Water availability influences morphology, mycorrhizal associations, PSII efficiency and polyamine metabolism at early growth phase of Scots pine seedlings

Muilu‐Mäkelä, Riina; Vuosku, Jaana; Läärä, Esa; Saarinen, Markku; Heiskanen, Juha; Häggman, Hely; Sarjala, Tytti

doi:10.1016/j.plaphy.2015.01.009

Cited by 15 publications

(18 citation statements)

References 38 publications

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“…This was also confirmed in our previous study with Scots pine seedlings under drought stress (Muilu-Mäkelä et al 2015) and likewise the results of the present study support this finding. The transcription and metabolite-level investigation suggests that PA metabolism is maintained at a constant level under osmotic stress conditions in Scots pine cells by decreasing expression of catabolizing enzyme genes rather than activating PA biosynthesis.…”

Section: Discussionsupporting

confidence: 93%

“…LEA genes are expressed also in somatic coniferous embryos at the maturation phase (Stasolla et al 2003). Furthermore, expression of CAT is induced under drought stress in loblolly pine (Lorenz et al 2005) and Scots pine roots (Muilu-Mäkelä et al 2015). S-adenosyl methionine (SAM) is a common precursor of ethylene and PA biosynthesis (Moschou et al 2012), and SAM synthase (SAMS) is shown to be up-regulated under drought stress in pine tissues (Lorenz et al 2005).…”

Section: Discussionmentioning

confidence: 99%

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Osmotic stress affects polyamine homeostasis and phenolic content in proembryogenic liquid cell cultures of Scots pine

Muilu‐Mäkelä

Vuosku

Hamberg

et al. 2015

Plant Cell Tiss Organ Cult

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Polyamines (PAs) are ubiquitous polycations involved in many physiological processes in plants, including somatic embryogenesis, cellular growth and stress reactions. In the present study, we focus on the consequences in PA metabolism caused by polyethylene glycol (PEG) in proembryogenic Scots pine (Pinus sylvestris L.) liquid cultures. The growth and viability of the cell masses and changes in PA concentrations and phenolic secondary metabolites were investigated under control, 5 and 10 % PEG treatments. The effect of osmotic stress responses was investigated at the gene expression level including stress, cell division, programmed cell death and PA-related genes and PA metabolites. Moreover, the expression of ethylene and proline biosynthesis genes and phenylalanine ammonia lyase and stilbene synthase (psSTS) was analyzed. Under osmotic stress conditions, we found a consistent pattern of endogenous PAs in Scots pine proembryogenic cells. However, accumulation of free spermine (Spm) and methyl putrescine under osmotic stress might indicate their specific role in stress protection. Expression of polyamine oxidase was down-regulated under osmotic stress, suggesting the role of PA catabolism in regulation of Spm levels. Scots pine proliferating proembryogenic cells are in a developmentally undifferentiated stage where the content of secondary metabolites is generally low. However, in the present study the total content of phenolic compounds increased but the biosynthesis of phenylpropanoids and stilbenes, generally considered as stress-protective molecules, was not affected by osmotic stress.

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Section: Discussionsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Osmotic stress affects polyamine homeostasis and phenolic content in proembryogenic liquid cell cultures of Scots pine

Muilu‐Mäkelä

Vuosku

Hamberg

et al. 2015

Plant Cell Tiss Organ Cult

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“…Spring frost decreased expression of ADC, SPDS, ICE1 and LEA and the lower expression level of SPDS and ICE1 was maintained after the recovery in the needles. In our previous studies, we have shown that under drought or osmotic stresses various tissues are able to maintain consistent PA levels due to a downregulation PA catabolizing genes, which seems to be advantageous (Muilu-Mäkelä et al 2015a, 2015b. In the present study, the expression of PAO decreased in needles and roots after the recovery, which might be a consequence of the frost induced down-regulation of the PA biosynthesizing genes ADC and SPDS.…”

Section: Discussionsupporting

confidence: 52%

“…In our earlier study we have shown that under severe drought stress Scots pine seedlings invest in the shoots rather than roots (Muilu-Mäkelä et al 2015a). This is the case also after freezing stress as rising temperatures decreases the root/shoot ratio of Scots pine seedlings, apparently due to a preferential allocation of photosynthates to shoots (Vapaavuori et al 1992).…”

