Ting-Bi Zhang and Huan Zhu
Genetics Lab., Biology Department, Wuhan University, Wuchang, Hubei, China
To determine the duration of successive stages of meiosis, young panicles of cultivar Guanglai 4 were sampled and fixed at two-hour intervals for a day, in August at Wuchang. The duration of a stage (S/i) was estimated by the frequency of cells at the stage as follows:
No. of cells at stage i S/i=T X _______________________ Total cells in meiosiswhere T is the duration of meiosis. It was estimated to be 31 hours on the basis of increase of auricle distance as compared with the beginning and end of meiosis at a certain position of the panicle.
The results are shown in Table 1. The leptotene stage had a long duration exceeding 16 hours, followed by the pachytene stage of 5 hours. The shortest was 19 minutes for anaphase 1.
The data also showed that cells in different spikelets and in different anthers of the same spikelets are not synchronized in initiating meiosis, hence different stages were observed in the material fixed at each hour, but cells neighboring in the same anther were synchronized.
Table 1. Pollen mother cells at different meiotic stages in samples fixed at different hours _______________________________________________________________ AM PM Total Dura- Stage no. tion 1 3 5 7 9 11 1 3 5 7 9 11 h m _______________________________________________________________ Leptotene 21 23 26 19 21 17 23 23 23 17 21 17 251 16 05 Pachytene 5 7 4 11 5 9 9 5 5 7 4 7 78 5 00 Diplotene 1 1 2 1 1 6 23 Diakinesis 2 4 3 4 3 2 2 3 1 2 4 2 32 2 03 Metaphase I 6 2 4 2 3 5 5 2 4 5 1 1 40 2 34 Anaphase I 1 1 2 1 5 19 Telophase I 2 1 1 1 2 7 27 Prophase II 1 2 1 1 3 3 4 1 20 1 17 Metaphase II 4 3 1 2 1 2 3 4 2 2 2 1 25 1 36 Anaphase II 1 2 3 1 2 1 10 38 Telophase II 1 3 2 1 1 1 1 10 38 _______________________________________________________________ Total 43 41 47 45 38 41 47 47 35 37 35 28 484 31 00 _______________________________________________________________