PDF(Pubmed)
Abstract：
Rice sheath blight, caused by Rhizoctonia solani Kihn (R. solani), poses a significant threat to rice production and quality. Autotetraploid rice, developed through chromosome doubling of diploid rice, holds great potential for enhancing biological and yield traits. However, its resistance to sheath blight in the field has remained unclear. In this study, the field resistance of 35 autotetraploid genotypes and corresponding diploids was evaluated across three environments from 2020 to 2021. The booting stage was optimal for inoculating period based on the inoculation and analysis of R. solani at five rice growth stages. We found autotetraploids generally exhibited lower disease scores than diploids, indicating enhanced resistance after chromosome doubling. Among the 35 genotypes, 16 (45.71%) displayed increased resistance, 2 (5.71%) showed decreased resistance, and 17 (48.57%) displayed unstable resistance in different sowing dates. All combinations of the genotype, environment and ploidy, including the genotype-environment-ploidy interaction, contributed significantly to field resistance. Chromosome doubling increased sheath blight resistance in most genotypes, but was also dependent on the genotype-environment interaction. To elucidate the enhanced resistance mechanism, RNA-seq revealed autotetraploid recruited more down-regulated differentially expressed genes (DEGs), additionally, more resistance-related DEGs, were down-regulated at 24 h post inoculation in autotetraploid versus diploid. The ubiquinone/terpenoid quinone and diterpenoid biosynthesis pathways may play key roles in ploidy-specific resistance mechanisms. In summary, our findings shed light on the understanding of sheath blight resistance mechanisms in autotetraploid rice.
摘要：
水稻纹枯病,由根瘤菌引起的（R.solani)，对水稻产量和品质构成重大威胁。同源四倍体水稻,通过二倍体水稻的染色体加倍发展，具有增强生物学和产量性状的巨大潜力。然而,它在野外对纹枯病的抵抗力尚不清楚。在这项研究中,从2020年到2021年，在三种环境中评估了35种同源四倍体基因型和相应二倍体的田间抗性。根据水稻五个生长阶段的接种和分析，孕穗期是接种期的最佳选择。我们发现同源四倍体通常表现出比二倍体更低的疾病评分，表明染色体加倍后抗性增强。在35种基因型中，16（45.71％）显示电阻增加，2(5.71%)显示抗性下降，17（48.57％）在不同播期表现出不稳定的抗性。基因型的所有组合，环境和倍性，包括基因型-环境-倍性相互作用，对田间抗性有显著贡献。染色体加倍增加了大多数基因型的纹枯病抗性，但也依赖于基因型与环境的相互作用。为了阐明增强的抗性机制，RNA-seq揭示了同源四倍体招募了更多下调的差异表达基因（DEGs），此外，更多与电阻相关的DEG，与二倍体相比，同源四倍体在接种后24小时下调。泛醌/萜类醌和二萜生物合成途径可能在倍性特异性抗性机制中起关键作用。总之,我们的发现揭示了对同源四倍体水稻纹枯病抗性机制的理解。
