Regulation of vascular differentiation in leaf primordia during the rhythmic growth of Gnetum africanum

1986 ◽  
Vol 64 (1) ◽  
pp. 208-213 ◽  
Author(s):  
F. Mialoundama ◽  
P. Paulet
Keyword(s):  
Principal Axis ◽  
Vascular Tissue ◽  
Growth Period ◽  
Leaf Primordia ◽  
Single Pair ◽  
Vascular Bundles ◽  
Vascular Differentiation ◽  
Terminal Bud ◽  
Young Leaves ◽  
Rhythmic Growth

The growth of the principal axis of Gnetum africanum Welw. is achieved by successive growth and rest periods. During the phase of growth arrest, the terminal bud produces a single pair of leaf primordia containing no vascular tissue whereas observation of the terminal bud of the vinelike stem reveals that the oldest of the leaf primordia do contain vascular tissue before emerging. The differentiation of vascular bundles in the leaf primordia of the principal axis begins only with the return of the growth period during which time new young leaves are formed. The rhythm of formation of the leaves and their vascularization can be accelerated by removal of the young leaves. A prolonged exogenous treatment with abscisic acid after removal of the young leaves reestablishes the inhibition and prevents initiation of vascularization. It seems, therefore, that in the principal axis young leaves inhibit vascular differentiation of the leaf primordia, which may partly explain the inhibition of growth.

Early ontogeny defines the diversification of primary vascular bundle systems in angiosperms

2020 ◽  
Author(s):  
Regine Claßen-Bockhoff ◽  
Doris Franke ◽  
Hansjörg Krähmer
Keyword(s):  
Vascular Bundle ◽  
Vascular Tissue ◽  
Three Dimensional ◽  
Early Ontogeny ◽  
Leaf Primordia ◽  
Dimensional System ◽  
Vascular Bundles ◽  
Histological Data ◽  
Molecular Aspects ◽  
The One

Abstract Understanding vascular bundle systems in angiosperms is a challenge. On the one hand, the vascular tissue is extremely important in reconstructing the evolution and survivability of plants, but on the other hand, it forms a complicated three-dimensional system of controversially discussed phylogenetic and ontogenetic origin. To increase clarity, in this paper we briefly summarize histological, phylogenetic and molecular aspects of primary vascular bundle formation in angiosperms, adding histological data on early stages of vascular bundle formation, proposing a concept combining the different views and providing simplified illustrations to improve the understanding of primary vascular systems in angiosperms. Based on the auxin hypothesis, vascular bundle formation is stimulated by the development of leaf primordia. Provascular domains appear at the base of the leaf primordia and develop into two directions (leaf, internode). The low vs. high number of internodal bundles, their circular vs. scattered arrangement and the open vs. closed bundle construction in eudicots vs. monocots can be deduced to be due to processes below the shoot apical meristem. The most important processes distinguishing monocots from eudicots are the isolated bundle initiation outside the primary meristem, the enormous expansion of the leaf bases associated with a high number of vascular bundles and the early onset of primary thickening passively dislocating vascular bundles.

Regenerative studies on the detached leaves of Echeveria elegans. Anatomy and regeneration of leaves in sterile culture

1970 ◽  
Vol 48 (10) ◽  
pp. 1887-1891 ◽  
Author(s):  
M. V. S. Raju ◽  
Henry E. Mann
Keyword(s):  
Vascular Tissue ◽  
Agar Medium ◽  
Vascular Differentiation ◽  
Leaf Base ◽  
Adaxial Side ◽  
Regenerative Capacity ◽  
Abaxial Side ◽  
Sterile Culture ◽  
Detached Leaves ◽  
Young Leaves

Excised leaves, L1–L30, of Echeveria elegans Bgr. were cultured aseptically on an agar medium to study their regenerative capacity. The younger leaves tended to produce roots earlier than shoots and some had not produced shoots by the time of termination of the experiments. The older leaves produced shoots earlier than roots and in such instances the shoots appeared on the adaxial side. In no case was the appearance of shoots on the abaxial side of the leaf noticed and this suggested the possible manifestation of polarity of regeneration. The leaf regeneration to produce roots or shoots depended on the degree of vascular differentiation, particularly at the leaf base where regeneration normally occurs. In young leaves that had little or no vascular differentiation at the time of their isolation, abundant callus appeared in which the first primordia initiated were of roots. The old detached leaves had short petioles, which contained mature vascular tissue, and produced very little callus in culture.

scholarly journals The Dual Function of OsSWEET3a as a Gibberellin and Glucose Transporter Is Important for Young Shoot Development in Rice

