Effect of Lateral Root Formation on the Vascular Pattern of Barley Roots

The vascular pattern in the root of barley (Hordeum vulgare L.), characterized by discontinuous xylem, is markedly affected by its branching. The roots become divided into unbranched segments alternating with branched segments with a more complex vascular pattern, formed by two systems differing in origin and age: the primary vascular system derived from the procambium and ontogenetically younger connective vascular system derived from stelar parenchyma. Adjacent to the sites of the lateral root initiation, reprogramming of parent stelar parenchyma for connective vascular elements occurs. The connecting phloem is represented by small sieve elements and companion cells, the connecting xylem is composed of small vessel elements with reticulate or scalariform-reticulate wall thickenings and simple perforations. Development of the connective vascular system secures continuous lateral and axial vascular connection between lateral root and parent root. The extent of the vascular connection in the parent root increases in an acropetal direction. Hydraulic effects of connective vascular tissue formation and parent root segmentation are discussed.     

Some Observations on the Bleaching Effect of Ethylenediaminetetraacetic Acid on Green Barley Leaves

Green barley leaves (Hordeum vulgaris) floated on the surface of 0.05 m ethylenediamine disodium tetraacetate, EDTA-2Na, pH 7.0 and exposed to light (5000 lux) at 25 degrees exhibited a marked bleaching (EDTA-bleaching) visible to the naked eye and paralleled by a striking reduction in content of chlorophylls a and b. This loss of color did not occur in controls which were treated with H(2)O instead of EDTA (water controls). In darkness the leaves in the water controls were bleached while EDTA-treated leaves retained all their color.EDTA bleaching was observed only in intact leaves. When leaves were boiled EDTA protected their pigment against photodecomposition. Without EDTA boiled leaves were bleached completely in light.When intact green leaves which had been floated on water and exposed to light for 48 hr were treated with boiling ethanol or acetone, the chlorophylls extracted by this procedure did not undergo bleaching if EDTA were present in solution. Under these conditions a green fine grain precipitate formed which was insoluble in ethanol or acetone and was stable in light or darkness.EDTA bleaching of green barley leaves was inhibited by KCN, and by the addition of casein hydrolysate.     

Formation of the Pigment Apparatus in Etiolated Barley Leaves under the Influence of Levulinic Acid

The effects of levulinic acid (LA) on the synthesis of pigments and the membrane system of etioplasts were studied in etiolated leaves of barley (Hordeum vulgare L.). Growing in the solution of LA during a six-day period, which started one day after the soaking of seeds, resulted in a retardation of leaf growth, more than a twofold decrease in the level of carotenoids and protochlorophyllide (Pd) in the leaf tissue, and suppression of the synthesis of long-wave form of Pd₆₅₅; these effects depended on the LA concentration. In etioplasts isolated from the seedlings treated with 50 M LA and containing predominantly a short-wave form of Pd with a peak of fluorescence at 632 nm (–196°C), there was a membrane fraction whose location in the sucrose density gradient was identical to that of prolamellar bodies (PLB) in the control plants. The content of Pd and carotenoids in this fraction calculated on a protein basis was 2.46 and 1.3 times lower than in control seedlings, while the relative content of Pd oxidoreductase (POR) essentially did not change. Thus, the suppression of Pd synthesis did not affect translocation of POR from the cytoplasm to the membranes of etioplasts. In the PLB membranes, there was no transfer of energy from the molecules of lipophilic fluorescent probe pyrene (excitation at 337, 278, and 296 nm) to Pd; however, under pigment deficiency, the production therein of pyrene excimer form at the expense of energy transfer from protein tryptophanyls (excitation at 278 and 296 nm) became more efficient, which indicated changes in protein–lipid interactions. The obtained results suggest that the short-wave form of Pd₆₃₂ accumulating in etioplasts under the suppressed synthesis of tetrapyrroles is not a free pigment.     

Effect of Salicylic Acid on Leaf Anatomy and Chloroplast Ultrastructure of Barley Plants

Light and electron microscopy were used to relate histological and ultrastructural differences of barley leaves treated with different concentrations of salicylic acid (SA, 100 µM-1 mM). Light microscopy revealed that the thickness of all leaf tissue components decreased in SA-treated plants. The effect was most pronounced on the width of the adaxial epidermis and on the size of the bulliform cells. The chloroplast ultrastructure was also affected by SA treatment. Swelling of grana thylakoids in various degrees, coagulation of the stroma, and increase in chloroplast volume were observed. 1 mM SA caused a vast destruction of the whole plastid structure.     

