Department of Botany and Microbiology, University College of Wales, SY23 3DA, Aberystwyth, Dyfed, UK.
Planta. 1988 Mar;173(3):397-404. doi: 10.1007/BF00401027.
Using (13)C-labelled internal standards and gas chromatography-mass spectrometry/multiple-ion monitoring the levels of xanthoxin (Xan) and 2-trans-xanthoxin (t-Xan) have been determined in stressed and non-stressed leaves of wildtype tomato (Lycopersicon esculentum Mill cv. Ailsa Craig), and the wilty mutants, notabilis (not), flacca (flc) and sitiens (sit). Levels of Xan were very low in all tissues. Ratios of t-Xan: Xan ranged from 10:1 to <500:1. In the wild-type and flc, t-Xan levels increased following stress. The results from feeding experiments using [(13)C]Xan and t-Xan demonstrated that whilst wild-type and not plants readily converted Xan into abscisic acid (ABA), flc and sit plants converted only a small amount of applied Xan into ABA. In all plants t-Xan was not converted into ABA. These results indicate that the flc and sit mutants are impaired in ABA biosynthesis because they are unable to convert Xan into ABA, whereas the not mutant is blocked at a metabolic step prior to Xan. Another possible ABA precursor, ABA-1',4'-trans-diol (ABA-t-diol) was found to occur in wild-type and mutant tissue. All four tissues could convert [(2)H]ABA-t-diol to ABA. Incubation of stressed leaves in the presence of (18)O2 provided evidence consistent with Xan and ABA originating via oxidative cleavage of a xanthophyll such as violaxanthin.
利用（13）C 标记的内标物和气相色谱-质谱/多离子监测法，测定了野生型番茄（Lycopersicon esculentum Mill cv. Ailsa Craig）、萎蔫突变体 notabilis（not）、flacca（flc）和 sitiens（sit）的胁迫和非胁迫叶片中黄氧素（Xan）和 2-反式黄氧素（t-Xan）的水平。所有组织中的 Xan 水平都非常低。t-Xan:Xan 的比值范围为 10:1 至 <500:1。在野生型和 flc 中，t-Xan 水平在胁迫后增加。使用 [(13)C]Xan 和 t-Xan 的饲喂实验结果表明，尽管野生型和 not 植物能将 Xan 迅速转化为脱落酸（ABA），但 flc 和 sit 植物仅将少量施加的 Xan 转化为 ABA。在所有植物中，t-Xan 都不能转化为 ABA。这些结果表明，flc 和 sit 突变体在 ABA 生物合成中受损，因为它们无法将 Xan 转化为 ABA，而 not 突变体则在 Xan 之前的代谢步骤受阻。还发现另一种可能的 ABA 前体，ABA-1',4'-反式二醇（ABA-t-diol）存在于野生型和突变体组织中。所有四种组织都可以将 [(2)H]ABA-t-diol 转化为 ABA。在（18）O2 的存在下孵育胁迫叶片，提供了与 Xan 和 ABA 通过叶黄素（如 violaxanthin）的氧化裂解起源一致的证据。
