Lesion mimic1 medium size Round necrotic lesions that appear on leaf tissue at seedling stage as tiny watery green spots that become chlorotic then brown necrotic then bleached and die while at the same time enlarging in marginal tissue in concentric circles going thro

Lesion mimic1 Lesion Mimic; seedling, favorable conditions: First three leaves of a Les1-N843/+ mutant seedling under cool conducive greenhouse conditions showing early onset and rapid development of large necrotic lesions that coalesce to produce early leaf senescence. Resembles symptoms of fungal leaf blight infection but no evidence of hyphae or spores.

Lesion mimic1 lesion mimic; Comparison with fungal infection: section of 8th leaf of Les1-N843/+ mutant plant that has been infected with H. maydis. Note that Les1 lesions and H. maydis infection sites are not individually distinguishable by simple observation.

Lesion mimic1 Lesion Mimic; mutant comparison: Leaves of two Les mutant plants. Top, Les2-N845A/+, extreme expression resulting from favorable modifiers and conditions showing small round white lesions that do not enlarge much after original advent. Bottom, Les1-N843/+, standard expression showing rapidly enlarging lesions with concentric circles of characteristic sequential incursion into healthy tissue.

Lesion mimic1 Lesion Mimic; Les1 & Les2 comparison and interaction: Leaf of a Les1-N843/+, Les2-N845A/+ plant, grown under winter conditions in the greenhouse, showing large dark Les1 lesions with white centers and small round white necrotic Les2 lesions on the same leaf. It should be noted that the presence of Les2 delays and reduces expression of Les1 lesions, but not vice versa.

Lesion mimic1 Lesion mimic; Dramatic expression: leaf of Les1-N843/+ mutant plant showing dramatic target spot distribution of lesions, resulting from growth under winter greenhouse conditions near an outside door.

Lesion mimic1 Lesion Mimic; Development, top vs bottom of leaf: Leaf of Les1-N843/+ mutant plant seen from top surface, showing target spot distribution of lesions with older white necrotic center lesion and ring of newer light grey developing lesions.

Lesion mimic1 Lesion Mimic; Development, top vs bottom of leaf: Leaf of Les1-N843/+ mutant plant seen from bottom surface, showing target spot distribution of lesions and indicating that lesions go all the way through the leaf, but are less developed on underside. Therefore initiation begins on top surface towards the sunlight.

Lesion mimic1 Lesion Mimic; Sunlight response; Les1-N843/+, wt1 mutant seedling, (sunlight mask fig. 1) with midsection of first leaf covered by a foil mask for 66 hours (under conditions favorable for lesion formation, see mask fig. 2 below) Photo courtesy D. Hoisington.

Lesion mimic1 Lesion Mimic; Sunlight response; Les1-N843/+, wt1 mutant seedling, (sunlight mask fig.2 Midsection of first leaf covered with foil mask for 66 hours under conditions favorable for lesion formation (see masking fig. 1, above). Mask removed, showing profuse lesion formation above and below masked area, but absence of lesions in area that had been covered, except for faint tiny spots which are initiation points for new lesions already started from short light exposure (photo courtesy D. Hoisington).

Lesion mimic1 Les1-N843 wt1 seedling with aluminum mask, and cutout on first leaf after 4 days, showing lesions in unmasked area; see ummasked leaf (next image). Photo courtesy D. Hoisington.

Lesion mimic1 Lesion Mimic; Sunlight response; Les1-N843/+, wt1 mutant seedling, (sunlight mask fig.2 First leaf covered with foil mask for 66 hours under conditions favorable for lesion formation (see masking fig. 1, above). Mask removed, showing profuse lesion formation in unmasked area, but absence of lesions in area that had been covered, except for faint tiny spots which are initiation points for new lesions already started from short light exposure. Photo courtesy D. Hoisington.