3.1 Establishment of anther length with timeline and cell type specification in the anther
Anther development from primordium within developing spikelets on a spike to a pollen shed, corresponding to anther lengths of 100 to 2300 µm (or more depending on the cultivar), respectively. Subsequently, anther length is gradual and goes to stabilization. To correlate length and time, anthers were dissected from spikelets of spike and the neighboring spikelets were dissected minimum 24 h later from the same position. In Figure 1 , results showed that anthers got double in length from 100 to 200 µm in 2.5 days in the passage from day 1 to 3.5, and double again to 400 by day 7, and then the elongation in length decrease gradually over the 32 days to achieve 2300 µm. The floral meristem consists of three germ layers: namely L1, L2, and L3, which are involved to make pollen grains finally in the last stage. Except the EPI, vascular system (VS) and connective tissue (CT), which are the result of division of L1 and L3 cells, respectively, while L2 form AR cells from the four corners of each anther primordium. The mitotic division of the AR cells occur which produce EN, SPL and PMC cells. The SPL then divide to form ML and TA cells. Subsequently, PMC undergoes meiosis to form Tds, which differentiate into MP rapidly and MP differentiate into PG after cell division. The AR cells appear in < 150 µm anthers and then disappear at > 150 µm after formation of EN, SPL and PMC cells. Subsequently, SPL cells disappear almost at 400 µm after formation of ML and TA cells. Similarly, PMC cells disappear near to 700 µm after the formation of microspore (MP) which differentiate into pollen grain (PG) which released in the environment by opening the epidermal cells from stomium region.