Identification and expression analysis of miRNAs and elucidation of their role in salt tolerance in rice varieties susceptible and tolerant to salinity

Abstract

Soil salinization is a serious problem for cultivation of rice, as among cereals rice is the most salt sensitive crop, and more than 40% of the total agricultural land amounting to approximately 80 million ha the world over is salt affected. Salinity affects a plant in a varieties of ways, including ion toxicity, osmotic stress and oxidative damage. Since miRNAs occupy the top place in biochemical events determining a trait, understanding their role in salt tolerance is highly desirable, which may allow introduction of the trait in the rice cultivars of choice through biotechnological interventions. High throughput sequencing of sRNAs in the root and shoot tissues of the seedlings of the control and NaCl treated Pokkali, a salt-tolerant rice variety, identified 75 conserved miRNAs and mapped 200 sRNAs to the rice genome as novel miRNAs. Expression of nine novel miRNAs and two conserved miRNAs were confirmed by Northern blotting. Several of both conserved and novel miRNAs that expressed differentially in root and/or shoot tissues targeted transcription factors like AP2/ EREBP domain protein, ARF, NAC, MYB, NF-YA, HD-Zip III, TCP and SBP reported to be involved in salt tolerance or in abiotic stress tolerance in general. Most of the novel miRNAs expressed in the salt tolerant wild rice Oryza coarctata, suggesting conservation of miRNAs in taxonomically related species. One of the novel miRNAs, osa-miR12477, also targeted Lascorbate oxidase (LAO), indicating build-up of oxidative stress in the plant upon salt treatment, which was confirmed by DAB staining. Thus, salt tolerance might involve miRNAmediated regulation of 1) cellular abundance of the hormone signaling components like EREBP and ARF, 2) synthesis of abiotic stress related transcription factors, and 3) antioxidative component like LAO for mitigation of oxidative damage. The study clearly indicated importance of osa-miR12477 regulated expression of LAO in salt tolerance in the plant.

The miR528-AO Module Confers Enhanced Salt Tolerance in Rice by Modulating the Ascorbic Acid and Abscisic Acid Metabolism and ROS Scavenging

“…Salinity stress is one of the major limiting factors for plant growth and crop productivity, which garners increasing attention in that soil salinization becomes more and more serious worldwide owing to various natural and human activities. , Around the world, approximately 40% of the total agricultural lands are affected by soil salinization . High salinity causes severe damages to plant cells due to the detrimental osmotic, ionic, and secondary stresses by interfering with the ion balance of cells, inhibiting photosynthesis, and destroying the membrane system, protein synthesis, and metabolism pathways. , As known, the plasma membrane (PM) of a plant cell is the most sensitive to salinity. , Under salt stress, amounts of reactive oxygen species (ROS) are accumulated in the cell to attack the unsaturated fatty acids in the PM and disintegrate the membrane system, consequently resulting in plant death. , …”

Waterlogging-Stress-Responsive LncRNAs, Their Regulatory Relationships with miRNAs and Target Genes in Cucumber (Cucumis sativus L.)

“…In plants, miRNAs regulate proper tissue differentiation, organ and the vascular system development [ 16 ]. The increased expression of miRNA data was also demonstrated in plants subjected to various stress factors, such as drought [ 17 ], salinity [ 18 ], heat [ 19 ], nutrient deficiency [ 20 ], or heavy metals [ 21 ], which indicate that miRNAs are also involved in the adaptation mechanisms to stressful conditions [ 22 ]. When it comes to hypoxia, studies concerning identification of miRNAs were conducted in Arabidopsis thaliana [ 23 ], Zea mays [ 24 ], Populus tomentosa [ 25 ], Medicago sativa [ 26 ], Solanum habrochaites [ 27 ] and Cucumis sativus in the context of adventitious roots formation [ 28 ].…”

Biogenesis, Trafficking, and Function of Small RNAs in Plants

“…Moreover, in the chilling environment, sRNA mediates hypermethylation of the dormancy-related gene DAM and initiates dormancy ( Zhu et al, 2020a ). Meanwhile, Osa-miR12477 regulates the expression of gene LAO to tolerate salt and reduces oxidative damage ( Parmar et al, 2020 ). It has been reported that RdDM occurs in plants in response to abiotic stress environments, e.g., drought and salinization and biological stresses ( Erdmann and Picard, 2020 ; Liu and He, 2020 ; Kumar and Mohapatra, 2021 ; Table 1 ).…”