scholarly journals Effects of Temperature on Ethylene-induced Phenylalanine Ammonia Lyase Activity and Russet Spotting in Harvested Iceberg Lettuce

1995 ◽  
Vol 120 (1) ◽  
pp. 84-87 ◽  
Author(s):  
M.A. Ritenour ◽  
M.J. Ahrens ◽  
M.E. Saltveit
Keyword(s):  
Phenolic Compounds ◽  
Phenylalanine Ammonia Lyase ◽  
Rapid Decrease ◽  
Effect Of Temperature ◽  
Pal Activity ◽  
Iceberg Lettuce ◽  
Lyase Activity ◽  
Lag Period ◽  
Effects Of Temperature ◽  
Phenylalanine Ammonia Lyase Activity

Experiments were conducted to study the effect of temperature on the ethylene inducibility of phenylalanine ammonia lyase (PAL, EC 4.3.1.5) activity and the development of russet spotting (RS) in Iceberg lettuce (Lactucu sutiva L.). Tissue exposed to ethylene and held at 15 or 20C showed earlier hut lower peaks in PAL activity than tissue held at 5C. Accumulation of total soluble phenolic compounds, and the development of RS paralleled increases in PAL activity after a short lag period. Lettuce tissue transferred from 5 to 15C after 1 to 3 days showed later hut higher peaks in PAL activity than tissue continuously held at 15C. Transferring ethylene-exposed tissue to 0C before RS symptoms developed greatly limited further rise in PAL activity and RS development. Discontinuing ethylene exposure after 4 days resulted in a rapid decrease in PAL activity. Lettuce tissue exposed to ethylene for 4 days and then transferred from 5 to 0C after the development of moderate RS symptoms showed no difference in RS after 8 days compared to tissue stored continuously at 5C.

scholarly journals EFFECT OF TIME/TEMPERATURE TREATMENTS ON PHENYLALANINE AMMONIA-LYASE ACTIVITY AND DEVELOPMENT OF RUSSET SPOTTING IN ICEBERG LETTUCE

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1127c-1127
Author(s):  
M.A. Ritenour ◽  
M.E. Saltveit ◽  
M.J. Ahrens
Keyword(s):  
Phenylalanine Ammonia Lyase ◽  
Phenolic Content ◽  
Subjective Evaluation ◽  
Pal Activity ◽  
Iceberg Lettuce ◽  
Lyase Activity ◽  
Highly Correlated ◽  
Phenylalanine Ammonia Lyase Activity ◽  
Kinetics Of ◽  
Practical Implications

Russet spotting (RS) is an important postharvest disorder in Iceberg lettuce (Lactuca sativa L.). Previous studies showed that RS is induced by exposure to ∼5 ppm (ul/l) ethylene at ∼5C for 3 days and is characterized by the appearance of 1 to 2 mm diam. oval, brown sunken spots along the midrib. Increases in phenylalanine ammonia-lyase (PAL) activity and phenolic content are highly correlated with RS development. Ethylene-induced PAL activity is much less at higher (12C) or lower (0C) temperatures. In this study isolated whole leaves were exposed to a log series of ethylene concentrations from 0.1 to 10 ppm at temperatures from 0.0C to 20C for up to 8 days. Tissue was transferred among these various treatments to investigate the kinetics of PAL induction, activity and deactivation, phenolic accumulation, and RS development. A subjective evaluation was then made of RS development using a 1 to 9 scoring system in which 1 was no RS, and then PAL activity and phenolic content were measured. Preliminary results indicate that ethylene-induced PAL activity was decreased more rapidly upon transfer to temperatures above 10C than to 0.0C. Accumulation of phenolic compounds and development of RS paralleled each other, and were positively related to PAL activity. Practical implications of these results will be discussed.

scholarly journals Phenylalanine Ammonia-lyase Inhibitors Do Not Prevent Russet Spotting Lesion Development in Lettuce Midribs

1998 ◽  
Vol 123 (4) ◽  
pp. 687-691 ◽  
Author(s):  
Galen Peiser ◽  
Gloria López-Gálvez ◽  
Marita Cantwell ◽  
Mikal E. Saltveit
Keyword(s):  
Phenolic Compounds ◽  
Phenylalanine Ammonia Lyase ◽  
Phenylpropanoid Pathway ◽  
Aminooxyacetic Acid ◽  
Physiological Disorder ◽  
Phenolic Metabolism ◽  
Pal Activity ◽  
Iceberg Lettuce ◽  
Tartaric Acids ◽  
Lyase Activity

