Nodulation of rooted leaves in leguminous plants

Summary Root formation was obtained on the petioles of detached leaves of several leguminous plants, particularly on the primary leaves of bean. Root formation is easily obtained in artificial light at a temperature of 22 to 24°C. In the greenhouse it is optimal in early spring and late autumn. During hot summer seasons no roots but callus was formed on the petioles. Root formation was inhibited when the pulvinus was left on the petiole. Nodulation of the rooted leaves is inhibited by combined nitrogen and high temperatures. The optimum light intensity for rooted leaves is low in comparison with that of intact plants. Far-red light reduces root-nodule formation; its inhibitory effect is partly eliminated by subsequent irradiation with red light.     

Mechanism of Indole-3-acetic Acid Conjugation: No Induction by Ethylene

Formation of indole-3-acetic acid-aspartate in detached primary leaves of cowpea (Vigna sinensis Endl.) floating on (14)C-indole-3-acetic acid (3 muc; 3.15 mum, phosphate-citrate buffer, pH 4.75), almost doubled when leaves were pretreated with 31.5 mum(12)C-indole-3-acetic acid for 17 hr and then transferred to (14)C-indole-3-acetic acid for 4 hours as compared with leaves preincubated in buffer only. When leaves were preincubated with ethylene (11.0 and 104 mul/l) instead of (12)C-indole-3-acetic acid, no induction of indole-3-acetylaspartic acid formation was observed, and the rate of indole-3-acetylaspartic acid formation decreased as compared with control leaves. Rhizobitoxine (1.87 mum) inhibited indole-3-acetic acid-induced ethylene production but did not prevent the formation of indole-3-acetylaspartic acid. In view of the similarity of these results and those previously obtained with alpha-naphthaleneacetic acid, it is concluded that ethylene has no role in the auxin-induced indole-3-acetylaspartic acid formation in cowpea leaves.     

Morphogenetic changes in ambiol-treated regenerates of parent and transgenic potato plants

The effects of ambiol, a new growth regulator, on the formation of leaves and roots in parent and defensin gene-transformed regenerants of potato Solanum tuberosum L. (cultivar Desire). Various concentrations of ambiol induced differences in morphogenetic parameters between parent and transgenic plants. In some cases, ambiol caused the formation of shoots without leaves or with rudimentary leaves. The data suggest that features of root and leaves formation in parent and transgenic regenerants induced by ambiol are due to changes in hormone balance in transgenic plants caused by expression of the defensin gene and the effect of ambiol on the plant hormonal balance.     

Cytokinins in the leaves of Ginkgo biloba. II. Metabolism and transport of 8 (14C) zeatin applied to shoot explants

Irrespective of their age, leaves of Ginkgo biloba metabolised applied 8 (¹⁴C) zeatin to compounds of similar chromatographic properties. Glucosylation is apparently not a normal feature of cytokinin metabolism in immature leaves. However, the application of zeatin to these leaves did result in the formation of metabolites which co-chromatographed with glucosylated cytokinins. As far as cytokinin metabolism is concerned therefore, this application of excess zeatin allowed immature leaves to behave as mature or senescing leaves. Overall metabolism was fastest in immature leaves. From the metabolites formed it would appear as if oxidation, which resulted in the formation of a metabolite which co-eluted with N-(purin-6-yl)glycine, was also important in immature leaves. In senescing leaves glucosylation was the major form of metabolism. Extraction and re-application of the polar metabolites (formed from zeatin) to mature leaves resulted in the formation of compounds which co-chromatographed with zeatin. This suggests that these compounds could serve as precursors for zeatin or could be hydrolysed to form zeatin.Very little of the applied radioactivity was exported from the leaves irrespective of their physiological age. When the metabolites, obtained after zeatin application to mature leaves, were extracted and reapplied to the leaves, export of radioactive material was much improved. The results suggest that should cytokinins such as zeatin be translocated to mature leaves of this deciduous gymnosperm their export from the leaves would be unlikely unless first metabolised. In all probability the metabolites concerned are cytokinin glucosides.The financial support of the C.S.I.R., Pretoria, is gratefully acknowledged.     

