TPO and fungal infectious disease: The expression of components of the thioredoxin system appears to show caste- and isolate-specific patterns: TXNL4A is highly expressed in winged imagoes; TRx-like-Fd exhibits higher expression in workers and winged imagoes against all fungal infections; TXN1 and TPx mainly are expressed against isolate 02049 among workers and winged imagoes; TXN2 is expressed at higher levels among nymphs and winged imagoes against the infection of isolate 02049 (Table 3), implying that thioredoxin components play a crucial role in antioxidant defense against virulent isolates in the mentioned castes.