Balance between Potassium and Phosphorus in the Nutrition of Barley: I. The Influence on Amine Content

Potassium-deficient barley accumulates the amines agmatine andputrescine, the latter of which is known to produce necroticspots on the leaves in some seasons. The severity of potassiumdeficiency symptoms is strongly influenced by the external levelof phosphorus. An experiment was conducted in water culture,using two-week-old barley to discover whether amine accumulationwas similarly affected. Four levels of potassium —1/64,1/6, 1/4, and 1/1 of full supply—were combined factoriallywith the same levels of phosphorus, the diagonal in this designbeing a series of ‘balanced’ solutions in whichpotassium and phosphorus were present in the same ratio as inthe full nutrient. The plants were sampled three times duringthe ten-week period of growth, and the form of the results wassimilar each time. Whenever potassium was reduced, putrescinecontent rose above normal, but for large amounts of putrescineto be accumulated, phosphorus supply had to be in excess ofpotassium. The highest levels of agmatine were also found wherepotassium was low and phosphorus in excess, but significantaccumulations also developed whenever phosphorus was low relativeto potassium, that is, where high levels of potassium were observedin the plants. Since agmatine and putrescine are very closely related biochemicallyand together make up 90 per cent of the amine content of barley,the influence of potassium and phosphorus on their summed contentwas considered. Potassium was found to have the dominant effect:at any one level of phosphorus supply, the summed content wasminimal at the highest level of potassium, and reduction inpotassium always increased it. The effect of phosphorus dependedon the degree of imbalance between potassium and phosphorusin the nutrient. High summed contents were found where eitherpotassium or phosphorus was present in excess, and minimum contentwas found where the levels were balanced. There were significantpartial correlations between summed amine content and the potassiumand phosphorus contents of the plants. The high significanceof correlations between amine content and the proportion ofdead and moribund shoot material suggested that amine accumulationmight be partly responsible for the rapid death of the leavesof the deficient plants as well as for the production of necroses,which are only limited in area.     

The Effect of the Conversion of Indolebutyric Acid into Indoleacetic Acid on Root Formation on Microcuttings of Malus

The uptake and metabolism of tritiated indolebutyric acid (IBA)and indoleacetic acid (IAA) were related to root regenerationon stem bases of apple (Malus cv "Jork") shootlets culturedin vitro. The major part of the auxins taken up from the mediumwas located in the bottom 1 mm of the stem basis, the locationwhere the roots emerge. In this part of the shoot about 4% ofthe accumulated IBA-³H remained in the free acid. Analysis onnormal phase TLC followed by reversed phase HPLC revealed thatabout 1% of the IBA-metabolites co-chromatographed with standardIAA. Incubation of shoots on medium with IAA led also to anIAA^int content of about 1% of the amount absorbed. IAA was notconverted into IBA. A medium concentration of 3.2 µM IAAor IBA induced maximum root formation of 9 and 13 roots pershoot, respectively. The IAA^int content in the stem base was0.5 µmol per kg FW after 5 days regardless of the auxinsource. Incubation on medium with IBA led to an IBA^int concentrationof 3.4 µmol per kg FW. IBA may exert its action partlyvia conversion into IAA. However, the fact that IBA inducedmore roots than IAA suggests that IBA itself is also active,or modulates the activity of IAA. The partition of absorbed auxin over active free auxin acidand individual conjugates was not directly related to root formation.At inductive and non-inductive auxin concentrations no shiftin the ratio of free auxin acids to total absorbed auxin wasobserved during root formation. (Received March 4, 1992; Accepted May 25, 1992)     

The Effect of Diuron and 5-Aminolevulinic Acid on the Maintenance of Stable Chlorophyll Content in Greening Barley Leaves

Chlorophyll (Chl) accumulation and delayed luminescence of PSII were compared in greening barley leaves pretreated and untreated with diuron (DCMU) in the etiolated state, and reactions of two photosystems were studied in the plastids isolated from the pretreated and untreated leaves. The effect of treatment in light of post-etiolated leaves after 40-h illumination with 5-aminolevulinic acid (ALA), on the content of Chl and its precursor, protochlorophyllide (PChld) was also studied. The pretreatment of etiolated leaves with DCMU did not affect the rate of greening and the stable level of Chl content in barley. ALA, when introduced to leaves after the termination of Chl accumulation, increased PChld, but not Chl level. We suppose that the primary cause of greening cessation in etiolated leaves is the inhibition and cessation of the synthesis of apoproteins of pigment–protein complexes. The exhaustion of binding sites for newly synthesized Chl molecules leads to their retention in the so-called retroinhibitory pool of Chl, thus resulting in the inhibition of ALA synthesis by a negative feedback mechanism.     

