Avena leaves

There is evidence that the growth of petioles is dependent on auxin from the blade. Blade removal in Helianthus inhibits petiole elongation about 90%, an effect which is partially overcome if auxin is supplied to the cut surface of the petiole (Palmer 1972). Application of auxin to either the upper or lower surfaces of debladed petioles causes an increase in growth rate. Dayanadan et al. (1976) have found that auxin, but not GA or kinetin, promotes cell elongation in parenchyma, collenchyma and vascular elements of the sheath pulvinus of Avena leaves. 

Ohnishi J.I. and yamada M. (1980) Glycerolipid synthesis in Avena leaves during greening of etiolated seedlings 111. 

DEVELOPMENT OF FATTY ACID SYNTHESIS IN GREENING AVENA LEAVES... 

There were two increases in novo synthesis of fatty acids during greening of Avena leaves (Fig.lA). The first rise occurred 3 hour after illumination in which the prolamellar bodies are degenerated. The second... 

Fig. 1 (A) Level of fatty acid synthesizing activity in etiolated and greening Avena leaves. -(B) Level of fatty acid synthesizing activity in the crude plastids isolated from etiolated and greening Avena leaves (Ohnishi and Yamada 1980)... 

In addition to maize, spinach and castor bean, lipid transfer proteins have been detected in other plant tissues seeds of barley (Coutos-Thevenot, unpublished) and sunflower (Arondel, unpublished), wheat (Monnet, unpublished), tobacco (Gawer, unpublished), pea (Kader et al., 1985) and Avena leaves (Yamada et al., 1980). 

Fig. 2 Effect of TLM on the synthesis of PC and MGDG in greening Avena leaves. Etio ted leaf sections (4 cm length from the top) were fed with [1- Oacetate (40 pCi/0.2 ml) and TLM (100 pg/ml) in the light (2,400 lux, 25°C) for 25 hr.

Fig. 4 shows changes of lipid composition in Avena leaves greened from their etiolated leaves in the presence of TLM for 24 hr. In the total lipid composition PC remained unchanged, but MCDG markedly decreased by TLM treatment. Since Avena is a typical l8 3-plant in which the eukaryotic path from l8 2/l8 2-PC to l8 3/l8 3-MGBG is actively operated, the effect of TLM seems to appear in MGDG as end product, but not in PC as intermediate. In spite of the unchanged... 

Table 4 Effect of TLM on the fatty acid composition of greened Avena leaves. The experimental condition was the same as in Fig. 4 ...

Cleland R (1964) Role of endogenous auxin in the elongation of Avena leaf sections. Physiol Plant 17 126-135... 

Wubben et al (1996) Detoxification of oat leaf saponins by Septoria avenae. Phytopathology 86 986... 

Morrissey JP et al (2000) Stagonospora avenae secretes multiple enzymes that hydrolyze oat leaf saponins. Mol Plant Microbe Interact 13 1041... 

Dihydropyrenophorin, from Drechslera avenae, is a leaf pathogen of both wild and cultivated oats. It causes reddish brown lesions with a necrotic sunken center. At least one compound isolated from broth cultures of this fungus caused comparable lesions on oats and a variety of other plants at 3.2 x 10" M (15). The phytotoxin was characterized by spectrometric analyses and chemical conversion as (-)-dihydropyrenophorin (Vl), an important di lactone macrolide (15). However, the major product obtained in our extraction procedure used to isolate (-)-dihydropyrenophorin was the diol VII (j 6), which was not active in our bioassay tests. 

The effects of brassinolide were similar in the light and in the dark, but the coleoptile and mesocotyl were elongated more and leaf growth was retarded more in the dark than in the light by brassinolide at 10° ppm. These results were in sharp contrast to those experimental results obtained with Avena coleoptiles (5) and with soybean and mung bean tissues (i, 6). 

Nisius A (1988) The Stromacentre in Avena Plastids An Aggregation of /J-Glucosidase Responsible for the Activation of Oat-Leaf Saponins. Planta 173 474... 

There are two types of receptor, termed fast and slow sites [21]. The fast responses (detectable in <5 min) appear to be brought about by membrane-mediated phenomena, while the slow responses, which involve protein synthesis, are not detectable within the first half hour. The receptor types have different molecular requirements, and the fast reaction is not a pre-requisite for the slow. Growth assays employed to assess activity include Avena coleoptile, lettuce hypocotyl, rice seedling, and bean axis. Other types include lettuce seed and wheat embryo germination, transpiration assays, leaf disk senescence, and more recently, a-amylase production. Stomatal closing using epidermal strips is an assay for the fast receptor. 

Table 9.3 Compounds were applied with the adjuvant A12127 used at 0.5% at a rate of 60 g ha on barley and wheat, 30 g ha on Alomy (Alopecurus myosuroide), Avefa Avena fatua), Loipe (Lolium perenne), Setfa Setaria faberi) at 2 leaf stage.

Mimosa tenuiflora leaf extract Mistletoe (Viscum album) extract Mountain ash (Sorbus aucuparia) extract Mullein (Verbascum thapsus) extract Myrrh (Commiphora myrrha) extract Nettle (Urtica dioica) extract Oat (Avena sativa) protein Oleoresin capsicum Orris root extract Pansy (Viola tricolor) extract Parsley (Carum petroselinum) extract Passionflower (Passiflora incarnata) extract Periwinkle (Vinca minor) extract Quillaja (Quillaja saponaria) Rye (Secale cereale) extract... 

Hayes AB, Lippincott JA (1976) Growth and gravitational response in the development of leaf blade hyponasty. Am J Bot 63 383-387 Hemberg T (1972 a) Interaction of kinetin and abscisic acid in the Avena straight growth test. Physiol Plant 26 108-109... 

Carbyne controls wild oat (Avena fatua) in spring wheat, durum wheat, barley, flax, peas, sugarbeets, lentils and soybean. Its main disadvantage is it must be applied in the second leaf stage of wild oats. 

Oats Dark leaf spot, speckle blotch S. avenae Leptosphaeria avenaria... 

Oats Leaf spot, seedling blight Septoria tritici) Pyrenophora avenae... 

Seeds of oat, Avena sativa Lvar Victory I(The General Swedish Company, Limited), were germinated at 25 C on vermiculite and grown in the dark for 8 days. Etiolated seedlings were exposed to light(2400 lux, 25 C). The first leaves from greening Avena seedlings were excised and 2 cm sections located between 4 cm and 6 cm from the leaf base were used for the analysis. 

A series of bioassays established the credibility of the route of volatile terpenes produced by the plants to the soil. Toxin production from roots was eliminated in the preliminary experiments, but leaf material, in contrast, was highly toxic when assayed in direct contact with germinating seeds and also when crushed leaves were present in a sealed bioassay chamber in which only vapor transport of toxins to seeds was possible. Avena fatua root growth was reduced 50% by volatiles from 0.5 g of Artemisia califomica, and 64% by 0.5 g of S. leucophylla (Muller et al. 1964). Volatile inhibitors were also indicated by observations that the bare and inhibition zones were similar in extent on both the uphill and downhill sides of S, leucophylla stands (Muller 1966). 

Hampp R (1980) Rapid separation of the plastid, mitochondrial and cytoplasmic fractions from intact leaf protoplasts of Avena, Planta 150, 291-298. 

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