Plant Internode Research Articles

MSMA and Pyrithiobac Effects on Cotton (Gossypium hirsutum) Development, Yield and Quality

Field research was conducted in Tennessee at Jackson in 1991 and at Milan in 1992 to compare the effect of MSMA and pyrithiobac on cotton development, yield, and quality. In separate treatments to different plots, pyrithiobac at 0.14 kg ai ha–1did not affect development, yield, and quality of cotton. MSMA at 2.24 kg ai ha–1decreased cotton plant internode length 10 to 15% and height by 15% 5 wk after late treatment both years. MSMA applied to 50 cm cotton reduced subsequent plant height in 1992, but other plant characteristics were not affected. In 1991, MSMA increased squares and decreased blooms and bolls for monopodia and sympodia position one and two, which suggested a delay in plant development. In 1991, mechanical harvest lint yields were decreased by MSMA at first harvest while increasing second harvest lint yields. However, in 1991 only MSMA applied late decreased total harvest lint yield 20%. Plant mapping data determined that the yield decrease was a result of decreased yields at sympodia positions one and two. Cotton seed arsenic analysis indicated that MSMA-late increased arsenic levels by ≈ 1 ppmw in 1991 for sympodia at position one and two compared to the untreated check, while position two contained the highest level of 1.8 ppmw.

The predominant role of the pith in the growth and development of internodes in Liquidambar styraciflua (Hamamelidaceae). II. Pattern of tissue stress and response of different tissues to specific surgical procedures

Isolated pith segments when freed of the restraint of contiguous vascular tissue during different stages of internode development expand rapidly, whereas, peripheral tissues when separated from each other immediately shrink, confirming the existence of physical stresses first described by 19th century botanists. Evidence is presented that the rapid production and differentiation of vascular tissue in elongating internodes of Liquidambar contribute significantly to the development of compressive forces in the pith by restraining the growth of pith cells. Heretofore, the role of tensile stresses affecting the growth of internodes in herbaceous plants has been ascribed only to the less extensible outer peripheral tissues, especially the epidermis. Different surgical procedures applied to elongating internodes, including disruption of the central core of pith cells without disturbing the vascular and other peripheral tissues, or conversely, injuring or removing portions of the outer tissues leaving the pith intact, confirm the histological observations that the developing pith is the driving force for internodal elongation.

The Predominant Role of the Pith in the Growth and Development of Internodes in Liquidambar styraciflua (Hamamelidaceae). II. Pattern of Tissue Stress and Response of Different Tissues to Specific Surgical Procedures

Isolated pith segments when freed of the restraint of contiguous vascular tissue during different stages of internode development expand rapidly, whereas, peripheral tissues when separated from each other immediately shrink, confirming the existence of physical stresses first described by 19th century botanists. Evidence is presented that the rapid production and differentiation of vascular tissue in elongating internodes of Liquidambar contribute significantly to the development of compressive forces in the pith by restraining the growth of pith cells. Heretofore, the role of tensile stresses affecting the growth of internodes in herbaceous plants has been ascribed only to the less extensible outer peripheral tissues, especially the epidermis. Different surgical procedures applied to elongating internodes, including disruption of the central core of pith cells without disturbing the vascular and other peripheral tissues, or conversely, injuring or removing portions of the outer tissues leaving the pith intact, confirm the histological observations that the developing pith is the driving force for internodal elongation.

DNA sequence analysis of a cyclophilin gene from maize: developmental expression and regulation by salicylic acid.

