FIGURE 4.

Silencing of GhGB1 and GhGB2 in cotton induces expression of defense‐related genes and accumulation of reactive oxygen species (ROS) and salicylic acid (SA). (a) Transcript levels of three pathogenesis‐related (GhPR) genes, GhPR1, GhPR4, and GhPR5, in leaves of empty vector control (TRV:00) and GhGB1‐silenced (TRV:β1) cotton plants. One‐week‐old Gossypium hirsutum cv. “TM1” were infiltrated with Agrobacterium carrying virus‐induced gene silencing (VIGS) vector, TRV:00, or TRV:β1. qRT‐PCR was performed at 7, 9, 11, and 13 days after infiltration (dai). Gene expression was normalized to the cotton Ubiquitin 7 (GhUB7). (b) Representative leaves of plants infiltrated with VIGS vectors at 7, 9, 11, and 13 dai before (upper row) and after (lower row) DAB staining. (c) Endogenous H₂O₂ and (d) SA levels in leaves of TRV:00 and TRV:β1 plants at 13 dai. For (a), (c), and (d), bars represent means ± SEM, n = 5. Asterisks indicates significant difference evaluated by Student's t‐test, **P < .01. “ns” indicates no significant difference