School of Life Sciences, Sambalpur University, Jyoti vihar, Sambalpur, 768019, India.
Siksha 'O' Anusandhan University, Bhubaneswar, 751030, India.
Sci Rep. 2021 Mar 10;11(1):5573. doi: 10.1038/s41598-021-84663-2.
Control of stage specific spike in ethylene production at anthesis has been a vauable route to potentially enhance genetic ceiling for grain filling of rice spikelet. A number of genes controlling ethylene homeostasis and starch synthesis have been identified so long, but lack of credible information on master modulation of gene expression by miRNAs and their target genes associated with hormonal dynamics obfuscate mechanisms controlling genotype difference in quantum of grain filling. The confusion accounts for consequent shrinkage of options for yield manipulation. In a two by two factorial design, miRNA regulation of spikelet specific grain development in low against high sterile recombinant inbred lines of rice Oryza sativa L. namely CR 3856-62-11-3-1-1-1-1-1-1 (SR 157) and CR 3856-63-1-1-1-1-1-1-1 (SR 159) respectively, and inferior verses superior spikelets were compared during first 10 days after anthesis. Grain filling was poorer in SR159 than SR157 and inferior spikelets in the former were most vulnerable. Between the cultivars, overall expression of unique miRNAs with targets on ethylene pathway genes was higher in SR159 than SR157 and the situation was opposite for auxin pathway genes. Precision analysis in psTarget server database identified up-regulation of MIR2877 and MIR530-5p having Os11t0141000-02 and Os07t0239400-01 (PP2A regulatory subunit-like protein and ethylene-responsive small GTP-binding proteins) and MIR396h having Os01t0643300-02 (an auxin efflux carrier protein) and Os01t0643300-01 (a PIN1-like auxin transport protein), as targets with highest probability at anthesis and 5 days after anthesis respectively, in the inferior spikelet and the fold change values of DGE matched with pattern of gene expression (relative transcript level) in the qRT-PCR studies conducted for relevant miRNAs and protein factors for ethylene and auxin signalling. In conclusion, epigenetic regulation of both auxin and ethylene homeostasis control grain filling of rice spikelet was established, but evidences were more robust for the latter.
在开花期控制特定阶段的乙烯产生一直是一种有价值的途径，可以潜在地提高水稻小穗灌浆的遗传上限。长期以来，已经确定了许多控制乙烯动态平衡和淀粉合成的基因，但缺乏关于 miRNA 对基因表达的主调控以及与激素动态相关的靶基因的可信信息，这使得控制基因型差异的机制变得模糊不清。这种混淆导致了产量操纵的选择余地缩小。在二因素析因设计中，比较了低不育重组自交系 CR 3856-62-11-3-1-1-1-1-1-1（SR 157）和 CR 3856-63-1-1-1-1-1-1（SR 159）与高不育重组自交系水稻 Oryza sativa L. 的小穗特异性籽粒发育的 miRNA 调控，以及开花后前 10 天的劣等和优等小穗。SR159 的灌浆情况比 SR157 差，而且前者的劣等小穗最脆弱。在两个品种之间，具有乙烯途径基因靶点的独特 miRNA 的整体表达在 SR159 中高于 SR157，而在生长素途径基因中则相反。在 psTarget 服务器数据库中的精确分析表明，MIR2877 和 MIR530-5p 的上调，它们的靶标是 Os11t0141000-02 和 Os07t0239400-01（PP2A 调节亚基样蛋白和乙烯反应性小 GTP 结合蛋白）和 MIR396h 的靶标是 Os01t0643300-02（生长素外排载体蛋白）和 Os01t0643300-01（PIN1 样生长素转运蛋白），在开花期和开花后 5 天的劣等小穗中具有最高的靶标概率，并且 DGE 的折叠变化值与 qRT-PCR 研究中相关 miRNA 和乙烯和生长素信号转导的蛋白质因子的基因表达（相对转录水平）模式相匹配。总之，建立了生长素和乙烯动态平衡的表观遗传调控控制水稻小穗的灌浆，但后者的证据更可靠。