2020 ◽  
Vol 61 (11) ◽  
pp. 1935-1945 ◽  
Author(s):  
Minami Morii ◽  
Akihiko Sugihara ◽  
Sayaka Takehara ◽  
Yuri Kanno ◽  
Kyosuke Kawai ◽  
...  
Keyword(s):  
Glucose Transporter ◽  
Vascular Tissue ◽  
Shoot Development ◽  
Dual Function ◽  
Vascular Bundles ◽  
Long Distance ◽  
Reverse Transcription Pcr ◽  
Long Distance Transport ◽  
Sweet Proteins ◽  
Young Leaves

Abstract Translocation and long-distance transport of phytohormones are considered important processes for phytohormone responses, as well as their synthesis and signaling. Here, we report on the dual function of OsSWEET3a, a bidirectional sugar transporter from clade I of the rice SWEET family of proteins, as both a gibberellin (GA) and a glucose transporter. OsSWEET3a efficiently transports GAs in the C13-hydroxylation pathway of GA biosynthesis. Both knockout and overexpression lines of OsSWEET3a showed defects in germination and early shoot development, which were partially restored by GA, especially GA20. Quantitative reverse transcription PCR, GUS staining and in situ hybridization revealed that OsSWEET3a was expressed in vascular bundles in basal parts of the seedlings. OsSWEET3a expression was co-localized with OsGA20ox1 expression in the vascular bundles but not with OsGA3ox2, whose expression was restricted to leaf primordia and young leaves. These results suggest that OsSWEET3a is expressed in the vascular tissue of basal parts of seedlings and is involved in the transport of both GA20 and glucose to young leaves, where GA20 is possibly converted to the bioactive GA1 form by OsGA3ox2, during early plant development. We also indicated that such GA transport activities of SWEET proteins have sporadically appeared in the evolution of plants: GA transporters in Arabidopsis have evolved from sucrose transporters, while those in rice and sorghum have evolved from glucose transporters.

Cytological and histological changes induced by cold temperature in the young shoots of Marquillo × Kenya Farmer wheat dwarf 1

1972 ◽  
Vol 50 (3) ◽  
pp. 403-408 ◽  
Author(s):  
J. D. Mahon ◽  
D. T. Canvin
Keyword(s):  
Apical Meristem ◽  
Leaf Primordia ◽  
Vascular Bundles ◽  
Vascular Differentiation ◽  
Main Shoot ◽  
Histological Changes ◽  
Whole Plant ◽  
Meristematic Activity ◽  
Extensive Cell ◽  
Extent Of Damage

The growth of Marquillo × Kenya Farmer 1 heat plants has been shown to be irreversibly terminated if they are exposed to a 16° temperature when 10 days old and it has been proposed that this low temperature sensitivity proceeds through a rapid inactivation of the shoot apical meristem. Histological and microautoradiographic techniques were used to study the effects of 16° treatment on the morphology and meristematic activity of the young shoots of both Marquillo × Kenya Farmer 1 and normal Marquillo plants.Within 12 h of the beginning of 16° treatment, damaged cells were visible in the young developing leaf and stem tissues and such cells became numerous after longer periods at 16°. The cells most rapidly destroyed were those surrounding the vascular bundles in both leaf primordia and stem tissues and the extent of damage in a tissue was closely related to the stage of vascular differentiation in the adjacent bundles.Cell division in the apical meristem of the main shoot was inhibited even more rapidly. The proportion of cells dividing and the incorporation of 3H-thymidine into the nuclei of meristem cells decreased rapidly at 16° and the reversibility of these effects was similar to that of the whole plant effects.It is suggested that the cessation of growth in Mql × KF 1 exposed to 16° is due to the lack of cell division and that the permanence of this effect is due to the extensive cell destruction that occurs in the meristematic regions.

Foliar influences on the vegetative development of grapevine

OENO One ◽  
1997 ◽  
Vol 31 (4) ◽  
pp. 165
Author(s):  
Jean-Claude Fournioux
Keyword(s):  
Growth Arrest ◽  
Nutrient Deficiency ◽  
Growth Period ◽  
Vegetative Development ◽  
Single Leaf ◽  
Apical Bud ◽  
Terminal Bud ◽  
Young Leaves ◽  
The One ◽  
Apical Senescence

