Modulation of organic acids and sugar content in tomato fruits by an abscisic acid‐regulated transcription factor

Abstract

Casaretto, JA (reprint author), Univ Talca, Inst Biol Vegetal & Biotecnol, Talca, Chile.Growing evidence suggests that the phytohormone abscisic acid (ABA) plays a role in fruit development. ABA signaling components of developmental programs and responses to stress conditions include the group of basic leucine zipper transcriptional activators known as ABA-response element binding factors (AREBs/ABFs). AREB transcription factors mediate ABA-regulated gene expression involved in desiccation tolerance and are expressed mainly in seeds and in vegetative tissues under stress; however, they are also expressed in some fruits such as tomato. In order to get an insight into the role of ABA signaling in fruit development, the expression of two AREB-like factors were investigated during different developmental stages. In addition, tomato transgenic lines that overexpress and downregulate one AREB-like transcription factor, SlAREB1, were used to determine its effect on the levels of some metabolites determining fruit quality. Higher levels of citric acid, malic acid, glutamic acid, glucose and fructose were observed in SlAREB1-overexpressing lines compared with those in antisense suppression lines in red mature fruit pericarp. The higher hexose concentration correlated with increased expression of genes encoding a vacuolar invertase (EC 3.2.1.26) and a sucrose synthase (EC 2.4.1.13). No significant changes were found in ethylene content which agrees with the normal ripening phenotype observed in transgenic fruits. These results suggest that an AREB-mediated ABA signal affects the metabolism of these compounds during the fruit developmental program

The Basic Leucine Zipper Transcription Factor ABSCISIC ACID RESPONSE ELEMENT-BINDING FACTOR2 Is an Important Transcriptional Regulator of Abscisic Acid-Dependent Grape Berry Ripening Processes

“…In this context, AREB/ABF bZIP transcription factors that act as regulators of ABA and stress responses in plants are good candidates for the regulation of ABA-mediated fruit ripening. Moreover, a possible role of AREB/ABF transcription factors has been reported for the ripening climacteric fruits (Bastías et al, 2011).…”

“…The phylogenetic tree represents VvABF2 (black circle) and its orthologs (boldface) from the A subgroup of bZIP transcription factors in Arabidopsis (AT) and grape (VIT). The closest ortholog of VvABF2 from tomato (SlAREB1; Bastías et al, 2011) and representative Arabidopsis bZIP transcription factors from other bZIP subgroups (subgroup G, AtGBF2; H, AtHY5; I, AtbZIP29; E, AtbZIP34; D, AtTGA3; S, AtATB2; B, bZIP28; and C, AtBZO2H2) are also reported according to Jakoby et al (2002) and Corrêa et al (2008). The gene identifiers as well as synonyms (published names) are given.…”

The effect of phytohormones on the growth, cellulose production and pellicle properties of Gluconacetobacter xylinus ATCC 53582

“…In plants, ABA serves to induce senescence while auxins, giberellins and cytokinins can delay senescence in a concentration-dependent manner. 28,[44][45][46] IAA is a plant growth promoting hormone synthesized by many plant growth promoting bacteria including Gluconacetobacter diazotrophicus. 35,47 In contrast to G. diazotrophicus, G. xylinus does not synthesize IAA; however, exogenously supplied, this hormone greatly influenced growth and development.…”

ABA-deficiency and molecular mechanisms involved in the dehydration response and ripening of citrus fruit

“…Work performed in citrus fruit further revealed a crosstalk between ABA and ethylene for triggering fruit abscission (Gómez-Cadenas et al, 2000;Agustí et al, 2008). Results obtained in mature sweet cherry, which are very prone to abscission, suggested, however, that the ABA increase observed at late stages of fruit ripening was more likely related to Introduction ethylene in the development and ripening of climacteric fruits, such as nectarine and tomato, is well known (Ziliotto et al, 2008;Zhang et al, 2009b) since several reports suggested that the ABA accumulation just before the peak of ethylene production triggers ethylene biosynthesis responsible for climacteric fruit ripening (Zhang et al, 2001;Zhang et al, 2009a;Bastías et al, 2011). The role of ABA in non-climacteric fruit is less clear in spite of several reports have correlated the increase in ABA levels during fruit ripening with the increase in sugars content and the decrease in organic acids or fruit colouration, which are classical traits occurring during fruit maturation (Giribaldi et al, 2010;Chai et al, 2011;Ren et al, 2011;Gambetta et al, 2011;Li et al, 2012b).…”

“…This hormone is also crucial for the regulation of a number of physiological processes under non-stressful conditions (Finkelstein et al, 2002;Gómez-Cadenas et al, 2002;Shinozaki and Yamaguchi-Shinozaki, 2007;Kim et al, 2012). The involvement of ABA in the ripening of both climacteric and non-climacteric fruits has been also studied (Lafuente et al, 1997;Alférez and Zacarías, 1999;Zhang et al, 2001;Rodrigo et al, 2003;Zhang et al, 2009a;Sun et al, 2010;Bastías et al, 2011;Jia et al, 2011). In climacteric fruits, ABA accumulates just before the peak of ethylene production, triggering ethylene biosynthesis responsible for fruit ripening (Zhang et al, 2009b).…”