Tandem mass tags (TMT)-based quantitative analysis was used to investigate the profiles of proteins related to lipid and carbohydrate metabolism in 4-, 6- and 8.5-mm O. longistaminata spikelets before flowering. O. longistaminata plants were sampled at three important stages of pollen development: 4-mm spikelet (Ls-4mm, primary sporogenous cells, Stage 4), 6-mm spikelet (Ls-6mm, microspore mother cells, Stage 6) and 8.5-mm spikelet (Ls-8.5mm, second mitosis cells, Stage 12) .