Kostenyuk Igor A, Zoń Jerzy, Burns Jacqueline K
Citrus Research and Education Center, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850-2299, USA Institute of Organic Chemistry, Biochemistry and Biotechnology, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27,50-340 Wroclaw, Poland.
Physiol Plant. 2002 Sep;116(1):106-112. doi: 10.1034/j.1399-3054.2002.1160113.x.
Phenylalanine ammonia lyase (PAL) gene expression was examined in fruit and leaf abscission zones of Valencia orange for periods up to 72 h after induction of abscission with Ethrel(R) (CEPA) or the citrus mature fruit-specific abscission material 5-chloro-3-methyl-4-nitro-1H-pyrazole (CMN-P). PAL gene expression was detected in mature fruit abscission zones beginning 6 and 24 h after CEPA and CMN-P application, respectively, and continued up to 72 h. PAL gene expression was detected in leaf abscission zones 6 h after CEPA application and continued throughout the remainder of the study. In contrast, PAL gene expression was not detected in leaf abscission zones treated with CMN-P. 2-aminoindan-2-phosphonic acid (AIP), a specific inhibitor of PAL enzyme activity, decreased CMN-P-induced PAL expression in fruit abscission zones, and this was accompanied by a lack of fruit drop. PAL transcripts were low in abscission zones of immature fruit; however, the transcript was induced by CMN-P but less by CEPA application. The data suggest that downstream products of PAL activity may be important not only for wound healing and defense reactions that occur at the abscission zone fracture plane, but also for regulation of PAL gene expression during abscission.
在用乙烯利（CEPA）或柑橘成熟果实特异性脱落物质5-氯-3-甲基-4-硝基-1H-吡唑（CMN-P）诱导脱落长达72小时的时间段内，检测了伏令夏橙果实和叶片脱落区中苯丙氨酸解氨酶（PAL）基因的表达。分别在施用CEPA和CMN-P后6小时和24小时开始在成熟果实脱落区检测到PAL基因表达，并持续至72小时。在施用CEPA后6小时在叶片脱落区检测到PAL基因表达，并在研究的其余时间持续存在。相比之下，在用CMN-P处理的叶片脱落区未检测到PAL基因表达。2-氨基茚-2-膦酸（AIP），一种PAL酶活性的特异性抑制剂，降低了CMN-P诱导的果实脱落区PAL表达，并且这伴随着果实脱落的缺乏。在未成熟果实的脱落区PAL转录本较低；然而，该转录本由CMN-P诱导，但施用CEPA诱导程度较低。数据表明，PAL活性的下游产物不仅对于在脱落区断裂平面发生的伤口愈合和防御反应可能很重要，而且对于脱落过程中PAL基因表达的调节也很重要。
