| In contrast to conventional CMS(cytoplasmic male sterility) system, two-line hybrid, which is based on PTGMS (photo-thermo-sensitive genie male sterile), neither requires maintainers for seed multiplication nor the restores for hybrid seed production. Any line can be transformed into a PTGMS line and can be used as a pollen parent thus paving the way for widening the genetic base of hybrids. Some new developed combinations based on PTGMS have showed a great potential in developing hybrids. However, the fertility of PTGMS lines has been strongly influenced by the environmental conditions during rice growing seasons. PTGMS lines will change from sterile to fertile condition when it meets extremely low temperature during its fertility sensitive stage, and it leads to degradation in purity of hybrid rice seed. So it is very important to research and insight the fertility sensitivity of PTGMS lines.The main contents studied in the current undertaken project are as follows: Under the regime of natural conditions in Hangzhou, the determination of the sensitivity to temperature among several indica TGMS(thermo-sensitive genie male sterile) lines which were bred newly by our group and the control Peiai64S was insighted by the AMMI(additive main effects and multiplicative interaction) analyzing model, fertility alteration of two indica (Oryza sativa L.) TGMS lines (RTS7 and RTS18) was observed, responses of PTGMS lines of indica and japonica rice to gibberellic acid were contrasted, effects of paclobutrazol combined with gibberellic acid on flowering and morphological characters of male parent in hybrid rice seed production were researched, and the difference between sterile and fertile young panicle of TGMS indica rice Peiai64S was compared by mRNA differential display technology. The main results are summarized as below:New method based on natural conditions to identify TGMS lines in rice, was offered, i.e. Average temperatures of fertility sensitive stage were classified into twelve levels, and fertile pollen fertility data (i. e. normal pollen percentages) of six TGMS and control Peiai64S grown by sequential sowing were categorized according to the average temperatures of fertility sensitive stage belong to which one of twelve temperature levels, then the determination of the sensitivity to temperature among different TGMS lines was performedby AMMI analysis. The results showed that the pollen fertility among genotypes in response to high temperature was varied greatly. Based on their fertile pollen percentages, five genotypes were identified as TGMS lines, which were lower than or close to that of the control, with the exception of an unstable line RTS19 (V6). When fertility sensitive stage temperatures were at VII-XII, I-IV and V-VI, the percentages of fertile pollen vary in the ranges 3.49%-5.87%. 46.46%-48.49% and 19.62%-22.79%, respectively. The critical temperatures for sterility and fertility in the five TGMS lines were 25.TC, and 23.0℃, respectively. Considering the amounts and directions of main effect and their IPCA (interaction principal components analysis), the lines and temperature levels were classfied 4 and 3 groups, respectively, and the characteristics of genotype temperature interaction and fertility alteration were described, thus offering the information and tools for the development and utility of thermo-sensitive male sterile lines.By sequential sowing under natural conditions, the fertility and alternation characteristic of two TGMS lines, RTS7 and RTS18, were researched, and compared with that of the control Peiai64S in 2002 and 2003. The results of investigations on pollen and spikelet fertilities showed that the fertility of the three TGMS lines was all sensitive to temperature. The sensitive stages and critical point of temperature of fertility alteration in the three lines were different. The sensitive stage of Peiai64S and RTS18 was pollen mother cell formation stage, and RTS7 was from meiotic division of pollen mother cell to filling stage of pollen. The critical point t...
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