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Tomato (Solanum lycopersicum L.) SlIPT3 and SlIPT4 isopentenyltransferases mediate salt stress response in tomato.

Žižková E, Dobrev PI, Muhovski Y, Hošek P, Hoyerová K, Haisel D, Procházková D, Lutts S, Motyka V, Hichri I - BMC Plant Biol. (2015)

Bottom Line: SlIPT3 overexpression in tomato resulted in high accumulation of different CK metabolites, following modifications of CK biosynthesis-, signaling- and degradation-gene expression.In addition, 35S::SlIPT3 tomato plants displayed improved tolerance to salinity consecutive to photosynthetic pigments and K(+)/Na(+) ratio retention.The substantial participation of SlIPT3 in CK metabolism during salt stress has been determined in 35S::SlIPT3 tomato transformants, where enhancement of CKs accumulation significantly improved plant tolerance to salinity, underlining the importance of this phytohormone in stress response.

View Article: PubMed Central - PubMed

Affiliation: Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague, 165 02, Czech Republic. zizkovae@ueb.cas.cz.

ABSTRACT

Background: Cytokinins (CKs) are involved in response to various environmental cues, including salinity. It has been previously reported that enhancing CK contents improved salt stress tolerance in tomato. However, the underlying mechanisms of CK metabolism and signaling under salt stress conditions remain to be deciphered.

Results: Two tomato isopentenyltransferases, SlIPT3 and SlIPT4, were characterized in tomato and Arabidopsis. Both proteins displayed isopentenyltransferase (IPT) activity in vitro, while their encoding genes exhibited different spatio-temporal expression patterns during tomato plant development. SlIPT3 and SlIPT4 were affected by the endogenous CK status, tightly connected with CKs feedback regulation, as revealed by hormonal treatements. In response to salt stress, SlIPT3 and SlIPT4 were strongly repressed in tomato roots, and differently affected in young and old leaves. SlIPT3 overexpression in tomato resulted in high accumulation of different CK metabolites, following modifications of CK biosynthesis-, signaling- and degradation-gene expression. In addition, 35S::SlIPT3 tomato plants displayed improved tolerance to salinity consecutive to photosynthetic pigments and K(+)/Na(+) ratio retention. Involvement of SlIPT3 and SlIPT4 in salt stress response was also observed in Arabidopsis ipt3 knock-out complemented plants, through maintenance of CK homeostasis.

Conclusions: SlIPT3 and SlIPT4 are functional IPTs encoded by differently expressed genes, distinctively taking part in the salinity response. The substantial participation of SlIPT3 in CK metabolism during salt stress has been determined in 35S::SlIPT3 tomato transformants, where enhancement of CKs accumulation significantly improved plant tolerance to salinity, underlining the importance of this phytohormone in stress response.

No MeSH data available.


Related in: MedlinePlus

In vitrodetermination of DMAPP:AMP, ADP and ATP isopentenyltransferase activity of SlIPT3 (A) and SlIPT4 (B) proteins. ADP: adenosine diphosphate, ATP: adenosine triphosphate, iPMP: isopentenyladenosine-5′monophosphate; iPDP: isopentenyladenosine-5′-diphosphate, iPTP: isopentenyladenosine-5′-triphosphate. Note that vertical scales are not the same for SlIPT3 and SlIPT4.
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Fig2: In vitrodetermination of DMAPP:AMP, ADP and ATP isopentenyltransferase activity of SlIPT3 (A) and SlIPT4 (B) proteins. ADP: adenosine diphosphate, ATP: adenosine triphosphate, iPMP: isopentenyladenosine-5′monophosphate; iPDP: isopentenyladenosine-5′-diphosphate, iPTP: isopentenyladenosine-5′-triphosphate. Note that vertical scales are not the same for SlIPT3 and SlIPT4.

Mentions: To examine the ability of SlIPT3 and SlIPT4 to catalyze CK biosynthesis, a functional analysis of both proteins was carried out. As SlIPT3 and SlIPT4 are highly insoluble when produced in bacteria, both proteins were produced in vitro. The enzymatic activity of SlIPT3 and SlIPT4 was determined using in vitro assays based on conversion of radiolabeled adenylated substrates ([3H]AMP, [3H]ADP or [3H]ATP) in the presence of DMAPP to isopentenylated products. Both enzymes were able to convert tritium-labeled AMP/ADP/ATP to the corresponding iPRMP/iPRDP/iPRTP in time-dependent manner (Figure 2A and B). The prevailing metabolites formed by both SlIPT3 and SlIPT4 were iPRMP and iPRDP, with almost 10-fold higher catalytic activity shown by SlIPT4 compared to SlIPT3. These results clearly demonstrate that SlIPT3 and SlIPT4 display CK biosynthetic activity in in vitro conditions.Figure 2


Tomato (Solanum lycopersicum L.) SlIPT3 and SlIPT4 isopentenyltransferases mediate salt stress response in tomato.

