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Overexpression of two PsnAP1 genes from Populus simonii × P. nigra causes early flowering in transgenic tobacco and Arabidopsis.

Zheng T, Li S, Zang L, Dai L, Yang C, Qu GZ - PLoS ONE (2014)

Bottom Line: Overexpression of PsnAP1-1 and PsnAP1-2 in tobacco under the control of a CaMV 35S promoter significantly enhanced early flowering.These transgenic plants also showed much earlier stem initiation and higher rates of photosynthesis than did wild-type tobacco. qRT-PCR analysis further indicated that overexpression of PsnAP1-1 and PsnAP1-2 resulted in up-regulation of genes related to flowering, such as NtMADS4, NtMADS5 and NtMADS11.Overexpression of PsnAP1-1 and PsnAP1-2 in Arabidopsis also induced early flowering, but did not complement the ap1-10 floral morphology to any noticeable extent.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Tree Genetics and Breeding (Northeast Forestry University), Harbin, China.

ABSTRACT
In Arabidopsis, AP1 is a floral meristem identity gene and plays an important role in floral organ development. In this study, PsnAP1-1 and PsnAP1-2 were isolated from the male reproductive buds of poplar (Populus simonii × P. nigra), which are the orthologs of AP1 in Arabidopsis, by sequence analysis. Northern blot and qRT-PCR analysis showed that PsnAP1-1 and PsnAP1-2 exhibited high expression level in early inflorescence development of poplar. Subcellular localization showed the PsnAP1-1 and PsnAP1-2 proteins are localized in the nucleus. Overexpression of PsnAP1-1 and PsnAP1-2 in tobacco under the control of a CaMV 35S promoter significantly enhanced early flowering. These transgenic plants also showed much earlier stem initiation and higher rates of photosynthesis than did wild-type tobacco. qRT-PCR analysis further indicated that overexpression of PsnAP1-1 and PsnAP1-2 resulted in up-regulation of genes related to flowering, such as NtMADS4, NtMADS5 and NtMADS11. Overexpression of PsnAP1-1 and PsnAP1-2 in Arabidopsis also induced early flowering, but did not complement the ap1-10 floral morphology to any noticeable extent. This study indicates that PsnAP1-1 and PsnAP1-2 play a role in floral transition of poplar.

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Plant height at different times.The tobacco seedlings were grown in a greenhouse. Each test was performed with 9 seedlings from 3 homozygous transgenic lines.
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pone-0111725-g006: Plant height at different times.The tobacco seedlings were grown in a greenhouse. Each test was performed with 9 seedlings from 3 homozygous transgenic lines.

Mentions: We first overexpressed PsnAP1-1 and PsnAP1-2 genes independently in tobacco under the control of a CaMV 35S promoter (Fig. 4A, B). More than 10 independent transgenic tobacco lines (35S::PsnAP1) were generated from each construct, and at least two thirds of them showed clear phenotypic alterations. Northern blot analysis showed that five of the transgenic lines displayed a distinct band of the transgene and that the wild-type line did not, confirming successful transformation and expression of the transgene (Fig. 4C, D). When cultured on differentiation medium, transgenic leaf disks exhibited strikingly different growth morphology, showing that all the normal apical and lateral shoots developed as terminal rudimentary flower in which the petals, stamens, and some floral organs were not well developed, but no flower buds were observed in the wild-type plants (Fig. 5A, B, C). When the shoot explants were cultured on rooting medium, the first flower buds were detected on the transgenic shoots after 7 d, and the flowers opened completely about two weeks later, showing normal flower size and morphology (Fig. 5D). When the cultured plantlets were transferred into soil, the flowers of some transgenic lines faded as soon as the petals opened, and they were unable to form fruits (Fig. 5E). Flower buds were first visible about 4 weeks after sowing. The height of the aerial parts remained under 3 cm (Fig. 5F, G). However, there was no significant morphologic variation in flower and fruit between transgenic and wild-type plants, except that transgenic plants produced fewer fruits (Fig. 5H, I, J). Under long-day conditions with a 16 h light/8 h dark cycle, all the transformants flowered less than 40 d after sowing, whereas wild-type remained for more than 65 d before flowering (Fig. 5K). The transformants were dwarfed, producing less than 8 leaves. Wild-type plants produced more than 15 leaves before flowering. The transformants had much smaller leaves than wild-type tobacco (Fig. 5L). Stem initiation took place much earlier in transgenic plants than that in wild type. However, the transformants were dwarfed, with final aerial heights less than 15 cm, and wild-type plants had final aerial heights more than 60 cm after more than 90 d of growth (Fig. 6). Transgenic plants flowered considerably earlier than wild-type plants, indicating that overexpression of PsnAP1-1 or PsnAP1-2 is sufficient to promote the transition from vegetative to reproductive development, suggesting that PsnAP1-1 and PsnAP1-2 may be functionally redundant.