茉莉酸对水稻侧根发生的影响

实验材料为水稻(Oryza sativa L.)栽培品种"IR8"(国际水稻所8号)及其少侧根突变体MT10.将2 d水稻幼苗种子根全部浸入0.016～50 μmol/L 茉莉酸(JA)溶液处理2 d,结果表明JA显著抑制种子根的伸长,其抑制程度与JA浓度成正比.不高于2 μmol/L的JA显著促进侧根的发生,每cm的侧根数目随浓度的增加而增加,最多可增加到原来的168%("IR8")和285%(MT10).10 μmol/L的JA仍促进处理过程中和处理后生成根区段的侧根数目的增加,但明显抑制处理前生成根区段侧根的发生,每cm的侧根数目有所下降.     

Abscisic Acid and Gibberellic Acid Contents in Ripening Barley Seeds

The ABA and GA3 contents were investigated in barley seeds during maturation and after harvest. The highest amount of ABA was found in milk and wax ripeness – 13 ng and 11 ng per seed respectively. The level decreased during the later stages of maturation and during release of dormancy and was 1 ng per seed 6 weeks after harvest. The content of gibberellic acid decreased in a similar way but in an earlier stage of maturation. The determined amounts of GA₃ were: 0.4, 0.1, 0.03 and about 0.05 ng per seed respectively, in milk, wax and full ripeness and after harvest. The results of quantitative determination, obtained with the GLC method, corresponded to the growth effects in the test of the first leaf of oat.     

Effect of Feeding Palm Oil By-Products Based Diets on Muscle Fatty Acid Composition in Goats

The present study aims to evaluate the effects of feeding palm oil by-products based diets on different muscle fatty acid profiles in goats. Thirty-two Cacang × Boer goats were randomly assigned to four dietary treatments: (1) control diet (CD), (2) 80% decanter cake diet (DCD), (3) 80% palm kernel cake diet (PKCD) and (4) CD plus 5% palm oil (PO) supplemented diet (CPOD). After 100 days of feeding, four goats from each group were slaughtered and longissimus dorsi (LD), infraspinatus (IS) and biceps femoris (BF) were sampled for analysis of fatty acids. Goats fed the PKCD had higher (P<0.05) concentration of lauric acid (C12:0) than those fed the other diets in all the muscles tested. Compared to the other diets, the concentrations of palmitic acid (C16:0) and stearic acid (C18:0) were lower (P<0.05) and that of linoleic acid (C18:2 n-6) was higher (P<0.05) in the muscles from goats fed the CD. It was concluded that palm kernel cake and decanter cake can be included in the diet of goats up to 80% with more beneficial than detrimental effects on the fatty acid profile of their meat.     

The Formation of Ribulose Diphosphate Carboxylase Protein during Chloroplast Development in Barley

Ribulose 1,5-diphosphate carboxylase is synthesized in barley leaves growing in the dark. Upon illumination there is a marked increase in the rate of synthesis of the enzyme. The specific activity of the enzyme expressed as cpm incorporated into phosphoglyceric acid per μg of fraction I protein, after isolation shows no change either during dark growth or greening. During early stages of illumination of 7 day dark grown leaves with 320 foot-candles the enzymic activity in the water soluble protein fraction of the leaf shows a short term decline after 15 min which lasts for 30 min. Leaves greening at 2 foot-candles show a similar decline which is shifted to a time between the fourth and eighth hr after the onset of illumination.     

Detection of Glycollic Acid in Etiolated Barley Shoots

A modified method for carboxylic acid analysis has been developedin order to study the metabolism of glycollic acid in barleysap. Glycollic, malic, citric, malonic, succinic, and fumaric acidshave been detected in alcoholic extracts from etiolated barleyshoots, and the amounts present roughly estimated.     

Vacuolar Deposition of Ascorbate-derived Oxalic Acid in Barley

l-[1-(14)C]Ascorbic acid was supplied to detached barley seedlings to determine the subcellular location of oxalic acid, one of its metabolic products. Intact vacuoles isolated from protoplasts of labeled leaves contained [(14)C]oxalic acid which accounted for about 70% of the intraprotoplast soluble oxalic acid. Tracer-labeled oxalate accounted for 36 and 72% of the (14)C associated with leaf vacuoles of seedlings labeled for 22 and 96 hours, respectively.