Abstract
The microRNA319 (miR319) family is conserved among diverse plant species. In rice (Oryza sativa L.), the miR319 gene family is comprised of two members, Osa-miR319a and Osa-miR319b. We found that overexpressing Osa-miR319b in rice resulted in wider leaf blades and delayed development. Here, we focused on the biological function and potential molecular mechanism of the Osa-miR319b gene in response to cold stress in rice. The expression of Osa-miR319b was down-regulated by cold stress, and the overexpression of Osa-miR319b led to an enhanced tolerance to cold stress, as evidenced by higher survival rates and proline content. Also, the expression of a handful of cold stress responsive genes, such as DREB1A/B/C, DREB2A, TPP1/2, was increased in Osa-miR319b transgenic lines. Furthermore, we demonstrated the nuclear localization of the transcription factors, OsPCF6 and OsTCP21, which may be Osa-miR319b-targeted genes. We also showed that OsPCF6 and OsTCP21 expression was largely induced by cold stress, and the degree of induction was obviously repressed in plants overexpressing Osa-miR319b. As expected, the down-regulation of OsPCF6 and OsTCP21 resulted in enhanced tolerance to cold stress, partially by modifying active oxygen scavenging. Taken together, our findings suggest that Osa-miR319b plays an important role in plant response to cold stress, maybe by targeting OsPCF6 and OsTCP21.
Highlights
Rice is a kind of important food and economic crop, and its production is frequently affected by cold stress
We investigated the roles of OsPCF6 and OsTCP21 in plant cold response and reactive oxygen species (ROS) accumulation under cold stress by using overexpression and RNA interference (RNAi) transgenic rice
We focused on the OsamiR319b gene, which was obviously down-regulated under cold stress
Summary
Rice is a kind of important food and economic crop, and its production is frequently affected by cold stress. Cold stress is one of the most important limiting factors affecting rice production in temperate and high elevation areas [1]. During the early growth stages, cold stress severely inhibits rice seedling establishment and eventually leads to non-uniform maturation [2]. To understand the underlying molecular mechanisms of the cold stress response, many intensive studies have been performed. Several studies have reported the involvement of miRNAs and their target genes in plant responses to stress conditions [9,10,11]. The up- or downregulation of miRNAs modifies the transcript abundance of their target genes [12,13]
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