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Abiotic stress miRNomes in the Triticeae

View Article: PubMed Central - PubMed

ABSTRACT

The continued growth in world population necessitates increases in both the quantity and quality of agricultural production. Triticeae members, particularly wheat and barley, make an important contribution to world food reserves by providing rich sources of carbohydrate and protein. These crops are grown over diverse production environments that are characterized by a range of environmental or abiotic stresses. Abiotic stresses such as drought, heat, salinity, or nutrient deficiencies and toxicities cause large yield losses resulting in economic and environmental damage. The negative effects of abiotic stresses have increased at an alarming rate in recent years and are predicted to further deteriorate due to climate change, land degradation, and declining water supply. New technologies have provided an important tool with great potential for improving crop tolerance to the abiotic stresses: microRNAs (miRNAs). miRNAs are small regulators of gene expression that act on many different molecular and biochemical processes such as development, environmental adaptation, and stress tolerance. miRNAs can act at both the transcriptional and post-transcriptional levels, although post-transcriptional regulation is the most common in plants where miRNAs can inhibit the translation of their mRNA targets via complementary binding and cleavage. To date, expression of several miRNA families such as miR156, miR159, and miR398 has been detected as responsive to environmental conditions to regulate stress-associated molecular mechanisms individually and/or together with their various miRNA partners. Manipulation of these miRNAs and their targets may pave the way to improve crop performance under several abiotic stresses. Here, we summarize the current status of our knowledge on abiotic stress-associated miRNAs in members of the Triticeae tribe, specifically in wheat and barley, and the miRNA-based regulatory mechanisms triggered by stress conditions. Exploration of further miRNA families together with their functions under stress will improve our knowledge and provide opportunities to enhance plant performance to help us meet global food demand.

No MeSH data available.


Major steps in miRNA biogenesis. The MIR loci in the genome are transcribed through the action of RNA polymerase II, or in some cases RNA polymerase III, and forms the pri-miRNA structure. Pri-miRNA is then processed into pre-miRNA through the action of DCL-1 and its interacting partners. Mature miRNA/miRNA* duplex from the pre-miRNA may be generated via two different mechanisms: stem-to-loop or loop-to-base. Mature miRNA duplex may undergo some biochemical changes before it is transported to the cytoplasm through the activity of HASTY. Mature plant miRNAs are methylated by HEN1 before they are exported to the cytoplasm. The exported mature miRNA duplex is separated, and functional mature miRNA loads onto the RISC complex in order to regulate the expression of its target transcript
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Fig2: Major steps in miRNA biogenesis. The MIR loci in the genome are transcribed through the action of RNA polymerase II, or in some cases RNA polymerase III, and forms the pri-miRNA structure. Pri-miRNA is then processed into pre-miRNA through the action of DCL-1 and its interacting partners. Mature miRNA/miRNA* duplex from the pre-miRNA may be generated via two different mechanisms: stem-to-loop or loop-to-base. Mature miRNA duplex may undergo some biochemical changes before it is transported to the cytoplasm through the activity of HASTY. Mature plant miRNAs are methylated by HEN1 before they are exported to the cytoplasm. The exported mature miRNA duplex is separated, and functional mature miRNA loads onto the RISC complex in order to regulate the expression of its target transcript

Mentions: The initial step of miRNA biogenesis is transcription of the primary miRNA which mostly resides in the intergenic regions although a few miRNAs originate from the intronic or exonic sequences of protein-coding genes (Colaiacovo et al., 2012; Q. Liu, 2012). In addition, MIR loci may be located within transposable elements (TEs) where the processed miRNAs are called “transposable element-related miRNAs (TE-miRs)” (Li et al. 2011; Lucas and Budak 2012; Kurtoglu et al. 2014). Primary transcript (pri-miRNA), which is synthesized by RNA polymerase II (in some cases RNA polymerase III might take place), folds back into an imperfect hairpin, stem-loop, structure (Fig. 2). The stem-loop of the primary transcript is further recognized by the members of the DCL family of ribonucleases to form the precursor miRNAs (pre-miRNAs) and mature miRNA. The DCL1-mediated cleavage of the pri-miRNA is assisted by DCL1 interacting proteins, hyponastic leaves 1 (HYL1), serrate (SE), and nuclear cap-binding complex (CBC). While DCL1 and HYL1 are specific to the miRNA biogenesis machinery, SE and CBC have broader functions in mRNA metabolism (Voinnet, 2009). Non-lethal mutations of dcl1, hyl1, and se revealed that nuclear complex formation through these proteins is crucial for precise processing of pri-miRNAs into pre-miRNAs (Jones-Rhoades et al. 2006; Liu et al. 2011). Additionally, several studies have shown the importance of different CBP elements such as CBP20 and CBP80 together with SE in pri-miRNA processing (Kim et al. 2008; Laubinger et al. 2008). Although the contribution of these proteins in miRNA biogenesis has been found, their main functions remain elusive.Fig. 2


