Abstract
BackgroundMicroRNA319 (miR319) acts as an essential regulator of gene expression during plant development and under stress conditions. Although the role of miR319a in regulating leaf development has been well studied in tomato (Solanum lycopersicum), the function of the recently discovered wild tomato Solanum habrochaites miRNA319d (sha-miR319d) remains poorly understood. In this study, we overexpressed sha-miR319d in cultivated tomato ‘Micro-Tom’ to further investigate its role in tomato temperature stress responses.ResultsUnder chilling or heat stress, sha-miR319d-overexpressing plants showed enhanced stress tolerance, including lower relative electrolyte leakage (REL), malondialdehyde (MDA) concentration, O2− generation and H2O2 concentration and higher chlorophyll contents and Fv/Fm values than wild-type (WT) plants. Overexpression of sha-miR319d enhanced the activities of superoxide dismutase (SOD) and catalase (CAT), with possible correlation with elevated expression levels of the genes FeSOD, CuZnSOD and CAT. Moreover, different expression levels of key genes involved in chilling (MYB83 and CBF1), heat (HsfA1a, HsfA1b and Hsp90), and reactive oxygen species (ROS) (ZAT12 and ZAT10) signaling in transgenic plants and WT were determined, suggesting a role for sha-miR319d in regulating tomato temperature stress via chilling, heat and ROS signaling. Silencing GAMYB-like1 increased tomato chilling tolerance as well as the expression levels of CBF1, CuZnSOD, CAT, APX1, APX2, ZAT12 and ZAT10. Additionally, overexpression of sha-miR319d in tomato caused plant leaf crinkling and reduced height.ConclusionsOverexpression of sha-miR319d confers chilling and heat stress tolerance in tomato. Sha-miR319d regulates tomato chilling tolerance, possibly by inhibiting expression of GAMYB-like1 and further alters chilling, heat and ROS signal transduction. Our research provides insight for further study of the role of sha-miR319d in tomato growth and stress regulation and lays a foundation for the genetic improvement of tomato.
Highlights
MicroRNA319 acts as an essential regulator of gene expression during plant development and under stress conditions
In the process of miRNA biosynthesis, changes in the AGO1 conformation, the removal of passenger strands in the miRNA/miRNA* double chain complex, and the formation of the RISC silencing complex all require the participation of Hsp90 dimers [24]. These results suggest a potential role for heat shock protein (Hsp) and heat shock transcription factors (Hsfs) in heat stress tolerance and miRNA biosynthesis
Our results reveal a positive role for sha-miR319d in chilling and heat stress tolerance regulation, with miR319 family members being responsible for the regulation of plant responses to temperature stress
Summary
MicroRNA319 (miR319) acts as an essential regulator of gene expression during plant development and under stress conditions. We overexpressed sha-miR319d in cultivated tomato ‘Micro-Tom’ to further investigate its role in tomato temperature stress responses. Increasing evidence suggests that miRNAs play a vital role in plant developmental growth as well as in the adaptation to various stress conditions [3,4,5,6,7,8]. High expression levels of OsamiR319 in transgenic rice (Oryza sativa) and creeping bentgrass (Agrostis stolonifera) increased plant tolerance to salinity and drought stress [10, 11], and OsamiR319-overexpressing lines showed enhanced chill tolerance [7, 12]. It has been suggested that the enhanced stress tolerance of miR319-overexpressing lines may be explained, at least in part, by morphological changes in leaves [12]
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