MicroRNA expression under phosphate deficiency stress in red clover (Trifolium pratense L.): a three-year field experiment

Abstract

Phosphate deficiency is a stress factor often limiting crop growth and development. The aim of this study was to determine the expression of microRNAs (miRNAs) in response to long-term phosphate stress in red clover populations in field conditions. The sensitivity of six red clover populations to phosphate stress was determined in a three-year field experiment. The results revealed that the declines in hay yield and quality under phosphate stress were less pronounced for two populations compared to the other four. Molecular analysis revealed significant down-regulation (miRNA156, miRNA171 and miRNA2111) and up-regulation (miRNA399) in the phosphate stress-tolerant populations exposed to phosphate stress, but no changes were observed in the non-phosphate stress-tolerant populations. The results collectively suggest that miRNA156, miRNA171, miRNA399 and miRNA2111 could be responsible for tolerance to phosphate limited conditions in some red clovers. These miRNAs could be used for the development of red clover plants that are tolerant of phosphate-deficient soils. In addition, since phosphate stress-tolerant populations should require less phosphate fertiliser, they would have the potential to mitigate environmental pollution from farming soils with elevated phosphate levels.