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Retranslocation of boron in broccoli and lupin during early reproductive growth
Author(s) -
Marentes Eduardo,
Shelp Barry J.,
Vanderpool Richard A.,
Spiers Graeme A.
Publication year - 1997
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1997.tb04797.x
Subject(s) - phloem , inflorescence , xylem , lupinus , biology , brassica oleracea , brassica , botany , horticulture
The objective of the present study was to determine if boron (B) retranslocation depends on plant‐B status and external‐B supply. The stable 10 B isotope was supplied to the root system of broccoli ( Brassica oleracea var. italica Plenck cv. Commander) and lupin ( Lupinus albus L. cv. Ultra) plants to provide a quantitative picture of B distribution during early reproductive development. Regardless of the B regime (i.e. continuous supply with luxury, sufficient or deficient B; transfer at inflorescence emergence from either a luxury‐ or sufficient‐B supply to a deficient one) and whether 10 B was acquired before or during inflorescence development, a significant proportion of the B recovered in broccoli florets and lupin fruit was 10 B enriched. B acquired during inflorescence development was an important source of B for reproductive structures, but the relative importance of B acquired before and after inflorescence emergence appeared to be species dependent. The occurrence of B retranslocation was not dependent upon the induction of B deficiency. The concentrations of B in phloem exudates (0.38 to 0.03 mM) were 4‐ to 23‐fold those in xylem sap, and more similar to the concentrations in the reproductive structures (0.86 to 0.07 mM) than those in source leaves (2.4 to 0.19 mM). The decreasing acropetal gradient of tissue‐B concentrations with luxury‐B supply declined dramatically or was reversed in plants grown with sufficient or deficient B. The data are consistent with B being a phloem‐mobile element, and suggest that newly acquired B is particularly important during the early reproductive growth of plants.