Abstract:

In order to explore the genetic stability of critical temperature inducing male sterility of TGMS(thermo-sensitive genic male sterile) line , the response differences of fertility of consecutive 6 generational TGMS lines of 96-5-2S (developed from Pei’ai64S) to low temperature were studied in rice. The results were as follows: (1) All generational 96-5-2S lines were sterile with zero of selfed seed set setting rate and 0–0.9% of stainable pollen grains when they were treated with artificial cold water of constant 23.5℃(water depth 20 cm about) for 10 days or met natural cold air of average daily mean temperature 22.9–23.1℃(average daily minimum temperature 21.7–22.0℃) for 2–3 days at their thermo-sensitive stages inducing male fertility alternation(Table 1 and 2). (2) All generational 96-5-2S lines were fertile with 0.2%–7.1% of selfed seed setting rate and 1.1%–19.5% of stainable pollen grains when they were treated with artificial cold water of constant 21℃ and 22℃ for 10 days or natural cold air of average daily mean temperature 22.9℃(average daily minimum temperature 20.7℃) for 4 days at the same thermo-sensitive stages, but the selfed seed setting rate and stainable pollen grains percentage are different among different generations. As the multiplication generation increased, the bagged seed set and stainable pollen grains got more, and those of the 5th or 6th generation were significantly high than those of the first generation. (3) The selfed seed setting rate and stainable pollen grains percentage of Pei’ai64S (control) were much significantly higher than those of all generational 96-5-2S lines under the same low temperature condition. Based on above results, it is confident that the critical temperature of TGMS lines of 96-5-2S is genetically changeable slowly with the multiplication generation increase ,and this change will be obviously shown on the percentages of stainable pollen grains and selfed seed setting when 96-5-2S multiplicate to 5th or 6th generation respectively. However, the difference of critical temperature of 96-5-2S among different generations caused by genetically drift is less than that between 96-5-2S and Pei’ai64S. Therefore, it is a very important effective way to decrease critical temperature through pureline selection from the TGMS line population, which has relatively higher critical temperature.

Key words: Rice TGMS line, Critical temperature, Fertility, Low temperature, Genetic drift