| 1. |
- Smolka, Anders, et al.
(författare)
-
Effects of transgenic rootstocks on growth and development of non-transgenic scion cultivars in apple
- 2010
-
Ingår i: Transgenic Research. - : Springer Science and Business Media LLC. - 0962-8819 .- 1573-9368. ; 19, s. 933-948
-
Tidskriftsartikel (refereegranskat)abstract
- Although cultivation of genetic modified (GM) annual crops has been steadily increasing in the recent 10 years, the commercial cultivation of GM fruit tree is still very limited and reports of field trials on GM fruit trees are rare. This is probably because development and evaluation of GM fruit trees require a long period of time due to long life cycles of trees. In this study, we report results from a field trial on three rolB transgenic dwarfing apple rootstocks of M26 and M9 together with non-transgenic controls grafted with five non-transgenic scion cultivars. We intended to investigate the effects of transgenic rootstock on non-transgenic scion cultivars under natural conditions as well as to evaluate the potential value of using the rolB gene to modify difficult-to-root rootstocks of fruit trees. The results showed that all rolB transgenic rootstocks significantly reduced vegetative growth including tree height regardless of scion cultivar, compared with the non-transgenic rootstocks. Flowering and fruiting were also decreased for cultivars grown on the transgenic rootstocks in most cases, but the fruit quality was not clearly affected by the transgenic rootstocks. Cutting experiment and RTPCR analysis showed that the rolB gene was stably expressed under field conditions. PCR and RT-PCR analyses displayed that the rolB gene or its mRNA were not detectable in the scion cultivars, indicating no translocation of the transgene or its mRNA from rootstock to scion. Our results suggest that rolB modified rootstocks should be used in combination with vigorous scion cultivars in order to obtain sufficient vegetative growth and good yield. Alternatively, the rolB gene could be used to dwarf vigorous rootstocks of fruit trees or produce bonzai plants as it can significantly reduce the vegetative growth of plants.
|
|
| 2. |
- Smolka, Anders, et al.
(författare)
-
Involvement of the ARRO-1 gene in adventitious root formation in apple
- 2009
-
Ingår i: Plant Science. - : Elsevier BV. - 0168-9452 .- 1873-2259. ; 177, s. 710-715
-
Tidskriftsartikel (refereegranskat)abstract
- Adventitious root formation is a limiting factor for vegetative propagation in apple. The molecular mechanisms underlying the rooting process are still largely unknown and need to be extensively investigated. The Adventitious Rooting Related Oxygenase (ARRO-1) has previously been isolated from apple and has been shown to be upregulated during adventitious root induction. However, the function of this gene is still unclear. The aim of this study was to downregulate the ARRO-1 gene expression, using RNAi technique, to study the function of ARRO-I in adventitious root formation in apple. The apple rootstock M26 was transformed with the RNAi-ARRO-1 construct. The transgenic clones, confirmed by PCR and Southern blot analysis, showed significantly reduced adventitious root formation both with microcuttings and stem discs, indicating the involvement of ARRO-1 in adventitious root formation. The transgenic clones also appeared to be more sensitive to exogenous hormones compared to the untransformed control plants, Suggesting that ARRO-1 may be involved in regulating hormone homeostasis. Relative quantification of the ARRO-1 mRNA showed no obvious difference in transcript levels between untransformed control and the transformants. A possible explanation for this is that the downregulation of the ARRO-1 gene might be translational rather than transcriptional. (C) 2009 Elsevier Ireland Ltd. All rights reserved.
|
|
| 3. |
- Welander, Margareta
(författare)
-
Effect of desiccation on somatic embryo regeneration in date palm (Phoenix dactylifera L.) cultured in vitro
- 2020
-
Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 1285, s. 125-130
-
Konferensbidrag (refereegranskat)abstract
- This work studied somatic embryo formation, maturation and germination using partial desiccation treatment in either sealed test tubes or Plantform bioreactor vessels for different numbers of days. After desiccation, embryogenic callus was transferred to a regeneration medium for 16 weeks. During the study it was found that embryogenic callus subjected to desiccation in both test tubes and sterile bioreactor significantly increased somatic embryo formation, and germinated, when compared to sealed test tubes. However, a perfuse numbers of somatic embryos with good synchronization were obtained whit the use of the TIS (temporary immersion system) system, containing 500 mL liquid MS medium, 0.1 mg L-1 benzylaminopurine, 0.1 mg L-1 2ip and 0.1 mg L-1 kinetin, and a high level of sucrose (100 g L-1).
|
|
| 4. |
- Welander, Margareta, et al.
