| Rice blast is the worst diseases of rice. In recent years, there is plenty of Rice blast across the country year after year, which caused serious losses of grain production in China. The fundamental reason is that the hybrid rice varieties we are planting is generally poor in resistance to rice blast. Breeding hybrid rice varieties having broad and spectrum durable resistance to blast is the key method to ensuring food security of China. Resistance gene pyramiding could significantly increase the resistance and the resistance spectrum of rice varieties. Molecular marker-assisted selection is a achievement and effective way to obtain gene pyramiding plants. In this study, Digu B(Pi-d(t)1,Pi-d2), BL123 (Pi1,Pi2) and FJ-Pi9(Pi9) were used as resistance gene donor materials and D62B, G2480B, D200B, G46B, YiXiang B and Guangzhan 63s were used as resistance gene receptor materials. After hybrid and F1 complex hybrid, Pi-d(t)1, Pi-d2, B, Pi1, Pi2and Pi9were selected by molecular marker-assisted selection technology in the later generation populations. Finally, we have polymerized all or partly of the 5 blast resistance genes into the receptor materials. The result are following:1.Using Digu B(Pi-d(t)1, Pi-d2), BL123(Pi1, Pi2) and FJ-Pi9(Pi9) as resistance gene donor material to hybrid with D62B respectively and offspring backcross with D62B in succession. Pi-d(t)1, Pi-d2, B, Pi1, Pi2 and Pi9were selected respectively by molecular marker-assisted selection technology in the segregating generation. The resistance genes, Pi-d(t)1, Pi-d2, Pi1, Pi2 and Pi9, were conferred successfully into genetic background of D62B respectively and obtained single-gene homozygous lines.2.The blast resistance inoculation result of the single-gene homozygous lines of Pi-d(t)1, Pi-d2, Pi1, Pi2 and Pi9 on the genetic background of D62B identified that both the seedling blast and panicle blast resistance of Pil are 1 degration responses, reaching a resistance level. And, the seedling blast and panicle blast resistance of Pi2 and Pi-d2 both are 0 degration responses, reaching a high resistance level. but Pi-d(t)1 and Pi9 on seedling blast and panicle blast resistance level responses are 3, displaying the intermediate level.3.6 multiple genes pyramiding populations with the receptors such as D62B, G2480B, D200B, G46B, YiXiang B and Guangzhan 63s were Constructed. And by using molecular marker-assisted selection, the 5 blast resistance genes, Pi-d(t)1, Pi-d2, Pi1, Pi2 and Pi9 were pyramided into the genetic background of D62B, G2480B, D200B, G46B, YiXiang B and Guangzhan 63S respectively at the same time. 34 5-genes pyramiding lines were obtaid. The result of resistance identification suggest that pyramiding the 5 blast resistance genes, Pi-d(t)1,Pi-d2,Pi1,Pi2 and Pi9, have significantly increased the resistance of the receptor parents to the Rice blast disease.4.Result of the blast resistance identification inoculation of Pi-d(t)1 and Pi-d2 double gene pyramiding lines DiguB, ChuanguB,G80B and GuxiangB indicated that the resistance level is significantly influenced by the genetic background.5. Using marker-assisted selection technology, we have cultivate three male sterile lines, ChuanGu A, G80A and Guxiang A, which displayed high quality rice blast resistance. |
