Short Oommunications Kinins in Germinating Lettuoe Seed

Abstract

The presence, in plants extracts, of factors capable of promoting cell division has been known for some time (Goldacre and Bottomley 1959;Miller 1961) and such compounds have been partially purified (Miller 1961; Zwar, Bottomley, and Kelford 1963). The germination of seeds normally involves cell division as well as cell enlargement (Mayer and Poljakolf-Mayber 1963). Therefore it seemed of interest to investigate whether kinins occur in seeds or are formed during their germination. Lettuce seeds were used because their physiology has been studied extensively. We have also tried to partially characterize their kinins. MethodsKinin activity was assayed biologically. The test objects were disks of stem pith from tobacco, Nicotiana tabacum cv. Seratina. The pith was removed from externally sterilized stem sections, taken 20 em from the stem apex. The disks, 2-3 mm in diameter and 2-3 mm thick, were obtained aseptically and were prepared fresh for each experiment. They were floated in petri dishes on culture medium prior to sowiug into erlenmeyer flasks containing 20 ml of medium solidified with agar. The medium was that of Zwar and Skoog (1963), but with their concentrations of inorganic nutrients doubled.Two controls were used: in both 0·2 p.p.m. 3-indolylacetic acid (IAA) was added to the basal medium and in one 0·2p.p.m. of kinetin was also added. In those containing 0·2 p.p.m. kinetin normally 9 out of 10 sections grew, while in those without kinetin growth was absent. When extracts were tested they were substituted for the kinetin. The flasks were kept in the dark at 26'0 and covered with polythene in order to reduce drying out of the culture. IGnin activity was assayed visually by determining whether the pith had undergone cell division after 2-4 weeks Zwar, Bottomley, and Kelford 1963;Zwar and Skoog 1963). Oen division could be easily detected visually and was confirmed by microscopic examination of cells from the disks. Kinin activity is expressed as the number of disks showing cell division in a given number of replicates as compared to controls without kinin.Lots of 1 g of lettuce seeds, cv. Grand Rapids, were germinated in petri dishes with 3 ml water and given a light stimulus of 30 sec exposure to red light after imbibition for I hr, and then placed in the dark at 26'0 (EvenariandNeumann 1953). Mter 48 hr germination was 100%. >I< Manuscript

Cytokinin Antagonizes Abscisic Acid-Mediated Inhibition of Cotyledon Greening by Promoting the Degradation of ABSCISIC ACID INSENSITIVE5 Protein in Arabidopsis

“…In addition to ABA and GA, cytokinin has been implied to play an important role in regulating seed germination (Barzilai and Mayer, 1964;Khan, 1971;Black et al, 1974;Thomas et al, 1997). Cytokinin is an essential phytohormone involved in the regulation of various aspects of plant growth and development, including seed germination (Werner and Schmülling, 2009).…”

Appearance of the zeatin riboside type of cytokinin inPinus sylvestrisseeds after red light treatment

“…In the classical photosensitive material, achenes oí Lactuca sativa L. cv. Grand Rapids, Barzilai & Mayer (1964) found cell division promoting substances, particularly after 48 h germination. The same coincidence between increased cytokinin activity and radicle emergence has been documented also for a number of photoinsensitive species such as Acer (Julin-Tegelman & Pinfield, 1982), and Rosa (Julin-Tegelman, 1983).…”

Short‐Term Metabolism of Radioactive Kinetin during Lettuce Seed Germination

“…Barzilai and Mayer (1964) were unable to detect cytokinins in dry lettuce seeds. Van Staden (1973a) later showed that cytokinins were present in dry lettuce seed, but in a bound, water‐soluble storage form.…”

“…Barzilai and Mayer (1964) were unable to detect any cytokinins in dry lettuce seeds. These compounds did appear during germination.…”