Amylolytic Enzyme Activities Research Articles

Bermudagrass Response to Chilling Temperatures as Influenced by Iron and Benzyladenine

Chilling temperatures (10 to 15 °C down to 0 °C) disrupt photosynthesis, reduce growth, and discolor bermudagrass (Cynodon spp.) turf. We studied the effects of chilling in controlled environments on the CO2 exchange rate (CER), total nonstructural carbohydrate (TNC) content, amylolytic enzyme activity (AEA), chlorophyll content, and turf color in two bermudagrasses to determine the influence of iron and benzyladenine (BA) upon these parameters. Grasses were grown on a Frederick silt loam (clayey, kaolinitic mesic Typic Hapludult) at pH 5.7 with 4.8 g N m−2 month−1. Daytime CER of ‘Midiron’ and ‘Tifgreen’ declined 71 and 82% and night‐time CER declined 55 and 52%, respectively, during 4 d at chilling (10/7 °C day/ night) temperatures. Midiron CER was 70% of the original daytime rate at 30 °C but Tifgreen returned to within only 27% when returned to 30 °C for 2 h after the chilling treatment. In contrast, night‐time CER fully recovered. Tifgreen's low daytime CER was associated with a 25% decrease in chlorophyll content, 60% decrease in AEA, and 160% increase in leaf TNC during chilling. Midiron chlorophyll content was unchanged, AEA decreased 30%, and leaf TNC increased 88% during chilling. The Fe treatments had similar prechill daytime CER. However, 120 mg Fe m−2 as FeDTPA maintained a 23% higher average daytime CER than 0 mg Fe m−2 after chilling and following recovery from chilling. Night‐time CER before and after the chilling regime was not affected by Fe. Average night‐time CER was 28% higher for the 120 than the 0 mg Fe m−2 treatment after the recovery period. Leaf TNC accumulation was similar for the Fe treatments. Darker green turf color was observed for 120 than for 0 mg Fe m−2 after the chilling period although no difference in chlorophyll content occurred. Daytime and night‐time CER, chlorophyll content, TNC, and color scores for the 0 and 12.4 mg BA m−2 treatments were similar at each temperature regime. Although chlorophyll loss and TNC accumulation in leaves are associated with photosynthetic inactivity in chill‐sensitive bermudagrasses, disruption of carbon partitioning and utilization probably contribute to reduced growth and turf quality of bermudagrasses at chilling temperatures. Foliarly applied Fe may facilitate the maintenance of physiological activity and more desirable turf quality of bermudagrass exposed to chilling temperatures.

The effect of the etched (et) mutation on the amylolytic enzyme activities in germinating kernels and seedlings of Zea mays

The etched (et) mutation in maize causes distinct depressions and structural gaps in the endosperm and also gives rise to virescent seedlings, α- and β-Amylase activities were observed to be higher in et (+) et (+) kernels and seedlings as compared to that of the et et mutant. The total amylase and β-amylase trends during germination also differed between normal and mutant kernels and seedlings (it increases in the wildtype and decreases in et et). On the contrary, the overall α-amylase trend was found to be similar in both genotypes (slight decrease during germination). The native gel electrophoresis of crude enzyme extracts did not reveal any qualitative differences in α and β amylases during germination. The germinating et et kernels initially showed lower levels of starch compared with the wild type kernels, whereas no such difference was found at later stages of germination. It is concluded that et gene associated endosperm lesions lead to an impairment of starch degradation in germinating kernels resulting in virescent seedlings.

EFFECT OF MAGNETIC SEED TREATMENT ON AMYLOLYTIC ACTIVITY OF QUIESCENT AND GERMINATING BARLEY AND WHEAT SEEDS

Pre-imbibition exposure of quiescent seeds of barley (Hordeum vulgare L. ’Olli’ and ’Conquest’) and of hard red winter wheat (Triticum aestivum L. ’Kharkov 22 MC’) to a nonhomogeneous magnetic field reduced the amount of amylolytic enzyme activity in subsequently imbibed seed parts, whole seeds, or very young seedlings.

