Regulation of the Krebs cycle and pentose phosphate pathway activities in the control of dormancy of Avena fatua

Catalase activity in grapevine (Vitis vinifera L.) buds cv. ;Perlette.' increased to a maximum in October and thereafter decreased within 3 months to less than half its maximal rate. The decrease in catalase activity coincided with the decline in temperature during winter. The rate of sprouting of buds forced at 23 degrees C was negatively related to the activity of catalase. Artificial chilling of grapevine canes at 5 degrees C resulted in a 25% decrease of catalase activity in the buds after 3 days and 31% after 17 days. The activity of catalase increased to the control level only 96 hours after removing canes from 5 degrees C to room temperature. Efficient buddormancy breaking agents, such as thiourea and cyanamide decreased catalase activity to 64 and 50% of the controls respectively, while the activity of peroxidase remained the same under those conditions. A less efficient dormancy breaking agent dinitro-ortho-cresol, did not decrease catalase activity.

Section: Catalase In Grapevine Dormancy Results and Discussionsupporting

confidence: 75%

Changes in the Activity of Catalase (EC 1.11.1.6) in Relation to the Dormancy of Grapevine (Vitis vinifera L.) Buds

Nir¹,

Shulman²,

Fanberstein³

et al. 1986

“…The activation ofthe pentose-phosphate pathway is thought to be necessary for the breaking of dormancy in buds and seeds (19). Glucose-6-phosphate dehydrogenase, which catalyzes the rate limiting step in the pentose-phosphate pathway, is not only dependent on the availability of NADP+, but is inhibited by NADPH (6).…”

Section: Kiwifruitmentioning

confidence: 99%

Effect of Hydrogen Cyanamide on Amino Acid Profiles in Kiwifruit Buds during Budbreak

Walton¹,

Clark²,

Boldingh³

1991

Buds, and resultant shoots, were collected from kiwifruit (Actinidia deliciosa [A. Chev.] CF Liang et AR Ferguson var deliciosa cv Hayward) vines from late autumn until late spring with and without hydrogen cyanamide treatment. Those samples were weighed and analyzed for total nitrogen and free amino acids. By 7 days after hydrogen cyanamide treatment, the amount of proline had risen to nearly one-quarter of the total amino acid pool in the treated buds and that proportion was maintained for at least 14 days before it declined. The maximum concentration detected in treated buds was 25.8 micromoles per gram dry weight, 6.6 times that detected in untreated buds. By 95 days after treatment, the relative amounts of proline were not significantly different.

“…They concluded that a block in phosphate metabolism appeared to be associated with the dormant state. Pradet et al (13) noted that the energy charge of germinating lettuce seeds was reduced under anaerobic conditions, and Simmonds and Simpson (17) found that dry storage of wild oat caryopses in an atmosphere of nitrogen resulted in a decreased rate of germination of the excised embryos in response to gibberellic acid while storage in oxygen resulted in an increased response of the embryos to gibberellic acid. Although Ching and Ching (6) recently observed a steep rise in the energy charge of embryos during stratification of ponderosa pine seeds, a causal relationship between the low temperature treatment and a high energy charge has not been established.…”

mentioning

confidence: 99%

High Energy Charge as a Requirement for Axis Elongation in Response to Gibberellic Acid and Kinetin during Stratification of Acer saccharum Seeds

Simmonds¹,

Dumbroff²

1974

Self Cite

The growth potential of embryonic axes of Acer saccharum Marsh. increased during moist storage at 5 C but not at 20 C. During the period of increasing growth potential, the oxygen consumption of the axes remained constant. It was possible to distinguish three phases of the stratification-germination process at 5 C with respect to response of the axis to gibberellic acid and kinetin. From 0 to 10 days the growth regulators had no effect on elongation; from 10 to 60 days axis elongation was stimulated; and between day 60 and day 75, when germination had begun, the growth substances were inhibitory. The adenylate energy charge remained low (0.15) in axes of dry dormant seeds but increased to 0.78 following imbibition of water and 10 days of moist storage at 5 C. This phenomenon was not specifically related to low temperature stratification, since a rapid increase in the energy charge of the axes also occurred following imbibition and moist storage at 20 C. The excised axes would elongate in response to the growth substances only when a high energy charge (approximately 0.8) was maintained.as half the average number of anhydride-bound phosphate groups per adenosine moiety) for the termination of dormancy is provided from several sources. Olney and Pollock (10) reported that during stratification of cherry seeds an increased rate of respiration occurred in the embryonic leaf primordia, and this was accompanied by the accumulation of phosphate within the axis in the form of sugar phosphates, high energy nucleotides, and nucleic acids. They concluded that a block in phosphate metabolism appeared to be associated with the dormant state. Pradet et al. (13) noted that the energy charge of germinating lettuce seeds was reduced under anaerobic conditions, and Simmonds and Simpson (17) found that dry storage of wild oat caryopses in an atmosphere of nitrogen resulted in a decreased rate of germination of the excised embryos in response to gibberellic acid while storage in oxygen resulted in an increased response of the embryos to gibberellic acid. Although Ching and Ching (6) recently observed a steep rise in the energy charge of embryos during stratification of ponderosa pine seeds, a causal relationship between the low temperature treatment and a high energy charge has not been established.The objectives of the present work were to observe the response of the embryonic axis of A. saccharum to applied hormones during the various stages of stratification and to determine the effect of both low and high temperature stratification on the amounts of available energy in the adenylate system of the axis during these phases.Seeds of Acer saccharum Marsh. have morphologically mature but dormant embryos which require a period of stratification under cold, moist conditions before germination will occur (20). Previous work with this genus (7,21) has shown that the stratification-germination period of intact seeds may be divided into three phases: (a) the initial phase, evidenced by a rapid rise in respiratory activity and at l...