Žižková E, Dobrev PI, Muhovski Y, Hošek P, Hoyerová K, Haisel D, Procházková D, Lutts S, Motyka V, Hichri I - BMC Plant Biol. (2015)

In vitrodetermination of DMAPP:AMP, ADP and ATP isopentenyltransferase activity of SlIPT3 (A) and SlIPT4 (B) proteins. ADP: adenosine diphosphate, ATP: adenosine triphosphate, iPMP: isopentenyladenosine-5′monophosphate; iPDP: isopentenyladenosine-5′-diphosphate, iPTP: isopentenyladenosine-5′-triphosphate. Note that vertical scales are not the same for SlIPT3 and SlIPT4.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4404076&req=5

Fig2: In vitrodetermination of DMAPP:AMP, ADP and ATP isopentenyltransferase activity of SlIPT3 (A) and SlIPT4 (B) proteins. ADP: adenosine diphosphate, ATP: adenosine triphosphate, iPMP: isopentenyladenosine-5′monophosphate; iPDP: isopentenyladenosine-5′-diphosphate, iPTP: isopentenyladenosine-5′-triphosphate. Note that vertical scales are not the same for SlIPT3 and SlIPT4.
Mentions: To examine the ability of SlIPT3 and SlIPT4 to catalyze CK biosynthesis, a functional analysis of both proteins was carried out. As SlIPT3 and SlIPT4 are highly insoluble when produced in bacteria, both proteins were produced in vitro. The enzymatic activity of SlIPT3 and SlIPT4 was determined using in vitro assays based on conversion of radiolabeled adenylated substrates ([3H]AMP, [3H]ADP or [3H]ATP) in the presence of DMAPP to isopentenylated products. Both enzymes were able to convert tritium-labeled AMP/ADP/ATP to the corresponding iPRMP/iPRDP/iPRTP in time-dependent manner (Figure 2A and B). The prevailing metabolites formed by both SlIPT3 and SlIPT4 were iPRMP and iPRDP, with almost 10-fold higher catalytic activity shown by SlIPT4 compared to SlIPT3. These results clearly demonstrate that SlIPT3 and SlIPT4 display CK biosynthetic activity in in vitro conditions.Figure 2

Bottom Line: SlIPT3 overexpression in tomato resulted in high accumulation of different CK metabolites, following modifications of CK biosynthesis-, signaling- and degradation-gene expression.In addition, 35S::SlIPT3 tomato plants displayed improved tolerance to salinity consecutive to photosynthetic pigments and K(+)/Na(+) ratio retention.The substantial participation of SlIPT3 in CK metabolism during salt stress has been determined in 35S::SlIPT3 tomato transformants, where enhancement of CKs accumulation significantly improved plant tolerance to salinity, underlining the importance of this phytohormone in stress response.

View Article: PubMed Central - PubMed

Affiliation: Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague, 165 02, Czech Republic. zizkovae@ueb.cas.cz.

ABSTRACT

Background: Cytokinins (CKs) are involved in response to various environmental cues, including salinity. It has been previously reported that enhancing CK contents improved salt stress tolerance in tomato. However, the underlying mechanisms of CK metabolism and signaling under salt stress conditions remain to be deciphered.

Results: Two tomato isopentenyltransferases, SlIPT3 and SlIPT4, were characterized in tomato and Arabidopsis. Both proteins displayed isopentenyltransferase (IPT) activity in vitro, while their encoding genes exhibited different spatio-temporal expression patterns during tomato plant development. SlIPT3 and SlIPT4 were affected by the endogenous CK status, tightly connected with CKs feedback regulation, as revealed by hormonal treatements. In response to salt stress, SlIPT3 and SlIPT4 were strongly repressed in tomato roots, and differently affected in young and old leaves. SlIPT3 overexpression in tomato resulted in high accumulation of different CK metabolites, following modifications of CK biosynthesis-, signaling- and degradation-gene expression. In addition, 35S::SlIPT3 tomato plants displayed improved tolerance to salinity consecutive to photosynthetic pigments and K(+)/Na(+) ratio retention. Involvement of SlIPT3 and SlIPT4 in salt stress response was also observed in Arabidopsis ipt3 knock-out complemented plants, through maintenance of CK homeostasis.

Conclusions: SlIPT3 and SlIPT4 are functional IPTs encoded by differently expressed genes, distinctively taking part in the salinity response. The substantial participation of SlIPT3 in CK metabolism during salt stress has been determined in 35S::SlIPT3 tomato transformants, where enhancement of CKs accumulation significantly improved plant tolerance to salinity, underlining the importance of this phytohormone in stress response.

No MeSH data available.


Related in: MedlinePlus