Postharvest Physiology and Biochemistry Laboratory, Department of Horticulture and Landscape Architecture, Washington State University, P.O. Box 646414, Pullman, WA 99164-6414, USA.
Planta. 2010 Nov;232(6):1433-45. doi: 10.1007/s00425-010-1269-8. Epub 2010 Sep 14.
Wounding of potato (Solanum tuberosum L.) tubers induces the development of a suberized closing layer and wound periderm that resists desiccation and microbial invasion. Wound-healing ability declines with tuber age (storage period). The mechanism of loss in healing capacity with age is not known; however, upregulation of superoxide production, increased ABA biosynthesis and phenylalanine ammonia lyase (PAL) activity in response to wounding are processes critical to the development of a suberized closing layer and wound periderm. Therefore, the role of ABA in modulating the age-induced loss of wound-healing ability of tubers was examined. Non-wounded older tubers had 86% less ABA (dry matter basis) than younger tubers. PAL transcript increased in younger tubers within 24 h of wounding, but transcription was delayed by 5 days in older tubers. Wound-induced PAL activity increased more rapidly in younger than older tubers. ABA treatment increased PAL expression and activity in tissue from both ages of tubers and restored the 24 h transcription time line in older tubers. Moreover, ABA treatment of wounded older tubers enhanced their resistance to water vapor loss following a 6-day wound-healing period. Wound-induced accumulation of suberin poly(phenolic(s)) (SPP) and suberin poly(aliphatic(s)) (SPA) was measurably slower in older versus younger tubers. ABA treatment hastened SPP accumulation in older tubers to match that in younger tubers, but only enhanced SPA accumulations over the initial 4 days of healing. Age-induced loss of wound-healing ability is thus partly due to reduced ability to accumulate ABA and modulate the production of SPP through PAL in response to wounding and to dysfunction in the downstream signaling events that couple SPA biosynthesis and/or deposition to ABA. ABA treatment partly restored the healing ability of older tubers by enhancing the accumulation of SPP without restoring wound-induced superoxide forming ability to the level of younger tubers. The coupling of phenolic monomers into the poly(phenolic) domain of suberin was therefore not limited by the diminished wound-induced superoxide production of older tubers.
马铃薯（Solanum tuberosum L.）块茎受伤后会形成木栓化的封闭层和愈伤周皮，从而抵抗干燥和微生物入侵。随着块茎年龄（贮藏期）的增加，其愈合能力会下降。至于这种随年龄增长而丧失愈合能力的机制尚不清楚；然而，超氧化物产生的上调、ABA 生物合成的增加以及苯丙氨酸解氨酶（PAL）活性的增加，是形成木栓化封闭层和愈伤周皮的关键过程。因此，研究了 ABA 对调节块茎年龄诱导的愈合能力丧失的作用。与年轻块茎相比，非受伤的老块茎中 ABA（干物质基础）含量低 86%。受伤后 24 小时内，年轻块茎中 PAL 转录增加，但在老块茎中延迟了 5 天。年轻块茎中，诱导性 PAL 活性增加的速度快于老块茎。ABA 处理增加了来自年轻和年老块茎组织的 PAL 表达和活性，并恢复了老块茎的 24 小时转录时间线。此外，ABA 处理受伤的老块茎可增强其在 6 天愈合期后对水蒸气损失的抗性。与年轻块茎相比，年老块茎中木栓化多（酚类）（SPP）和木栓化多（脂肪族）（SPA）的诱导性积累速度较慢。ABA 处理加快了老块茎中 SPP 的积累，使其与年轻块茎相匹配，但仅在愈合的最初 4 天内增强了 SPA 的积累。因此，年龄诱导的愈合能力丧失部分归因于受伤时 ABA 积累能力降低，以及通过 PAL 调节 SPP 的产生，以及下游信号事件的功能障碍，这些信号事件将 SPA 生物合成和/或沉积与 ABA 偶联。ABA 处理通过增强 SPP 的积累，部分恢复了老块茎的愈合能力，而没有将受伤诱导的超氧化物形成能力恢复到年轻块茎的水平。因此，将酚单体偶联到木栓质的多（酚类）域中并不受老块茎中受伤诱导的超氧化物产生减少的限制。
