Sulphate and micronutrients can modulate the expression levels of myrosinases in Sinapis alba plants |
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Authors: | Seetha Visvalingam,Torunn G. Hø nsi, Atle M. Bones |
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Affiliation: | S. Visvalingam, T. G. Hønsi (present address: Molecular Cell Biology, Dept of Biology, Univ. of Oslo, N‐0315 Oslo, Norway) and A. M. Bones (corresponding author, e‐mail;), UNIGEN Center for Molecular Biology and Dept of Botany, MTFS, Norwegian Univ. of Science and Technology, N‐7005 Trondheim, Norway. |
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Abstract: | The myrosinase‐glucosinolate system is considered to be a major component of the preformed defence system of Brassicaceae species. This hypothesis has influenced the belief that the components of the myrosinase‐glucosinolate system are present at fixed levels which are independent of environmental factors. In the present study we show that external availability of nutrients can modulate the expression levels of myrosinase enzymes (EC 3.2.3.1). Nutrients such as sulphate, iron, copper, zinc and manganese were tested for their modulation effect on myrosinase expression levels and activity in roots, stems, cotyledons and buds of Sinapis alba seedlings at four different developmental stages. The most sensitive organ was the bud where iron deficiency approximately doubled the myrosinase activity. Removal of sulphate and all four micronutrients reduced the myrosinase activity to approximately half of the activity in plants supplemented with all these nutrients. The myrosinase polypeptides can be divided into classes based on molecular mass after reduction. The nutritional status influenced mainly the 68‐kDa class of myrosinases as revealed by western blot and laser scan densitometry of the immunolabelled blots. |
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Keywords: | Micronutrients myrosinase (thioglucoside glucohydrolase, EC 3.2.3.1) Sinapis alba sulphate |
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