Natural variation in the control of flowering and shoot architecture in diploid Fragaria species

In perennial fruit and berry crops of the Rosaceae family, flower initiation occurs in late summer or autumn after downregulation of a strong repressor TERMINAL FLOWER1 (TFL1) and flowering and fruiting takes place the following growing season. Rosaceous fruit trees typically form two types of axillary shoots, short flower-bearing shoots called spurs and long shoots that are respectively analogous to branch crowns and stolons in strawberry. However, regulation of flowering and shoot architecture differs between species and environmental and endogenous controlling mechanisms have just started to emerge. In woodland strawberry (Fragaria vesca L.), long days maintain vegetative meristems and promote stolon formation by activating TFL1 and GIBBERELLIN 20-OXIDASE4 (GA20ox4), respectively, while silencing of these factors by short days and cool temperatures induces flowering and branch crown formation. We characterized flowering responses of 14 accessions of seven diploid Fragaria species native to diverse habitats in the northern hemisphere, and selected two species with contrasting environmental responses, F. bucharica Losinsk. and F. nilgerrensis Schlecht. ex J. Gay for detailed studies together with F. vesca. Similar to F. vesca, F. bucharica was induced to flower in short days at 18°C and regardless of photoperiod at 11°C after silencing of TFL1. F. nilgerrensis maintained higher TFL1 expression level and likely required cooler temperatures or longer exposure to inductive treatments to flower. We also found that high expression of GA20ox4 was associated with stolon formation in all three species, and its downregulation by short days and cool temperature caused branch crown formation in F. vesca and F. nilgerrensis, although the latter did not flower. F. bucharica, in contrast, rarely formed branch crowns, regardless of flowering or GA20ox4 expression level. Our findings highlighted diploid Fragaria species as a rich source of genetic variation controlling flowering and plant architecture, with potential applications in breeding of Rosaceous crops.

Proximate, Ultimate and Calorific Analysis of European Beech Tree (Fagus sylvatica) Components for Fuel

Aims: The three different above ground biomass components (branch, crown, bark) of European Beech (Fagus sylvatica) were evaluated, regarding energy and combustion properties. Study Design: The proximate, ultimate and calorific analysis conducted on components of European Beech tree from three different age stands (10-, 20-, 30 years old). For each group of sample, separate experiments were carried out under similar conditions and experimental findings presented comparatively. The results obtained may be suggested for the selection of the best parts and age group for the improvement of fuel properties of selected tree and could provide useful evaluation of the test methods employed. Methodology: The three different above ground biomass components (branch, crown, bark) of European Beech (Fagus sylvatica) were selected for the investigation. For comparatively determining the combustion behavior and energy properties of the of European Beech tree components, the chips were prepared. These chips were dried (air dried, 12%) in laboratory conditions at 20 °C and 50% relative humidity before being subjected to evaluations. Typically, the combustion is preceded by evaporation of the moisture, distillation and burning of the volatiles before the fixed carbon burns. However, fixed carbon is the solid combustible residue that remains after a wood or bark are heated and the volatile matter is expelled. It is determined by subtracting the percentages of moisture, volatile matter, and ash from the sample. The combustion properties of a given substrate can be found by ultimate and proximate analysis. For determining volatile and ash contents, a TGA instrument (Leco TGA701 Thermogravimetric Analyzer) was utulized according to the ASTM D 5142 protocol. The moisture content determined at 105 °C, ash at 750 °C, volatiles at 950 °C in this experimental process. The heat values were determined by a calorimetry bomb instrument (Leco AC–500). At the end of the process, the energy levels of samples were found in calorific value (Kcal/Kg). The sulfur and carbon content were determined by using a carbon/sulfur analyzer instrument (Leco SC-144) and was determined at 1350 ºC at 3.0 min durations. Experimental Findings: It has found that selected variables (European Beech components and age groups) have influenced combustion and calorific properties in some level. However, bark was found to be show the lowest fixed carbon ratio of 13.7% in 10 years old samples. The highest volatile matter content of 84.6% was obtained with a 30 years old branch wood sample. Moreover, the highest level of ash content (3.7-9.9%) was found to be with bark samples in all three age groups, regardless of conditions. The measured calorific values looks like very similar in crown wood (4207.8 kcal/kg to 4263.8 kcal/kg) and branch wood samples (4137.8 kcal/kg to 4563.5 kcal/kg) while considerably lower for bark (3776.6 kcal/kg to 4200.7 kcal/kg). It is also important to note that European Beech tree have only showed trace amount of sulfur element (0.03-0.13%) in regardless of maturity and parts of tree.

GRAS transcription factor LOSS OF AXILLARY MERISTEMS is essential for stamen and runner formation in wild strawberry

Axillary bud development is a major factor that impacts plant architecture. A runner is an elongated shoot that develops from axillary buds and is frequently used for clonal propagation of strawberry. However, the genetic control underlying runner production is largely unknown. Here, we identified and characterized loss of axillary meristems (lam), an EMS-induced mutant of the diploid woodland strawberry (Fragaria vesca) that lacked stamens in flowers and had reduced numbers of branch crowns and runners. The reduced branch crown and runner phenotypes were caused by a failure of axillary meristem initiation. The causative mutation of lam was located in FvH4_3g41310, which encodes a GRAS transcription factor, and was validated by a complementation test. lamCR mutants generated by CRISPR/Cas9 produced flowers without stamens and had fewer runners than the wild type. LAM was broadly expressed in meristematic tissues. Gibberellic acid (GA) application induced runner outgrowth from the remaining buds in lam, but failed to do so at the empty axils of lam. In contrast, treatment with the GA biosynthesis inhibitor paclobutrazol (PBZ) converted the runners into branch crowns. Moreover, genetic studies indicated that lam is epistatic to suppressor of runnerless (srl), a mutant of FveRGA1 in the gibberellic acid pathway, during runner formation. Our results demonstrate that LAM is required for stamen and runner formation and acts sequentially with GA from bud initiation to runner outgrowth, providing insights into the molecular regulation of these economically important organs in strawberry.

Prohexadione-calcium Decreases Fall Runners and Advances Branch Crowns of `Chandler' Strawberry in a Cold-climate Annual Production System

Balancing vegetative growth with fruiting is a primary concern in strawberry (Fragaria ×ananassa Duch.) production. Where nursery plant selection and preconditioning are inadequate for runner control, additional approaches are needed. The gibberellin biosynthesis inhibitor prohexadione-Ca (commercial formulation Apogee) was tested over two seasons for suppressing fall runners of `Chandler' plug plants in a cold-climate annual hill production system. Prohexadione-Ca was applied as a foliar spray at active ingredient concentrations ranging from 60 to 480 mg·L-1, either as a single application 1 week after planting, or repeated at 3-week intervals. The lowest rate resulted in inadequate runner control, with some runners producing malformed daughter plants. Higher rates resulted in 57% to 93% reductions in fall runner numbers, with a concomitant increase in fall branch crown formation. There were no effects of the prohexadione-Ca treatments on plant morphology the following spring, and no adverse effects on fruit characteristics or yield. Chemical names used: prohexadione-calcium, calcium 3-oxido-4-propionyl-5-oxo-3-cyclohexene-carboxylate.