Botrytis cinerea Infection of Tomato Leaves

Tomatoes (S. lycopersicum) cv. Jinpeng 1 were used as host plants; they were grown in a greenhouse at a 16-h day/8-h night cycle, at 22–28°C. At the age of 6 weeks, plants were inoculated using a solution containing B. cinerea conidia (2 × 10⁶ spores ml⁻¹), 5 mM glucose, and 2.5 mM KH₂PO₄. The inoculation solution was applied to both leaf surfaces using a soft brush. After inoculation, the plants were kept at 100% relative humidity to ensure spore germination. The B. cinerea- and mock-inoculated leaves were harvested at 5 time points (0 days, 0.5 days, 1 days, 3 days, and 7 days) after treatment, in 3 biological replicates. We found that the B. cinerea spores appeared on the leaves at 7 dpi. The 7-dpi leaves of B. cinerea-infected (TD7d) and control (TC7d) plants were sent to BGI (Shenzheng, China) for the deep sequencing of sRNAs. The samples were frozen in liquid nitrogen and stored at −70°C for the studies of transcript expression.
Total RNAs were extracted from leaf tissues using TRIzol reagent (Invitrogen, Carlsbad, CA, USA), followed by RNase-free DNase treatment (Takara, Dalian, China). Their concentrations were quantified using a NanoDrop ND-1000 spectrophotometer.