L. Chvojka

The effect of kinetin and auxin on the chloroplast structure and chlorophyll content in wheat coleoptiles

Kinetin and auxin when applied to excised segments of wheat coleoptiles bring about changes in chloroplast structure and chlorophyll content of parenchymatous cells. Auxin (IAA) alone at a concentration of 10-5M stimulated the elongation (growth), but the chloroplast membrane system was less developed and the chlorophyll content was lowest in comparison with control and other variants. Kinetin (KIN) exhibited various effects depending on the concentration used. 10-6M KIN somehow stimulated the elongation and enhanced the amount of grana coming to one chloroplast section, but the individual grana were relatively small and the chlorophyll content a little higher than in the control. On the other hand 10-5M KIN which did not promote the elongation of wheat coleoptiles, had the maximum stimulatory effect on the chloroplast membrane system, especially on the occurrence of large grana, and the chlorophyll content was highest in comparison with the other variants. The occurrence of starch grains in chloroplasts was lower than in the other variants. The effect of a joint treatment of KIN and IAA did not exceed that of KIN (10-5M) alone. Thus the development of chloroplasts and the accumulation of chlorophyll in wheat coleoptiles are stimulated by the concentration of KIN which does not promote the elongation of coleoptiles.

The orientation of cell wall microtubules in wheat coleoptile segments subjected to phytohormone treatment

The effect of plant hormones was studied on the growth of excised coleoptile segments of wheat plantlets grown under daylight conditions. In addition to the change in growth, that in the orientation of microtubules and cellulose microfibrils was investigated in parenchyma cells. Following a 6-h treatment gibberellin, and still more kinetin, stímulated the thickening of segments, which became evident also in an altered orientation of microtubules. Whereas in the control the microtubules and wall microfibrils were oriented randomly, following gibberellin treatment they were all parallel and formed an acute angle with the longitudinal cell axis. A still more pronounced difference resulted after kinetin treatment, when microtubules were localized parallel with the longitudinal cell axis. Auxin had the opposite effect: it stimulated the elongation of the segments, which became evident in a transverse orientation of both wall microtubules and microfibrils.

Transport, localization and physiological effect of 6-benzyladenme-8-14C in apple shoots

The transport of radioactivity of 6-benzyladenine-8-14C applied to one-year old apple shoots was studied. Simultaneously, labelled metabolites of this cytokinin were studied separately in the xylem and phloem above and below the place of application. According to the results obtained, it can be assumed that 6-B and its metabolites are transported in one-year old apple shoots acropetally through the xylem and basipetally through the phloem, while penetrating from the xylem to the phloem. Besides 6-B-8-14C, a complex of cytokinin with sugar, also adenosine and adenine were found in the phloem.AbstractV této práci byl studován. transport radioaktivity 6-benzyladenimi-8-14C aplikovaného na jednoloté jabloňové výhony. Současně byly sledovány radioaktivní metabolity tohoto cytokininu v xylému a floému nad a pod místem podání 6-B-8-14C. Z výsledků lze usoudit, že 6.B a jeho metabolity jsou v jednoletých jabloňových výhonech transportovány xylémem akropetálně a floémem basipetálně, přičemž dochází jejich pronikání z xylému do floému. Z metabolitů byly identifikovány ve floému vodle 6-B-8-14C komplex tohoto cytokininu a cukernou složkou, dále adenosin a adenin.

The influence of stimulating doses of 6-benzylaminopurine on awakening apple buds and on their consumption of oxygen

Byl sledován vliv 6-benzylaminopurinu na dýchání pupenů jabloně odrůdy Boskooaké v průběhu 5 dnů po pod7#x00E1;ní kininu. Bylo zjištěno, že spotřeba kyslíku stanovovaná přímou metodou Warburgovou je vyšší již prvního dne po podání 6-benzylaminopurmu a stoupá stále výrazněji až do pátého dne, kdy je spotřeba kyslíku u pupenů stimulovaných o 75% vyšší, než u pupenů kontrolních.SummaryThe influence of 6-benzylaminopurine on the respiration of apple buds of the Boskoop variety for 5 days after application of kinine was observed. It was discovered that the consumption of oxygen determined by the direct method of Warburg is higher from the first day after application of 6-benzyl-amonipurine and the increase is continually more marked up to the fifth day, when the consumption of oxygen in stimulated buds is 75 per cent higher than in the control buds.AbstractВ течение 5 дней после введения 6-бензиламинопурина было изучено его влияние на дыхание ночек яблони. Авторы определяли потребление кислорода методом Варбурга. Было найдено, что потребление кислорода почками увеличивается с первого дня после введения 6-бензиламинопурина и на пятый день превышает на 75% потребление кислорода контрольными почками.

