Agriculture & Food, Volume 6, 2018

Abstract: 2,4-Dichlorphenoxyacetic acid (2,4-D) is a synthetic auxin analogue, mainly used as a herbicide that is absorbed through the leaves and translocate in the plant. It is a substrate for LAX-transporters and about 75% thereof requires "influx" carrier to enter the cell, especially if its concentration outside the cell is low. Phosphorus is one of the most important macronutrients required for normal development of plants. The phytohormones auxin and strigolactone participate in the plant response associated with the phosphate signalling. The aim of the study was to monitor the effect and influence of exogenous application of 2,4-D on the growth and development of root system and expression level of the analysed MtLAX3 gene in extreme phosphate conditions. For this purpose, seeds from T1 Medicago truncatula plants with modified auxin transport and wild type plants, were germinated and subsequently grown in phosphate deprivation or excess conditions, and additionally treated with 2,4-D. Furthermore, relative transcript level of the strigolactone gene MtMAX2 was examined in the same plants to reveal the interaction of auxin and strigolactones in these conditions. The expression of GUS reporter gene fused to MtLAX3 promoter was traced in different organs and tissues by histochemical GUS assay before and after application of exogenous 2,4-D.