| As one of the most important food crops in the world,Oryza sativa L.is an important part of China’s food security.Since Yuan Longping found that the CMS lines of rice have completed the three line matching,the hybrid rice in China has completed a leap forward development;and the emergence of two-line CMS lines provides a broader stage for hybrid rice and heterosis utilization.However,because of the environmental factors,especially the temperature,the two line sterile lines seriously restrict their application and value in seed production.Therefore,how to effectively prevent the failure of seed production caused by abnormal low temperature is an urgent problem in hybrid rice seed production in China.In the preliminary research,Through the screening of related drugs and spraying on the sterile lines after fertility transformation,the transcriptomics and physiological and biochemical analysis of their young panicles were carried out,and it was determined that the treatment of chemical substances D-Arg,GABA and ethephon could significantly inhibit the fertility transformation of the thermo sensitive genic male sterile lines induced by low temperature;the differential expression of transcription factors,genes related to ethylene synthesis,carbohydrates and cells synthesis and lipid metabolism in young panicles may be involved in the inhibition of fertility transformation of TGMS.In this study,based on the previous laboratory research,the chemical substances sprayed were further screened and the concentration of application was determined,the process and specification of chemical system spraying were improved,and the guidance was provided for the practical use of production.The physiological and biochemical analysis was carried out on the young panicles of the thermo sensitive male sterile line after spraying,and the molecular mechanism of drug spraying to inhibit its fertility transformation was explored.The main results are as follows:1.Through artificial low temperature induction of Jing 4155S in the fertility sensitive period,spraying ethephon,GABA and D-Arg during the low temperature induction period,and then carrying out pollen microscopic examination and bagged seed setting rate statistical analysis,it was found that under the condition of 40.65%of the control(spraying equal volume water),the percentage of the pollen staining rate of spraying ethephon 2400mg/L was 19.94,Compared with the control,the decrease was 20.67%;The pollen staining rate that could be stained by ethephon 1200mg/L was 18.65%lower than that of the control,but its damage to plants was less than that of ethephon 2400mg/L,and the effect of spraying high concentration of GABA and D-Arg was better than that of low concentration.In addition,the dynamic parameters of chlorophyll fluorescence in the inverted three leaves of the plant after spraying the above chemicals were measured,and the results showed that the three substances used had no substantial effect on the photosynthetic performance of Jing 4155S.2.The results of pollen staining rate and the bagged seed setting rate showed that the percentage of Pollen staining by ethephon 1200 mg/L+ GABA 10mmol/L decreased about 20%compared with the control,and ethephon and D-Arg decreased about 20%compared with D-Arg 5mmol/L and 10mmol/L had little effect on the percentage of dyeable pollen.Thus,it was determined that ethephon 1200mg/L +GABA 10mmol/L was the main drug combination for treatment.3.The surface tension and the maximum retention on the rice leaf surface of the five pesticide adjuvant purchased on the market with ethephon 1200 mg/L+GABA 10 mmol/L were measured in the mixed solution,and then spraying was carried out to test the effect on inhibiting fertility conversion.The results showed that compared with the control,NF-100 reduced the surface tension of solution by 23.3%,BD-3077A increased the solution by 11.397mg/cm2,and NF-100 and bd-3077a significantly reduced the percentage of pollen staining rate and the bagged seed setting rate by 23.69%and 22.25%,respectively reduce 23.58%,20.01%.4.The best spraying time was determined by spraying Jing 4155S at different time before and after low temperature induction.The results showed that there were significant differences in the percentage of pollens that could be stained and the rate of bagged seed setting between the two days before low temperature and the day after low temperature(P2,P1,A0,A1).From the day before low temperature to the day after low temperature(P1,A0,Al),the percentage of pollen staining was less than 2%,and the percentage of bagged seed setting was 0.5.After spraying ethephon 1200mg/L+GABA10mmol/L,the agronomic characters,physiology and biochemistry of the young panicles were studied.It was found that:(1)spraying ethephon containing treatment significantly increased the angle between the flag leaves of rice;spraying ethephon+GABA combined treatment significantly reduced the total exposure rate of stigma,the bilateral exposure rate significantly decreased,the unilateral exposure rate significantly increased,and the initial heading stage was the same as other treatments about two days later.(2)By observing the microstructure of anther with paraffin section,it was found that the low fertility conversion of Jing 4155S caused by combined spraying might be due to the early programmed death of tapetum cells.(3)The results of the determination of polyamine content in young panicles by ultra-high liquid chromatography suggested that the effect of put concentration on the fertility of TGMS was not significant,but the application of GABA might have more effect on the decrease of spermidine concentration,which was probably related to the fertility of TGMS.(4)Through the analysis of the relative expression of the key genes of ethylene pathway,phospholipid pathway,pectin metabolism pathway and jasmonate metabolism pathway,it is inferred that the significant up regulation of OsAC5 and OsACO5,as well as the changes of PME1 gene and LOS5 expression are all related to the fertility of rice. |
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