łлияне плодов н а осмо тнческоое давление клеточнопо Аока лнстьев и закладкг цветочных поŇ ек у ябл они

Autor studoval v průběhu dvou let osmotický tlak 70 stromů 7 odrůd jabloně, ze kterých 5 odrůd plodí periodicky a 2 ka Edoročně. Na začátku pokusu polovina stromů byla bez plodů a polovina s násadou plodů. Pokus byl proveden na 10 až 121et ch stromeoh (podnož M II, M IX a M IV) v severozápadni jabloňárské oblasti Čech (Střížovice, Těchobuzice). 3 až 4krát za vegetačni období byly odebirány listy brachyblastŮ plodíoích a odpočívajících jabloní a stanoven osmotický tlak jejich buněčné štávy, jakož i její elektrická vodivost. Jednou za sezónu byly odebrány terminálni pupeny brachyblastŮ, z kterých obyčejně vznikaji květní pupeny, a zpraeovány stejně jako listy.Ze získaných ůdajŞ plyne, že rostouci plody jsou příčinou snižení osmotického tlaku buněčné štávy listů jabloně 2 až 6 atmosfér v závislosti od množstvč násady a období. Toto snižení málo závisí na počasi a rozdíly v osmotickém tlaku buněcné štávy jabloní plodíeích a odpočívajících jsou v červenci vysoce průkazné. Osmotický tlak buněčné štávy pupenů je snižován méně: 1 až 2 atmosféry. Byla nalezena průkazná kladná korelace mezi hodnotou osmotického tlaku odrüdy Boskoopské červené a zakládáním květnich pupenů. U každoročně plodíeích odrťd taková korelace nebyla pozorována.РезюмеВ течение двух лет автор исследовал осм отическое давление 70 деревЬев 7 сорТов пблони, из кото рых 5 сортов плодоноси с периодичесни и 2 сорт а ежегодно. В начале оп ыта одна половина дср евьев имела большое количество завязавшихся плодик ов, аругая половина бы ла без урожая. Опыт был проведен на 10–12-лет них деревьях (подвой М II, М IX и м IV) в северозападно й яблоневой области Чехии (Стржижовице, Техобузице).В период закладки FветоGных почек, 3–4 раз а, с июня по сентябрь отбирались листья из брахибластов плодон осящих и беплодных я блоней и определялось осмот иGесŃое давление кле точного сока и електр опроводность. Раз в сезон отбиралис ь длп исследования нл етжчного сока термин альные почки брахибластов, которяе обячно дают начало цвеРочным почкам.Из полученных данных вытекает, что расРущи е плодл снижают осмот ическое давление клеточного сока листьев яблони на 2–6 атмосфер в зависи мости от общего количества плодв на дереве и вре мени после цветения. ЭТа разница относите льно постоянна при различных внпшних условиях в пределах нормы. В июл е меАяце разница осмж тических давлений ст атистически достоверна.Осмотическое давлен ие клетозного сока почек плодоносяйшх и бесплодных деревьев отличается только на 1–2 атм. Найде на положительная коррелKцип междг уро внем осмотического давления клетосока листьев и закладкой цветочных почек у зим него сорта Ьоскопски й красавец красный. У ежегодно пл одоносящих сортоВ не наблNдаетсO такой коррелпции.AbstractThe author investigated in the course of two years the osmotic pressure of 70 trees of 7 apple tree sorts, 5 of these bearing fruit periodically and 2 every year. At the beginning of the experiment, one half of the trees were without fruit and the other half with fruit-set. The experiment was carried out on 10–12-year-old trees (stock M II, M IX and M IV) in the NW apple-growing region of Bohemia (Střčžovice, Těchobuzice). Three or four times during every vegetation season leaves of brachyblasts of fruit-bearing and resting apple trees were removed and the osmotic pressure of their cell sap as well as its electric conductivity were measured. Once in every season, terminal buds of brachyblasts usually giving rise to flower buds were removed and treated identically as the leaves.It follows from the data obtained that growing fruits bring about a decrease in osmotic pressure of leaves of apple trees by 2–6 atmospheres, depending on the amount of fruit-set and on the season. This decrease depends very little on weather and differences in osmotic pressure of the cell sap of fruit-bearing and resting apple trees are highly significant in July. The cell sap osmotic pressure in buds is decreased less — by 1–2 atmospheres. A significant positive correlation between the value of osmotic pressure and flöwer-bud formation of the sort Boskopská červená was demonstrated. In sorts bearing fruit annually, no such correlation, could be observed.