Russet spotting is a physiological disorder of lettuce (Lactuca sativa L.) caused by exposure to hormonal levels (<1 μL·L-1) of ethylene in air at ≈5 °C. Enhanced phenolic metabolism and the accumulation of phenolic compounds accompany the appearance of brown, oval lesions on the leaf midrib. Phenylalanine ammonia-lyase (PAL) is the first committed enzyme in the phenylpropanoid pathway. Three inhibitors of PAL activity [2-aminoindan-2-phosphonic acid (AIP), α-aminooxyacetic acid (AOA), and α-aminooxi-β-phenylpropionic acid (AOPP)] greatly reduced the accumulation of phenolic compounds and browning of lesions. At a concentration of 50 μm, AIP inhibited the formation of chlorogenic and dicaffeoyl tartaric acids in cut midribs of iceberg lettuce by 92% and 98%, respectively. AIP competitively inhibited PAL activity from a lettuce midrib homogenate with an apparent Ki of 22 nm. While the formation of phenolic compounds was strongly inhibited by AIP, the number of lesions associated with russet spotting was not affected. Only the color of the lesions was affected by AIP. In control midribs the russet spotting lesions were brown while those in the AIP-treated midribs were initially olive green and after 3 to 7 days these lesions turned the characteristic brown color. No tyrosine ammonia-lyase activity was detected in a homogenate of lettuce midrib tissue. These results indicate that the early development of russet spotting lesions is independent of the increase in PAL activity and phenolic compounds rather than an effect of these increases as previously suggested. However, accumulation of phenolic compounds does contribute to the subsequent browning symptoms indicative of russet spotting.

Effects of Herbicides on Growth and Extractable Phenylalanine Ammonia-Lyase Activity in Light- and Dark-Grown Soybean (Glycine max) Seedlings

Weed Science ◽  
1981 ◽  
Vol 29 (4) ◽  
pp. 433-439 ◽  
Author(s):  
Robert E. Hoagland ◽  
Stephen O. Duke
Keyword(s):  
Glycine Max ◽  
Phenylalanine Ammonia Lyase ◽  
Dry Weight ◽  
Root Tip ◽  
Continuous Darkness ◽  
Soybean Seedlings ◽  
Pal Activity ◽  
Lyase Activity ◽  
Phenylalanine Ammonia Lyase Activity

Effects of 16 herbicides representing 14 herbicide classes on growth and extractable phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) were examined in light- and dark-grown soybean [Glycine max(L.) Merr. ‘Hill’] seedlings. High purity (96 to 100%) herbicides were supplied via aqueous culture at various concentrations: 0.5 mM amitrole (3-amino-s-triazole), 0.1 mM atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine], 0.07 mM diclofop-methyl {methyl ester of 2-[4-(2,4-dichlorophenoxy)phenoxy] propanoicacid}, 0.5 mM DSMA (disodium methanearsonate), 0.2 mM fenuron (1,1-dimethyl-3-phenylurea), 0.05 mM fluridone {1-methyl-3-phenyl-[3-(trifluoromethyl)phenyl]-4(1H)-pyridinone}, 0.5 mM MH (1,2-dihydro-3,6-pyridazinedione), 0.5 mM metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one], 1.8 μM nitralin [4-(methylsulfonyl)-2,6-dinitro-N,N-dipropylaniline], 0.5 mM norflurazon [4-chloro-5-(methylamino)-2-(α,α,α-trifluoro-m-tolyl)-3(2H)-pyridazinone], 0.05 mM paraquat (1,1′-dimethyl-4,4′-bipyridinium ion), 0.15 mM perfluidone {1,1,1-trifluoro-N-[2-methyl-4-(phenylsulfonyl)phenyl] methanesulfonamide}, 0.2 mM propanil (3′,4′-dichloropropionanilide), 0.1 mM propham (isopropyl carbanilate), 0.5 mM TCA (trichloroacetic acid), and 0.05 mM 2,4-D [(2,4-dichlorophenoxy)acetic acid]. Dark-grown soybean seedlings (3-day-old) were transferred to control solutions (2 mM CaSO4) or to herbicide solutions (in 2 mM CaSO4) and grown at 25 C in continuous white light (200 μE•m-2•s-1) or continuous darkness until harvested 24 or 48 h after transfer. After 48 h, growth (fresh weight, dry weight, elongation) was inhibited by most of the chemicals. Other signs of toxicity (necrosis, secondary root stunting, and root tip swelling) were noted for some treatments. Roots were most affected, although hypocotyls were generally not changed. Hypocotyl elongation was stimulated by atrazine, fluridone, and norflurazon after 48 h light. Extractable PAL activity from soybean axes was decreased by atrazine, fenuron, metribuzin, norflurazon, propanil, propham, and 2,4-D. Amitrole and paraquat were the only herbicides that increased extractable PAL activity. Other compounds tested had no effect on the enzyme. None of the herbicides significantly affected in vitro PAL activity.

Effects of DPX-4189 (2-chloro-N-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)aminocarbonyl)benzenesulfonamide) on anthocyanin synthesis, phenylalanine ammonia lyase activity, and ethylene production in soybean hypocotyls

1982 ◽  
Vol 60 (6) ◽  
pp. 741-745 ◽  
Author(s):  
Jeffrey C. Suttle ◽  
Donald R. Schreiner
Keyword(s):  
Ethylene Production ◽  
Phenylalanine Ammonia Lyase ◽  
Anthocyanin Synthesis ◽  
Anthocyanin Content ◽  
Anthocyanin Accumulation ◽  
Soybean Seedlings ◽  
Pal Activity ◽  
Lyase Activity ◽  
Endogenous Ethylene ◽  
Phenylalanine Ammonia Lyase Activity

The effects of the herbicide DPX-4189 (2-chloro-N-((4-methoxy-6-methyl-1,3,5-triazin-2-yl)aminocarbonyl)benzenesulfonamide) on anthocyanin accumulation, phenylalanine ammonia lyase (PAL) activity, and ethylene production in seedlings of soybean (Glycine max L.) were investigated. Application of 1 μg DPX-4189 per plant led to an increase in anthocyanin content in soybean hypocotyls. The increase in anthocyanin content became evident 4 days after application of the herbicide. Accompanying the increase in anthocyanin content was an eightfold increase in extractable PAL activity. An increase in endogenous ethylene evolution also accompanied the increase in anthocyanin content. Application of silver nitrate (an inhibitor of ethylene action) to herbicide-treated seedlings did not prevent the increase in anthocyanin content. Application of 2-chloroethylphosphonic acid (an ethylene-releasing compound) to soybean seedlings stimulated PAL activity but had no effect on anthocyanin content. These results indicated that ethylene did not play a role in DPX-4189 mediated anthocyanin accumulation.

Changes in L-phenylalanine ammonia-lyase activity and isoflavone phytoalexins accumulation in soybean seedlings infected with Sclerotinia sclerotiorum

2013 ◽  
Vol 8 (9) ◽  
pp. 921-929
Author(s):  
Djordje Malenčić ◽  
Jelena Cvejić ◽  
Vesna Tepavčević ◽  
Mira Bursać ◽  
Biljana Kiprovski ◽  
...  
Keyword(s):  
Glycine Max ◽  
Sclerotinia Sclerotiorum ◽  
Phenylalanine Ammonia Lyase ◽  
Soybean Seedlings ◽  
Soybean Cultivars ◽  
Pal Activity ◽  
Isoflavone Content ◽  
Lyase Activity ◽  
Glycine Max L ◽  
Phenylalanine Ammonia Lyase Activity

AbstractSoybean [Glycine max (L.) Merr.] cultivars (Meli, Alisa, Sava and 1511/99) were grown up to V1 phase (first trifoliate and one node above unifoliate) and then inoculated with Sclerotinia sclerotiorum (Lib.) de Bary under controlled conditions. Changes in L-phenylalanine ammonia-lyase (PAL) activity and isoflavone phytoalexins were recorded 12, 24, 48 and 72 h after the inoculation. Results showed an increase in PAL activity in all four examined soybean cultivars 48 h after the inoculation, being the highest in Alisa (2-fold higher). Different contents of total daidzein, genistein, glycitein and coumestrol were detected in all samples. Alisa and Sava increased their total isoflavone content (33.9% and 6.2% higher than control, respectively) as well as 1511/99, although 48 h after the inoculation its content decreased significantly. Meli exhibited the highest rate of coumestrol biosynthesis (72 h after the inoculation) and PAL activity (48 h after the inoculation). All investigated cultivars are invariably susceptible to this pathogen. Recorded changes could point to possible differences in mechanisms of tolerance among them.

Comparison of Isomers of Fluorophenylalanine as Inhibitors of Ion Transport Across Barley Roots

1975 ◽  
Vol 2 (4) ◽  
pp. 659 ◽  
Author(s):  
RA Wildes ◽  
MG Pitman ◽  
N Schaefer
Keyword(s):  
Phenolic Compounds ◽  
Ion Transport ◽  
Phenylalanine Ammonia Lyase ◽  
Cl Transport ◽  
Lyase Activity ◽  
Phenylalanine Ammonia Lyase Activity

Earlier reports of inhibition of Cl- transport across the root to the xylem by p-fluorophenylalanine (p-FPA) were used to support the need for continual production of a protein used as a carrier. It is now shown that o-FPA and m-FPA are also effective as inhibitors of transport, ruling out the possibility that p-FPA was acting by inhibition of phenylalanine ammonia-lyase activity and so changing endogenous concentration of phenolic compounds.

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