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Field assay of seedling and adult‐plant resistance to southern leaf blight in maize
Author(s) -
Gao Z. S.,
Cai H. W.,
Liang G. H.
Publication year - 2005
Publication title -
plant breeding
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.583
H-Index - 71
eISSN - 1439-0523
pISSN - 0179-9541
DOI - 10.1111/j.1439-0523.2005.01067.x
Subject(s) - biology , amplified fragment length polymorphism , locus (genetics) , blight , seedling , restriction fragment length polymorphism , conidium , allele , population , quantitative trait locus , plant disease resistance , genetic marker , genetics , horticulture , botany , genotype , gene , genetic diversity , demography , sociology
Resistance to southern corn leaf blight is under the control of a single recessive allele, rhm , and can be scored from lesion number, size, type and sporulation in the lesion, which are best expressed by plants growing under field conditions, although resistance also can be measured at the seedling stage. An assay procedure that can unequivocally score disease severity from the seedling stage to post‐flowering in the field is desirable. We analysed pairs of isogenic lines H95/H95rhm and B73/B73Htrhm, the F 2 population of H95 × H95rhm consisting of a total of 687 individuals, and 120 F 3 families, which were inoculated with conidia of Bipolaris maydis race O. The disease ratings were also studied together with the segregation scores of a single copy DNA probe, agrP144. Among 687 F 2 plants derived from the cross H95 x H95rhm, 161 plants were rated as resistant and 526 susceptible, suggesting a 1: 3 ratio. Among the 120 F 3 families, there were 32 susceptible, 58 segregating and 30 resistant rows, fitting the expected 1:2:1 ratio for a single gene model. Using agrP144 as a marker, 99.5% restriction fragment length polymorphism (RFLP) allelic segregation scores corresponded to the disease ratings obtained from field data, indicating that the marker agrP144 is tightly linked to the rhm locus. Similarly, the amplified fragment length polymorphism (AFLP) marker p7m36 also is closely linked to the locus but on the opposite side of the marker agrP144.