Interaction of Growth Retardants and Temperature in Growth, Flowering, Regeneration, and Auxin Activity of Begonia × cheimantha Everett

Soil application of CCC reduced stem and leaf growth in Begonia plants. This effect was evident with all concentrations tested at 18°C, whereas at 21 and 24°C no growth–retarding effect was observed with 2 × 10^?2 M CCC, and with 5 × 10^?3 M growth was even stimulated. Flowering was promoted by CCC in long day and neur–critical temperature, particularly under low light intensity in the winter. The formation of adventitious buds in leaves of plants grown at 21 and 24°C was stimulated when the plants received 5 × 10^?2 and 2 × 10^?2 M CCC, while 8 7times; 10^?2 M was inhibitory. In plants grown at 18°C bud formation was inhibited by all CCC concentrations. Root formation in the the leaves was usually stimulated by high CCC concentrations, while root elongation was reduced. The level of ether–extractable. acidic auxin (presumably IAA) in the leaves was lowered by CCC treatment of the plants, hut this required higher CCC concentrations at higt than at low temperature. When applied to detached leaves CCC stimulated bud formation at concentrations ranging from 10^?4 to 10^?2 M in leaves planted at 18 and 21°C. At 24°C budding was inhibited by 10^?2 M CCC, the lower concentrations being stimulatory also at this temperature. Root formation and growth were not much affected by CCC treatment of the leaves, but increased with the temperature. Soil application of Phosfon (4 × 10^?4 M) had no effect on growth and flowering, nov did it affect the subsequent regeneration of buds and roots in the leaves. In detached leaves Phosfon stimulated bud formation with au optimum at 10^?6 M. Root formation was stimulated by Phosfon at all temperatures, the optimal concentration being 10^?5 M, whereas root length was conversely affected. Foliar application of B-995 to intact plants and treatment of detached leaves greatly inhibited the formation of buds and had little effect on root formation. B-99D reduced the growth and delayed flowering in the plants.     

Incorporation of C-Photosynthate into Protein during Leaf Development in Young Populus Plants

Gas exchange and protein metabolism were studied in expanding, mature, and near-senescent leaves of young clonal Populus × euramericana cv. Wisconsin-5 plants. Dark respiration, CO₂ evolution in the light, and CO₂ compensation concentrations were highest in unexpanded leaves but declined markedly as leaves matured and aged. Net photosynthesis was highest in nearly mature leaves. Fresh weight continued to increase after leaf expansion was complete, whereas soluble protein levels declined. Changes in the distribution of photosynthetically incorporated ¹⁴C indicated that a high level of protein synthesis and rapid formation of structural components occurred only in expanding leaves. Protein turnover was slight in expanding leaves but was substantial after leaves were mature. Expanding leaves synthesized predominantly fraction I protein (ribulose diphosphate carboxylase). However, formation of this protein from photosynthate was slight once leaves matured.     

Comparison of the localization of nucleic acid synthesis during bud formation on leaf fragments and on intact undetached leaves ofBegonia rex Putz.

The budding capacity ofBegonia rex leaf fragments is well known; that of undetached leaves has been shown by us only recently after treating the leaves with 6γγ DMAAP. Benzyladenine is as effective as 6γγ DMAAP in stimulating budding. Lower temperatures (17°, 22–12°, 12°) are also capable of inducing bud formation but only after a small cut has been made in a main vein of the undetached leaf. Root formation can also be provoked on undetached leaves which have a cut in the main leaf vein by higher temperatures (24–22°) or by an IAA treatment. Differences in the first stages of bud formation on leaf fragments and on undetached leaves are observed using histochemical and histoautoradiographic techniques.     

Morphogenetic Changes in Ambiol-Treated Regenerants of Parent and Transgenic Potato Plants

The effects of ambiol, a new growth regulator, on the formation of leaves and roots in parent and defensin-gene-transformed regenerants of potato Solanum tuberosum L. (cultivarDesire) were studied. Various concentrations of ambiol induced differences in morphogenetic parameters between parent and transgenic plants. In some cases, ambiol caused the formation of shoots without leaves or with rudimentary leaves. The data suggest that features of root and leaf formation in parent and transgenic regenerants induced by ambiol are due to changes in hormone balance in transgenic plants caused by expression of the defensin gene and the effect of ambiol on the plant hormonal balance.     

Effect of gall formation by a cynipid wasp, Andricus symbioticus, on the development of the leaves and shoots of Quercus dentata

The sexual generation of a cynipid wasp, Andricus symbioticus Kovalev, forms its leaf galls most frequently near and on the leaf petiole of Quercus trees. I examined the effect of gall formation by A. symbioticus on the leaf development of a host plant, Quercus dentata Thunberg, by comparing the size and shape of galled and ungalled leaves. I also examined the effect of gall formation on shoot development by comparing the length of shoots with and without galled leaves. Three of seven Q. dentata trees surveyed were heavily infested with A. symbioticus. Leaf size did not differ between galled and ungalled leaves. However, the ratio of leaf width to length was greater in galled leaves, which is regarded to be a result of gall formation by A. symbioticus inhibiting the growth in length of Q. dentata leaves. Shoot length did not differ significantly between shoots with and without galled leaves. These results suggest that galls of A. symbioticus act as a sink that competes with leaves for reserved photoassimilates.     

榆树叶片虫瘿形成过程中蛋白质组学分析

为探究榆树虫瘿叶片形成的分子机制,以不同时期榆瘿蚜取食诱导的榆树叶片为试材,利用iTRAQ技术分析榆树虫瘿叶片形成过程中蛋白表达丰度的差异。通过质谱鉴定,共得到2 689个蛋白,与KEEG数据库进行比对,发现2 145个蛋白被注释到126个不同的代谢通路中,和本研究相关的蛋白有12条,涉及代谢途径的蛋白数量最多,为813(37.9%)个。未被榆瘿蚜取食的叶片与榆瘿蚜取食诱导叶片形成虫瘿的前期、中期、后期相比,差异蛋白分别有418个、390个、244个,筛选出虫瘿发育的共有差异蛋白29个,这些蛋白在榆瘿蚜取食形成虫瘿的初始形成期和成长分化期持续发挥作用的有过氧化物酶、过氧化氢酶等氧化还原酶类;在前期持续发挥作用的有翻译控制肿瘤蛋白TCTP和肌动蛋白;在榆瘿蚜取食形成虫瘿的开裂期起到重要抗性作用的有溶质的抗坏血酸过氧化物酶、70 kD热激蛋白等。在榆树虫瘿叶片发展过程中,数个蛋白基因涉及了应激防御反应、氧化还原、免疫系统过程和光合作用等生理反应过程,建议进一步进行榆树虫瘿叶片形成的分子机制研究。     

Dynamics of morphological and anatomical changes in leaf tissues of an interspecific hybrid of oil palm during acquisition and development of somatic embryogenesis

Oil palm is an economically important plant species due to its high oil production per unit area. Large-scale clonal propagation of the species’s elite specimens is only possible through somatic embryogenesis, although methodology is partially still unknown and insufficiently understood. Current study characterizes in morphological and anatomical terms the acquisition and development stages of somatic embryogenesis of the oil palm’s immature leaves. The respective embryogenic stages were analyzed and characterized: immature leaves (initial explants); leaves with calli formation; leaves which failed to respond to calli formation; leaves with formation of root structures; primary calli; primary calli with differentiation of embryogenic calli; embryogenic calli; pro-embryogenic calli; calli with differentiated somatic embryos; somatic embryos at globular and torpedo stage; and mature fruit zygotic embryos. Cell masses emerged after approximately 60 days of cultivation through the proliferation of cells associated to initial explants´ vascular bundles. Consequently, the formation of two different types of calli was identified, namely, primary and embryogenic, respectively consisting partially and completely of meristematic cell clusters. After 420 days of cultivation, the propagules formed somatic embryos with no connection to source tissues, initially composed (globular stage) of a very characteristic ground meristem and protoderm. After 480 days of cultivation, as the cultures matured (torpedo stage), procambial strands, a structural characteristic also observed in mature zygotic embryos, were reported. The results provide an in-depth understanding of somatic embryogenesis of immature leaves of oil palm. Further, current analysis develops morphological markers at different stages of development obtained during the process.     