In plants, such as maize, cyclophilin (Cyp) genes are expressed at a basal level in all tissues. Amounts of Cyp mRNA above the basic level are observed in germinating seedlings, in growing tissues/organs such as roots and leaf meristematic tissue of young maize plants, nodes and embryonic female inflorescences of adult plants and also in non-proliferating tissues such as the internodes of adult plants. Salicylic acid (SA) enhances the transcription of maize Cyp genes. The possible involvement of SA in the pathway leading to defense responses induced by abiotic stresses such as mercuric chloride treatment is discussed. A maize Cyp genomic clone isolated using a maize Cyp cDNA probe contains 737 bp of the 5' upstream and the entire coding region. This Cyp gene is not interrupted by intervening sequences. In the 5' upstream region, characteristic transcription signals as well as putative regulatory sequences were identified. Two TATA boxes are found at positions -56 bp and -66 bp with respect to the transcription start site. Two putative heat shock elements were identified in the promoter region; a metal regulatory element and a third heat shock element were localized in the 5' untranslated leader. Several putative polyadenylation signals and (G)T-rich sequence motifs were identified in the 3' untranslated region.

Effects of (+)-S-Abscisic Acid on the Quality of Stored Cucumber and Tomato Seedlings

Effects of ABA on the quality of stored cucumber (Cucumis sativus L.) and tomato (Lycopersicon esculentum Mill.) seedlings were investigated in two experiments. Foliarly applied ABA (20, 100, or 500 mg·liter–1) decreased transpiration of stored, pot-grown, cucumber seedlings at 8, 15, and 20C. Seedlings stored at 15 and 20C were slender with long internodes. At these temperatures, ABA at 100 and 500 mg·liter-1 reduced plant internode length. Seedlings stored at 8C and those not stored were short, and ABA did not affect internode length. A decrease of chlorophyll content in the first leaf of seedlings stored at 20C was less pronounced with ABA. In the second experiment, the effect of a foliar ABA application on stored, plug-grown, cucumber and tomato seedlings was determined. When seedlings were stored at 20C, those sprayed with ABA did not wilt, but nontreated seedlings did wilt. No seedlings wilted when stored at 8 and 15C. These results suggest that ABA could be used to maintain the quality of cucumber and tomato seedlings stored at 15 or 20C. Chemical name used: (+)-S-abscisic acid (ABA).

Control of Internode Length in Pisum sativum (Further Evidence for the Involvement of Indole-3-Acetic Acid).

The effects of altered endogenous indole-3-acetic (IAA) levels on elongation in garden pea (Pisum sativum L.) plants were investigated. The auxin transport inhibitors 2,3,5-triiodobenzoic acid (TIBA) and 9-hydroxyfluorene-9-carboxylic acid (HFCA) were applied to elongating internodes of wild-type and mutant lkb plants. The lkb mutant was included because elongating lkb internodes contained 2- to 3-fold less free IAA than those of the wild type. In the wild type, TIBA reduced both the IAA level and internode elongation below the site of application. Both TIBA and HFCA strongly promoted the elongation of lkb internodes and also raised IAA levels above the application site. The synthetic auxin 2,4-dichlorophenoxyacetic acid (2,4-D) also markedly increased internode elongation in lkb plants and virtually restored petioles and tendrils to their wild-type length. In contrast, treatment of wild-type plants with TIBA, HFCA, or 2,4-D caused little or no increase in elongation above the application site. The ethylene synthesis inhibitor aminoethoxyvinylglycine also increased stem elongation in lkb plants, and combined application of HFCA and aminoethoxy-vinylglycine restored lkb internodes to the wild-type length. It is concluded that the level of IAA in wild-type internodes is necessary for normal elongation, and that the reduced stature of lkb plants is at least partially attributable to a reduction in free IAA level in this mutant.

The competence of cells for cell division and regeneration in tobacco explants depends on cellular location, cell cycle phase and ploidy level