<p style="text-align: justify;">Various defoliation treatments were applied to grapevine shoots during the whole duration of the growth period: full defoliation of every shoot of vine, defoliations retaining a various number of adult leaves to the base of every shoot and defoliations retaining a various number of young leaves to the top. The effects of these treatments allow to identify the major foliar influences on the vegetative development. Total defoliation induced a lesser intemodal elongation. This result is probably due, in part, to a carbohydrates deficiency consecutive to this drastic treatment. The defoliations with variation of the number of young leaves showed that the length of internodes increased when this number was greater. This result indicates that young leaves seems exercise a morphogenetical influence on the longitudinal growth of intemodes. For the three defoliation modalities, the rythm of leaves initiation was unchanged. So, it appears that, contrary to many other species, the leaves exercise no control on the plastochronic activity of terminal bud. The results of experiments with variation of the number of leaves maintained on the shoots permit to clarify the relation between foliage and "cane ripening". The already known positive correlation between the length of the suberized part of the shoot and the number of adult leaves has been confirmed. However, the effects of these treatments indicated that this correlation was not linear. Moreover, it seems that every shoot has specific " cane ripening " potentialities determined by other factors that their foliage. The leaves seem act only as revelators of these potentialities. These same experiments retaining adult leaves showed also that such treatments induced a more growth of the not removed leaves. Their laminar extension was increased. The thickness of their lamina and so the one of their palisade parenchyma were more important that in leaves of the control. These observations confirm and explain the compensatory phenomena consecutive to a reduction of the foliar apparatus already described in previous works by other autors. The two mean results of this study consists in the demonstration of the role played by adult leaves both in growth arrest and in apical senescence towards the end of the growing season. A single leaf retained in the upper or lower part of the shoot was sufficient to cause the growth arrest. On the other hand, only old leaves inserted at the base of the shoot can produce the death of the apex. These two last results are analysed and discussed taking in consideration both our experimental results and bibliographical elements. The growth arrest is probably not only determined by the foliar influence. We can expect that a decreasing production of cytokinins by the roots contributes also to this stopping of the apical bud activity. With regard the question of the apical senescence, some results showed that this phenomenom is not caused by a nutrient deficiency. Therefore, it is a question of a correlative process in which the adult leaves inserted to the base ofthe shoot are implicated. This last foliar influence was, so far, completely unknown.</p>

Xanthomonas campestris pv. graminis. [Descriptions of Fungi and Bacteria].

1987 ◽  
Author(s):  
K. E. Reay
Keyword(s):  
Geographical Distribution ◽  
Festuca Arundinacea ◽  
Xanthomonas Campestris ◽  
Natural Infection ◽  
Dactylis Glomerata ◽  
Phleum Pratense ◽  
Vascular Bundles ◽  
Poor Growth ◽  
Young Leaves ◽  
Natural Host Range

Abstract A description is provided for Xanthomonas campestris pv. graminis. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Lolium italicum, L. multiflorum, L. perenne, Dactylis glomerata, Festuca pratensis, and Trisetum flavescens. Single cases of natural infection of Agropyron repens, Phalaris arundinacea and Phleum pratense are also recorded (62, 241), but their status in the natural host range is unknown. In inoculation tests (Egli et al., 1975; Egli & Schmidt, 1982) the following were highly susceptible: Alopecurus pratensis, Dactylis glomerata, Festuca arundinacea, F. pratensis, F. rubra, Lolium loliaceum, L. multiforum, L. parabolicae, L. perenne, L. remotum, L. temulentum, Phleum arenarium and P. bertolonii. Showing much less susceptibility were Agrostis alba, Arrhenatherum elatius, Phleum alpinum, P. phleoides, P. pratense, Poa annua, P. compressa, P. fertilis, P. memoralis, P. pratensis and P. trivialis. Leyns et al. (61, 6162) found that Agrosas tenuis and Festuca ovina were moderately susceptible when inoculated. Egli et al. (1975) recorded doubtful symptoms on Hordeum vulgare and Triacum aestivam on inoculation, but consider that they are unlikely to be naturally infected. DISEASE: Bacterial wilt of forage grasses. Symptoms usually first noticed at the heading stage, when young leaves curl and wither, and shoots remain stunted or may die. Other plants will continue to make poor growth and produce small, distorted inflorescences. Chlorotic and necrotic zones form on the older leaves along long stretches of vascular bundles, often extending into the sheaths. Bacterial streaming may be seen under the microscope from the cut ends of vascular bundles of infected tissue mounted in water. GEOGRAPHICAL DISTRIBUTION: CMI Map 533, ed. 1, 1979 lists France, Germany, Switzerland and Wales, to which must be added Scotland (63, 2925), Belgium (61, 4199), Netherlands, Norway (62, 241), and New Zealand (62, 241). Possibly in USA (IL; 61, 5045) though this disease is currently attributed to a Rickettsia- like organism. TRANSMISSION: Within the crop transmission is presumed to be by the blades of mowing machines.

