroxylating dioxygenases are present in the predicted LLS1 protein, suggesting that it may function to degrade a phenolic mediator of cell death.