This work concerns application of flow cytometry (FCM) and confocal laser scanning microscopy (CLSM) to investigate the competence of cells for cell division and regeneration. FCM analysis of freshly-cut thin cell layer (TCL) explants of Nicotiana tabacum, excised from upper internodes of vegetative plants, revealed that one-quarter of the cells had the 2C nuclear DNA content, whereas of the other cells most nuclei had the 4C and some had the 8C DNA content. Cytometric examination using CLSM showed that the 2C nuclei were mainly located in the epidermis and subepidermis, and the 4C nuclei predominantly in the cortical tissue. During culture of the explants, part of the cortical cells went through mitosis from the first day onwards, and formed callus from which predominantly diploid and some tetraploid roots regenerated at low frequency. Most cortical cells were thus in the G 2 phase of the diploid cell cycle. FCM analysis showed that another fraction of the 4C cortical cells was induced to endoreduplicate to 8C cells. These cells thus had previously switched to the G 1 phase of the tetraploid cell cycle. CLSM analysis revealed that subepidermal and epidermal cells, respectively, underwent cell division from the second and third day onwards. Shoot primordia developed from cells of both cell layers together. Most shoot regenerants were normal diploids, some were mixoploids or tetraploids. The combination of FCM and CLSM allowed identification of the cell cycle phase, the ploidy level, the position of the cell, and the cellular development. The results give insight into the involvement of these parameters in the competence for cell division and regeneration at the level of the individual explant cells, and are therefore relevant for cellular and molecular approaches to plant transformation.

Xylem development and hydraulic conductance in sun and shade shoots of grapevine (Vitis vinifera L.): evidence that low light uncouples water transport capacity from leaf area

Morphology, water relations, and xylem anatomy of high-light (sun)- and low-light (shade)-grown Vitis vinifera L. shoots were studied to determine the effects of shading on the hydraulic conductance of the pathway for water flow from the roots to the leaves. Shade shoots developed leaf area ratios (leaf area: plant dry weight) that were nearly threefold greater than sun shoots. Water-potential gradients (ΔΨ·m−1) in the shoot xylem accounted for most of the ΔΨ·m−1 between soil and shoot apex at low and high transpiration rates in both sun and shade shoots, but the gradients were two- to fourfold greater in shade-grown plants. Low light reduced xylem conduit number in petioles, but had an additional slight effect on conduit diameter in internodes. The hydraulic conductance per unit length (Kh) and the specific hydraulic conductivity (ks, i.e. Kh per xylem cross-sectional area) of internodes, leaf petioles, and leaf laminae at different developmental stages leaf plastochron index was calculated from measurements of water potential and water flow in intact plants, from flow through excised organs, and from vessel and tracheid lumen diameters according to Hagen-Poiseuille's equation. For all methods and conductance parameters, the propensity to transport water to sink leaves was severalfold greater in internodes than in petioles. The Kh and ks increased logarithmically until growth ceased, independent of treatment and measurement method, and increased further in pressurized-flow experiments and Hagen-Poiseuille predictions. However, the increase was less in shade internodes than in sun internodes. Mature internodes of shade-grown plants had a two- to fourfold reduced Kh and significantly lower ks than sun internodes. Except very early in development, leaf lamina conductance and ks from shade-grown plants was also reduced. The strong reduction in Kh with only a slight reduction in leaf area (17% of sun shoots) in the shade shoots indicated a decoupling of water-transport capacity from the transpirational surface supplied by that capacity. This decoupling resulted in strongly reduced leaf specific conductivities and Huber values for both internodes and petioles, which may increase the likelihood of cavitation under conditions of high evaporative demand or soil drought.

Control of Stem Elongation by Gibberellin A1: Evidence From Genetic Studies Including the Slender Mutant sln

Information from well-known stem length mutants, both short and elongated, is discussed in the context of criteria necessary to demonstrate that the level of GA1 controls stem elongation in wild- type plants of the garden pea. Whilst this evidence is compelling, a mutant which over-produces GA1 would afford further insight, particularly into whether GA1 levels are saturating for growth in the wild-type. In this paper we further characterise the first reported garden pea mutant (sln) which possesses elevated levels of GA1. Evidence is presented from studies using this mutant that GA1 is normally limiting for growth over the early internodes in wild-type plants. In the developing seed, the mutant sin is shown to block the metabolism of [13C, 3H]GA29 to [13C, 3H]GA29-catabolite, particularly in the testa. Associated with this there were dramatically elevated GAGA29 levels in the dry seed from sln plants (400 times) compared with seeds from Sln plants. Upon germination, it appears that some of this GAGA20 is converted to GAGA1, which leads to substantial elongation of the early internodes. This hypothesis is supported by the observation that the inhibitor of an early step in GA biosynthesis, paclobutrazol, reduces elongation of sln plants when applied to developing seeds but not when applied at the start of germination. By contrast, prohexadione-calcium (BX-112), which inhibits the step GA20 to GA1, dramatically reduces internode length of sln plants when applied to seeds at the start of germination. Finally, application of GA20 to the dry seed of a wild-type (Sln) line (before sowing) resulted in a phenocopy of the sln mutant.

