Small RNA and degradome sequencing used to elucidate the basis of tolerance to salinity and alkalinity in wheat

Abstract Background Soil 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. Results The 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. Conclusions This 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.