Regulation of color break in citrus fruits. Changes in pigment profiling and gene expression induced by gibberellins and nitrate, two ripening retardants
Regulation of color break in citrus fruits. Changes in pigment profiling and gene expression induced by gibberellins and nitrate, two ripening retardants
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DOI：
10.1021/jf0606712
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发表时间：
2006-06-28
影响因子：
6.1
通讯作者：
Talon, Manuel
中科院分区：
文献类型：
--
作者：
Alos, Enriqueta;Cercos, Manuel;Talon, Manuel
用硝酸盐和赤霉素两种外部后熟延缓剂，从成熟的绿色到破皮期，对柑橘果实进行反复处理。天然色变的特征在于叶绿素浓度的降低，β，ε-类胡萝卜素，β-胡萝卜素，新黄质和全E-紫黄质的减少，以及β，β-叶黄素[主要是（9 Z）-紫黄质和β-隐黄质]的增加。这两种延缓剂延缓了叶绿素耗竭和总类胡萝卜素积累，并改变了类胡萝卜素的组成。经处理的果实较长时间保持绿色果实的典型类胡萝卜素成分，并减少β，β-叶黄素积累。自然降解伴随着1-脱氧-D-木酮糖5-磷酸合酶（DXS）和香叶基香叶基还原酶（CHLP）的转录水平显着下降，而相反，脱镁叶绿酸a加氧酶（PaO）和八氢番茄红素合酶（PSY）基因表达增加。赤霉素和硝酸盐延迟DXS表达的减少和PaO和PSY转录本积累的诱导，而CHL P没有观察到差异。这些数据表明，这两个成熟延迟抑制自然PaO和PSY的表达，这表明一个机械的基础上，叶绿素水平升高和较低的类胡萝卜素浓度导致的赤霉素和氮处理和随之而来的颜色打破延迟在柑橘果皮。
Citrus clementina fruits were repeatedly treated on-tree from mature green until breaker stages with either nitrate or gibberellin, two retardants of external ripening. The natural color break was characterized by a reduction in chlorophyll concentration, a decrease in beta, epsilon-carotenoids, beta-carotene, neoxanthin, and all-E-violaxanthin, and an increase in beta,beta-xanthophylls [mainly (9Z)-violaxanthin and,beta-cryptoxanthin]. The two retardants delayed both chlorophyll depletion and total carotenoid accumulation and in addition altered carotenoid composition. Treated fruits maintained longer the typical carotenoid composition of green fruits and reduced beta,beta-xanthophyll accumulation. Natural degreening was accompanied by a marked decrease in transcript levels of 1-deoxy-D-xylulose 5-phosphate synthase (DXS) and geranylgeranyl reductase (CHL P) while, conversely, pheophorbide a oxygenase (PaO) and phytoene synthase (PSY) gene expression increased. Gibberellin and nitrate delayed the reduction of DXS expression and the induction of PaO and PSY transcript accumulation, while no differences in CHL P were observed. The data indicate that both ripening retardants repressed natural PaO and PSY expression, suggesting a mechanistic basis for the elevated levels of chlorophyll and lower carotenoid concentration resulting from the gibberellin and nitrogen treatments and the consequent color break delay in citrus fruit peels.