ATP-levels of germinating seeds in relation to vigor

Determination of seed vigor was attempted by comparing ATP-levels of deteriorating seed to germination percentage and production of dry matter. Immediately after imbibition of any seed lot investigated, a production of ATP took place. This ATP-accumulation invariably reached a plateau after 6 h of imbibition. Two well germinating seed lots of rape, one of cauliflower and one of sugar beet, were artificially aged by means of elevated storage temperature and humidity. Every second week through 16 weeks of deterioration the levels of ATP, ADP and AMP after 7 h of imbibition were compared with the germination percentage. While ADP- and AMP-contents of germinating seed displayed no change (when imbibed 7 h) during the period of artificial aging, seed deterioration was reflected in the ATP-levels long before loss of viability could be detected by the conventional germination test.
When ATP-levels per seed were related to germination percentage throughout the aging, all four seed lots displayed similar patterns although the absolute figures differed. In contrast to the conventional "per seed' basis, however, ATP per gram seed not only displayed similar deterioration patterns, but the absolute values were also of the same magnitude.     

Effects of high temperature on the germination of maize (Zea mays L.)

Poor emergence of maize seedlings, due to high soil temperatures, is a major limitation of crop potential in the lowland tropics. Ability to germinate at high temperature (>c. 37° C) is related to the temperature sensitivity of the embryo, and there is considerable genotypic variation for this character.Respiration and mitochondrial phosphorylation proceed normally in seeds imbibing at 41° C, and ATP levels are adequate for germination. However, the specific activities of several important enzymes are lower, and the rate of protein synthesis is severely reduced compared with seeds imbibing at 28° C. The depression of the rate of protein synthesis in the embryos of several tropical hybrids imbibing at high temperature correlated with their known temperature sensitivity. It is concluded that protein synthesis is an especially temperature sensitive process in germinating maize embryos, and that this is the principal reason for the sensitivity of germinating maize seeds to high temperature.Abbreviations ADP adenosine-5-diphosphate - ATP adenosine-5-triphosphate - BSA bovine serum albumin - EDTA ethylenediaminetetra-acetic acid - HEPES N-2-hydroxyethylpiperazinc-N-2-ethanesulphonic acid - NADH nicotinamide-adenine dinucleotide, reduced form - PPO 2, 5-diphenyloxazole - PVP polyvinylpyrrolidone - SEM standard error of the mean - tris tris (hydroxymethyl)-methylamine     

Red-light- and gibberellic-acid-enhanced α-galactosidase activity in germinating lettuce seeds,cv. Grand Rapids

Dry lettuce (Lactuca sativa L.) seeds (achenes) contain -galactosidase (EC 3.2.122) at a level which is maintained in the imbibed dormant state in darkness. Both red light (R) and gibberellic acid promote an increase in enzyme activity several hours prior to the completion of germination. Germination and enzyme activity are not essentially linked, however, for the latter can increase while the former is inhibited. -Galactosidase activity increases within the cotyledons and the endosperm following R stimulation, but the axis is essential to perceive the stimulus and to promote and maintain the increase in enzyme activity. A diffusible factor (or factors) is produced by and-or released from irradiated axes, and it migrates to the cotyledons (and possibly endosperm) to promote the increase in -galactosidase activity. Gibberellic acid, particularly in the presence of benzyladenine, can replace the requirement for irradiated axes.Abbreviations GA₃ gibberellic acid - R red light     

Effects of microtubule-inhibitors on nuclear migration and rhizoid differentiation in germinating fern spores (Onoclea sensibilis)

Summary Germinating spores of the sensitive fern,Onoclea sensibilis L., undergo premitotic nuclear migration before a highly asymmetric cell division partitions each spore into a large protonemal cell and a small rhizoid initial. Nuclear movement and subsequent rhizoid formation were inhibited by the microtubule (MT) inhibitors, colchicine, isopropyl-N-3-chlorophenyl carbamate (CIPC) and griseofulvin. Colchicine prevented polar nuclear movement and cell division so that spores developed into enlarged, uninucleate single cells. CIPC and griseofulvin prevented nuclear migration, but not cell division, so that spores divided into daughter cells of approximately equal size. In colchicine-treated spores, MT were not observed at any time during germination. CIPC prevented MT formation at a time coincident with nuclear movement in the control and caused a disorientation of the spindle MT. Both colchicine and CIPC appeared to act at a time prior to the onset of normal nuclear movement. The effects of colchicine were reversible but those of CIPC were not. Cytochalasin b had no effect upon nuclear movement or rhizoid differentiation. These results suggests that MT mediate nuclear movement and that a highly asymmetric cell division is essential for rhizoid differentiation.     