Substances with cytokinin activity extracted from growing apices of apple-tree shoots

The presence of native cytokinins was studied in growing apices of apple-tree annual shoots. During June the presence of two compounds showing cytokinin activity in biotest was observed and their RF value was determined in three chromatographic systems.

The effect of phenylacetic acid on ethylene formation in wheat seedlings

Phenylacetic acid (PAA) was found to induce ethylene formation in wheat coleoptile segments. In its most effective concentration (0.5 mM) PAA was by approximately 60 % less active than 0.1 mM indole-3-acetic acid (IAA). PAA-induced ethylene formation was stimulated with 0.1 mM L-methionine by 24 % and totally inhibited by 2.5 and 5 μ gml-1 aminoethoxyvinylglycin (AVG) and 10 μg ml-1 cycloheximide. Cyoloheximide in lower concentration (5 μg ml-1) and actinomycin D (10 μg ml-1) inhibited PAA-induced ethylene formation by 50 % and 40 %, respectively.After the simultaneous addition of PAA and IAA ethylene formation was by 35 % lower than in the presence of IAA itself. Further, the coleoptile segments preincubated in IAA and then incubated in PAA solution produced by 35 % less ethylene than those incubated in plain buffer after preincubation in IAA. Quite the opposite effect was found when the segments were preincubated in PAA and then transferred into IAA solution. This treatment resulted in 70 % stimulation of ethylene formation over segments preincubated in PAA and incubated in buffer.

Electron microscopic autoradiographic study of RNA isolated from apple-tree callus tissue labelled with 6-Benzylaminopurine-8-C14

In the present paper RNA from apple-tree callus tissue labelled with 6-benzyl-minopurine14) was studied. The RNA isolated from this tissue was prepared as sample for electron microscopic studies and was also used as biochemical control. The electron microscopic autoradiograms obtained showed the labelled structure of RNA, sRNA and rRNA. The incorporation of labelled purine rings was confirmed in all three RNA types by the radioactivity, which was also proved in nucleotides after hydrolysation of RNA fractions. The results were compared with RNA isolated from tissue cultivated on a non-radiactive medium.AbstractV této práci byla metodou elektronmikroskopické autoradiografie studována inkorporace C14 značených basí do RNK, isolované z kulusů jabloně, pěstovaných in vitro v modiu se značenym 6-benzylaminopurinem-S-C14. Radioaktivita byla stanovena jak u autoradiogramů sumární RNK, tak r-RNK a s-RNK. Důkazem, že se jedná skutečnou inkorporaci, je stanovení radioaktivity mononukleotidů, získaných zásaditou hydrolysou těohto nukloových kyselin. Výsledky byly srovnány s RNK isolovanou z tkání, pěstovaných na ueznačené živné půdě.

The occurrence of auxins in the old leaves of apple trees

A relatively high auxin level was found in old leaves from the lower part of long shoots of young apple trees using the straight growth bioassay on wheat coleoptile segments. The auxin level remains almost constant during summer and autumn.

Transport and localization of 6-(γ,γ-dimethylallylamino)-purine-8-14C cytokinin in apple trees

When cytokinin 6-(γ,γ-dimethylallylamino)-purine-8-14C was injected into the side root of a one-year-old apple graft, variety Coxs Orange Pippin, it was mainly transported acropetally, but a certain part of the radioactivity was also transported basipetally into the root below the place of injection. 6 days after application of the labelled cytokinin most of the radioactivity was detected in the xylem, 20–30 cm above the place of application. An appreciable quantity of radioactivity was transported toward the apical part of the plant as far as 100 cm from the point of application. Special analysis showed that 6 days after exposition about half of the remaining radioactivity was present in 6-(γ,γ-dimethylallylamino)-purine-8-C14 and the rest went to the other metabolites. The cytokinin was transported acropetally mainly in the transpiration stream.AbstractStudovali jsme transport a lokalizaci cytokininu 6-(γ,γ-dimethylallylamino)-purinu-8-C14 v jednoletých jabloních odr⫲dy Coxova reneta, očkovaných na M IV. 6 dn⫲ po podání značeného cytokininu bylo nalezeno největší množství radioaktivity v xylému nadzemní části, a to ve vzdálenosti 20 až 30 cm nad dvouletým kořenem, do kterého byl cytokinin podán v roztoku. Značná část radioaktivity byla transportována také do apikální části rostliny na vzdálenost více než 100 cm od místa aplikace. Speciální analýzou bylo prokázáno, že asi polovina zbylé radioaktivity připadala na podaný cytokinin, zatím co zbytek byl metabolizován. Podaný cytokinin byl transportován z kořene do nadzemní části ve vodním roztoku hlavně jako součást transpiračního proudu.