Heat shocks applied either before or after wounding reduce browning of lettuce leaf tissue

By Julio G. Loaiza-Velarde, M. Saltveit. 2001

103 citations recorded by the source corpus.

Wounds and injuries incurred during preparation of fresh-cut lettuce ( Lactuca sativa L.) stimulate phenolic metabolism, which leads to tissue browning. Phenylalanine ammonia-lyase (PAL, EC 4.3.1.5.) is the first committed enzyme in the phenylpropanoid pathway and regulates its overall activity. Maximum activity of wound-induced PAL occurred sooner as the storage temperature increased from 0 to 25 °C, but the maximums were lower. A heat shock at 50 °C for 90 seconds protected fresh-cut lettuce tissue against browning, helped retain greenness, and decreased subsequent production of phenolics when applied either after or before wounding. Browning was reduced when the heat shock was applied up to 36 hours after wounding, while the maximum effect occurs around 6 hours before cutting. Like the heat-shock treatment, the protein synthesis inhibitor cycloheximide reduced wound-induced PAL activity, but it did not prevent tissue browning. When cycloheximide was applied in combination with heat-shock treatments, browning did not occur. Heat shocks may control tissue browning by more than just interfering with protein synthesis.

Subfields: Biochemistry, Molecular Biology, Plant Science

View Paper: https://www.semanticscholar.org/paper/5e19f6d32102dbed400ddea67ff369e4bcb37c53

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In Biochemistry

1. M. Saltveit

In Molecular Biology

1. M. Saltveit
2. H. Nonogaki

In Plant Science

1. R. Campos
2. T. Suslow
3. H. Nonogaki
4. M. Saltveit

Citations in the corpus

• Isolation and characterization of a wound inducible phenylalanine ammonia‐lyase gene (LsPAL1) from Romaine lettuce leaves (2004, result): “These kinetics of wound-induced PAL activity are similar to those previously reported for fresh cut Iceberg and Romaine lettuce (Ke and Saltveit 1989a, Lopez-Galvez et al. 1996b, Loaiza-Velarde and Saltveit 2001).”
• Wound induced changes in phenolic metabolism and tissue browning are altered by heat shock (2000, unknown): “An 8 mM aqueous solution of CHX did reduce wound-induced PAL activity in mid-rib segments of lettuce, but it had to be applied within a few hours of wounding for maximal effect (Loaiza-Velarde and Saltveit, 2000).”