Internode length in Pisum. Gene lkd

A new, single gene, recessive internode length mutant in Pisum, lkd, is described. The internodes of lkd plants are ca. 40% shorter than comparable Lkd plants and this difference appears greater in the dark than in the light. The mutant does not appear to be dwarfed due to modified gibberellin (GA) levels, as determined by gas-chromatography-selected ion monitoring (GC-SIM) for GA1 and GA20. In relative terms, the mutant responds as well as the wild-type to applied GA1. However due to its initial short stature it does not elongate to the same extent as the wild-type to high doses of GA1 suggesting that some other factor, unrelated to GA levels or perception is probably limiting growth in this mutant.

Thigmomorphogenesis and its Interaction with Gravity in Climbing Plants of Epipremnum aureum

Summary The touch-mediated increase in the leaf lamina area of climbing Epipremnum aureum (Linden and Andre) Bunt. plants was characterized. The touch stimulation was provided by coupling plant internodes to a support, whereas hanging plants were regarded as mechanically unstimulated controls. We show that the thigmosensitive regions is located in the youngest internodes and is restricted to the stem flank facing the support's surface, i.e., the flank which forms adventitious aerial clasping roots. Further, two different interactions between the gravity- and the mechanical-sensing response systems were found: ( i ) The touch-mediated promotion of leaf size was best expressed in upwards-oriented stems and was completely absent in horizontally oriented stems. Thus, the gravitational vector dictates permissive or non-permissive conditions for expression of the response to the touch stimulus. ( ii ) In down-hanging stems, the negative gravitropic curvature response of the shoot apex was too weak to prevent downward growth. However, touch stimulation of the apex induced a negative gravitropic tip curvature response sufficiently strong to invert the stem growth to an opposite direction of the gravity vector. Hence, the touch signal alters the expression of the apex's response to gravity.

Transgenic Tobacco Plants Coexpressing the Agrobacterium tumefaciens iaaM and iaaH Genes Display Altered Growth and Indoleacetic Acid Metabolism

Transgenic tobacco (Nicotiana tabacum) SR1 plants expressing the Agrobacterium tumefaciens nopaline transferred DNA iaaH gene were transformed with a 35S-iaaM construct. The transformants displayed several morphological aberrations, such as adventitious root formation on stem and leaves, dwarfism, epinastic leaf growth, increased apical dominance, and an overall retardation in development. In addition, xylem lignification was higher than in wild type. Free and conjugated indoleacetic acid (IAA) levels were quantified by gas chromatography-multiple ion monitoring-mass spectrometry in leaves and internodes of wild-type plants and two transformed lines with different phenotypes. Both transformed lines contained elevated levels of free and conjugated IAA, which was associated with increased transcription of the iaaM gene. The line with the highest IAA level also had the most altered pattern of growth and development. These IAA-overproducing plants will provide a model system for studies on IAA metabolism, IAA interactions with other phytohormones, and IAA roles in regulating plant growth and development.

Role of the Leaf Sheath in Elongation of the Internodes of Rice Plants.

