Soybean shoot apical meristem after 4-short-day, replicate 1
Soybean (Glycine max L. cv. Bragg) seeds were sown and grown in a growth chamber under controlled conditions. The plants were first grown under LD (400 mol m-2 s-1, 25 C, 70% of humidity, and day-length of 16 h) for 10 days (LD10 or SD0), then plants were transferred to SD (conditions as for LD, but with 10 h light/ 14 h dark as photoperiod) to induce flowering. SAMs were collected on SD0, SD1, SD2, SD3, SD4, SD6 and LD16, while leaves were harvested on SD0, SD1, SD2, and SD3. SAMs were dissected under a 40X microscope with a 26G syringe needle and frozen by liquid nitrogen immediately, about 60 SAMs were micro-dissected at each collection time. Three biological replicates were used for both SAM and leaf samples. SAM and leaf tissues were first ground using a Retsch Mixer Mill MM 400 (Retsch GmbH, Germany). Total RNA isolation was performed with mirVana miRNA Isolation Kit (Thermo Fisher Scientific, USA) according to manufacturer's instructions. Possible DNA contamination was removed by applying TURBO DNA-free kit (Life Technologies, USA). Small RNA sequencing library was constructed and sequencing was carried out on a BGISEQ-500 platform to generate 50 bp single-end reads.