水稻重离子诱变早熟突变体M85S特征特性及配合力遗传力分析

为了利用水稻光温敏核不育系重离子诱变早熟突变体M85S的潜在育种价值,对水稻光温敏核不育系早熟突变体M85S的特征特性及其所配组的F_1代产量构成性状体现的配合力及遗传力进行分析。利用2个光温敏水稻不育系和8个恢复系按2×8不完全双列杂交(NCⅡ)设计配组,对亲本配合力及遗传力进行分析,结果表明,12个农艺性状及产量相关性状区组间差异不显著,组合间差异极显著,说明组合间存在真实的遗传差异,12个性状的遗传受基因加性效应和非加性效应的共同影响,遗传关系复杂。M85S播始历期一般配合力的相对效应值为负值(-2.40%),单株产量一般配合力的相对效应值为正(0.18%),表现为正效应。播始历期、有效穗数、一次枝梗数、穗长、千粒重和粒长的群体一般配合力方差占绝对高的比例,基因的遗传效应占主导作用;株高、总粒数、实粒数和单株产量的群体特殊配合力方差占绝对高的比例,环境效应占主导作用。12个性状的广义遗传力从大到小依次为:粒长>播始历期>千粒重>总粒数>穗长>实粒数>粒宽>一次枝梗数>有效穗数>单株产量>结实率>株高。综合两个条件,在试验中所组配的16个杂交F_1代中,根据各性状的特殊配合力与一般配合力可知,M85S/创香5号与M85S/航恢1179两个组合较符合早熟与丰产的要求,可见M85S是水稻育种中具有较高应用价值的早熟种质资源,可从遗传上间接协调早熟与丰产矛盾。

Blast-Resistance Inheritance of Space-Induced Rice Lines and Their Genomic Polymorphism by Microsatellite Markers

To understand the resistance inheritance basis of space-induced rice lines to blast, and to probe mutants＇ genomic DNA polymorphism compared with ground control by microsatellite markers, three space-induced lines were crossed with a highly susceptible variety LTH, and their F1 and F2 populations were inoculated by two representative blast isolates with broad pathogenicity to analyze their resistance inheritance basis. Meanwhile three mutant lines and the ground control were analyzed by 225 rice SSR （simple sequence repeat） primer pairs selected throughout the 12 chromosomes of whole rice genome, to scan the mutagenesis in genome of the mutant lines. The results indicated the blast-resistant genes harbored in these mutant lines were dominant. It was demonstrated that the resistance of mutant H1 to isolate GD0193 and GD3286 was controlled by a single gene, respectively; while mutants H2 and H3 were controlled by two pairs of major genes against isolate GD3286 and H2 showed complicated genetic mechanism to isolate GD0193. H3＇s resistance to isolate GD0193 was verified to be controlled by a single gene. According to the results of SSR analysis, three mutant lines showed different mutant rates as compared with the ground control, and the mutant rates also varied. Resistance genes can be induced from rice by space mutation, and different genomic variations were detected in blast-resistant lines.

Development of elite restoring lines by integrating blast resistance and low amylose content using MAS

Blast resistance and grain quality are major problems in hybrid rice production in China. In this study, two resistance （R） genes, Pi46 and Pita, along with the gene Wxb, which mainly affects rice endosperm amylose content （AC）, were introgressed into an elite indica restoring line, R8166, which has little blast resistance and poor grain quality through marker-assisted selection （MAS）. Eight improved lines were found to have recurrent genome recovery ratios ranging from 88.68 to 96.23%. Two improved lines, R163 and R167, were selected for subsequent studies. R167, which has the highest recovery ratio （96.23%）, showed no significant differences in multiple agronomic traits. In contrast, R163 with the lowest recovery ratio （88.68%） exhibited significant differences in heading date and yield per plant compared with the recurrent parent. At two developmental stages, R163 and R167 had greatly enhanced resistance to blast over the recurrent parent. Similar trends were also observed for agronomic traits and blast resistance in R163- and R167-derived hybrids when compared with the counterparts from R8166. In addition, R163, R167, and their derived hybrids significantly improved the grain quality traits, including amylose content （AC）, gel consistency （GC）, chalky grain rate （CGR）, and degree of endosperm chalkiness （DEC）. It confirmed the success of efficiently developing elite restoring lines using MAS in this study.

Pyramiding of Pi46 and Pita to improve blast resistance and to evaluate the resistance effect of the two R genes

Utilization of R（resistance） genes to develop resistant cultivars is an effective strategy to combat against rice blast disease. In this study, R genes Pi46 and Pita in a resistant accession H4 were introgressed into an elite restorer line Hang-Hui-179（HH179） using the marker-assisted backcross breeding（MABB） procedure. As a result, three improved lines（e.g., R1791 carrying Pi46 alone, R1792 carrying Pita alone and R1793 carrying both Pi46 and Pita） were developed. The three improved lines had significant genetic similarities with the recurrent parent HH179. Thus, they and HH179 could be recognized as near isogenic lines（NILs）. The resistance spectrum of the three improved lines, which was tested at seedling stage, reached 91.1, 64.7 and 97.1%, respectively. This was markedly broader than that of HH179（23.5%）. Interestingly, R1793 showed resistance to panicle blast but neither R1791 nor R1792 exhibited resistance at two natural blast nurseries. The results implied that the stacking of Pi46 and Pita resulted in enhanced resistance, which was unachievable by either R gene alone. Further comparison indicated that the three improved lines were similar to HH179 in multiple agronomic traits; including plant height, tillers per plant, panicle length, spikelet fertility, and 1 000-grain weight. Thus, the three improved lines with different R genes can be used as new sources of resistance for developing variety. There is a complementary effect between the two R genes Pi46 and Pita.

优质抗病恢复系航恢1378的选育

航恢1378是利用航天诱变获得的优质品系华航油占与优质新品系H-37为亲本进行杂交后经系谱法选择育成的新的优良恢复系。该恢复系具有恢复力强、稻米品质优、稻瘟病抗性好等特点。利用该恢复系配制的恒丰优1378、深两优1378、Y两1378已通过广东省农作物品种审定委员会审定。

水稻不育系G软华A稻米品质配合力分析

采用不完全双列杂交设计分析了G软华A等5个不育系所配杂交组合的稻米品质性状及其配合力表现。结果表明,杂交组合稻米品质各性状主要受基因加性效应的影响,也有基因加性与非加性效应共同作用。在参试的5个不育系中,G软华A表现较为突出,其胶稠度和整精米率的一般配合力最高,垩白粒率和垩白度的一般配合力最低,直链淀粉含量一般配合力较低,是改良杂交水稻品质的优良亲本。