Are phytochrome-mediated effects on leaf growth, carbon partitioning and extractable sucrose-phosphatesynthase activity the mere consequence of stem-growthresponses in light-grown mustard?

YANOVSKY M.J.; SALERNO, G; SANCHEZ, RA; CASAL, JJ

JOURNAL OF EXPERIMENTAL BOTANY

OXFORD UNIV PRESS

Lugar: Oxford; Año: 1995 vol. 46 p. 753 - 757

0022-0957

Growth, carbohydrate pools and extractable sucrose-phosphate synthase (SPS) activity were studied in the leaves of light-grown mustard seedlings exposed tored or far-red end-of-day light pulses. Over a single dark period far-red, compared to red light (a) had no effect on leaf amounts of reducing sugars, sucrose, starch, and hemicellulose, (b) reduced cellulose accu-mulation in the leaves, and (c) caused a rapid promo-tion of extractable activity for SPS (lag ≻≻0.5 h, ≺1 h).Within a plant, one leaf of the first pair was coveredwhile the other leaf and the rest of the shoot were exposed to end-of-day far-red. The leaf exposed to far-red showed (a) lower rates of extension growth, (b)reduced accumulation of dry matter and structural carbohydrates, and (c) higher activities of SPS, thanthe leaf covered during the far-red pulse, despite the fact that both leaves were attached to the same inter-node. We conclude that phytochrome-mediated effectson leaf growth, carbon partitioning and extractable SPS activity are not the mere consequence of changes in in ternode growth and carbon demand.