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Phospholipase A2beta mediates light-induced stomatal opening in Arabidopsis.

Seo J, Lee HY, Choi H, Choi Y, Lee Y, Kim YW, Ryu SB, Lee Y - J. Exp. Bot. (2008)

Bottom Line: Light-induced stomatal opening in PLA(2)alpha knockout plants did not differ from wild-type plants.Aristolochic acid, which inhibits light-induced stomatal opening, inhibited the activity of purified PLA(2)beta.Collectively, these results provide evidence that PLA(2)beta is involved in light-induced stomatal opening in Arabidopsis.

View Article: PubMed Central - PubMed

Affiliation: Division of Molecular and Life Sciences, POSTECH, Pohang 790-784, Korea.

ABSTRACT
Phospholipase A(2) (PLA(2)) catalyses the hydrolysis of phospholipids into lysophospholipids and free fatty acids. Physiological studies have indicated that PLA(2) is involved in stomatal movement. However, genetic evidence of a role of PLA(2) in guard cell signalling has not yet been reported. To identify PLA(2) gene(s) that is (are) involved in light-induced stomatal opening, stomatal movement was examined in Arabidopsis thaliana plants in which the expression of PLA(2) isoforms was reduced or knocked-out. Light-induced stomatal opening in PLA(2)alpha knockout plants did not differ from wild-type plants. Plants in which PLA(2)beta was silenced by RNA interference exhibited delayed light-induced stomatal opening, and this phenotype was reversed by exogenous lysophospholipids, which are products of PLA(2). Stomatal opening in transgenic plants that over-expressed PLA(2)beta was faster than wild-type plants. The expression of PLA(2)beta was localized to the endoplasmic reticulum of guard cells, and increased in response to light in the mature leaf. Aristolochic acid, which inhibits light-induced stomatal opening, inhibited the activity of purified PLA(2)beta. Collectively, these results provide evidence that PLA(2)beta is involved in light-induced stomatal opening in Arabidopsis.

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Light-induced stomatal opening in PLA2β-silenced, PLA2β over-expressing, and PLA2α knockout plants. (A) The levels of PLA2β mRNA in wild-type and PLA2β RNAi-silenced plants, determined by RT-PCR. (B) The levels of PLA2α mRNA in wild-type and PLA2α knockout plants, determined by RT-PCR. (C–E) Light-induced stomatal opening in PLA2β RNAi-silenced (C), PLA2β over-expressing (D), and PLA2α knockout (E) Arabidopsis plants. Leaves were floated on a solution containing 10 mM KCl and 30 mM MES-KOH (pH 6.1), then illuminated with white light (200–250 μmol m−2 s−1) for 3 h. Values represent the means ±SE of n=140–228 for (C), 138–203 for (D) and 230–320 for (E) from three independent experiments.
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fig1: Light-induced stomatal opening in PLA2β-silenced, PLA2β over-expressing, and PLA2α knockout plants. (A) The levels of PLA2β mRNA in wild-type and PLA2β RNAi-silenced plants, determined by RT-PCR. (B) The levels of PLA2α mRNA in wild-type and PLA2α knockout plants, determined by RT-PCR. (C–E) Light-induced stomatal opening in PLA2β RNAi-silenced (C), PLA2β over-expressing (D), and PLA2α knockout (E) Arabidopsis plants. Leaves were floated on a solution containing 10 mM KCl and 30 mM MES-KOH (pH 6.1), then illuminated with white light (200–250 μmol m−2 s−1) for 3 h. Values represent the means ±SE of n=140–228 for (C), 138–203 for (D) and 230–320 for (E) from three independent experiments.

Mentions: Among the four low molecular weight PLA2 genes in Arabidopsis, PLA2α and PLA2β are expressed throughout plant tissues, while PLA2γ and PLA2δ are expressed almost exclusively in the floral tissues (Lee et al., 2005). To determine whether PLA2α and PLA2β are involved in stomatal opening, several genetically modified plant lines were analysed: two RNAi lines (PLA2β-RNAi H and I), in which PLA2β mRNA levels were reduced by RNAi silencing (Fig. 1A); PLA2α knockout plants in which PLA2α mRNA was undetectable (Fig. 1B); and three plant lines over-expressing PLA2β (PLA2β OX 1-1, 4-9, and 6-8), in which the levels of PLA2β transcripts were increased, and PLA2β activity was approximately 1.5–1.6-fold higher compared to wild-type plants (Lee et al., 2003). The RNAi lines showed similar growth to that of the wild type under normal growth and experimental conditions with a short photoperiod, although, under long-day conditions, the RNAi lines grew more slowly than the wild type at the early developmental stages. This is probably because PLA2 is also involved in cell elongation (Lee et al., 2003).


