The climacteric-like behaviour of young, mature and wounded citrus leaves

Katz, Ehud; Riov, Joseph; Weiss, David; Goldschmidt, Eliezer E.

doi:10.1093/jxb/eri137

Cited by 14 publications

(15 citation statements)

References 49 publications

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“…Analysis of the dephytylation step in ripening fruits has been limited nearly exclusively to Citrus spp. (Amir-Shapira et al, 1987;Trebitsh et al, 1993;Jacob-Wilk et al, 1999;Azoulay Shemer et al, 2008), where leaf senescence-related chlorophyll breakdown has not been studied in detail (Katz et al, 2005). We chose tomato as a model because, besides a rather short life cycle, it offers established genetic tools as well as well-defined methods for fruit ripening and leaf senescence analysis (Akhtar et al, 1999;Barry et al, 2008) and, thus, allowed the simultaneous analysis of dephytylation during leaf senescence and fruit ripening (Figs.…”

Section: Discussionmentioning

confidence: 99%

Different Mechanisms Are Responsible for Chlorophyll Dephytylation during Fruit Ripening and Leaf Senescence in Tomato

et al. 2014

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Chlorophyll breakdown occurs in different green plant tissues (e.g. during leaf senescence and in ripening fruits). For different plant species, the PHEOPHORBIDE A OXYGENASE (PAO)/phyllobilin pathway has been described to be the major chlorophyll catabolic pathway. In this pathway, pheophorbide (i.e. magnesium-and phytol-free chlorophyll) occurs as a core intermediate. Most of the enzymes involved in the PAO/phyllobilin pathway are known; however, the mechanism of dephytylation remains uncertain. During Arabidopsis (Arabidopsis thaliana) leaf senescence, phytol hydrolysis is catalyzed by PHEOPHYTINASE (PPH), which is specific for pheophytin (i.e. magnesium-free chlorophyll). By contrast, in fruits of different Citrus spp., chlorophyllase, hydrolyzing phytol from chlorophyll, was shown to be active. Here, we enlighten the process of chlorophyll breakdown in tomato (Solanum lycopersicum), both in leaves and fruits. We demonstrate the activity of the PAO/phyllobilin pathway and identify tomato PPH (SlPPH), which, like its Arabidopsis ortholog, was specifically active on pheophytin. SlPPH localized to chloroplasts and was transcriptionally up-regulated during leaf senescence and fruit ripening. SlPPH-silencing tomato lines were impaired in chlorophyll breakdown and accumulated pheophytin during leaf senescence. However, although pheophytin transiently accumulated in ripening fruits of SlPPH-silencing lines, ultimately these fruits were able to degrade chlorophyll like the wild type. We conclude that PPH is the core phytol-hydrolytic enzyme during leaf senescence in different plant species; however, fruit ripening involves other hydrolases, which are active in parallel to PPH or are the core hydrolases in fruits. These hydrolases remain unidentified, and we discuss the question of whether chlorophyllases might be involved.

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Section: Discussionmentioning

confidence: 99%

Different Mechanisms Are Responsible for Chlorophyll Dephytylation during Fruit Ripening and Leaf Senescence in Tomato

et al. 2014

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“…However, recent studies showed that the abscission behavior of young citrus leaves and fruitlets resembled climacteric fruits in that ethylene treatment induced a peak of endogenous ethylene production (Katz et al 2005). But no such increase has been observed in ethylene-treated mature fruit (Katz et al 2004).…”

Section: Ethylene Signaling Is Generally Activated During Ethylene-inmentioning

confidence: 99%

Profiling gene expression in citrus fruit calyx abscission zone (AZ-C) treated with ethylene

et al. 2015

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On-tree storage and harvesting of mature fruit account for a large proportion of cost in the production of citrus, and a reduction of the cost would not be achieved without a thorough understanding of the mechani sm of the mature fruit abscission. Genome-wide gene expression changes in ethylene-treated fruit calyx abscission zone (AZ-C) of Citrus sinensis cv. Olinda were therefore investigated using a citrus genome array representing up to 33,879 citrus transcripts. In total, 1313 and 1044 differentially regulated genes were identified in AZ-C treated with ethylene for 4 and 24 h, respectively. The results showed that mature citrus fruit abscission commenced with the activation of ethylene signal transduction pathway that led to the activation of ethylene responsive transcription factors and the subsequent transcriptional regulation of a large set of ethylene responsive genes. Significantly down-regulated genes included those of starch/sugar biosynthesis, transportation of water and growth promoting hormone synthesis and signaling, whereas significantly up-regulated genes were those involved in defense, cell wall degradation, and secondary metabolism. Our data unraveled the underlying mechanisms of some known important biochemical events occurring at AZ-C and should provide informative suggestions for future manipulation of the events to achieve a controllable abscission for mature citrus fruit.

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“…A recent paper of Katz et al (2005) provided evidence that two types of ethylene production, an autocatalytic and an autoinhibitory system might operate in leaves, both of which could also be induced by wounding. After young, fully expanded leaves were detached from citrus plants (Citrus sinensis), a first phase of ethylene production up to 6 days after detachment was observed.…”

Section: Wound Ethylene In Vegetative Tissuesmentioning

confidence: 99%

Ethylene and Plant Responses to Abiotic Stress

Druege¹

2006

Ethylene Action in Plants

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Exposure to physical, chemical or biological stresses is an intrinsic characteristic of plant life not only in the natural environment but also under more or less controlled conditions in horticultural and agricultural systems. Globalisation and concentration of plant production throughout the world, on the one hand, allows for optimizing of growth conditions, but, on the other, increasingly involves post-harvest stress during storage and transport of intermediate and final products (Çelikel and Reid 2002;Kadner and Druege 2004). According to Levitt (1980), the term stress is used for any external factor capable of inducing a potentially injurious strain in the plant. With regard to the condition of the plant, plant stress can be described as a state in which increasing demands made on a plant lead to an initial destabilization of functions, followed by adaptive responses towards normalization, which may even lead to over-compensation of functions and improved resistance (Larcher 1995). However, if the acute tolerance or adaptive capacity is overtaxed, permanent damage or death may result. Within a network of hormonal cross-talk (Gazzarrini and McCourt 2003), ethylene production and signalling are highly involved not only in stress-induced symptoms of disturbed growth, senescence or injury, but also in acclimation processes which aid plant performance and survival.

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The climacteric-like behaviour of young, mature and wounded citrus leaves

Cited by 14 publications

References 49 publications

Different Mechanisms Are Responsible for Chlorophyll Dephytylation during Fruit Ripening and Leaf Senescence in Tomato

Different Mechanisms Are Responsible for Chlorophyll Dephytylation during Fruit Ripening and Leaf Senescence in Tomato

Profiling gene expression in citrus fruit calyx abscission zone (AZ-C) treated with ethylene

Ethylene and Plant Responses to Abiotic Stress

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