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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

Relative expression of CK metabolic and response genes in tomato young leaves of35S::SlIPT3and WT plants. Transcript abundance of CK biosynthetic genes (A), genes involved in CK signaling (B) and degradation (C) pathways. Actin and GAPDH were used as internal controls for normalization of candidate genes expression. Data represent means and SD of two replicates. *statistically significant difference from WT (unpaired two-tailed Student’s t-test, p ≤ 0.05). **statistically significant difference from WT after Šidák correction for testing of multiple lines (multiple unpaired two-tailed Student’s t-test, overall α = 0.05, individual p ≤ 0.017).
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Fig7: Relative expression of CK metabolic and response genes in tomato young leaves of35S::SlIPT3and WT plants. Transcript abundance of CK biosynthetic genes (A), genes involved in CK signaling (B) and degradation (C) pathways. Actin and GAPDH were used as internal controls for normalization of candidate genes expression. Data represent means and SD of two replicates. *statistically significant difference from WT (unpaired two-tailed Student’s t-test, p ≤ 0.05). **statistically significant difference from WT after Šidák correction for testing of multiple lines (multiple unpaired two-tailed Student’s t-test, overall α = 0.05, individual p ≤ 0.017).

Mentions: To understand the impact of SlIPT3 and SlIPT4 overexpression on CK metabolism and verify the enzymes activity in planta, we attempted to generate transgenic lines constitutively expressing SlIPT3 or SlIPT4. Several 35S::SlIPT3 transgenic lines were able to develop and survive repotting into soil, while no 35S::SlIPT4 tomato plants could be regenerated from transgenic calli in vitro. For further characterization, three 35S::SlIPT3 transgenic lines (L6, L8, L9) were selected, with transgene expression in leaves increasing up to 14-fold (L9) compared to WT (Figure 7A).Figure 7


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)

Relative expression of CK metabolic and response genes in tomato young leaves of35S::SlIPT3and WT plants. Transcript abundance of CK biosynthetic genes (A), genes involved in CK signaling (B) and degradation (C) pathways. Actin and GAPDH were used as internal controls for normalization of candidate genes expression. Data represent means and SD of two replicates. *statistically significant difference from WT (unpaired two-tailed Student’s t-test, p ≤ 0.05). **statistically significant difference from WT after Šidák correction for testing of multiple lines (multiple unpaired two-tailed Student’s t-test, overall α = 0.05, individual p ≤ 0.017).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig7: Relative expression of CK metabolic and response genes in tomato young leaves of35S::SlIPT3and WT plants. Transcript abundance of CK biosynthetic genes (A), genes involved in CK signaling (B) and degradation (C) pathways. Actin and GAPDH were used as internal controls for normalization of candidate genes expression. Data represent means and SD of two replicates. *statistically significant difference from WT (unpaired two-tailed Student’s t-test, p ≤ 0.05). **statistically significant difference from WT after Šidák correction for testing of multiple lines (multiple unpaired two-tailed Student’s t-test, overall α = 0.05, individual p ≤ 0.017).
Mentions: To understand the impact of SlIPT3 and SlIPT4 overexpression on CK metabolism and verify the enzymes activity in planta, we attempted to generate transgenic lines constitutively expressing SlIPT3 or SlIPT4. Several 35S::SlIPT3 transgenic lines were able to develop and survive repotting into soil, while no 35S::SlIPT4 tomato plants could be regenerated from transgenic calli in vitro. For further characterization, three 35S::SlIPT3 transgenic lines (L6, L8, L9) were selected, with transgene expression in leaves increasing up to 14-fold (L9) compared to WT (Figure 7A).Figure 7

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