Overexpression of Arabidopsis FLOWERING LOCUS T (FT) gene improves floral development in cassava (Manihot esculenta, Crantz)

Cassava is a tropical storage-root crop that serves as a worldwide source of staple food for over 800 million people. Flowering is one of the most important breeding challenges in cassava because in most lines flowering is late and non-synchronized, and flower production is sparse. The FLOWERING LOCUS T (FT) gene is pivotal for floral induction in all examined angiosperms. The objective of the current work was to determine the potential roles of the FT signaling system in cassava. The Arabidopsis thaliana FT gene (atFT) was transformed into the cassava cultivar 60444 through Agrobacterium-mediated transformation and was found to be overexpressed constitutively. FT overexpression hastened flower initiation and associated fork-type branching, indicating that cassava has the necessary signaling factors to interact with and respond to the atFT gene product. In addition, overexpression stimulated lateral branching, increased the prolificacy of flower production and extended the longevity of flower development. While FT homologs in some plant species stimulate development of vegetative storage organs, atFT inhibited storage-root development and decreased root harvest index in cassava. These findings collectively contribute to our understanding of flower development in cassava and have the potential for applications in breeding

Control of Flowering in Strawberries

Strawberries (Fragaria sp.) are small perennial plants capable of both sexual reproduction through seeds and clonal reproduction via runners. Because vegetative and generative developmental programs are tightly connected, the control of flowering is presented here in the context of the yearly growth cycle. The rosette crown of strawberry consists of a stem with short internodes produced from the apical meristem. Each node harbors one trifoliate leaf and an axillary bud. The fate of axillary buds is dictated by environmental conditions; high temperatures and long days (LDs) promote axillary bud development into runners, whereas cool temperature and short days (SDs) favor the formation of branch crowns. SDs and cool temperature also promote flowering; under these conditions, the main shoot apical meristem is converted into a terminal inflorescence, and vegetative growth is continued from the uppermost axillary branch crown. The environmental factors that regulate vegetative and generative development in strawberries have been reasonably well characterized and are reviewed in the first two chapters. The genetic basis of the physiological responses in strawberries is much less clear. To provide a point of reference for the flowering pathways described in strawberries so far, a short review on the molecular mechanisms controlling flowering in the model plant Arabidopsis is given. The last two chapters will then describe the current knowledge on the molecular mechanisms controlling the physiological responses in strawberries.Peer reviewe

[Retracted] The mRNA of the Arabidopsis gene FT moves from leaf to shoot apex and induces flowering

We wish to retract our Research Article “The mRNA of the Arabidopsis gene FT moves from leaf to shoot apex and induces flowering” (1). After the first author (T.H.) left the Umeå Plant Science Centre for another position, analysis of his original data revealed several anomalies. It is apparent from these files that data from the real-time RT-PCR were analyzed incorrectly. Certain data points were removed, while other data points were given increased weight in the statistical analysis. When all the primary real-time RT-PCR data are subjected to correct statistical analysis, most of the reported significant differences between time points disappear. Because of this, we are retracting the paper in its entirety. In new experiments, we have reproduced the floral induction caused by a heat-shock induction of FT in a single leaf, but we have failed to detect movement of the transgenic FT mRNA from leaf to shoot apex. We therefore retract the conclusion that FT mRNA is part of the floral inductive signal moving from leaf to shoot apex. We deeply regret any scientific misconceptions that have resulted from the publication of these data. The first author of the paper (T.H.) strongly objects to the retraction of the paper and has therefore declined to be an author of the retraction. Our related Science Report on the CO/FT regulatory module in trees (2) is not affected by this Retraction. In this paper, T.H. was involved in the construction and analysis of the PtCENL1 experiments reported in the Supporting Online Material. These data have been reevaluated and found to be correctly reported. See: https://doi.org/10.1126/science.316.5823.367bInternational audienc

The epigenetic memory of temperature during embryogenesis modifies the expression of bud burst-related genes in Norway spruce epitypes

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