Profiling of cold-stress-responsive miRNAs in rice by microarrays.

MicroRNAs (miRNAs) are small single-stranded RNAs with a length of about 21 nt; these non-coding RNAs regulate developmental and stress responses in plants by cleaving mRNAs. Cold stress is one of the most severe abiotic stresses and adversely affects rice yields by restraining sowing time, causing tissue damage, and stunting growth. Although many miRNAs have been identified in rice, little is known about the role of miRNAs in the response to cold stress. In this study, we identified 18 cold-responsive rice miRNAs using microarrays. Most were down-regulated. Members of the miR-167 and miR-319 families showed similar profiles. Intriguingly, members of miR-171 family showed diverse expression patterns. Three miRNAs derived from transposable element sequence were clustered within an intron and proved to be co-transcribed with the host gene only under cold stress. The existence of hormone-responsive elements in the upstream regions of the cold-responsive miRNAs indicates the importance of hormones in this defense system mediated by miRNAs. Two miRNA target pairs validated by 5' RACE showed opposite expression profiles under cold stress. Finally, the predicted stress-related targets of these miRNAs provided further evidence supporting our results. These findings confirm the role of miRNAs as ubiquitous regulators in rice.

Lv DK ，Bai X ，Li Y ，Ding XD ，Ge Y ，Cai H ，Ji W ，Wu N ，Zhu YM ... -  《-》

Stress-responsive microRNAs in Populus.

Lu S ，Sun YH ，Chiang VL 《-》

Identification of novel stress-regulated microRNAs from Oryza sativa L.

MicroRNAs (miRNAs) are a type of small non-coding RNA found in eukaryotes. They play a key role in gene expression by down-regulating gene expression and are involved in the environment stress response in plants. Although a large number of miRNAs have been identified from Arabidopsis, few studies have focused on Oryza sativa miRNAs, especially on stress-related miRNAs. Five cDNA libraries of small RNAs from rice seedlings treated with cold, dehydration, salinity, and abscisic acid (ABA), as well as wild-type seedlings, were constructed. Seven rice novel miRNAs were identified by Northern analysis, and their expression patterns under different stress treatments were determined. Results showed that the expression of several novel miRNAs was regulated by one or more stress treatments. Our identification of novel stress-related miRNAs in rice suggests that these miRNAs might be involved in rice stress response pathways.

Jian X ，Zhang L ，Li G ，Zhang L ，Wang X ，Cao X ，Fang X ，Chen F ... -  《-》

Heavy metal-regulated new microRNAs from rice.

MicroRNAs (miRNAs) are a novel class of short, endogenous non-coding small RNAs that have the ability to base pair with their target mRNAs to repress their translation or induce their degradation in both plants and animals. To identify heavy metal stress-regulated novel miRNAs, we constructed a library of small RNAs from rice seedlings that were exposed to toxic levels of cadmium (Cd(2+)). Sequencing of the library and subsequent analysis revealed 19 new miRNAs representing six families. These cloned new rice miRNAs have sequence conservation neither in Arabidopsis nor in any other species. Most of the new rice miRNAs were up- or down-regulated in response to the metal exposure. On the base of sequence complementarity, a total of 34 miRNA targets were predicted, of which 23 targets are functionally annotated and the other 11 records belong to unknown proteins. Some predicted targets of miRNAs are associated with the regulation of the response to heavy metal-induced stresses. In addition to the new miRNAs, we detected nine previously reported miRNAs and 56 other novel endogenous small RNAs in rice. These findings suggest that the number of new miRNAs in rice is unsaturated and some of them may play critical roles in plant responses to environmental stresses.

Huang SQ ，Peng J ，Qiu CX ，Yang ZM ... -  《-》

Identification of drought-induced microRNAs in rice.

Zhao B ，Liang R ，Ge L ，Li W ，Xiao H ，Lin H ，Ruan K ，Jin Y ... -  《BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS》