Avena

Various assay methods have been used to detect the presence of inhibitory substances. These include some of the classical tests used by investigators of growth-promoting substances—i.e., the various Avena coleoptile assays which utilize intact, decapitated, or isolated cylinders and the split pea stem test. Effects on seed germination and seedling shoot or root growth and development have also been measured in addition to other visible expressions of inhibition. Details of many of these tests have been compiled by Mitchell et al. (99). Tests have been carried out in Petri dishes, with various solution culture techniques, and by sand and soil culture. Effects so measured may or may not be similar to those obtained under field situations— i.e., the establishment of inhibition under controlled conditions pro-... 

Naringenin (5, 7, 4 -trihydroxyflavanone), isolated in pure form from dormant peach flower buds, strongly inhibited the growth of Avena coleoptiles at 4.6 X 10-4 M (71). Naringenin is the aglycone of the glycoside naringin. 

Parasorbic acid (Figure 2) was isolated from fruits of Sorbus aucuparia. Germination of mustard seed Sinapis alba) was affected adversely by parasorbic acid at 3.5 X 10-3 M and growth of excised tomato roots was inhibited at approximately 8.5 X 10 4 M (25). The acid also antagonized indoleacetic acid (IAA) in the Avena assay. Cornman 29,30) reported that parasorbic acid slowed down mitosis. Metaphase stages were observed to accumulate, but abnormalities were not detected. 

Coumarin, the lactone of o-hydroxycinnamic acid, and some of its derivatives have been isolated from many plant species 31). Thimann and Bonner 141) attributed the growth-inhibiting effects of coumarin to its action on enzyme sulfhydryl groups. Inhibitory effects of coumarin on Avena coleoptiles and pea stem sections could be overcome by 2,3-dimercaptopropanol (BAL). Coumarin has also been reported to disrupt mitosis 29,30). 

Simonetti E. Veronico P. Melillo M. T. Delibes A. Andres M.F. Lopez-Brana I. (2009) Analysis of class III peroxidase genes expressed in roots of resistant and susceptible wheat lines infected by Heterodera avenae / / Mol. Plant-Microbe Interact. V. 22. P. 1081-1092. 

Pierce, W.S. Higinbothom, N. (1970). Compartments and fluxes of and Cl" in Avena coleoptile cells. Plant Physiology, 46, 666-73. 

Johnson, G.R. Frey, K.J. (1967). Heritabilities of quantitative attributes of oat (Avena sp.) at varying levels of environmental stress. Crop Science, 7, 43-6. 

B. R. Kerry, D. H. Crump, and C. A. Mullen, Studies of the cereal cyst nematode Heterodera avenae, under continuous cereals, 1975-1978 II. Fungal parasitism of nematode females and eggs. Annals of Applied Biology /00 489 (1982). 

Z. Varanini, R. Pinton, M. G. De Biasi, S. Astolfi, and A. Maggioni, Low molecular weight humic substances stimulate H -ATPase activity of plasma membrane vesicles isolated from oat (Avena sativa L.) roots. Plant Soil I53 6 (1993). 

A technique utilizing genetically modified bacteria to report the presence of particular compounds in soil has also been developed (37). These bacteria respond to the presence of specific compounds in their environment by producing ice-nucleation proteins that enter into cell membranes, enabling cells to be detected by means of a droplet freezing assay. The presence of trytophan in 1-10 i molar concentrations has been detected using reporter bacteria in a study examining loss of amino acids from roots of Avena barbata into soil (38). 

The total monetary loss resulting from weed competition in the cereal crops was 1.3 billion annually. The most frequently reported weeds were mustards (Brassica spp.) followed by wild oats (Avena fatua L.), bromes (Bromus spp.), and wild garlic (Allium vineale L.) (11). Losses in vegetables was 5% of the total while in fruit and nuts the loss was 7% of the total. Crabgrass, bermudagrass [Cynodon dactylon (L. )... 

Abbreviations of plant species As, Avena satlva Gm, Glycine max Hv, Hordeum vulgare Ta, Trltlcum aestlvum. 

Another limitation to the studies in Table 1 is the small number of plant species tested. Primarily monocotyledonous plants have been studied, although McClure et al. (26) found ferulic acid inhibitory in soybean. The restriction of studies to monocots is probably because the mechanism of mineral absorption has been more fully elucidated with monocots. Harper and Balke (32) reported some minor differences in the inhibition of K+ absorption by salicylic acid among oats (Avena sativa L.), wheat (Triticum aestlvum L.), barley, and maize roots. 

The implication that "living crops" can allelopathically suppress weeds has been made by Putnam and Duke (28) and Leather (29). These studies demonstrated that the potential for suppression of weeds could be enhanced by crop selection. Putnam and Duke (28) suggested that there is potential for breeding crops to better suppress weeds by utilizing and improving allelopathic characteristics. Fay and Duke (30) evaluated the amount of scopoletin (6-methoxy-7-hydroxy coumarin) exuded from 3,000 accessions of Avena sp. They suggested that the "wild types" of crop varieties could have once possessed allelopathic potential, but this character has been inadvertently selected against over time. 

Avena fatua, dead litter Ferulic and coumaric acids 70, 71... 

Halavaty, A. S. and K. Moffat (2007). N- and C-terminal flanking regions modulate light-induced signal transduction in the LOV2 domain of the blue-light sensor photo tropin 1 from Avena sativa. Biochemistry 46 14001-14009. 

Jenkins R. L., Loxdale H. D., Brookes C. P., and Dixon A. F. G. (1999). The major carotenoid pigments of the grain aphid, Sitobion avenae (F.) (Hemiptera Aphididae). Physiol Entomol 24 171-178. 

Andersen, S. (1965) Heredity of race 1 or race 2 in Heterodera avenae. Nematohgica... 

Andersen, S. and Andersen, K. (1982) Suggestions for determination and terminology of pathotypes and genes for resistance in cyst-forming nematodes, especially Heterodera avenae. OEPP/EPPO Bulletin 12, 379. 

Cook, R. and York, P.A. (1982) Resistance of cereals to Heterodera avenaer. methods of investigation, sources, and inheritance of resistance. OEPP/EPPO Bulletin 12, 423-434. 

Person, F. and Rivoal, R. (1979) Hybridation entre les races Frl etFr4 d Heterodera avenae Wollenweber en France et etude du comportement d agressivite des descendants FI. Revue de Nematologie 2, 177. 

Aphidius rhopalosiphi Sitobion avenae Host sex pheromone [attraction, increased parasitization] (4aS,7S,7aR)-Nepetalactone 26 (lR,4aS,7S,7aR)-nepetalactol 27 [76]... 

Poaceae (cereals) Avena sativa (oats) Hordeum vulgare (barley) Oryza sativa (rice)... 

Liming H U and Schlosser E (1976), Role of saponins in antifungal resistance. VI. Interactions Avena sativa-Drechslera avenacea , J Plant Dis Protect, 83, 317-327. 

Shirtliffe, S.J., Entz, M.H. and Van Acker, R.C. (2000). Avena fatua development and seed shatter as related to thermal time. Weed Sci., 48, 555-560. 

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