Abstract
BackgroundSoil salinity and/or alkalinity impose a major constraint over crop yield and quality. An understanding of the molecular basis of the plant response to these stresses could inform the breeding of more tolerant varieties. The bread wheat cultivar SR3 exhibits an enhanced level of salinity tolerance, while SR4 is distinguished by its superior tolerance of alkalinity.ResultsThe small RNA and degradome sequencing was used to explore the miRNAs and corresponding targets associated with the superior stress tolerance of the SR lines. An examination of the small RNA content of these two closely related lines revealed the presence of 98 known and 219 novel miRNA sequences. Degradome libraries were constructed in order to identify the targets of the miRNAs, leading to the identification of 58 genes targeted by 26 of the known miRNAs and 549 targeted by 65 of the novel ones. The function of two of the stress-responsive miRNAs was explored using virus-induced gene silencing.ConclusionsThis analysis indicated that regulation mediated by both auxin and epigenetic modification can be important in determining both salinity and alkalinity tolerance, while jasmonate signaling and carbohydrate metabolism are important for salinity tolerance, as is proton transport for alkalinity tolerance.
Highlights
Soil salinity and/or alkalinity impose a major constraint over crop yield and quality
Responses of wheat to salinity and alkalinity stress When two-leaf-stage seedlings of Jinan 177 (JN177), SR3, and SR4 were exposed to either 200 mM NaCl or 100 mM Na2CO3/NaHCO3 for seven days, both SR lines tolerated more effectively than did JN177 to both stresses; SR3 exhibited a higher tolerance of salinity than SR4, while SR4 showed more tolerant to alkalinity than SR3 (Fig. 1 A,B)
SR3 plants experiencing salinity stress accumulated a much higher level of reactive oxygen species (ROS) than did either JN177 or SR4 plants, while under alkalinity stress, SR4 plants were better able to restrict the level of ROS than either JN177 or SR3 ones (Additional file 1: Figure S1)
Summary
Soil salinity and/or alkalinity impose a major constraint over crop yield and quality. Elucidating the molecular basis of the plant response to saline/alkaline conditions could accelerate the breeding of crop varieties better able to tolerate these stresses. Single-stranded RNA molecules ranging in length between 20 nt and 24 nt are referred to as microRNAs (miRNAs) Their biological significance lies in the observation that they negatively regulate up to 30% of eukaryotic genes, either through their guiding the cleavage of a complementary mRNA or via their inhibition of translation [8]. This mode of regulation acts in plants to modulate both development and the response to stress [9]. The abundance of miR398 is modulated by the oxidation status of plant tissue, thereby affecting the activity of target genes which encode scavengers of superoxide [11]
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