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ARS Home » Southeast Area » Gainesville, Florida » Center for Medical, Agricultural and Veterinary Entomology » Chemistry Research » Research » Publications at this Location » Publication #322256

Research Project: Disease Defense Responses Signaling in Maize

Location: Chemistry Research

Title: A zebra-band phenotype in maize can be suppressed in constant light, and results from mutation of a PPOXlike gene (protophorphyrinogen oxidase IX-like) for porphyrin biosynthesis

item SAUNDERS, JONATHAN - University Of Florida
item Hunter, Charles
item BOUCHER, ALEX - University Of Florida
item LUBKOWITZ, MARK - University Of Florida
item BRAUN, DAVID - University Of Florida
item KOCH, KAREN - University Of Florida

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/30/2015
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: A zebra-band phenotype was identified in a maize population of transposon-tagged mutants (UniformMu, searchable by sequence at Genotype-phenotype analysis of an F2 family showed that the zebra stripes co-segregated with a single Mu insertion in the second exon of a Protoporphyrinogen oxidase IX (PPOX)-like gene. The association was confirmed by presence of the phenotype in two additional alleles from the UniformMu population as well as by allelism tests between the three lines. Although roles of PPOX have been studied in Arabidopsis and elsewhere, the effects of its mutation have not been previously linked to zebra-striping. The PPOX enzyme catalyzes the last step in common for both heme and chlorophyll biosynthesis. If the reaction is defective, then toxic, photosensitive precursors accumulate. In maize, our analyses indicate that a PPOX deficiency leads to wide, non-green bands that form perpendicular to the long axis of the first 5 leaves. Each of the cross-bands arises from a series of closely-packed, parallel, non-green stripes associated with major vascular bundles. The whitest stripes within the cross-bands often include narrow, open gaps where cells have died. The phenotype is most pronounced in field-grown plants (high light), but persists under low-light intensities. Cross-bands of this mutant are unique among diurnal-banding phenotypes in maize due to their combination of developmental timing, degree of severity, and pronounced enhancement near major vascular bundles. Light-dark shift experiments alter band patterns, however, continuous light suppresses zebra-banding and leads to solidgreen leaves. Results are consistent with the accumulation of phytotoxic intermediates in darkness, but also indicate the involvement of light- and clock-regulation. The zebra-banding mutant described here will facilitate further investigations into roles and regulation of porphyrin biosynthesis.