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Molecular basis of catecholamine biosynthesis in banana fruit
Year:
2009
Authors :
Quansah, Lydia
;
.
Volume :
Co-Authors:
Facilitators :
Friedman, Haya
;
.
Rodov, Victor
;
.
From page:
0
To page:
0
(
Total pages:
1
)
Abstract:

supervision: prof  Eliezer Goldshmidt

dr Victor Rodov, dr haya friedman

Catecholamines (dopamine, norepinephrine and epinephrine) are a group of biogenic amines involved in impulse transmission in animal nervous systems. Tyrosine hydroxylase (TH) is a rate limiting enzyme of catecholamine biosynthesis in mammals, resulting in L-dopa biosynthesis which leads to dopamine and the other catecholamines. Dopamine has been found in high amount in banana peel and in lower quantity in the pulp. Neither function nor biosynthesis of dopamine in plants is fully understood. Two possible pathways have been postulated; one through L-dopa, like in animals, and the second through tyramine produced by decarboxylation of tyrosine and further hydroxylated by an oxidase presumably belonging to polyphenol oxidase (PPO) family. Content of both catecholamine precursors in food has a major impact on human health since products rich in L-dopa may replace L-dopa administration in Parkinson's disease patients and high tyramine causes hypertensive crises with patients on monoamine oxidase inhibitors (MAOIs). This work aimed at isolating the genes for enzymes involved in the dopamine biosynthesis in banana. Our work has confirmed that higher levels of dopamine exist in peel than in pulp. Tyrdec and PPO partial genes sequences have been cloned from banana sub variety Grand Nain and the expression level after harvest has been determined and related to ripening parameters. In this cultivar and in six additional cultivars, expression of the transcript levels of both enzymes Tyrdec and PPO was higher in peel in most of the cultivars analyzed than in pulp. Cloning of the gene encoding TH has not been successful even in the additional cultivars and mucuna a plant with high levels of L-dopa. However, through western blot, TH-like protein was detected in the peel of Grand Nain but not in the pulp. Tyrdec expression was highest in green fruit, while PPO expression was highest in the climacteric stage of ripening. Hence, Tyrdec gene expression decreases with ethylene production while PPO was correlated with increase in ethylene production. It is still not clear if the PPO pattern of expression corresponds to PPO activity in the tissue since PPO may exist as a multi gene family in banana. Our results suggest that all these enzymes might participate in dopamine synthesis since all exhibit higher levels in peel than in pulp and their levels decrease at post climacteric stage which was found to be in correlation with dopamine levels. This work laid the ground for manipulating levels of catecholamines and their precursors in banana fruit.

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banana
biosynthesis
catecholamine
Dopamine
Epinephrine
Norepinephrine
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DOI :
Article number:
0
Affiliations:
Database:
Publication Type:
Dissertation
;
.
Language:
Hebrew
Editors' remarks:
ID:
42932
Last updated date:
02/03/2022 17:27
Creation date:
31/07/2019 12:17
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Scientific Publication
Molecular basis of catecholamine biosynthesis in banana fruit

supervision: prof  Eliezer Goldshmidt

dr Victor Rodov, dr haya friedman

Catecholamines (dopamine, norepinephrine and epinephrine) are a group of biogenic amines involved in impulse transmission in animal nervous systems. Tyrosine hydroxylase (TH) is a rate limiting enzyme of catecholamine biosynthesis in mammals, resulting in L-dopa biosynthesis which leads to dopamine and the other catecholamines. Dopamine has been found in high amount in banana peel and in lower quantity in the pulp. Neither function nor biosynthesis of dopamine in plants is fully understood. Two possible pathways have been postulated; one through L-dopa, like in animals, and the second through tyramine produced by decarboxylation of tyrosine and further hydroxylated by an oxidase presumably belonging to polyphenol oxidase (PPO) family. Content of both catecholamine precursors in food has a major impact on human health since products rich in L-dopa may replace L-dopa administration in Parkinson's disease patients and high tyramine causes hypertensive crises with patients on monoamine oxidase inhibitors (MAOIs). This work aimed at isolating the genes for enzymes involved in the dopamine biosynthesis in banana. Our work has confirmed that higher levels of dopamine exist in peel than in pulp. Tyrdec and PPO partial genes sequences have been cloned from banana sub variety Grand Nain and the expression level after harvest has been determined and related to ripening parameters. In this cultivar and in six additional cultivars, expression of the transcript levels of both enzymes Tyrdec and PPO was higher in peel in most of the cultivars analyzed than in pulp. Cloning of the gene encoding TH has not been successful even in the additional cultivars and mucuna a plant with high levels of L-dopa. However, through western blot, TH-like protein was detected in the peel of Grand Nain but not in the pulp. Tyrdec expression was highest in green fruit, while PPO expression was highest in the climacteric stage of ripening. Hence, Tyrdec gene expression decreases with ethylene production while PPO was correlated with increase in ethylene production. It is still not clear if the PPO pattern of expression corresponds to PPO activity in the tissue since PPO may exist as a multi gene family in banana. Our results suggest that all these enzymes might participate in dopamine synthesis since all exhibit higher levels in peel than in pulp and their levels decrease at post climacteric stage which was found to be in correlation with dopamine levels. This work laid the ground for manipulating levels of catecholamines and their precursors in banana fruit.

Scientific Publication
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