(författare)
-
Evaluation of a new vessel system based on temporary immersion system for micropropagation
- 2014
-
Ingår i: Scientia Horticulturae. - : Elsevier BV. - 0304-4238 .- 1879-1018. ; 179, s. 227-232
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to evaluate a new culture vessel Plantform bioreactor, based on the temporary immersion system principle for micropropagation of Digitalis lutea x purpurea, Echinacea purpurea and Rubus idaeus. The multiplication ratio and shoot quality in bioreactor were either similar to or better than these on agar medium. The shoot number was similar in both systems for Digitalis and Rubus, while Echinacea had a significantly higher shoot number of good quality in bioreactor. Digitalis and Echinacea gained more fresh weights in bioreactor, while more for Rubus on agar medium. However, the dry weight was similar between the two systems for all three species. Changes in carbohydrate were evident for all species. Autoclaving media could breakdown sucrose, which is both pH- and nutrient-dependent. This study has demonstrated that the Plantform bioreactor is suitable for plant micropropagation. (C) 2014 Elsevier B.V. All rights reserved.
|
|
| 5. |
- Welander, Margareta, et al.
(författare)
-
Mikroförökning av trädgårdsväxter
- 2011
-
Ingår i: Fakta. Trädgård / fritid. - 1102-1969.
-
Annan publikation (populärvet., debatt m.m.)
|
|
| 6. |
- Welander, Margareta, et al.
(författare)
-
Origin, timing, and gene expression profile of adventitious rooting in Arabidopsis hypocotyls and stems
- 2014
-
Ingår i: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 101, s. 255-266
-
Tidskriftsartikel (refereegranskat)abstract
- Premise of the study: Adventitious root (AR) formation is indispensable for vegetative propagation, but diffi cult to achieve in many crops. Understanding its molecular mechanisms is thus important for such species. Here we aimed at developing a rooting protocol for direct AR formation in stems, locating cellular AR origins in stems and exploring molecular differences underlying adventitious rooting in hypocotyls and stems. Methods: In-vitro-grown hypocotyls or stems of wild-type and transgenic ecotype Columbia (Col-0) of Arabidopsis thalianawere rooted on rooting media. Anatomy of AR formation, qRT-PCR of some rooting-related genes and in situ GUS expression were carried out during rooting from hypocotyls and stems. Key results: We developed a rooting protocol for AR formation in stems and traced back root origins in stems by anatomicaland in situ expression studies. Unlike rooting in hypocotyls, rooting in stems was slower, and AR origins were mainly from lateral parenchyma of vascular bundles and neighboring starch sheath cells as well as, to a lesser extent, from phloem cap and xylem parenchyma. Transcript levels of GH3-3 , LBD16 , LBD29 , and LRP1 in hypocotyls and stems were similar, but transcript accumulation was delayed in stems. In situ expression signals of DR5::GUS , LBD16::GUS , LBD29::GUS , and rolB::GUS reporters in stems mainly occurred at the root initiation sites, suggesting their involvement in AR formation. Conclusions: We have developed an effi cient rooting protocol using half-strength Lepoivre medium for studying AR formation instems, traced back the cellular AR origins in stems, and correlated expression of rooting-related genes with root initiation sites.
|
|
| 7. |
- Welander, Margareta, et al.
(författare)
-
Studies of rooting ability in the tobacco rac mutant impaired in rooting
- 2023
-
Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 1359, s. 203-208
-
Konferensbidrag (refereegranskat)abstract
- The rolB gene from Agrobacterium rhizogenes has proven to significantly stimulate adventitious rooting in several species. The rac mutant of Nicotiana tabacum L. ‘Xanthii’ is impaired in rooting. The objective of the present study was to explore if the rolB gene introduced into rac mutant could restore the rooting ability. Leaves of the rac and wild-type (WT) tobacco shoots were transformed by Agrobacterium strain C58C1 holding the binary vector pCMB-B:GUS harboring nptII, rolB and gus genes was used for transformation. Four transformed lines were obtained expressing the rolB gene. However, the rooting ability was not restored. The rac can only be propagated in vitro due to lack of roots. To obtain seeds from rac for further studies on rooting we grafted rac shoots onto WT seedlings in vitro. The successful grafted plants were then transferred to pots in the greenhouse to obtained seeds by selfing. The grafted plants flowered normally but were weaker with smaller leaves. Fruit setting and seed production were poor in the rac mutans. In vitro rooting showed that the roots from WT seedlings penetrated the seed coat after 3 days. After 6 days elongated roots were covered with root hair. Roots from the grafted rac seeds penetrated seed coat first after 6 days and at day eight root growth ceased. The root tip was swollen and covered with minor root hair. Since it has been shown that the root tip in the rac contains 14 times more auxin than WT we were interested to investigate if the rac was impaired in some PIN genes responsible for lateral auxin transport from the root meristem. We performed Western blot analysis with various PIN antibodies using the protein extracts from petioles and leaves of WT and rac. Both PIN 2 and 3 gave good signals. Next will be immunolocalization of PINs in the root.
