Figure 1. Avh307 corresponds to Avr3b based on genetic mapping, sequence polymorphisms, and bioassays.

(A) Co-segregation of Avh307 with the Avr3b virulence phenotype in F₂ progeny from a cross between P. sojae isolates P6497 and P7076. A virulence assay was performed with cultures scored as virulent (V) or avirulent (A) on Rps3b soybean plants. Cleaved amplified polymorphic (CAP) markers, co-dominant and specific for Avh307, were scored using genomic DNA from the avirulent (A) and virulent (V) parents and F₁ and F₂ progeny. Shown is a photograph of an ethidium bromide-stained agarose gel of the CAP marker results for Avh307. (B) Physical map of the Avh307 region. Predicted RXLR genes and CAP DNA markers for genetic mapping are shown. Genes (black color) and CAP markers (blue color) are shown on P. sojae P6497 genome sequence scaffold_3 (assembly version 5.0), not to scale. (C) Predicted amino acid sequences of Avh307^P6497 (from P6497 and other Rps3b-avirulent strains) and Avh307^P7076 (from P7076 and other Rps3b-virulent strains). Predicted signal peptide, RXLR-dEER motif, W-motif, and a Nudix hydrolase motif are shown in grey, blue, green and orange frames. (D) Transient expression assays of Avh307 alleles in Rps3b plant tissue. Soybean hypocotyls of cultivars Williams (rps), L88-1479 (Rps3b), and PRX146-36 (Rps3b) were transformed by co-bombardment with a plasmid mixture consisting of a glucuronidase reporter gene (GUS) expression vector and a test construct. Expression of the GUS reporter and Avh307 alleles were controlled by the 35S promoter. The test constructs used in combination with the GUS reporter are shown on the top of the panel.