REDČENJE PLODIČEV JABLANE SORT GALA IN ZLATI DELIŠES Z BA, NAA IN NJUNIMI KOMBINACIJAMI

Apple trees, eight-year-old ‘Gala’/M.9 and four-year-old ‘Golden Delicious’/M.9 have been thinned with 6- benzyladenine (BA) 50 ppm, 100 ppm and 200 ppm, with 1-naphthaleneacetic acid (NAA) 5 ppm, 10 ppm and 20 ppm, and with the tank mix combinations of BA 50 ppm + NAA 5 ppm or BA 20 ppm + NAA 5 ppm, all at 9-10 mm fruitlet diameter. All applied concentrations of BA and NAA thinned both cultivars significantly and no significant difference was found between BA or NAA thinning action. No concentration response on thinning was observed with neither BA nor NAA application. All BA or NAA separate treatments caused yield of fruit to shift to bigger size class. The only concentration response effect was found on evaluation of mean fruit weight data on ‘Golden Delicious’. The higher concentration of BA was used, the higher was the weight of ‘Golden Delicious’ fruit. On the opposite, the higher concentration of NAA was used, the lower was the weight of ‘Golden Delicious’ fruit (not significantly). When BA and NAA were sprayed on ‘Gala’ or ‘Golden Delicious’ as a tank mix combination, similar effect on thinning or fruit growth occurred comparing to BA or NAA when sprayed alone. Return bloom was enhanced on all thinned ‘Gala’ trees while flower formation of ‘Golden Delicious’ was better in the case of BA 200 ppm, NAA 5 ppm, NAA 20 ppm or tank mix spraying of BA 20 ppm + NAA 5 ppm.Sedem let stare jablane sorte Gala/M.9 in štiri leta stare jablane sorte Zlati delišes/M.9 smo redčili s 6- benziladeninom (BA) v koncentraciji 50 ppm, 100 ppm in 200 ppm, nadalje z 1-naftilocetno kislino (NAA) v koncentraciji 5 ppm, 10 ppm in 20 ppm, ter s kombinacijo obeh sredstev, to je z mešanico BA 50 ppm + NAA 5 ppm, ter BA 20 ppm + NAA 5 ppm. Sredstva za redčenje smo nanesli v času poprečnega premera plodičev 9-10 mm. BA in NAA sta redčili obe preskušani sorti značilno in s približno isto stopnjo trebljenja plodičev. Trebljenje plodičev po nanosu različnih koncentracij BA oziroma NAA ni bilo odvisno od uporabljenih koncentracij. Pridelek plodov večjega velikostnega razreda se je pri obeh sortah povečal pri vseh nanosih BA ali NAA. Pri sorti Zlati delišes smo opazili učinek koncentracij uporabljenega sredstva na poprečno težo plodov. Po nanosu večje koncentracije BA je bila tudi poprečna teža plodov sorte Zlati delišes večja. Obratno pa je nanos večje koncentracije NAA povzročil manjšo poprečno težo plodov (statistično neznačilno) sorte Zlati delišes. V primeru škropljenja mešanice BA + NAA, sta obe obravnavani sorti reagirali z enako intenziteto trebljenja plodičev, kot v primeru samostojnega nanosa enega od obeh sredstev. Povratno cvetenje je bilo značilno boljše pri vseh redčenih drevesih sorte Gala, pri sorti Zlati delišes pa se je nastavek cvetja izboljšal le po nanosih BA 200 ppm, NAA 5 ppm, NAA 20 ppm in pri mešanici BA 20 ppm + NAA 5 ppm

UČINEK ETEFONA, NAA, BA IN NJIHOVIH KOMBINACIJ NA REDČENJE PLODIČEV JABLANE SORTE SUMMERRED

The chemical thinning of \u27Summerred\u27/M.9 was investigated on three years old apple trees. The application of ethephon 200 ppm was done at the start of flowering time, 6-benzyladenine (BA) 100 ppm and 1- naphthaleneacetic acid (NAA) 10 ppm was applied at 10 mm fruitlet diameter and the combination spraying of these thinners was done as a multiple (ethephon + BA, ethephon + NAA) or tank mix (BA + NAA) application. The alone application of ethephon or NAA reduced the final fruit number but did not enhance the mean fruit weight, similar as the consecutive (multiple) application of ethephon and NAA. On the contrary, when BA was applied (alone or in combination with ethephon) a nice fruit growth happened after the thinning of fruitlets. The tank mix spraying of BA + NAA reduced the fruit number adequately and the fruit growth was enhanced. The strongest thinning (overthinning) occurred when ethephon spraying was followed by the mixture of BA and NAA three weeks later. Significantly better return bloom was observed in the case of BA and NAA alone application, ethephon + BA, BA + NAA and ethephon + BA + NAA treatments

UČINEK ETEFONA, NAA, BA IN NJIHOVIH KOMBINACIJ NA REDČENJE PLODIČEV JABLANE SORTE SUMMERRED

The chemical thinning of \u27Summerred\u27/M.9 was investigated on three years old apple trees. The application of ethephon 200 ppm was done at the start of flowering time, 6-benzyladenine (BA) 100 ppm and 1- naphthaleneacetic acid (NAA) 10 ppm was applied at 10 mm fruitlet diameter and the combination spraying of these thinners was done as a multiple (ethephon + BA, ethephon + NAA) or tank mix (BA + NAA) application. The alone application of ethephon or NAA reduced the final fruit number but did not enhance the mean fruit weight, similar as the consecutive (multiple) application of ethephon and NAA. On the contrary, when BA was applied (alone or in combination with ethephon) a nice fruit growth happened after the thinning of fruitlets. The tank mix spraying of BA + NAA reduced the fruit number adequately and the fruit growth was enhanced. The strongest thinning (overthinning) occurred when ethephon spraying was followed by the mixture of BA and NAA three weeks later. Significantly better return bloom was observed in the case of BA and NAA alone application, ethephon + BA, BA + NAA and ethephon + BA + NAA treatments

