Main conclusionThe MIR160 family in Gossypium hirsutum and G. barbadense was characterized, and miR160a_A05 was found to increase cotton-fiber length by downregulating its target gene (ARF17) and several GH3 genes.AbstractCotton fiber is the most important raw material for the textile industry. MicroRNAs are involved in regulating cotton-fiber development, but a role in fiber elongation has not been demonstrated. In this study, miR160a was found to be differentially expressed in elongating fibers between two interspecific (between Gossypium hirsutum and G. barbadense) backcross inbred lines (BILs) with different fiber lengths. The gene MIR160 colocalized with a previously mapped fiber-length quantitative trait locus. Its target gene ARF17 was differentially expressed between the two BILs during fiber elongation, but in the inverse fashion. Bioinformatics was used to analyze the MIR160 family in both G. hirsutum and G. barbadense. Moreover, qRT–PCR analysis identified MIR160a as the functional MIR160 gene encoding the miR160a precursor during fiber elongation. Using virus-induced gene silencing and overexpression, overexpressed MIR160a_A05 resulted in significantly longer fibers compared with wild type, whereas suppression of miR160 resulted in significantly shorter fibers. Expression levels of the target gene auxin-response factor 17 (ARF17) and related genes GH3 in the two BILs and/or the virus-infected plants demonstrated similar changes in response to modulation of miR160a level. Finally, overexpression or suppression of miR160 increased or decreased, respectively, the cellular level of indole-3-acetic acid, which is involved in fiber elongation. These results describe a specific regulatory mechanism for fiber elongation in cotton that can be utilized for future crop improvement.

中文翻译：

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MIR160基因家族分析及MIR160a_A05调控棉花纤维长度的作用

主要结论对陆地棉和G. barbadense中的MIR160家族进行了表征，发现miR160a_A05通过下调其靶基因（ARF17）和几个GH3基因来增加棉纤维长度。摘要棉纤维是纺织工业最重要的原料。MicroRNA 参与调节棉花纤维的发育，但尚未证实其在纤维伸长中的作用。在这项研究中，发现 miR160a 在具有不同纤维长度的两个种间（陆地棉和 G. barbadense 之间）回交自交系 (BIL) 之间的伸长纤维中差异表达。基因 MIR160 与先前映射的纤维长度数量性状基因座共定位。其靶基因 ARF17 在纤维伸长期间在两个 BIL 之间差异表达，但以相反的方式表达。生物信息学用于分析 G. hirsutum 和 G. barbadense 中的 MIR160 家族。此外，qRT-PCR 分析确定 MIR160a 是在纤维伸长过程中编码 miR160a 前体的功能性 MIR160 基因。使用病毒诱导的基因沉默和过表达，过表达的 MIR160a_A05 导致与野生型相比明显更长的纤维，而 miR160 的抑制导致明显更短的纤维。两种 BIL 和/或病毒感染的植物中靶基因生长素反应因子 17 (ARF17) 和相关基因 GH3 的表达水平表现出对 miR160a 水平调节的类似变化。最后，miR160的过表达或抑制分别增加或降低了参与纤维伸长的吲哚-3-乙酸的细胞水平。