Endogenous phytohormone profiles in Pteris fern species differing in arsenic accumulating ability

Abstract Physiological and biochemical processes in plants are regulated by phytohormones. Phytohormone profiles are unknown in the fern family Pteridaceae . In this work, we analysed phytohormones in fronds and roots of three Pteris fern varieties with differing abilities in arsenic (As) accumulation. The ferns (hyperaccumulating P. cretica var. Albo-lineata and var. Parkerii, and non-hyperaccumulating P. straminea ) were cultivated in a pot experiment with low contaminated soil (As total 16 mg kg -1 , As water soluble 0.15 mg kg -1 ) for 185 days and harvested four times during growth. Phytohormone profiles were determined using high-performance liquid chromatography coupled to a hybrid triple quadrupole/linear ion trap mass spectrometer. We found twenty-five phytohormones and their structural and functional analogues (including growth and stress hormones) at detectable levels in fronds and roots. Interactions between growth hormones promoted the growth of ferns in the absence of environmental stress. Cytokinins of cis- zeatin type affected biomass yield, especially in the non-hyperaccumulator P. straminea . Phytohormone correlations between fern fronds and roots indicate a significant role for xylem-phloem transport and highlight the importance of transport in stress response. We observed similarities in phytohormone correlation profiles in the hyperaccumulators P. cretica var. Albo-lineata and var. Parkerii. In P. cretica var. Albo-lineata, interaction between jasmonic and abscisic acids was demonstrated, representing significant feedback of the defence response against oxidative stress by As. On the other hand, we did not find significant correlation among stress phytohormones in P. straminea . Profiling of growth and stress hormones in ferns confirms that they have specific phenotypic regulation. Hormonal regulations in the hyperaccumulator P. cretica var. Albo-lineata significantly differed from the non-hyperaccumulator P. straminea . A greater number of phytohormone correlations in the two hyperaccumulators suggests they use biosynthesised phytohormones more effectively.