|
|
| 8. |
- Welander, Margareta
(författare)
-
Technical improvement of a new bioreactor for large scale micropropagation of several Vaccinium cultivars
- 2017
-
Konferensbidrag (refereegranskat)abstract
- The aim of this study was to evaluate the new Plantform bioreactor for large scale micropropagation of several Vaccinium cultivars. Micropropagation in the bioreactors was very cost effective by elimination of agar, more plants per unit, less handling due to no positioning of explants in the bioreactor and rooting in the same unit. Ex vitro was facilitated with no agar in the medium and due to aeration of the bioreactor the plant quality was improved.
|
|
| 9. |
- Welander, Margareta
(författare)
-
Teknisk utveckling av bioreaktorer för storskalig mikroförökning : slutredovisning av partnerskapsprojekt 2008-2010
- 2011
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Sammanfattning Vi har nu utvecklat en prisvärd attraktiv bioreaktor för storskalig mikroförökning. Den är transparent, autoklaverbar, stapelbar och väger lite. Bioreaktorn är konstruerad så att näringstillförsel och gasutbyte kan kontrolleras automatiskt. Anslutningarna sitter på sidan av den yttre behållaren vilket gör att hela den inre delen kan utnyttjas till odling växtmaterialet. Både näringslösning och växtmaterial är i samma bioreaktor vilket sparar odlingsutrymme. Bioreaktorn kommer att leda till reducerade kostnader men också ökad plantkvalité genom att växterna kan avhärdas redan i bioreaktorn. En annan stor fördel är att bioreaktorn också kan användas till grundläggande forskning genom att näringsupptagning kan studeras under tillväxtfasen. Gjutformarna till de olika delarna som ingår i bioreaktorn tillverkas i Kina och har en kapacitet för 200 000 enheter
|
|
| 10. |
- Zhu, Li-Hua, et al.
(författare)
-
Can Arabidopsis AP1 Gene Shorten the Juvenility of Apple?
- 2009
-
Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 829, s. 259-264
-
Konferensbidrag (refereegranskat)abstract
- Shortening of the juvenile phase is of great importance for apple breeding. Compared to conventional breeding methods, gene technology is more straightforward in reducing juvenility, as it can directly regulate expression of flowering-time genes. In model plant Arabidopsis, a number of flowering-time genes have been identified and characterised. Some of them have also been isolated from other species. Regulation of these genes has been proved to promote early flowering in a number of plant species. In this study, we have introduced the Arabidopsis APETALA1 (AP1) gene into the apple rootstock M26. The transgenic plants have been grown in the greenhouse for two years; however, no early flowering has been observed, although the AP1 gene is constitutively expressed in the transgenic clones, confirmed by RT-PCR analysis.
|
|
| 11. |
- Zhu, Li-Hua, et al.
(författare)
-
Plant Size Control in Apple through Genetic Engineering
- 2009
-
Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 839, s. 689-694
-
Konferensbidrag (refereegranskat)abstract
- Tree size control is essential for modern apple production. Chemical controls and different managements have been practically used in commercial production of apple rootstocks and cultivars in order to generate dwarf trees. However, these practices are either inefficient or unfriendly to human health and environment. In contrast, genetic engineering offers a better possibility to improve plant properties. By introducing well-characterised genes that control the growth vigour, it is possible to dwarf an existing genotype without disturbing its main genetic background. Up to now, some genes have been introduced into different plant species and proved to be effective in reducing plant size. Among the genes tested, the rolC, gai and GA oxidase have shown to be able to reduce plant size in most cases. In our previous studies, we have introduced the rolC and gai genes into apple rootstocks and cultivars. Both in vitro and grown analysis in greenhouse have shown that transgenic plants with one of these genes did display reduced plant height in most cases. Since plant height is mainly controlled by gibberellins, regulation of GA biosynthesis would be a better way to control plant size in the future.
|
|
