Abstract
MicroRNAs (miRNAs) play key roles in the regulation of plant growth and developmental processes. In this study, RNA-seq was used to examine the expression profiles of miRNAs in a novel, photo-thermosensitive genic male sterile (PTGMS) rice line, Wuxiang S (WXS), during fertility transition. A total of 497 known miRNAs and 273 novel miRNAs were identified. In a differential expression analysis, 26 miRNAs exhibited significant differential expression between WXS (Sterile, S) and WXS (Fertile, F). Some of these miRNAs were validated by quantitative real-time PCR. Among these miRNAs, 11 showed decreased expression levels, and 15 showed increased expression levels in WXS (S) compared to WXS (F). Some of these miRNAs, such as osa-miR156a-j, osa-miR164d, and osa-miR528, were shown to be negatively correlated with their targets. These targets have previously been reported to be related to pollen development and male sterility, suggesting that these miRNAs may be involved in the regulation of pollen development in the rice PTGMS line WXS. Furthermore, miRNA-mediated editing events were also observed. In this study, a possible model for the control of signaling pathways during the process of fertility transition in the rice PTGMS line WXS by miRNAs was developed. These findings contribute to our understanding of the roles of miRNAs during anther development in PTGMS lines in rice.
Highlights
MicroRNAs are endogenous, small (20–24 nt), non-coding RNAs that play important roles in various biological and metabolic processes, including development, signal transduction, and biotic and abiotic stress responses (Bartel, 2004, 2009)
Wuxiang S (WXS) was grown in the paddy field until the panicle length was approximately 1 cm, and 20 plants were selected and transferred to a cooling pond to treat them with low temperatures for 2 weeks
Under natural conditions, the WXS plants had thin anthers (Figure 1C) and a complete absence of I2-KI-stained pollen (Figure 1D), exhibited sterility with abnormal pollen mother cells (Figures 1E,e,f) and aberrant dyads and tetrads during meiosis (Figures 1E,g–k), and eventually produced cracked pollens (Figures 1E,l). These results suggested that the male sterile line WXS can display two different phenotypes under two different environmental conditions; these were named WXS (S, Sterile) and WXS (F, Fertile)
Summary
MicroRNAs (miRNAs) are endogenous, small (20–24 nt), non-coding RNAs that play important roles in various biological and metabolic processes, including development, signal transduction, and biotic and abiotic stress responses (Bartel, 2004, 2009). Differential expression patterns of miRNAs between the cytoplasmic male sterility (CMS) line and its maintainer line have been reported in maize (Shen et al, 2011), cotton (Wei et al, 2013), Brassica juncea (Yang et al, 2013), cabbage (Wei et al, 2015), and rice (Yan et al, 2015).
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