The SI-Induced Increase in PA Levels Is Mediated by PbrPLDδ1 in Pollen. The SI-Induced Increase in PA Levels Is Mediated by PbrPLDδ1 in Pollen. (A) RT-qPCR analysis of PbrPLD expression in control and treated (compatible and incompatible, 30 min) pollen samples at 4 h post-culture. PbrPLDδ1 mRNA levels significantly increased in response to SI treatment. Asterisks indicate significant statistical difference between SI treatment and mock as evaluated by ANOVA and Tukey’s test: **P < 0.01; n = 4; error bars indicate se. (B) Images of PBut and PA signals for the three genotypes after 60 min of incompatible PbrS-RNase treatment. Pear pollen was cultured for 4 h with 0.10% (v/v) 1-butanol plus 50 µM antisense (as) or sense (s) ODNs targeting PbrPLDα1, PbrPLDβ1, or PbrPLDδ1 before treatment. (C) and (D) PA and PBut levels are expressed as percentages compared with control samples. The as-ODN-mediated knockdown of PbrPLDδ1 significantly decreased PA levels in samples showing an SI response at 60 min. Different letters indicate significant differences, as determined by ANOVA followed by Tukey’s multiple comparison test (P < 0.05; n = 3); error bars indicate se. Jianqing Chen et al. Plant Cell 2018;30:1023-1039 ©2018 by American Society of Plant Biologists