Abiotic stress miRNomes in the Triticeae
Major steps in miRNA biogenesis. The MIR loci in the genome are transcribed through the action of RNA polymerase II, or in some cases RNA polymerase III, and forms the pri-miRNA structure. Pri-miRNA is then processed into pre-miRNA through the action of DCL-1 and its interacting partners. Mature miRNA/miRNA* duplex from the pre-miRNA may be generated via two different mechanisms: stem-to-loop or loop-to-base. Mature miRNA duplex may undergo some biochemical changes before it is transported to the cytoplasm through the activity of HASTY. Mature plant miRNAs are methylated by HEN1 before they are exported to the cytoplasm. The exported mature miRNA duplex is separated, and functional mature miRNA loads onto the RISC complex in order to regulate the expression of its target transcript
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC5383695&req=5

Fig2: Major steps in miRNA biogenesis. The MIR loci in the genome are transcribed through the action of RNA polymerase II, or in some cases RNA polymerase III, and forms the pri-miRNA structure. Pri-miRNA is then processed into pre-miRNA through the action of DCL-1 and its interacting partners. Mature miRNA/miRNA* duplex from the pre-miRNA may be generated via two different mechanisms: stem-to-loop or loop-to-base. Mature miRNA duplex may undergo some biochemical changes before it is transported to the cytoplasm through the activity of HASTY. Mature plant miRNAs are methylated by HEN1 before they are exported to the cytoplasm. The exported mature miRNA duplex is separated, and functional mature miRNA loads onto the RISC complex in order to regulate the expression of its target transcript
Mentions: The initial step of miRNA biogenesis is transcription of the primary miRNA which mostly resides in the intergenic regions although a few miRNAs originate from the intronic or exonic sequences of protein-coding genes (Colaiacovo et al., 2012; Q. Liu, 2012). In addition, MIR loci may be located within transposable elements (TEs) where the processed miRNAs are called “transposable element-related miRNAs (TE-miRs)” (Li et al. 2011; Lucas and Budak 2012; Kurtoglu et al. 2014). Primary transcript (pri-miRNA), which is synthesized by RNA polymerase II (in some cases RNA polymerase III might take place), folds back into an imperfect hairpin, stem-loop, structure (Fig. 2). The stem-loop of the primary transcript is further recognized by the members of the DCL family of ribonucleases to form the precursor miRNAs (pre-miRNAs) and mature miRNA. The DCL1-mediated cleavage of the pri-miRNA is assisted by DCL1 interacting proteins, hyponastic leaves 1 (HYL1), serrate (SE), and nuclear cap-binding complex (CBC). While DCL1 and HYL1 are specific to the miRNA biogenesis machinery, SE and CBC have broader functions in mRNA metabolism (Voinnet, 2009). Non-lethal mutations of dcl1, hyl1, and se revealed that nuclear complex formation through these proteins is crucial for precise processing of pri-miRNAs into pre-miRNAs (Jones-Rhoades et al. 2006; Liu et al. 2011). Additionally, several studies have shown the importance of different CBP elements such as CBP20 and CBP80 together with SE in pri-miRNA processing (Kim et al. 2008; Laubinger et al. 2008). Although the contribution of these proteins in miRNA biogenesis has been found, their main functions remain elusive.Fig. 2

View Article: PubMed Central - PubMed

ABSTRACT

The continued growth in world population necessitates increases in both the quantity and quality of agricultural production. Triticeae members, particularly wheat and barley, make an important contribution to world food reserves by providing rich sources of carbohydrate and protein. These crops are grown over diverse production environments that are characterized by a range of environmental or abiotic stresses. Abiotic stresses such as drought, heat, salinity, or nutrient deficiencies and toxicities cause large yield losses resulting in economic and environmental damage. The negative effects of abiotic stresses have increased at an alarming rate in recent years and are predicted to further deteriorate due to climate change, land degradation, and declining water supply. New technologies have provided an important tool with great potential for improving crop tolerance to the abiotic stresses: microRNAs (miRNAs). miRNAs are small regulators of gene expression that act on many different molecular and biochemical processes such as development, environmental adaptation, and stress tolerance. miRNAs can act at both the transcriptional and post-transcriptional levels, although post-transcriptional regulation is the most common in plants where miRNAs can inhibit the translation of their mRNA targets via complementary binding and cleavage. To date, expression of several miRNA families such as miR156, miR159, and miR398 has been detected as responsive to environmental conditions to regulate stress-associated molecular mechanisms individually and/or together with their various miRNA partners. Manipulation of these miRNAs and their targets may pave the way to improve crop performance under several abiotic stresses. Here, we summarize the current status of our knowledge on abiotic stress-associated miRNAs in members of the Triticeae tribe, specifically in wheat and barley, and the miRNA-based regulatory mechanisms triggered by stress conditions. Exploration of further miRNA families together with their functions under stress will improve our knowledge and provide opportunities to enhance plant performance to help us meet global food demand.

No MeSH data available.