Fig. 1.

Arbuscular mycorrhizal (AM)‐defective phenotype and molecular characterization of vpy‐3 in Petunia hybrida. (a) Molecular aspects of the new vpy‐3 allele. The petunia VAPYRIN coding sequence is shown from the ATG start codon to the insertion site of a dTPh1 transposon (triangle). The 8 bp target site duplication is in bold and underlined. Because of stop codons in all three reading frames of the dTPh1 sequence, the truncated protein can be predicted to contain only eight residual amino acids of VAPYRIN. (b) The colonization pattern in the wild‐type (wt) revealed by trypan blue staining. Infection by hyphal coils in hypodermal cells, and arbuscules in the cortex. (c–e) Colonization pattern in vpy mutants revealed by trypan blue staining. Infection by enlarged penetration pegs, and subsequent profusely branched hyphal colonization (arrows) without arbuscules in vpy‐3 (c), and for comparison, vpy‐1 (d) and vpy‐2 (e). a, arbuscules; c, hyphal coils; p, penetration peg; arrows indicate aberrant hyphal colonization in the cortex. Bars, 50 µm.