The rotated-lamina syndrome. I. Ulmaceae

1993 ◽  
Vol 71 (2) ◽  
pp. 211-221 ◽  
Author(s):  
W. A. Charlton
Keyword(s):  
Leaf Blade ◽  
Early Stage ◽  
Leaf Primordia ◽  
Leaf Primordium ◽  
Foliage Leaf ◽  
Normal Orientation ◽  
Ulmus Glabra ◽  
Young Leaves ◽  
Final Orientation ◽  
Zelkova Serrata

In a number of plants, mostly woody, the components of the buds are arranged so that the laminae of the young leaves all face towards the same (upper) side of the bud, rather than towards the bud apex; in axillary buds they usually face towards the parent axis. This situation has been known for many years. For convenience, the general case is here called the rotated-lamina syndrome. There have been very few developmental investigations of how the laminae attain their unusual orientation, and these have come to different conclusions about cases in the Ulmaceae. This paper reports a detailed investigation of the syndrome in Ulmus glabra and Zelkova serrata, with comparative observations on other Ulmaceae, including cases in Celtis that do not exhibit the syndrome. The syndrome arises by different means in Ulmus and Zelkova. In Ulmus the leaf primordium is asymmetrical from the outset, the leaf blade region is obliquely dorsiventral from an early stage, and further asymmetrical growth of the leaf buttress rotates the whole leaf blade region into its final orientation as it develops. Individual shoots show heteroblastic development in progressing from bud scale to foliage leaf initiation, in increasing accentuation of the rotated-lamina syndrome, and in an increasing degree of dorsiventrality. In Zelkova, as previously described, the leaf blade region appears first as a radially symmetrical upgrowth, and it acquires dorsiventral symmetry directly in the rotated position. In Celtis spp. the lamina arises in a quite normal orientation, but reorients as it emerges from the bud. The leaf primordia of all species studied show asymmetry in other aspects, particularly in respect of stipule development, and these seem to be general features of the organisation of dorsiventral shoots. Key words: Ulmus, Zelkova, Celtis, leaf, development, dorsiventrality, lamina rotation.

Les bruyères in vitro. VIII. Évolution du pH du milieu de culture et morphogenèse de l’Erica ×darleyensis. (B) Relation entre l'absorption et les phases de la croissance rythmique

1989 ◽  
Vol 67 (1) ◽  
pp. 161-166 ◽  
Author(s):  
J. D. Viémont ◽  
F. Beaujard
Keyword(s):  
Plant Development ◽  
Culture Medium ◽  
Growth Period ◽  
Rest Periods ◽  
Rhythmic Growth

Erica ×darleyensis grown in vitro on a medium containing nitrate presents a marked rhythmic growth. We observe an increase of the pH of the medium during plant development. The rest periods are characterized by release of small amounts of OH− (or equivalents), while during the growth period, large amounts of OH− are released into the culture medium. A relationship between root activities and rhythmic growth is recognized.

STRUCTURAL DAMAGE AND GALL INDUCTION BY PEGOMYA CURTICORNIS AND PEGOMYA EUPHORBIAE (DIPTERA: ANTHOMYIIDAE) WITHIN THE STEMS OF LEAFY SPURGE (EUPHORBIA × PSEUDOVIRGATA) (EUPHORBIACEAE)

1990 ◽  
Vol 122 (3) ◽  
pp. 429-439 ◽  
Author(s):  
Andre Gassmann ◽  
Joseph D. Shorthouse
Keyword(s):  
Structural Damage ◽  
Vascular Tissue ◽  
Leafy Spurge ◽  
Feeding Strategies ◽  
Vascular Bundles ◽  
European Origin ◽  
Gall Induction ◽  
Vascular Connections ◽  
Herbaceous Perennial ◽  
Thick Layers

AbstractLeafy spurge (Euphorbia × pseudovirgata [Schur]) is an herbaceous perennial and serious weed of European origin that has been accidently introduced into North America. The European anthomyiid flies Pegomya curticornis (Stein) and Pegomya euphorbiae (Kieffer) are found on several spurge species in Europe and also attack leafy spurge. The two flies induce identical galls on the subterranean stems of their host plants, and the shoots wilt and die. Eggs are laid on the shoot tip, and the larvae bore into the stem by eating pith which is later replaced by callus. This is a rare example of an insect with both boring and gall-inducing feeding strategies. Galls are induced when larvae feed on the ring of vascular tissue. There is no proliferation of nutritive cells but instead thick layers of gall parenchyma are produced. The vascular connections are broken at the gall level and concentric vascular bundles appear in the cortical and gall parenchyma. After pupation an inner periderm differentiates around the chamber surface.

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