Background levels of genetic alterations.
We confirmed the cals5-3 phenotype in vitro; pollen tubes grew normally, yet they lacked aniline staining above background levels and no callose plugs were observed, even with differential interference contrast microscopy (n = 150, Fig. 4k,l,o,p).
The former two mutants deposit less callose whereas the insensitive mutant deposit augmented levels of callose (de Torres-Zabala et al., 2007).
Our results show that at inoculum densities typically used for transient expression, AtGV3101 reduces ABA levels, elicits low levels of callose deposition and alters plant responses to virulent and non-host strains of P. syringae, suppressing necrosis, SA synthesis and PR1a expression, but increasing callose deposition.
We observed that at concentrations normally used for transient expression assays, AtGV3101 caused a significant decrease in ABA levels and elicited moderate callose deposition, and when plants were subsequently inoculated with P. syringae, we observed reduced SA synthesis and high levels of callose deposition.
However, callose deposition is sometimes seen in a host plant's response to pathogen infection as well as being a component of non-host resistance, and high levels of callose are formed in response to Las infection in citrus [ 28].
This is consistent with the observation that the Arabidopsis athub1 mutant plants accumulated increased levels of callose upon infection of B. cinerea [ 13].
Both maize genotypes had higher levels of callose when grown in acid soil, a response typically correlated with Al stress [ 45- 47].