The formation of chlorophyll from chlorophyllide in leaves containing proplastids is a four-step process

The time course of the different esters of chlorophyllide (Chlide) during the formation of chlorophyll a (Chl) in embryonic bean leaves containing proplastids was investigated by HPLC. After the reduction of photoactive Pchlide (Pchlide) to Chlide, three intermediates, i.e. Chlide geranylgeraniol, Chlide dihydrogeranylgeraniol and Chlide tetrahydrogeranylgeraniol were detected before the formation of Chlide phytol, i.e. authentic Chl. The transformation of Chlide to Chl was found to be much faster in leaves containing proplastids than in etiolated leaves with etioplasts.     

High root temperature blocks both linear and cyclic electron transport in the dark during chilling of the leaves of rice seedlings

The most photosynthetically active leaves of rice seedlings were severely damaged when shoots but not roots were chilled (10°C/25°C, respectively), but no such injury was observed when the whole seedling was chilled (10°C/10°C). To elucidate the mechanisms, we compared the photosynthetic characteristics of the seedlings during the dark chilling treatments. Simultaneous analyses of Chl fluorescence and the change in absorbance of P700 showed that electron transport almost disappeared in both PSII and PSI in the 10°C/25°C leaves, whereas the electron transport rate in PSI in the 10°C/10°C leaves was similar to or higher than that in non-chilled control leaves. Light-induced non-photochemical quenching in PSII was inhibited in the 10°C/25°C leaves, occurring at only half the level in the 10°C/10°C leaves, whereas non-light-induced non-photochemical quenching remained high in the 10°C/25°C leaves. The light induction of Chl a fluorescence (OJIP curves) in the 10°C/25°C leaves was similar to that in leaves treated with DCMU. The fluorescence decay after a single turnover saturating flash in the 10°C/25°C leaves was much slower than in the 10°C/10°C leaves. In vivo analyses of the 550-515 nm difference signal indicated decreased formation of a proton gradient across the thylakoid membrane and decreased zeaxanthin formation in the 10°C/25°C leaves. Our results suggest that electron transport was blocked between Q(A) and Q(B) in the dark 10°C/25°C leaves, but without irreversible damage to the components of this system. The consequent light-dependent losses of electron transport, proton gradient formation across the thylakoids and thermal dissipation may therefore be responsible for the visible injury.     

Induction of ethylene synthesis and lipid peroxidation in damaged or TMV-infected tobacco leaf tissues by light

The effect of light on ethylene and ethane production in damaged leaf tissues was investigated. When whole leaves of tobacco cv. Samsun NN were damaged with liquid nitrogen, the ethylene formation was the highest, if 100?% of leaves were injured and were kept in the light, the lowest when leaves after 100?% injury were kept in darkness. Ethane production (lipid peroxidation) could be detected only in damaged, but not in control leaves, and was much higher in light than in darkness. In addition, there was a strong degradation of chlorophyll of damaged leaves kept in light. In light aminoethoxy-vinylglycine (AVG) inhibited ethylene formation in control, non-damaged whole leaves effectively, but in leaves with 100?% damage the inhibitory effect was much weaker and similar to the effect of propyl gallate (PG), a free radical scavenger. Both AVG and PG treatments decreased ethylene formation by control leaf discs and discs with 100?% damage. Ethane production was significantly inhibited by PG and slightly by AVG in the case of 100?% damage. Tiron, another free radical scavenger gave similar results on leaf discs as PG did. Paraquat (methylviologen, Pq), as a photosynthesis inhibiting and reactive oxygen species (ROS) producing herbicide produced a large amount of ethylene and ethane in light but very small amount in darkness. In accordance, tobacco mosaic virus (TMV) infection on the necrotic host resulted in significantly larger amount of ethylene and ethane formation in light than in darkness. We conclude that ethylene and ethane production of damaged plant tissues is strongly induced by light and ROS that are involved in this induction.     