Overexpression of two PsnAP1 genes from Populus simonii × P. nigra causes early flowering in transgenic tobacco and Arabidopsis.

Zheng T, Li S, Zang L, Dai L, Yang C, Qu GZ - PLoS ONE (2014)

Plant height at different times.The tobacco seedlings were grown in a greenhouse. Each test was performed with 9 seedlings from 3 homozygous transgenic lines.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4216142&req=5

pone-0111725-g006: Plant height at different times.The tobacco seedlings were grown in a greenhouse. Each test was performed with 9 seedlings from 3 homozygous transgenic lines.
Mentions: We first overexpressed PsnAP1-1 and PsnAP1-2 genes independently in tobacco under the control of a CaMV 35S promoter (Fig. 4A, B). More than 10 independent transgenic tobacco lines (35S::PsnAP1) were generated from each construct, and at least two thirds of them showed clear phenotypic alterations. Northern blot analysis showed that five of the transgenic lines displayed a distinct band of the transgene and that the wild-type line did not, confirming successful transformation and expression of the transgene (Fig. 4C, D). When cultured on differentiation medium, transgenic leaf disks exhibited strikingly different growth morphology, showing that all the normal apical and lateral shoots developed as terminal rudimentary flower in which the petals, stamens, and some floral organs were not well developed, but no flower buds were observed in the wild-type plants (Fig. 5A, B, C). When the shoot explants were cultured on rooting medium, the first flower buds were detected on the transgenic shoots after 7 d, and the flowers opened completely about two weeks later, showing normal flower size and morphology (Fig. 5D). When the cultured plantlets were transferred into soil, the flowers of some transgenic lines faded as soon as the petals opened, and they were unable to form fruits (Fig. 5E). Flower buds were first visible about 4 weeks after sowing. The height of the aerial parts remained under 3 cm (Fig. 5F, G). However, there was no significant morphologic variation in flower and fruit between transgenic and wild-type plants, except that transgenic plants produced fewer fruits (Fig. 5H, I, J). Under long-day conditions with a 16 h light/8 h dark cycle, all the transformants flowered less than 40 d after sowing, whereas wild-type remained for more than 65 d before flowering (Fig. 5K). The transformants were dwarfed, producing less than 8 leaves. Wild-type plants produced more than 15 leaves before flowering. The transformants had much smaller leaves than wild-type tobacco (Fig. 5L). Stem initiation took place much earlier in transgenic plants than that in wild type. However, the transformants were dwarfed, with final aerial heights less than 15 cm, and wild-type plants had final aerial heights more than 60 cm after more than 90 d of growth (Fig. 6). Transgenic plants flowered considerably earlier than wild-type plants, indicating that overexpression of PsnAP1-1 or PsnAP1-2 is sufficient to promote the transition from vegetative to reproductive development, suggesting that PsnAP1-1 and PsnAP1-2 may be functionally redundant.

Bottom Line: Overexpression of PsnAP1-1 and PsnAP1-2 in tobacco under the control of a CaMV 35S promoter significantly enhanced early flowering.These transgenic plants also showed much earlier stem initiation and higher rates of photosynthesis than did wild-type tobacco. qRT-PCR analysis further indicated that overexpression of PsnAP1-1 and PsnAP1-2 resulted in up-regulation of genes related to flowering, such as NtMADS4, NtMADS5 and NtMADS11.Overexpression of PsnAP1-1 and PsnAP1-2 in Arabidopsis also induced early flowering, but did not complement the ap1-10 floral morphology to any noticeable extent.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Tree Genetics and Breeding (Northeast Forestry University), Harbin, China.

ABSTRACT
In Arabidopsis, AP1 is a floral meristem identity gene and plays an important role in floral organ development. In this study, PsnAP1-1 and PsnAP1-2 were isolated from the male reproductive buds of poplar (Populus simonii × P. nigra), which are the orthologs of AP1 in Arabidopsis, by sequence analysis. Northern blot and qRT-PCR analysis showed that PsnAP1-1 and PsnAP1-2 exhibited high expression level in early inflorescence development of poplar. Subcellular localization showed the PsnAP1-1 and PsnAP1-2 proteins are localized in the nucleus. Overexpression of PsnAP1-1 and PsnAP1-2 in tobacco under the control of a CaMV 35S promoter significantly enhanced early flowering. These transgenic plants also showed much earlier stem initiation and higher rates of photosynthesis than did wild-type tobacco. qRT-PCR analysis further indicated that overexpression of PsnAP1-1 and PsnAP1-2 resulted in up-regulation of genes related to flowering, such as NtMADS4, NtMADS5 and NtMADS11. Overexpression of PsnAP1-1 and PsnAP1-2 in Arabidopsis also induced early flowering, but did not complement the ap1-10 floral morphology to any noticeable extent. This study indicates that PsnAP1-1 and PsnAP1-2 play a role in floral transition of poplar.

Show MeSH