Effect of temperature on phytochrome—mediated anthocyanin synthesis in red cabbage

Abstract. A brief high temperature treatment (45 C) promoted anthocyanin synthesis in 2-d-old dark-grown red cabbage seedlings. The increased effectiveness of a temperature/red light treatment as opposed to the reverse sequence suggests that an elevated temperature 'induces' some component which facilitates the phytochrome response.     

Change in sensitivity to far-red irradiation on anthocyanin biosynthesis in red cabbage seedlings

Abstract. Anthocyanin biosynthesis in red cabbage seedlings has been shown to be under a red/far-red (R/FR) reversible phytochrome control. The 'escape' of anthocyanin synthesis from FR photoreversibility occurred between 12 and 20 h. However, a similarity exists between the escape curve and the temporal change in sensitivity to FR alone, which suggests that some of the 'escape' may be due to the promotive effect of FR. Some escape times may not therefore be a true measure of the duration of Pfr action, contrary to the traditional view.     

Development of Anthocyanin Pigmentation in Flowers of Lathyrus odoratus

A quantitative study has been made of developmental changesin the anthocyanins and a flavonol glycoside in the red/bluebicoloured flowers of Lathyrus odoratus L. Anthocyanin formationoccurs during the period of most rapid growth of the petals.At maturity about four times as much anthocyanin is presentin the standard petal as in the pair of wing petals, which aretogether comparable in fresh weight to the standard. The patternof development of flavonol glycoside is quite different; someare formed well before anthocyanin formation occurs and at maturityabout six times as much flavonol glycoside is present in thewings as in the standard per unit amount of anthocyanin. Somefurther evidence is thus provide that the flavonol glycosidemay be acting as a co-pigment which modifies the wing petalcolour to blue.     

Embryo-culture in Lathyrus

Development of 2-mm embryos of Lathyrus articulatus L. in vitrowas stimulated by placing them initially on an agar medium containing8 or 12 per cent sucrose. Germination took place after transferto a similar medium with 4 per cent sucrose. Successful cultureof 0.5-mm embryos was achieved under similar conditions butit was necessary to supplement the initial medium with 10 percent coconut milk. Using this technique, the hybrid L. clymenumL. x L. articulatus was raised from embryos which would haveotherwise aborted in vivo.     

Effects of Age and Gibberellic Acid on the Flavonol Content of Pisum sativum Leaves

Changes in the content of quercetin and kaempferol during leafdevelopment in Pisum sativum cv. Meteor are described. As theleaves matured the quercetin content decreased and that of kaempferolincreased during a period from 37 to 48 days from planting.Maximum flavonol content per leaf was found in leaves higheron the shoot as development proceeded, but total leaf flavonolcontent per plant remained relatively constant. There was noevidence to suggest that the quantitative changes in the individualflavonols were the result of conversion of quercetin into kaempferol. Treatment with gibberellic acid led to an accelerated fall inquercetin content in the mature leaves. This change was detectable24 h after treatment and before any apparent growth response.     

Dormancy in Light-sensitive Lettuce Seeds

Relatively brief treatment of imbibed seeds of positively photoblasticlettuce (Lactuca sativa L. cv. Cannington Forcing) with lowconcentrations of ethanol promotes germination. It is suggestedthat this effect is upon a cellular membrane, a view which issupported by the fact that a subsequent treatment with Ca²⁺markedly reduces the ethanol promotion. Data from experiments involving movement and transfer of seedsprovide no support for the involvement of a stable, leachable,endogenous inhibitor in the control of germination. It is concludedthat whether or not the seeds break dormancy is determined bythe interplay between forces generated in the developing embryoand the mechanical restraint provided by the tissues which envelopit.     

The Photocontrol of Respiration in Light-Sensitive Lettuce Seeds

The rate of respiration of positively photoblastic lettuce (Lactucasativa L. cv. Cannington Forcing) at 25 °C is increasedfollowing brief exposure to red light and is under phytochromecontrol. The higher rate is maintained until radicle emergencebegins, at which time a further increase takes place. At 30°C the rate of respiration is higher than at 25°C butno red light promotion occurs and very few-seeds germinate.     

The Initiation and Development of Lateral Meristems in the Pea Root: II. THE EFFECT OF INDOLE-3-ACETIC ACID

The results of the first paper in this series (Pecket, 1957)indicated that lateral root initiation in isolated pea rootsdepends upon an apically moving factor or complex of factorsprovided by the mature tissue of the root. The present investigationanalyses the effect of externally applied IAA on lateral rootformation and uses the methods employed in the earlier work.Observations made on roots in which three regions have beendistinguished show that increasing IAA concentration does notcause similar changes in all pans of the root, nor does it causeidentical effects on primordium initiation and on the subsequentemergence of the initials as lateral roots. The latter factexplains why the emphasis in the present work has been laidon initiation rather than on emergence. The results of experimentsare reported in which two variables are involved, IAA concentrationand the presence or absence of the two terminal regions of theroot. These results are considered to support the conclusionsof the earlier paper. It is suggested that the stimulant movingfrom mature tissue is not IAA itself but that the productionof the stimulant may be increased when IAA is supplied. A gradientof reaction to the stimulant appears to exist in the root, reactionbeing maximal in the mature tissue.