THE EFFECT OF ETHEPHON, NAA, BA AND THEIR COMBINATIONS ON THINNING INTENSITY OF 'SUMMERRED' APPLES

The chemical thinning of 'Summerred'/M.9 was investigated on three years old apple trees. The application of ethephon 200 ppm was done at the start of flowering time, 6-benzyladenine (BA) 100 ppm and 1- naphthaleneacetic acid (NAA) 10 ppm was applied at 10 mm fruitlet diameter and the combination spraying of these thinners was done as a multiple (ethephon + BA, ethephon + NAA) or tank mix (BA + NAA) application. The alone application of ethephon or NAA reduced the final fruit number but did not enhance the mean fruit weight, similar as the consecutive (multiple) application of ethephon and NAA. On the contrary, when BA was applied (alone or in combination with ethephon) a nice fruit growth happened after the thinning of fruitlets. The tank mix spraying of BA + NAA reduced the fruit number adequately and the fruit growth was enhanced. The strongest thinning (overthinning) occurred when ethephon spraying was followed by the mixture of BA and NAA three weeks later. Significantly better return bloom was observed in the case of BA and NAA alone application, ethephon + BA, BA + NAA and ethephon + BA + NAA treatments

Binary control of enzymatic cleavage of DNA origami by structural antideterminants

Controlling DNA nanostructure interaction with protein is essential in developing nanodevices with programmable function, reactivity, and stability for biological and medical applications. Here, we show that the sequence-specific action of restriction endonucleases towards sharp triangular or rectangular DNA origami exhibits a novel, binary 'on/off' behaviour, as canonical recognition sites are either essentially fully reactive, or strongly resistant to enzymatic cutting. Moreover, introduction of structural defects in the sharp triangle can activate an otherwise unreactive site, with a site-to-defect distance of ∼50 nm. We argue that site reactivity is dependent upon programmable, mechanical coupling in the two-dimensional DNA origami, with specific structural elements, including DNA nicks and branches proximal to the sites that can function as negative(anti) determinants of reactivity. Empirically modelling the constraints to DNA degrees of freedom associated with each recognition site in the sharp triangle can rationalize the pattern of suppressed reactivity towards nine restriction endonucleases, in substantial agreement with the experimental results. These results provide a basis for a predictive understanding of structure-reactivity correlates of specific DNA nanostructures, which will allow a better understanding of the behaviour of nucleic acids under nanoscale confinement, as well as in the rational design of functional nanodevices based on self-assembling nucleic acids

Viruses: incredible nanomachines. New advances with filamentous phages

During recent decades, bacteriophages have been at the cutting edge of new developments in molecular biology, biophysics, and, more recently, bionanotechnology. In particular filamentous viruses, for example bacteriophage M13, have a virion architecture that enables precision building of ordered and defect-free two and three-dimensional structures on a nanometre scale. This could not have been possible without detailed knowledge of coat protein structure and dynamics during the virus reproduction cycle. The results of the spectroscopic studies conducted in our group compellingly demonstrate a critical role of membrane embedment of the protein both during infectious entry of the virus into the host cell and during assembly of the new virion in the host membrane. The protein is effectively embedded in the membrane by a strong C-terminal interfacial anchor, which together with a simple tilt mechanism and a subtle structural adjustment of the extreme end of its N terminus provides favourable thermodynamical association of the protein in the lipid bilayer. This basic physicochemical rule cannot be violated and any new bionanotechnology that will emerge from bacteriophage M13 should take this into account

Global and local mechanical properties control endonuclease reactivity of a DNA origami nanostructure

We used coarse-grained molecular dynamics simulations to characterize the global and local mechanical properties of a DNA origami triangle nanostructure. The structure presents two metastable conformations separated by a free energy barrier that is lowered upon omission of four specific DNA staples (defect). In contrast, only one stable conformation is present upon removing eight staples. The metastability is explained in terms of the intrinsic conformations of the three trapezoidal substructures. We computationally modeled the local accessibility to endonucleases, to predict the reactivity of twenty sites, and found good agreement with the experimental data. We showed that global fluctuations affect local reactivity: the removal of the DNA staples increased the computed accessibility to a restriction enzyme, at sites as distant as 40 nm, due to an increase in global fluctuation. These results raise the intriguing possibility of the rational engineering of allosterically modulated DNA origami

Profiling of dynamics in protein–lipid–water systems: a time-resolved fluorescence study of a model membrane protein with the label BADAN at specific membrane depths

Profiles of lipid-water bilayer dynamics were determined from picosecond time-resolved fluorescence spectra of membrane-embedded BADAN-labeled M13 coat protein. For this purpose, the protein was labeled at seven key positions. This places the label at well-defined locations from the water phase to the center of the hydrophobic acyl chain region of a phospholipid model membrane, providing us with a nanoscale ruler to map membranes. Analysis of the time-resolved fluorescence spectroscopic data provides the characteristic time constant for the twisting motion of the BADAN label, which is sensitive to the local flexibility of the protein–lipid environment. In addition, we obtain information about the mobility of water molecules at the membrane–water interface. The results provide an unprecedented nanoscale profiling of the dynamics and distribution of water in membrane systems. This information gives clear evidence that the actual barrier of membranes for ions and aqueous solvents is located at the region of carbonyl groups of the acyl chains