The production of auxin by yeast ceils resembles the formation observed in other organisms such as Rhizopus and Rkizobiura (Thimann, 1939) I which "release" auxins into their culture medium. Thus, we have found far more auxin in the growth medium of yeast than KSgl and Kostermans 2 extracted from the cells. The amounts of auxin in the growth medium were found to vary considerably with the age o...

An effi cient protocol for organogenesis through leaves has been established for Launaea sarmentosa (Willd.) Sch. Bip. ex Kuntze, a highly valuable medicinal plant. The leaf explants produced microshoots on MS basal medium when fortifi ed with cytokinins and auxins. A combination of 6-benzylaminopurine (BAP) at 0.5mg/l and naphthaleneacetic acid (NAA) at 0.2mg/l resulted in the induction of hig...

A new technique is described for studying controlled in vitro extension of plant cell walls. This technique uses frozen-thawed Avena coleoptile segments in which turgor is replaced by a constant applied force. In this system rapid extension is induced by low pH (3.0-3.6) but not by auxins or CO(2). Extensions of over 30% have been achieved. Our results indicate that cell wall synthesis is not r...

A recent publication announces that auxin inhibits expansion by a mechanism based on the orientation of cortical microtubules. This is a textbook-revising claim, but as I argue here, a claim that is supported by neither the authors' data nor previous research, and is contradicted by a simple experiment.

including a-cellulose. It is concluded that the direct effect of auxin is probably on metabolism of matrix polysacchlar,ides and that the promotion of a-cellulose synthesis is induced by elongation. Fractionation of coleoptile tissue after 1-hour treatment with auxin does not show differences in incorporation as large as are observed after several hours of treatment. However, the data also demo...

Among the existing techniques used to enhance final fruit size in citrus, the use of synthetic auxins gives good results. The effect and mode of action of these substances has been studied over the last eight years and reproducible results are obtained. These substances act through an indirect effect, reducing fruitlet growth rate and promoting abscission, thus reducing competition; and through...

Since the early X-ork of Laibaclh (7 al)scission. lhas been consi(lere(l to be controlled bAauxin. but comlparative effects have heen reporte(l for onlI a few auxinls (4, 5, 13 ) an(l it is not clear to h-liat extent abscission activit, is reallrelate(l to auixinl activity. A\oreover, whlen comparative stud(lies have been imia(le only the inhibitory effects of aulxins have beeni compared (4). T...