Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078, USA.
Department of Crop, Soil, and Environmental Sciences, University of Arkansas, Fayetteville, AR 72701, USA.
Int J Mol Sci. 2023 Jul 19;24(14):11631. doi: 10.3390/ijms241411631.
High temperature impairs starch biosynthesis in developing rice grains and thereby increases chalkiness, affecting the grain quality. Genome encoded microRNAs (miRNAs) fine-tune target transcript abundances in a spatio-temporal specific manner, and this mode of gene regulation is critical for a myriad of developmental processes as well as stress responses. However, the role of miRNAs in maintaining rice grain quality/chalkiness during high daytime temperature (HDT) stress is relatively unknown. To uncover the role of miRNAs in this process, we used five contrasting rice genotypes (low chalky lines Cyp, Ben, and KB and high chalky lines LaGrue and NB) and compared the miRNA profiles in the R6 stage caryopsis samples from plants subjected to prolonged HDT (from the onset of fertilization through R6 stage of caryopsis development). Our small RNA analysis has identified approximately 744 miRNAs that can be grouped into 291 families. Of these, 186 miRNAs belonging to 103 families are differentially regulated under HDT. Only two miRNAs, Osa-miR444f and Osa-miR1866-5p, were upregulated in all genotypes, implying that the regulations greatly varied between the genotypes. Furthermore, not even a single miRNA was commonly up/down regulated specifically in the three tolerant genotypes. However, three miRNAs (Osa-miR1866-3p, Osa-miR5150-3p and canH-miR9774a,b-3p) were commonly upregulated and onemiRNA (Osa-miR393b-5p) was commonly downregulated specifically in the sensitive genotypes (LaGrue and NB). These observations suggest that few similarities exist within the low chalky or high chalky genotypes, possibly due to high genetic variation. Among the five genotypes used, Cypress and LaGrue are genetically closely related, but exhibit contrasting chalkiness under HDT, and thus, a comparison between them is most relevant. This comparison revealed a general tendency for Cypress to display miRNA regulations that could decrease chalkiness under HDT compared with LaGrue. This study suggests that miRNAs could play an important role in maintaining grain quality in HDT-stressed rice.
高温会损害发育中水稻籽粒的淀粉合成，从而增加垩白度，影响稻米品质。基因组编码的 microRNAs（miRNAs）以时空特异性的方式精细调节靶转录本的丰度，这种基因调控模式对于众多发育过程以及应激反应至关重要。然而，miRNAs 在维持高温白天（HDT）胁迫下水稻籽粒品质/垩白度方面的作用相对未知。为了揭示 miRNAs 在这个过程中的作用，我们使用了五个具有不同垩白度的水稻基因型（低垩白度的 Cyp、Ben 和 KB 以及高垩白度的 LaGrue 和 NB），并比较了在长时间 HDT 下（从受精开始到籽粒发育的 R6 期）处于 R6 期的颖果样品中 miRNA 的图谱。我们的小 RNA 分析鉴定了大约 744 个可以分为 291 个家族的 miRNAs。其中，186 个属于 103 个家族的 miRNAs 在 HDT 下受到差异调控。只有两个 miRNAs，Osa-miR444f 和 Osa-miR1866-5p，在所有基因型中均上调，这意味着这些调控在基因型之间存在很大差异。此外，甚至没有一个 miRNA 专门在三个耐受基因型中上调/下调。然而，有三个 miRNAs（Osa-miR1866-3p、Osa-miR5150-3p 和 canH-miR9774a，b-3p）在敏感基因型（LaGrue 和 NB）中普遍上调，一个 miRNA（Osa-miR393b-5p）普遍下调。这些观察结果表明，低垩白度或高垩白度基因型之间可能存在一些相似之处，这可能是由于遗传变异较高。在使用的五个基因型中，Cypress 和 LaGrue 在遗传上密切相关，但在 HDT 下表现出不同的垩白度，因此，它们之间的比较最为相关。这种比较表明，与 LaGrue 相比，Cypress 表现出的 miRNA 调控可能在 HDT 下降低垩白度。本研究表明，miRNAs 可能在维持高温胁迫下水稻籽粒品质方面发挥重要作用。