Phospholipase A2beta mediates light-induced stomatal opening in Arabidopsis.

Seo J, Lee HY, Choi H, Choi Y, Lee Y, Kim YW, Ryu SB, Lee Y - J. Exp. Bot. (2008)

Light-induced stomatal opening in PLA2β-silenced, PLA2β over-expressing, and PLA2α knockout plants. (A) The levels of PLA2β mRNA in wild-type and PLA2β RNAi-silenced plants, determined by RT-PCR. (B) The levels of PLA2α mRNA in wild-type and PLA2α knockout plants, determined by RT-PCR. (C–E) Light-induced stomatal opening in PLA2β RNAi-silenced (C), PLA2β over-expressing (D), and PLA2α knockout (E) Arabidopsis plants. Leaves were floated on a solution containing 10 mM KCl and 30 mM MES-KOH (pH 6.1), then illuminated with white light (200–250 μmol m−2 s−1) for 3 h. Values represent the means ±SE of n=140–228 for (C), 138–203 for (D) and 230–320 for (E) from three independent experiments.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2561155&req=5

fig1: Light-induced stomatal opening in PLA2β-silenced, PLA2β over-expressing, and PLA2α knockout plants. (A) The levels of PLA2β mRNA in wild-type and PLA2β RNAi-silenced plants, determined by RT-PCR. (B) The levels of PLA2α mRNA in wild-type and PLA2α knockout plants, determined by RT-PCR. (C–E) Light-induced stomatal opening in PLA2β RNAi-silenced (C), PLA2β over-expressing (D), and PLA2α knockout (E) Arabidopsis plants. Leaves were floated on a solution containing 10 mM KCl and 30 mM MES-KOH (pH 6.1), then illuminated with white light (200–250 μmol m−2 s−1) for 3 h. Values represent the means ±SE of n=140–228 for (C), 138–203 for (D) and 230–320 for (E) from three independent experiments.
Mentions: Among the four low molecular weight PLA2 genes in Arabidopsis, PLA2α and PLA2β are expressed throughout plant tissues, while PLA2γ and PLA2δ are expressed almost exclusively in the floral tissues (Lee et al., 2005). To determine whether PLA2α and PLA2β are involved in stomatal opening, several genetically modified plant lines were analysed: two RNAi lines (PLA2β-RNAi H and I), in which PLA2β mRNA levels were reduced by RNAi silencing (Fig. 1A); PLA2α knockout plants in which PLA2α mRNA was undetectable (Fig. 1B); and three plant lines over-expressing PLA2β (PLA2β OX 1-1, 4-9, and 6-8), in which the levels of PLA2β transcripts were increased, and PLA2β activity was approximately 1.5–1.6-fold higher compared to wild-type plants (Lee et al., 2003). The RNAi lines showed similar growth to that of the wild type under normal growth and experimental conditions with a short photoperiod, although, under long-day conditions, the RNAi lines grew more slowly than the wild type at the early developmental stages. This is probably because PLA2 is also involved in cell elongation (Lee et al., 2003).

Bottom Line: Light-induced stomatal opening in PLA(2)alpha knockout plants did not differ from wild-type plants.Aristolochic acid, which inhibits light-induced stomatal opening, inhibited the activity of purified PLA(2)beta.Collectively, these results provide evidence that PLA(2)beta is involved in light-induced stomatal opening in Arabidopsis.

View Article: PubMed Central - PubMed

Affiliation: Division of Molecular and Life Sciences, POSTECH, Pohang 790-784, Korea.

ABSTRACT
Phospholipase A(2) (PLA(2)) catalyses the hydrolysis of phospholipids into lysophospholipids and free fatty acids. Physiological studies have indicated that PLA(2) is involved in stomatal movement. However, genetic evidence of a role of PLA(2) in guard cell signalling has not yet been reported. To identify PLA(2) gene(s) that is (are) involved in light-induced stomatal opening, stomatal movement was examined in Arabidopsis thaliana plants in which the expression of PLA(2) isoforms was reduced or knocked-out. Light-induced stomatal opening in PLA(2)alpha knockout plants did not differ from wild-type plants. Plants in which PLA(2)beta was silenced by RNA interference exhibited delayed light-induced stomatal opening, and this phenotype was reversed by exogenous lysophospholipids, which are products of PLA(2). Stomatal opening in transgenic plants that over-expressed PLA(2)beta was faster than wild-type plants. The expression of PLA(2)beta was localized to the endoplasmic reticulum of guard cells, and increased in response to light in the mature leaf. Aristolochic acid, which inhibits light-induced stomatal opening, inhibited the activity of purified PLA(2)beta. Collectively, these results provide evidence that PLA(2)beta is involved in light-induced stomatal opening in Arabidopsis.

Show MeSH
Related in: MedlinePlus