Photosynthesis and Cold Hardening in Zoysia and Bermudagrass1

Objectives of this research were to evaluate ultrastructural and physiological factors associated with cold‐hardening in the field of three bermudagrass (Cynodon dactylon L.) and three zoysia (Zoysia spp.) cultivars. Cold tests of rhizome tissue in December showed that zoysia cultivars survived colder temperatures than bermudagrass cultivars which agrees with most field observations. Midwest zoysia and Midway bermudagrass were the most low temperature tolerant of their respective genera.During October, ultrastructural changes occurred which indicated differences between hardy and non‐hardy cultivars. For example, bermudagrass chloroplasts took on a globular shape compared with an elongated shape in late summer. Chloroplasts of zoysia cultivars usually showed no alteration in shape in October.During November in 1973 and 1974, plots of both zoysia and bermudagrass appeared to be only 10 to 12% green, but green tissue of zoysia was four to eight times more photosynthetically active than that of bermudagrass. Amylolytic enzyme activity was also higher in zoysia at that time. Grana lamellae of chloroplasts of green zoysia tissue were mostly still intact in November, but were usually damaged in bermudagrass. The higher photosynthetic rate observed in zoysia compared to bermudagrass during the cold hardening period would be an advantage since carbohydrate could be conserved or used to prepare the plant cells for winter when little or no growth was occurring.

Starch degradation by the mould Trichoderma viride. I. The mechanism of starch degradation.

The mechanism of starch degradation by the fungus Trichoderma viride was studied in strain CBS 354.44, which utilizes glucose, starch and dextrins but is unable to assimilate maltose. It was shown that the amylolytic enzyme system is completely extracellular, equally well induced by starch, amylose or amylopectin and that it consists mainly of enzymes of the glucoamylase type which yield glucose as the main product of starch hydrolysis. Small amounts of alpha-amylase are produced also. The enzymes produced in starch cultures degrade starch, amylose and amylopectin equally well. Enzyme synthesis in starch media takes place to a considerable extent after exhaustion of the carbon source when maximum growth has been attained. Low-molecular dextrins are degraded by extracellular enzymes of the glucoamylase type. These enzymes are produced in media containing starch or dextrins. Maltotriose is consumed for only one third leaving maltose in the culture filtrate. Maltose is hardly attacked and hardly induces any amylolytic enzyme activity. No stable alpha-glucosidase appears to be produced.

Amylolytic Activity of Orchardgrass and Starch and Sucrose Contents of Orchardgrass vs Pangola Digitgrass Leaf Blades as Influenced by Night Temperature and Gibberellic Acid1

This study was made to determine differences in sucrose and starch contents and amylolytic activities between Orchardgrass (Dactylis glomerata L.) and ‘Pangola’ digitgrass (Digitaria decumbens Stent.). This information could help explain why growth of tropical grasses is severely reduced by suboptimal night temperature (10C) whereas temperate species are much less affected.Orchardgrass and Pangola were treated with gibberellic acid (GA) and subjected to 30 or 10C 12‐hour nights with SOC days, after which sucrose and starch were determined. The starch‐degrading enzymes of Orchardgrass leaf blades were separated by means of polyacrylamide gel electrophoresis. Amylolytic enzyme activity was determined from densitometer tracings and by a colorimetric assay. In the case of Orchardgrass extracts, densitometer tracings of gels negatively stained by starch‐iodine showed the presence of 18 bands regardless of plant treatment. This was hi contrast to similar data previously obtained for Pangola. The temperate grass was found to contain more amylolytic isozymes and greater total amylolytic activity than Pangola. Neither the 10C night regime nor GA application affected total amylolytic activity or starch content of Orchardgrass, whereas both treatments affected amylolytic activity and starch content of Pangola. GA application did not affect the number of amylolytic isozymes in the leaf blades of either plant. Sucrose appeared to accumulate in leaves of both grasses during 10C exposure, in the presence and in the absence of GA. In the case of Orchardgrass, GA appeared to reduce leaf sucrose content at 30C.

Action of amylolytic enzymes on a chromogenic substrate

Action of amylolytic enzymes on a chromogenic substrate

Factors Affecting the Difference in Rheological Characteristics of Flour Dough Obtained from Japanese Domestic Wheat. : III. Effect of rain during ripening on the quality of wheat grain and its flour. : 2. Some varietal differences in the response against moist treatment.

Three days wetting at 20-25°C of wheat eals at "hard dough" stage resulted in the increases in the activity of proteolytic and amylolytic enzymes and in sulfhydril content, which were available for approximate estimation of the susceptibility of various wheat varieties to wet damage, if the test plants had not been wetted for some days preceding the treatment. By this procedure, some varietal differences in susceptibility to wet damage were shown. Among the nine varieties examined, Aoba-Komugi was more, and Norin No. 50 was less susceptible than the others. On varieties having stronger inclination to sprout under humid climate, more rapid increase in the activity of α-amylase occurred by the moist treatment than on those showing less sush characteristics, while such trend was not found in the activity of proteolytic enzyme.