Background

Rice blast caused by Magnaporthe oryzae is one of the most widespread biotic constraints that threaten rice production. Using major resistance genes for rice blast resistance improvement is considered to be an efficient and technically feasible approach to achieve optimal grain yield.

Results

We report here the introgression of the broad-spectrum blast resistance gene Pi2 into the genetic background of an elite PTGMS line, Feng39S, for enhancing it and its derived hybrid blast resistance through marker-assisted backcrossing (MABC) coupled with genomics-based background selection. Two PTGMS lines, designated as DB16206–34 and DB16206–38, stacking homozygous Pi2 were selected, and their genetic background had recurrent parent genome recovery of 99.67% detected by the SNP array RICE6K. DB16206–34 and DB16206–38 had high resistance frequency, with an average of 94.7%, when infected with 57 blast isolates over 2 years, and the resistance frequency of their derived hybrids ranged from 68.2% to 95.5% under inoculation of 22 blast isolates. The evaluation of results under natural blast epidemic field conditions showed that the selected PTGMS lines and their derived hybrids were resistant against leaf and neck blast. The characterizations of the critical temperature point of fertility-sterility alternation of the selected PTGMS lines, yield, main agronomic traits, and rice quality of the selected PTGMS lines and their hybrids were identical to those of the recurrent parent and its hybrids. DB16206–34/9311 or DB16206–38/9311 can be used as a blast-resistant version to replace the popular hybrid Fengliangyou 4. Likewise, DB16206–34/FXH No.1 or DB16206–38/FXH No.1 can also be used as a blast-resistant version to replace another popular hybrid Fengliangyou Xiang 1.

Conclusions

Our evaluation is the first successful case to apply MABC with genomics-based background selection to improve the blast resistance of PTGMS lines for two-line hybrid rice breeding.

中文翻译：

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通过分子标记辅助回交提高Feng39S的稻瘟病抗性。

背景

由稻瘟病菌引起的稻瘟病是威胁稻米生产的最普遍的生物限制之一。使用主要抗性基因提高稻瘟病抗性被认为是实现最佳谷物产量的有效且技术上可行的方法。

结果

我们在这里报告了广谱抗稻瘟病基因Pi2渗入精英PTGMS系Feng39S的遗传背景，以通过标记辅助回交（MABC）结合基于基因组学的背景选择来增强其及其衍生的杂种抗稻瘟病。两条PTGMS线，分别命名为DB16206–34和DB16206–38，堆叠纯合Pi2选择SNP阵列RICE6K后，他们的遗传背景具有99.67％的复发亲本基因组回收率。DB16206–34和DB16206–38在2年内被57株病原菌感染后，具有较高的抗药性，平均为94.7％，在接种22株病原菌后，其衍生杂种的抗药性范围为68.2％至95.5％。 。在自然爆炸流行场条件下的结果评估表明，所选的PTGMS品系及其衍生的杂种具有抗叶和颈瘟的能力。所选PTGMS品系的育性-不育交替临界温度点的特征，产量，主要农艺性状和所选PTGMS品系及其杂种的水稻品质与轮回亲本及其杂种相同。

结论

我们的评估是第一个成功的案例，将MABC与基于基因组学的背景选择相结合，可提高两系杂交水稻育种的PTGMS品系的抗稻瘟病性。