Fermentative products and dark CO2 fixation during germination of seeds of Cicer arietinum

During the germination of Cicer arietinum L. the amounts of ethanol, lactate and malate reached their highest values at 24 hr, the concentration of ethanol being about 4 times that of lactate and twice that of malate. The activities of phosphoenolpyruvate carboxylase and malic enzyme seem to be correlated with the ability of cotyledons to fix CO₂ from NaH¹⁴CO₃ into malate and with the further decrease in this metabolise from 36 hr onwards.     

Physiology and fine structure of sporangiospore germination in Piptocephalis unispora prior to infection

Germination of the sporangiospore of Piptocephalis unispora Benjamin, observed by means of light and electron microscopy, involved the formation of a new inner wall which became continous with the inner layer of the wall of the germ tube. The outer wall layer of the germ tube was continous with the original inner wall layer of the dormant spore. Preliminary details of appressorium structure were noted. Nutritional experiments indicated that sporangiospores required external sources of utilisable nitrogen and carbon compounds for maximal swelling and germ tube production. Limited development occurred when either nutrient was supplied singly. Comparison of germination of the asexual spore with that in other Mucorales, especially the Kickxellaceae, has been made, and the merosporangial status in P. unispora discussed.Non-Standard Abbreviations CH casein hydrolysate - Q spore quotient     

Specific template activity of ribonucleoprotein particles isolated from germinating Triticum aestivum embryo

A ribonucleoprotein (RNP) complex formed in wheat embryo at early germination stage was shown to be composed of 40-S RNP particle monomers and oligomers. RNA purified from this complex stimulated incorporation in vitro of various amino acids with efficiences dependent upon the frequencies of the corresponding codons calculated for this RNA from its base composition. Methionine was incorporated over the expected rate when the crude RNP complex, instead of the purified RNA, was used as the template. It is believed that the RNP complex represents a crude informosome fraction. The informosomes seem to contain a protein component that promotes the initiation of translation but does not involve the subsequent production of protein.     

Growth,radicle and root hair development ofDeschampsia flexuosa (L.) Trin. seedlings in relation to soil acidity

Deschampsia flexuosa (L.) Trin. is an abundant grass species in the ground flora of acidic beech forests in southern Sweden. Generally, the species is restricted to a limited soil pH range (pH 4–5). The main objective was to study the influence of different soil acidities on germination, initial root development and on the growth of the species. The experiments were carried out under controlled conditions and designed to simulate the physico-chemical conditions present in the field. By using forest soils within the pH range 4.0 to 8.3 and artificial variation in pH (3.2 to 7.6) of soil-water extracts, it was possible to evaluate the influence of soil reaction and the H⁺ per se. In all experiments seeds have been used. Germination was significantly delayed in the very acid soil (pH 4.0) in comparison to the germination in soils within the pH range (4.4 to 6.4). Soil substances, other than the H⁺, might be responsible for this delay in germination, whereas development of the radicle was markedly affected by increasing H⁺ concentrations. Especially the development of root hairs was sensitive to H⁺ and was significantly reduced at a pH<-3.8. By increasing soil acidity the injury symptoms, including curling and discolouring, became more intense and at the highest acidity (pH 3.2) the radicles appeared brown, stunted and the root hairs were lacking. Most favourable growth was obtained at pH 4.4 and 5.0. Soil pH levels above and below this range limited both shoot and root growth. The results showed very good correspondence with observations made in Beech forest soils in southern Sweden, where the species was growing in soils within the pH range 3.9 to 5.1 with a peak growth at pH 4.3. This study shows that in soils at pH≤3.8, the poor development of the radicle may be crucial in the establishment ofDeschampsia flexuosa. Root hair development was more sensitive to soil acidity than radicle elongation. Germination was delayed in very acid Beech forest soils but other factors than the H-ion per se may be responsible for this delay.     

Some molecular properties of plant starch phosphorylases and the levels of activity of the multiple forms

A number of plant tissues have two phosphorylase fractions (I and II) that can be separated by DEAE-cellulose chromatography. When only one is detectable, it corresponds to enzyme II. Peas differed from other legumes in showing an increase in enzyme I during seed germination. Examination of the I type enzymes, by sodium dodecyl sulphate polyacrylamide gel electrophoresis, sector cell ultracentrifugation and gel filtration, indicated that these were dimers composed of similar sub-units of MW near 90 000. When phosphorylase II enzymes were examined, the sub-unit MW was found to be higher, near 110 000 and, whereas ultracentrifugation techniques indicated a dimer of similar sub-units for the native enzyme, gel filtration gave higher MW values. Phosphorylase II from Victory Freezer peas differed from the other samples, in being able to form mixtures of dimer and tetramer.