This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Huff, A. Search for Related Content PubMed PubMed Citation Articles by Huff, A. Agricola Articles by Huff, A.

Articles

Sugar Regulation of Plastid Interconversions in Epicarp of Citrus Fruit ¹

Department of Plant Sciences, University of Arizona, Tucson, Arizona 85721

Seasonal transformations between chloroplasts and chromoplasts, as measured by changes in chlorophyll content, in the epicarp of degreening and regreening Citrus sinensis (L.) Osbeck cv Valencia fruit closely parallelled the accumulation and later loss of soluble sugars. At any stage of development, reversing the relative soluble sugar content in the epicarp by culturing pericarp segments on agar media with low (15 millimolar) or high (150 millimolar) sucrose concentrations reversed the direction of change in chlorophyll content. Fruit of C. madurensis Lour., which mature year around and do not regreen, also accumulated soluble sugars in the pericarp as degreening was initiated.

The epicarp of C. sinensis fruit accumulated nitrogen, but total nitrogen concentrations and amino acid concentrations changed little, during degreening and regreening of C. sinensis fruit. Cessation of nitrogen fertilization reduced the tendency of pericarp segments to regreen in vitro during subsequent years, but regreening tendency was restored by inclusion of KNO₃ in the media.

It is concluded that chloroplasts become chromoplasts and citrus fruit degreen partially in response to the accumulation of sugars in the epicarp and that the reverse transformation accompanying regreening of certain citrus species occurs when accumulated sugars disappear. Change in nitrogen flux to the fruit is probably not a factor in regulating seasonal transformations, but an abundance of nitrogen in the epicarp diminishes the effects of high sugar concentrations in inducing transformation of chloroplasts to chromoplasts, thereby retarding degreening and promoting regreening.

This article has been cited by other articles:

				M. W. Fidelibus, K. E. Koch, and F. S. Davies Gibberellic Acid Alters Sucrose, Hexoses, and Their Gradients in Peel Tissues During Color Break Delay in 'Hamlin' Orange J. Amer. Soc. Hort. Sci., November 1, 2008; 133(6): 760 - 767. [Abstract] [Full Text] [PDF]