The main aim of this paper is to present how the leaf sheath concerns internode elongation in rice, using the japonica cultivar Sasanishiki. Leaf sheaths were removed at the begining of the rapid elongation of the second internode, namely, the booting stage. Removal of a whole leaf sheath induced a marked growth inhibition of the first and second internodes. This inhibiting effect caused by the complete removal of the leaf sheath was just partly recovered only gibberellin A3 was applied. On the other hand, the effects of partial removal of the leaf sheaths are reversed by covering the internode itself or the whole panicle with aluminium foil or wrap film. These results suggest that the leaf sheath may act as a protective cover with regard to environmental stress in the young internodes and may help the tissue of the second internodes to retain the ability to respond to the endogenous gibberellin. The leaf sheath, especially that of the first leaf (flag leaf), may also stimulate the elongation of the first and second internodes through the enhancement of endogenous gibberellin production in the young panicles that are covered with these leaf sheaths.

Stable regeneration in Asparagus cooperi Baker as controlled by different factors

For in vitro regeneration spear, shoot tip, internode, node and root of mature plants of Asparagus cooperi were used as explants. Induction of callus from different explants depended on the photoperiod in addition to a specific combination of α-napthalene acetic acid (NAA) and kinetin (Kn) in the basal medium. The development of shoots from callus required 6-benzylaminopurine (BA), l-arginine, adenine and a low level of NAA. The individual shoots produced roots in the presence of indole-3-butyric acid (IBA) or indole-3-butyric acid containing potassium salt (KIBA). Regenerated plants were cytologically and phenotypically stable.

Two new myrmecophytic associations from the Malay Peninsula: Ants of the genusCladomyrma (Formicidae, Camponotinae) as partners ofSaraca thaipingensis (Caesalpiniaceae) andCrypteronia griffithii (Crypteroniaceae)

In Peninsular Malaysia the treesSaraca thaipingensis (Caesalpiniaceae) andCrypteronia griffithii (Crypteroniaceae) are inhabited by ants. In the vicinity of Gombak, near Kuala Lumpur, the hollow internodes of youngSaraca thaipingensis plants are colonized mainly by twoCladomyrma species. In larger trees aCrematogaster sp. is also found.Crypteronia griffithii is inhabited by a third species ofCladomyrma. None of these species is conspecific with any of the threeCladomyrma taxa so far described. The colonies are founded by single mated queens, which have a conspicuous, sphecid wasp-like behaviour when searching for host plants and nest sites. They chew holes into the plant internodes and hollow them out to provide nest sites. Coccids and pseudococcids are cultivated within the internodes. The homopterans are not carried by queens on their nuptial flights. They apparently find their way by themselves into the cavities or are perhaps carried there by the worker ants. TheCladomyrma ants onCrypteronia are not aggressive, in contrast to those onSaraca thaipingensis.

Internode length and anatomical changes in Pisum genotypes crys and cryc in response to extended daylength and applied gibberellin A1

Dwarf pea (Pisum sativum L.) plants with genotypes cryc and crys responded differently when an 8 h photoperiod (8 h daylight, 16 h dark) was extended to 24 h (8 h daylight, 16 h incandescent light). Genotype cryc showed up to a 4‐fold increase in internode length, sustained by increases in both cell length (particularly of epidermal cells) and cell number (particularly of cortical cells) while crys plants showed up to a 2‐fold increase in internode length sustained mostly by an increase in cell number. Under an 8 h (daylight) photoperiod the two genotypes did not differ in their sensitivity to applied gibberellin A1 (GA1) and they showed a similar pattern of response. GA1 significantly increased internode length, cell length and cell number in both genotypes. Incandescent light did not increase the size of the response to GA1 except for crys plants at high dose rates of GA1 (29–58 nmol). At saturating doses of GA1 the two genotypes attained a similar peak internode length; incandescent light increased the peak by about 40%. GA1 increased the rate of leaf appearance by up to 33% while incandescent light reduced the rate by 4–7%. The elongation response of the more mature internodes of cryc plants to GA1 or incandescent light was due primarily to an increase in cell length whereas increased cell number made a significant contribution in the case of internodes which were relatively immature at the time the stimulus was applied. The progressive increase in internode length of both genotypes during ontogeny was due primarily to an increase in cell number. In conclusion, alleles cryc and crys (background le La) do not confer a difference in sensitivity to GA1 and the increase in internode length in response to incandescent light is probably not the result of a real or perceived increase in GA1 level. Allele crys may partially block a phytochrome mediated response to light and the key difference between genotypes crys and cryc may lie in the greater elongation (extensibility?) of cryc epidermal cells in incandescent light.

