A study of calcium distribution and compartmentation in Brussels sprouts plants in relation to internal browning

• Main Author: Millar, F.
• Published: University of Aberdeen 1987
• Subjects: 571.2
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.593117

Internal Browning (IB), a physiological disorder of Brussels Sprouts characterised by necrosis of internal leaf tissue in the area above the meristem of the sprout button, is the cause of considerable annual financial loss to the Brussels Sprouts growing industry. An investigation is made of calcium uptake by and distribution within whole Brussels Sprouts plants and sprout buttons in relation to the occurrence of IB in the buttons, using Field plot and Glasshouse grown Brussels Sprouts plants---the latter grown to provide <SUP>45</SUP>Ca labelled material for efflux studies, and nutrient uptake data from unlabelled plants. When Sequential Extraction (SE) and Compartmental Analysis (CA) were compared as methods for producing useful information about distribution and compartmentation of calcium in sprout buttons, it was found that SE could only give an estimation of relative chemical forms of total cell calcium whereas CA revealed the quantitative distribution in and fluxes of ions between different cell compartments. SE did show that in tissue to which calcium transport is difficult or restricted, magnesium, being relatively more phloem-mobile, took the place of calcium; although if shortage of calcium is severe the amount of magnesium present may not be sufficient to maintain the integrity of cell walls and membranes. From the CA work, IB showed a link with a low calcium content in the Donnan free space (DFS), and it is suggested that a lack of calcium in the DFS leads to cell wall breakdown and the development of the visible symptoms of IB. Where sprout buttons not showing IB were found on the same plant as buttons showing the disorder, and the calcium content in the DFS of the former was still low, it is suggested that this points to a 'critical concentration' of calcium in the DFS below which IB occurs.