Fig. 2.

Phenotype comparison of 337S between NN and SL conditions. a The feature of 337S spikes planted at Oct. 30 that was defined as NN condition. b The feature of 337S spikes planted at Sept. 30 that was defined as SL condition. c The NN spikes of 337S at blooming stage. d The SL spikes of 337S at blooming stage. e A part of NN spike showed the elongated anthers at the pollination stage. Bar = 1 cm. f A part of SL spike showed glumes opening phenotype with a bigger angle at the pollination stage. Bar = 1 cm. g A NN anther (left) with slight yellow, smaller SL anther (right) at the mononuclear pollen stage. Bar = 1 mm. h Comparison between NN and SL anthers at late binuclear pollen stage. The SL anther was obvious shorter and yellow discolouration, while the NN anthers was still green. Bar = 1 mm. i Comparison between NN and SL spikelets after removing the lemma and palea, no visibly filled grains on SL plants at the filling stage. Bar = 2 mm. j and k Transverse section of single locule at microspore mother cell stage. Bars = 10 μM. l and m Transverse section of single locule at meiosis prophase stage, only cellular debris observed in the SL anther locule m. Bars = 10 μM. n and o Transverse section of single locule at dyad stage of meiosis, the meiotic cells further collapsed in the SL anther locule o. Bars = 10 μM. E, epidermis; En, endothecium; ML, middle layer; MC, meiocyte cell; MMC, microspore mother cell; DMC, degenerated meiocyte cell; Dy, dyad