Effect of sucrose on ascorbate level and expression of genes involved in the ascorbate biosynthesis and recycling pathway in harvested broccoli florets.
The relationship between sucrose (Suc) and ascorbate (AA) metabolism was investigated in harvested broccoli (Brassica oleracea L. var. italica) florets. Decreases in both Suc and AA content were observed in broccoli florets 48 h after all the leaves were excised, but none were observed when the plants were kept intact or with leaves attached in a room at 20 degrees C. In harvested broccoli plants without leaves and roots, continuous absorption of a 10% (w/v) Suc solution from the cut surface of the stem suppressed the degreening of sepals and the loss of AA content in florets. The expression of the genes related to AA metabolism in chloroplasts and its biosynthesis were up-regulated by Suc feeding in broccoli florets. These data suggest that a decline in Suc leads to considerable damage not only to AA biosynthesis but also to the hydrogen peroxide-scavenging system in chloroplasts. In addition, the cessation of the Suc supply from leaves can be the main factor of AA degradation in harvested broccoli florets.
Nishikawa
Fumie
F
The United Graduate School of Agricultural Science, Gifu University (Shizuoka University), Yanagido, Gifu, 501-1193 Japan. fumien@affrc.go.jp
Kato
Masaya
M
Hyodo
Hiroshi
H
Ikoma
Yoshinori
Y
Sugiura
Minoru
M
Yano
Masamichi
M
D001205:Ascorbic Acid / Q000378:metabolism*; D001937:Brassica / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects* / Q000502:physiology; D018515:Plant Leaves / Q000502:physiology; D018517:Plant Roots / Q000502:physiology; D013395:Sucrose / Q000378:metabolism / Q000494:pharmacology*; D013997:Time Factors; D015854:Up-Regulation
D013395:Sucrose; D001205:Ascorbic Acid