Mt-HA1 Is Required for the Mycorrhizal Symbiosis in M. truncatula.

(A) Mt-HA1 has 22 exons; Tnt1 insertions in exon 15 in line NF0905 and intron 6 in line NF10330.

(B) PCR genotyping of the F2 of a backcross of NF0905 with wild-type R108. A product size of 398 bp indicates homozygous insertion in Mt-HA1 (lane 3), a product size of 336 bp indicates homozygous wild type, and the two products in the same reaction indicates heterozygous plants.

(C) Expression level of Mt-HA1 in 1-week-old wild-type and Mt-ha1-1 mutant roots without inoculation with R. irregularis.

(D) Reduced colonization of Mt-ha1-1 roots 4 weeks postinoculation with R. irregularis. Total colonization measured (arbuscules, hyphae, and vesicles). Error bars indicate se of 8 to 10 plants.

(E) Mt-HA1 is induced upon colonization with R. irregularis at 10, 20, 30, and 40 d postinoculation (Dpi), measured by quantitative RT-PCR. Error bars are se.

(F) Quantification of arbuscule formation during colonization with R. irregularis at 10, 20, 30, and 40 d postinoculation. Error bars are se (n = 12 plants). This is a representative experiment that was repeated three times in (C) to (F).

[See online article for color version of this figure.]