Section: Discussionmentioning

confidence: 85%

Coping with spring frost-effects on polyamine metabolism of Scots pine seedlings

Muilu‐Mäkelä¹,

Vuosku²,

Saarinen³

et al. 2017

iForest

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(1) Polyamines (PA) are ubiquitous polycations known to be involved in several phases of plant development as well as in tolerance to abiotic stresses. Phenols are complex secondary metabolites produced via the phenylpropanoid pathway that contain, e.g., cell wall compounds and antioxidants. Phenols are known to enhance chilling tolerance of plants. PA and phenolic pathways are connected via conjugation. In boreal coniferous forests spring frost has been considered to have severe effects on the survival of tree seedlings. Such effects are likely to increase in the future. The present study focuses on the role of PA and phenylpropanoid syntheses in the coping strategies of Scots pine exposed to cold temperatures during the vulnerable early seedling phase in late spring and early summer. We found that spring frost affects the expression of genes regulating PA metabolism and phenylpropanoid synthesis differently in above and below ground parts of the seedlings, whereas PA or phenol contents in tissues were not affected. The results suggest that Scots pine seedlings may not have time to develop metabolite level responses during a short period of freezing stress and, therefore, the originally different PA levels, especially in roots, may influence the tolerance of Scots pine seedlings to spring frost.

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“…Our results suggest that the adaptability of PA homeostasis may be restricted in Scots pine and, thus, the manipulation of PA levels may not provide as practical tools for the enhancement of stress tolerance as in many flowering plants (Hussain et al, 2011;Marco et al, 2016). In both Scots pine seedlings and proembryogenic cells the expression of the PA biosynthetic and catabolic genes was down regulated rather than up regulated during drought/ osmotic stress, whereas PA contents remained quite stable (Muilu-Mäkelä et al, 2015a;Muilu-Mäkelä et al, 2015b). Therefore, we suggest that PAs may have more potential for biotechnological applications in development related processes such as somatic embryogenesis and the control of wood formation in Scots pine.…”

Section: Discussionmentioning

confidence: 91%

Thermospermine Synthase (ACL5) and Diamine Oxidase (DAO) Expression Is Needed for Zygotic Embryogenesis and Vascular Development in Scots Pine

et al. 2019

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Unlike in flowering plants, the detailed roles of the enzymes in the polyamine (PA) pathway in conifers are poorly known. We explored the sequence conservation of the PA biosynthetic genes and diamine oxidase (DAO) in conifers and flowering plants to reveal the potential functional diversification of the enzymes between the plant lineages. The expression of the genes showing different selective constraints was studied in Scots pine zygotic embryogenesis and early seedling development. We found that the arginine decarboxylase pathway is strongly preferred in putrescine production in the Scots pine as well as generally in conifers and that the reduced use of ornithine decarboxylase (ODC) has led to relaxed purifying selection in ODC genes. Thermospermine synthase (ACL5) genes evolve under strong purifying selection in conifers and the DAO gene is also highly conserved in pines. In developing Scots pine seeds, the expression of both ACL5 and DAO increased as embryogenesis proceeded. Strong ACL5 expression was present in the procambial cells of the embryo and in the megagametophyte cells destined to die via morphologically necrotic cell death. Thus, the high sequence conservation of ACL5 genes in conifers may indicate the necessity of ACL5 for both embryogenesis and vascular development. Moreover, the result suggests the involvement of ACL5 in morphologically necrotic cell death and supports the view of the genetic regulation of necrosis in Scots pine embryogenesis and in plant development. DAO transcripts were located close to the cell walls and between the walls of adjacent cells in Scots pine zygotic embryos and in the roots of young seedlings. We propose that DAO, in addition to the role in Put oxidation for providing H 2 O 2 during the cell-wall structural processes, may also participate in cell-to-cell communication at the mRNA level. To conclude, our findings indicate that the PA pathway of Scots pines possesses several special functional characteristics which differ from those of flowering plants.

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Water availability influences morphology, mycorrhizal associations, PSII efficiency and polyamine metabolism at early growth phase of Scots pine seedlings

Cited by 15 publications

References 38 publications

Osmotic stress affects polyamine homeostasis and phenolic content in proembryogenic liquid cell cultures of Scots pine

Osmotic stress affects polyamine homeostasis and phenolic content in proembryogenic liquid cell cultures of Scots pine

Coping with spring frost-effects on polyamine metabolism of Scots pine seedlings

Thermospermine Synthase (ACL5) and Diamine Oxidase (DAO) Expression Is Needed for Zygotic Embryogenesis and Vascular Development in Scots Pine

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