The Contribution of Photosynthesis to Chlorophyll Formation in Etiolated Mung Bean Leaves

Chlorophyll formation in seven day old etiolated mung bean leaves was inhibited by CMU. The inhibition was reversed by feeding sucrose, or by leaving the cotyledons attached to the leaves. Photosynthesis appeared to contribute substrates for further chloroplast development soon after its commencement. When sucrose was fed in the presence of CMU at a range of light intensities, there was a distinct light induced promotion of chlorophyll formation at light intensities of 500–2000 lux. Treatment of the leaves with salicyl-aldoxime, an inhibitor of cyclic photophosphorylation indicated that this process could play an important part in chloroplast development.     

Effect of light intensity on manganese toxicity symptoms and callose formation in cowpea (Vigna unguiculata (L.) Walp.)

In cowpea typical Mn toxicity symptoms are brown speckles on mature leaves representing depositions mainly in the cell walls and formation of non-constitutive callose. The histochemical charecterization of the brown speckles indicates the presence of oxidized Mn. However, the reducing agent hydroxylamine hydrochloride only slightly while thioglycolic acid almost completely decolorized the speckles. Brown boron-deficient roots treated with hydroxylamine hydrochloride and thioglycolic acid showed the same pattern of decoloration suggesting that the brown color of the Mn toxicity symptoms derives mainly from oxidized phenolics. To evaluate the effect of light on the formation of brown speckles by high Mn concentrations and non-constitutive callose in leaves, three approaches were used: (i) comparison of shaded and unshaded plants at different Mn supplies via the roots, (ii) local application of Mn to leaves in the light and in the dark, (iii) local application of Mn to leaves in the dark with subsequent light and dark treatments. Shading of whole plants (i) aggravated formation of both brown speckles and callose at similar Mn concentrations in the leaves. When the Mn application and the light treatments were locally confined (ii, iii), light had no effect on formation of either brown speckles or callose. The present results are in contradiction to the available reports in the literature showing aggravation of Mn toxicity by high light intensities.     

Methyl jasmonate induces the formation of secondary abscission zone in stem of Bryophyllum calycinum Salisb

Methyl jasmonate (JA-Me) at a concentration of 0.5 % induced the formation of secondary abscission zone and senescence in several types of stem explants (only internode segment, internode segment with nodes and without leaves, internode segment with nodes and debladed petioles) of Bryophyllum calycinum when it was applied in various places of the stem or the debladed petiole as lanolin paste. In the presence of small leaves in stem explants methyl jasmonate also induced the formation of secondary abscission zone and senescence but the presence of larger leaves completely inhibited methyl jasmonate-induced processes. Auxin, (indole-3-acetic acid, IAA), at a concentration of 0.1 % extremely prevented the formation of secondary abscission zones and senescence in the stem tissues induced by methyl jasmonate. Similar relationship between auxin and methyl jasmonate to induce the formation of secondary abscission zone and senescence was found in decapitated shoot of the intact plant. Mechanisms of the formation of secondary abscission zone are also discussed in terms of the interaction of methyl jasmonate with auxin.     

Elimination of POR expression correlates with red leaf formation in Amaranthus tricolor

Amaranthus tricolor L. tricolor cv. Earlysplendor, an ornamental amaranth, generates red leaves instead of green leaves in late summer to early autumn. Red leaf formation was promoted under short-day conditions and delayed by night-break treatments. Red leaves were characterized by lower levels of chlorophyll accumulation rather than higher levels of red pigment (betacyanin) accumulation. However, the metabolic activity toward the production of Mg-protoporphyrin, an intermediate in the biosynthesis pathway for chlorophyll, was detected in red leaves as well as in green leaves. RNA gel blot analysis was performed to assess the expression of nine genes encoding eight enzymes involved in chlorophyll biosynthesis. Among these enzymes, red-leaf-specific reduction of gene expression was observed only for NADPH-protochlorophyllide oxidoreductase (POR), a key enzyme catalyzing a later step of chlorophyll biosynthesis. In addition, immunoblot analysis showed no accumulation of POR protein(s) in red leaves. These data indicate that the repression of POR gene expression and resultant loss of chlorophyll synthesis activity plays a role in red leaf formation of A. tricolor.