Internode Length in Lathyrus odoratus L.: The Expression and Interaction of Genes L and Lb

A recessive allele that causes semidwarf stature in the sweet pea, Lathyrus odoratus L., was identified and designated lb. The recessive allele for dwarf habit, l, is epistatic to the Lb-lb pair of alleles in the sense that a clear dihybrid F2 segregation ratio of 9 tall (L- Lb-): 3 semidwarf (L- Iblb): 4 dwarf (II —) was obtained. However, a quantitative effect of lb was detected in the dwarf (II) class. The lb allele had its maximum effect in the upper internodes, which, in semidwarf plants, were only about 56% as long as those of wild-type (tall) plants. In contrast, the effect of I was obvious soon after shoot emergence, and internode length in dwarf plants rapidly fell to less than half that of tall plants. The shorter internodes of dwarf and semidwarf plants resulted from a reduction in both the length and the number of epidermal cells per internode. Compared with tall plants, dwarf (II) plants had smaller and more ovate leaves with shorter petioles, the foliage was darker green in color, the node of flower initiation was reduced slightly, and branching was increased markedly. In contrast, the effect of lb was confined largely to internode length, although some increase in basal branching also was noted in semidwarf plants.

Fructan Accumulation and Sucrose:sucrose Fructosyltransferase Activity in Stems of Spring Wheat Genotypes

Stems of wheat (Triticum aestivum L.) accumulate water‐soluble carbohydrates (WSC) during the first 3 wk after anthesis. These reserves can later contribute to grain filling. Two spring wheat genotypes (‘Kolibri’ and breeding line D) were tested in growth chambers to determine if they differ in the accumulation of WSC components and in the activation of sucrose:sucrose fructosyltransferase (SST) in stem tissue. Concentration of CO2 was supplied at 1000 or 300 μL CO2 L−1 after anthesis to alter photosynthate production. The WSC accumulation in the penultimate internode during the first 18 d post anthesis (DPA) was substantially higher in Genotype D than in Kolibri. The WSC accumulation up to 7 DPA was due to increases in hexoses and sucrose. Sucrose concentration was initially lower in Kolibri than in Genotype D, but increased to a comparable level for both genotypes and both CO2 treatments. Fructan synthesis was initiated at 7 DPA. At 18 DPA, fructan was the dominant component of WSC. Under both CO2, treatments Genotype D accumulated substantially higher fructan concentrations than Kolibri. In a second experiment, induction of SST activity was observed during the first 9 DPA in the penultimate internode of plants grown at 1000 and 200 μL CO, L−1. There was a positive relationship between sucrose concentration and in vivo SST activity, suggesting that sucrose induced SST activity; however, Kolibri exhibited a much lower SST activity at given sucrose concentration. Thus, the low fructan synthesis of Kolibri is associated with an initial lower sucrose concentration and with a less effective activation of SST by sucrose.

Chemical Composition of Phloem Sap from the Uppermost Internode of the Rice Plant

The chemical composition of phloem sap from the uppermost internode of rice plants, one week after anthesis, was compared with that of phloem sap from the leaf sheath of a young seedling. The pure phloem sap from rice plants was collected by an insect laser technique

Imazalil Seed Treatment Reduces Common Root Rot and Increases Yield of Barley Under Commercial Conditions

(...) The imazalil treatment was the Vitavax 200 treatment at the same rate plus Nuzone 10EC at 1.0 ml/kg. Isolations from 173 diseased subcrown internodes of plants in the control and imazalil treatments in 1986 yielded 106 isolates (61%) of Bipolaris but no Fusarium spp. Seed treatment with imazalil significantly (P=0.05) lowered disease severity in the subcrown internode, increased grain yield 6%, and increased test weight compared to the control treatment