The Occurrence of Abscisic Acid and Abscisyl-β-d-Glucopyranoside in Developing and Mature Citrus Fruit as Determined by Enzyme Immunoassay

Abstract

The contents of (+)-cis-abscisic acid (ABA) and alkaline-hydrolyzable ABA-conjugate(s) ABA and water-soluble ABA-conjugates are important components of the growth inhibitor complex of many plants (1). The levels of these compounds have been reported to increase during fruit maturation and this observation has given rise to speculation on their role in fruit ripening and other related developmental phenomena (16). Increases in ABA and ABA-conjugates in citrus fruit have been related to exocarp senescence and the transition of chloroplasts to chromoplasts that occurs in this tissue (6,7,23). Accumulation of ABA and possibly the 2,trans-isomer of ABA in fruit has been postulated to influence bud dormancy and contributed to biennial-bearing which is common in many citrus varieties (5, 10). Numerous reports on the endogenous level of growth inhibitors in citrus fruit have appeared in the literature (see Ref. 4 for review). For the most part, these reports have relied upon relatively nonspecific bioassays for the estimation of ABA. Although reports using GC or GC-MS have also appeared, the requirements for sample prepurification make routine analyses difficult by these methods. Furthermore, the variable sample loss incurred ' Supported from funds provided by the

GAMT2 Encodes a Methyltransferase of Gibberellic Acid That is Involved in Seed Maturation and Germination in Arabidopsis

“…From this point of view, the conversion from GA to Me-GA might be a part of a regulatory network for GA-ABA homeostasis during seed maturation and germination. The conjugation of phytohormones with methyl groups, sugars and amino acids has been proven as an effective way to regulate the phytohormones homeostasis in planta (Cohen and Bandurski 1982;Harris and Dugger 1986;Jackson et al 2001;Hou et al 2003;Qin et al 2005). For auxins, conjugates with sugars and amino acids were proven to be inactive (Cohen and Bandurski 1982) while MeIAA is more potent when exogenously applied (Qin et al 2005).…”

Mechanism of Carotenoid Accumulation in Citrus Fruit

“…NCED proteins from other plant species were imported into the chloroplast (Iuchi et al, 2000;Qin and Zeevaart, 1999;Tan et al, 2001Tan et al, , 2003. A previous report suggested that, in the flavedo, the increases in ABA levels were associated with senescence and development of the chromoplast (Harris and Dugger, 1986). Rodrigo et al (2003) reported that ABA may play a role in the regulation of the rate of fruit coloration in citrus fruit because fruits of the ABAdeficient mutant exhibited a delay in the rate of degreening.…”

Germination Inhibitor inCitrus unshuFruit Peelings: (+)-Abscisyl β-D-Glucopyranoside

“…It has been reported that a small increase in abscisic acid and a large increase in its glucose ester were observed in the fruit exocarp during the natural color transition from green to orange. 5) This suggests that increased abscisic acid is converted to the glucose ester, which would be physiologically inactive. The glucose ester of abscisic acid would have a different role from that of the other terpenoid glycosides which have been isolated from citrus fruit peelings.…”