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Abscisic Acid Biosynthesis and Catabolism and Their Regulation

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Abscisic Acid Biosynthesis and Catabolism and Their Regulation Abscisic acid biosynthesis and catabolism and their regulation roles in fruit ripening La biosíntesis y el catabolismo del ácido abscísico y sus funciones de regulación en la maduración del fruto Yang FW & XQ Feng Abstract. Abscisic acid (ABA) plays a series of significant Resumen. El ácido abscísico (ABA) desempeña una serie de fun- physiology roles in higher plants including but not limited to pro- ciones importantes en la fisiología de las plantas superiores, incluyendo mote bud and seed dormancy, accelerate foliage fall, induce stoma- pero no limitado a promover la dormancia de yemas y semillas, acelerar tal closure, inhibit growth and enhance resistance. Recently, it has la caída de follaje, inducir el cierre de los estomas, inhibir el crecimiento been revealed that ABA also has an important regulator role in the y mejorar la resistencia. Recientemente, se ha revelado que el ABA tam- growth, development and ripening of fruit. In higher plants ABA is bién tiene un papel regulador importante en el crecimiento, desarrollo produced from an indirect pathway from the cleavage products of y maduración de la fruta. En las plantas superiores ABA se produce a carotenoids. The accumulation of endogenous ABA levels in plants partir de una vía indirecta a partir de los productos de excisión de caro- is a dynamic balance controlled by the processes of biosynthesis tenoides. La acumulación de los niveles endógenos de ABA en las plan- and catabolism, through the regulation of key ABA biosynthetic tas es un equilibrio dinámico controlado por los procesos de biosíntesis gene and enzyme activities. It has been hypothesized that ABA y catabolismo, a través de la regulación de las actividades clave de en- levels could be part of the signal that trigger fruit ripening, and that zimas y genes relacionados con la biosíntesis de ABA. Se ha planteado ABA may play an important role in the regulation of ripening and la hipótesis de que los niveles de ABA podrían ser parte de la señal que senescence of both non-climacteric and climacteric fruit. The ex- desencadena la maduración del fruto, y que ABA puede desempeñar un pensive costs of natural ABA and labile active ABA for its chemical papel importante en la regulación de la maduración y senescencia de la synthesis limit its application in scientific research and agricultural fruta tanto no climatérica como climatérica. Los altos precios de ABA production. These findings that ABA has various of important roles natural y lábil activo de la síntesis de ABA químico limitan su aplica- in the regulation of growth and development, quality formation, ción en investigaciones científicas y la producción agrícola. El hecho de coloring and softening, ripening and senescence of fruit, are pro- que ABA tiene una variedad de roles importantes en la regulación del viding opportunities and challenges for Horticultural Science. This crecimiento y desarrollo, y la determinación de la calidad, color, ablan- is to elucidate the specific mechanism of response and biosynthe- damiento, maduración y senescencia de la fruta, están proporcionando sis, signal transduction, and receptor recognition of ABA in fruit, oportunidades y desafíos en el campo de las Ciencias Hortícolas. Estas employing comprehensive research methods, such as molecular bi- investigaciones son para dilucidar el mecanismo específico de respuesta ology, plant physiology and molecular genetics. Further and more y biosíntesis, transducción de señales, y reconocimiento del receptor de in-depth research about ABA has a great, realistic significance for ABA en la fruta, empleando métodos de investigación integrales, tales knowing the mechanisms behind the process of fruit ripening. como la biología molecular, la fisiología vegetal y la genética molecular. Se necesita investigación adicional y en profundidad sobre ABA, la que Keywords: Abscisic acid (ABA); Biosynthesis; Catabolism; tiene una gran importancia realista para conocer los mecanismos invo- Regulation; Fruit; Ripening. lucrados en la maduración de la fruta. Palabras clave: Ácido abscísico; Biosíntesis; Catabolismo; Regulación; Fruta; Maduración. Institute of Fruit and Vegetable Storage & Processing, Food Science Research Institute, Bohai University. No. 19 Keji Road, Taihe District, Jinzhou, Liaoning 121013, China. Address Correspondence to: Fang-wei Yang, e-mail: [email protected] ; Prof. Xu-qiao Feng, e-mail: [email protected] Recibido / Received 23.IX.2014. Aceptado / Accepted 5.X.2014. FYTON ISSN 0031 9457 (2015) 84: 444-453 Abscisic acid regulation of fruit ripening 445 INTRODUCTION ly from three C15 precursors or indirectly from those C40 carotenoids. Both direct and indirect pathways begin