Auxin and Leaf Formation

Snow, Mary; Snow, Robert W.

doi:10.1111/j.1469-8137.1937.tb06899.x

Cited by 74 publications

(23 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The question as to how auxin is causally related to these very different effects has given rise to several theories. These have been discussed and summarized in a valuable series of papers by Snow ( , 1938Snow ( , 1939Snow ( , 1940 and by Ferman (1938). Thus, in the 'direct' theory of Thim ann & Skoog (1934) the view is entertained that an excess of auxin is secreted by the terminal bud and that some of this auxin, on passing into the lateral buds; inhibits them by hindering their own production of auxin.…”

Section: (C) Isolated Lateral Segmentsmentioning

confidence: 99%

Experimental investigations of the shoot apex of Dryopteris aristata Druce

Wardlaw

1947

Phil. Trans. R. Soc. Lond. B

View full text Add to dashboard Cite

A method whereby the apical meristem of the fern Dryopteris aristata Druce can be partially isolated from the adjacent lateral organs and tissues is described. This procedure has been adopted as a means of investigating growth and morphogenesis at the shoot apex. The technique involves the severance of the incipient vascular tissue which originates immediately below the apical meristem; the isolated meristem is thus seated on a plug of growing medullary parenchyma. Leaf primordia can be similarly isolated. Meristems treated in this way are capable of growth. They develop into short vasculated shoots bearing leaves. The nutrients sustaining this growth must reach the apical meristem from below by diffusing through medullary parenchyma at the base of the isolated terminal region. Above the parenchymatous region a solenostelic vascular system is present in the new axis; this is in marked contrast to the dictyostelic configuration of the parental shoot below. On the further growth of the isolated meristem leaves are produced and the stele becomes dictyostelic. The new leaves, of which as many as fourteen have been observed after 11 weeks’ growth, show the normal phyllotactic arrangement, and this is continuous with that of the main shoot below. The procedure adopted has the effect of removing the physiological dominance of the apical meristem relative to the main shoot; thus numerous large buds develop on the lateral segments of the parental shoot but none on the isolated terminal region. The growth of isolated leaf primordia is very limited. The vascular system develops as a solenostele, foliar gaps are not formed in the region of confluence with the shoot stele, axillary buds are developed, and the leaf apex becomes directed outwards. These several features are in marked contrast to the normal development. The isolated lateral segments are also capable of further growth. The experimental procedure adopted involves the severance of the vascular tissues at various levels. An account is given of new and hitherto unrecorded morphological developments observed in these segments. Interesting features include the formation of large solenostelic buds, the solenostelic development of isolated meristeles, medullation of meristeles and the induction of a polycyclic stelar condition, in one instance by a process of cambium-like activity. These are all in marked contrast to the normal development of the intact shoot. The data which have been obtained are discussed with special reference to the path of translocation of nutrients to the terminal meristem and to leaf primordia, morphogenetic processes at the shoot apex, the factors influencing the differentiation of the vascular system, and theories of shoot formation and constitution. The results of these experiments give no support to phytonic theories but emphasize the difference in potentiality for development between shoot and leaf primordia. In this connexion the factors which determine the shape and system of segmentation of the apical initials of shoot and leaf are seen to require further investigation. The hypotheses that lateral buds are inhibited by substances proceeding from the apical meristem, that the initial differentiation of vascular tissue can be attributed to the basipetal diffusion of a substance or substances from the actively growing apical meristem, and that under conditions of tensile stress incipient vascular tissue undergoes a parenchymatous development, are supported by the data of these experiments. The observations afford a clear indication of the diversity of the morphogenetic activity in the growing region. Nutritional, mechanical and other factors are seen to be important in influencing the distribution of tissues during development. The view entertained by comparative morphologists that the vascular system in ferns is of a highly conservative nature and therefore of great value in phyletic studies is to some extent opposed by the data of these experiments. But notwithstanding the several unusual vascular configurations produced as a result of the experimental treatment, there is eventually a return to the typical vascular arrangements of the normal shoot. There is thus a need for harmonizing the data of the causal and phyletic aspects. The more thoroughly the operation of morphogenetic factors extrinsic to the specific hereditary substance is understood, the more critical will be the selection of criteria of comparison for phyletic purposes.

show abstract

Section: (C) Isolated Lateral Segmentsmentioning

confidence: 99%

Experimental investigations of the shoot apex of Dryopteris aristata Druce

Wardlaw

1947

Phil. Trans. R. Soc. Lond. B

View full text Add to dashboard Cite

show abstract

“…As early as the 1930s, Snow and Snow discovered that by applying lanolin paste containing auxin to shoot meristems of Lupin, ectopic growth of leaf or floral tissue could be induced (Snow and Snow 1937). More recently it was found that plants deficient in auxin transport activity developed pin-like apices devoid of lateral organs (Okada and others 1991).…”

Section: Auxin Transport and Phyllotaxismentioning

confidence: 99%

Modeling Auxin Transport and Plant Development

Heisler

Jönsson

2006

J Plant Growth Regul

View full text Add to dashboard Cite

SummaryThe plant hormone auxin plays a critical role in plant development. Central to its function is its distribution in plant tissues, which is in turn, largely shaped by intercellular polar transport processes. Auxin transport relies on diffusive uptake as well as carriermediated transport via influx and efflux carriers. Mathematical models have been used to both refine our theoretical understanding of these processes and to test new hypotheses regarding the localization of efflux carriers in order to understand auxin patterning at the tissue level. Here we review models for auxin transport and how they have been applied to patterning processes including the elaboration of plant vasculature and primordium positioning. Secondly we investigate the possible role of auxin influx carriers such as AUX1 in pattering auxin in the shoot meristem. We find that AUX1 and its relatives are likely to play a crucial role in maintaining high auxin levels in the meristem epidermis.We also show that auxin influx carriers may play an important role in stabilizing auxin distribution patterns generated by auxin-gradient type models for phyllotaxis.

show abstract

“…The formation of new leaves and flowers in the peripheral zone of the SAM is a result of locally increased concentration of the plant hormone auxin, application of which has long been known to induce new primordia (1). This increased auxin concentration results, at least in part, from regulated auxin transport mediated by the asymmetric distribution within SAM epidermal cells of proteins of the PIN-FORMED family of auxin efflux carriers.…”

Section: Introductionmentioning

confidence: 99%

LEAFY Controls Auxin Response Pathways in Floral Primordium Formation

Zhou

Liu

et al. 2013

Sci. Signal.

View full text Add to dashboard Cite

LEAFY is a transcription factor that acts as a master regulator of flowering and of flower development. It acts as a component of a switch that mediates the transition from the vegetative to the reproductive phase of plant development. Auxin is a plant hormone with many different roles in plant growth, including induction of new primordia of both leaves and flowers at the shoot apex. Here, we report that LEAFY acts in part by controlling the auxin response pathway in new primordia. Therefore, transcriptional master regulators of flower development and hormonal control of morphogenesis appear linked as interacting processes. We found that hormone perception not only controls, but is also controlled by, the transcriptional signals that create plant form.

show abstract

Auxin and Leaf Formation

Cited by 74 publications

References 11 publications

Experimental investigations of the shoot apex of Dryopteris aristata Druce

Experimental investigations of the shoot apex of Dryopteris aristata Druce

Modeling Auxin Transport and Plant Development

LEAFY Controls Auxin Response Pathways in Floral Primordium Formation

Contact Info

Product

Resources

About