Improving Resistances To Blast And Brown Planthopper In Rice 03S By Maker-Assited Selection

Blast and brown planthopper are destructive to the growth of rice, resulting in great loss of crop every year. Breeding and planting the rice cultivars with resistances to blast and brown planthopper is significative, not only to the rice production but also to the protection of envioroment. But the conventional breeding for developing rice cultivars with resistances to blast and brown planthopper is very difficult because of time consuming and cost. Marker Assisted Selection (MAS) gives a new way to develop the rice resistant to diseases and pests, owing to its effectiveness to identify the diseases and pest. In this thesis, we reported that the resistances of 03S to blast and brown planthopper was improved by MAS.The recurrent parent 03S was crossed with the blast resistance donor parents carrying Pid2 and RF48 carrying Pi9 and backcrossed to construct the backcross introgression lines for selecting new lines with both resistances to blast and the genetical background similar to the 03S. The molecular marker RM3 was used to select the blast resistance gene Pid2 in the backcross BC2F1 population derived from 03S with FuyiB, the best accurate rate is 95.24% for selection.The markers of AP5659-5 and AP5930 were used to select the blast resistance gene Pi9 in the backcross BC2F1 population derived from 03S with RF48.The results show the selecting accurate rate is 100% and much better than using the marker Pb8. Among 220 SSR markers covering 12 chromsomes,55 SSR markers were detected having polymorphism between 03S and FuyiB, then the 55 markers were used to analyse the background recovery rates of the resistant lines derived from the BC3F1 population. Among the selected lines, the maximum of the background recovery rates is 96.40%.To improve the resistance of 03S to brown planthopper, SSR markers RM570 and MS5 linking closely to brown planthopper resistance genes of Bph14 and Bph15 respectively were used to select the resistant genes in the backcross populations derived from B5(carrying the brown planthopper resistance gene Bph14 and Bph15) and 03S(the recurrent parent).48 out of 220 SSR markers covering 12 chromsomes were detected having polymorphism between 03S and FuyiB, The markers were used to analyse the background recovery rates of the resistant lines derived from the BC3F1 population. Among the selected lines, the maximum of the background recovery rates is 96.40%. The experiment results showing that the background recovery rates of the 42 resistant individuals derived from BC3F1 subpopulations vary from 81.20% to 100%, with the average of 93.16% much higher than the theoretical value 87.5%. Background selection can accelerates the recovery of the backgrounds of the lines selected for resistance, save time and enhance the efficiency for breeding.