with Abscisic acid (ABA) was first discovered and identified as Mevalonic acid (MVA) which is converted to Isopentenyl a substance controlling higher plant physiological processes diphosphate (IPP) or Dimethylallyl diphosphate (DMAPP) in the 1960s by several research groups. Thereafter, articles and Farnesyl pyrophosphate (FPP) by a series of biochemical and reviews of its discovery, structure, chemistry properties reactions and changes (Walton & Li, 1995). At this point, and biological functions were published. To date, ABA, indole three FPPs can form ABA by cyclization and oxidation in the acetic acid (IAA), gibberellins (GA), cytokinins (CTK) and direct pathway. However, in the indirect pathway, FPP con- ethylene (ETH) are recognized as five classic plant hormones tinues synthesis to Geranylgeranyl pyrophosphate (GGPP) ζ which regulate a multitude of significant plant physiological and C40 carotenoids (e.g., phytoene, -carotene, lycopene and β processes. These processes include, but are not limited to ab- -carotene) until appears the important precursor-Xanthoxin. scission, dormancy, germination, growth, ripening, root geot- In higher plants, the sesquiterpenoid ABA is produced from ropism, and stomatal functions (Taiz & Zeiger, 2006; Hop- an indirect pathway from the cleavage products of C40 carot- kins & Hüner, 2008). ABA is widely distributed in higher enoids (Schwartz et al., 2003; Galpaz et al., 2008). plants, and a variety of young and aging organs and tissues. Thus, there are two ABA biosynthesis pathways in na- It plays an important role in plant growth and development, ture (Seo & Koshiba, 2002; Nambara & Marion-Poll, 2005; such as the promotion of organ loss, bud and seed dormancy, Finkelstein, 2013). One is the C15 direct pathway. Three stomatal closure and increased plant resistance (Xiong et al., isopentenyl polymerizate into C15 precursors-FPP, by the 2002; Taiz & Zeiger, 2006; Hopkins & Hüner, 2008). In re- cyclization and oxidation FPP formed directly C15 ABA cent years, several studies have found that ABA is a key plant (Milborrow, 2001). The other is the C40 indirect pathway in hormone in the regulation of fruit ripening and senescence, higher plants. Further studies have identified the probable and the controlling mechanisms of such processes are be- biosynthesis pathways as cleavaging from C40 carotenoids. ing revealed gradually in detail (Rodrigo et al., 2006; Lund First, MVA polymerizates into C40 carotenoids in the plastid et al., 2008; Jia et al., 2011; Li et al., 2011). More and more (Walton & Li, 1995; Rodrigo et al., 2013; Ohmiya, 2013). ζ researchers believe that ABA plays an important role in the Second, C40 carotenoids (phytoene, -carotene, lycopene β growth and development, quality formation, coloring and and -carotene) transform into Zeaxanthin, and Zeaxanthin softening, ripening and senescence processes of fruit (Zhang create some epoxy-carotenoids by cyclization, such as 9-cis- et al., 2009a; Zhang et al., 2009b; Chai et al., 2011; Symons Violaxanthin, 9-cis-Neoxanthin, and then 9-cis-Violaxanthin et al., 2012). Generally, in the processes of growth, develop- or 9-cis-Neoxanthin will cleave into Xanthoxin in the plastid ment, ripening and senescence of fruit, endogenous ABA level (Seo & Koshiba, 2002; Cutler et al., 2010). And finally, Xan- gradually increases from the lower contents, reaches a peak thoxin as a C15 framework forms ABA by a series of changes and then slowly decline (Karppinen et al., 2013). Apparently, in the cytosol (Seo & Koshiba, 2002; Schwartz et al., 2003; endogenous ABA accumulation in the fruit depends primar- Nambara & Marion-Poll, 2005). Three possible pathways are ily on the ABA biosynthesis and catabolism (Nambara & proposed in the cytosol for the formation of ABA (Nambara Marion-Poll, 2005; Schwartz & Zeevaart, 2010). When the & Marion-Poll, 2005; Finkelstein, 2013). Most enzymes (in- ABA contents accumulated to a certain extent, it will regulate dicated in grey colour) and compound names discussed in this a series of physiological activities, such as growth and matura- article are shown in Figure 1. tion of the fruit through a complex signal transduction path- Enzymes involved in the synthesis of ABA mainly are way (Rodrigo et al., 2003). With these further investigations, Deoxyoxylulose-5-phosphate synthase (DXS), 3-Hydroxy- the key regulatory role of ABA in the growth and ripening 3-methylglutaryl-coenzyme A reductase (HMGR), Farne- process in fruit, especially in non-climacteric fruit, is gradually syl diphosphate synthase (FPS), Phytoene Synthase (PSY), being revealed (Rodrigo et al., 2006; Lund et al., 2008; Chai et Phytoene desaturase (PDS), Zeaxanthin epoxidase (ZEP), al., 2011; Jia et al., 2011; Sun et al., 2011; Liu et al., 2013; Sun Neoxanthin synthase (NXS), Xanthophyll isomerase (XISO) et al., 2013; Wang et al., 2013;
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