Figure 8.

Exogenous STIG1 Elevates the Overall Redox Potential of in Vitro–Cultured Pollen Tubes in a PI(3)P-Dependent and LePRK2-Dependent Manner.

(A) to (C) roGFP transiently expressed in tobacco pollen tubes responds to redox changes induced by incubation with H₂O₂ (B) or DTT (C) relative to levels in mock-treated tubes (A).

(D) The 405:488 ratio of roGFP fluorescence in tobacco pollen tubes in (A) to (C). n > 6. Water was used as a mock control.

(E) to (G) The effects of DMSO (E), exogenous STIG1 (F), and the phosphoinositide 3-kinase inhibitor wortmannin (G) on the redox status of transgenic tomato pollen tubes expressing roGFP.

(H) The 405:488 ratio of roGFP fluorescence in tomato pollen tubes in (E) to (G). n > 6. DMSO was used as a mock control.

Three independent experiments were performed. Insets in (A) and (E) show the color scales for the ratio values. Bars = 10 μm.

(I) The 405:488 ratio of roGFP fluorescence in transgenic tomato pollen tubes treated with STIG1 alone or pretreated with wortmannin and then 250 nM STIG1. n > 6. Three independent experiments were performed. DMSO was used as a mock control.

(J) Intracellular ROS-promoting effects of exogenous STIG1 on roGFP-expressing pollen tubes in either the wild-type or the LePRK2 RNAi background. n > 6. Three independent experiments were performed.

(K) Effects of STIG1 deletion or substitution mutants on the redox status of transgenic tomato pollen tubes expressing roGFP. n > 6. Three independent experiments were performed.

For (J) and (K), equal amounts of recombinant protein (250 nM each) were used. The 405:488 ratio of mock-treated pollen tubes was set as 1.

Asterisks indicate significant differences from the mock control (P < 0.05, Student’s t test). Error bars indicate sd (D) or se ([H] to [K]).