隨著香蕉從成熟變?yōu)楦癄€,，亮黃色的果皮出現(xiàn)棕色和黑色的斑點(diǎn)，它們生長迅速,，而且最終包裹了整個(gè)香蕉,。這種斑點(diǎn)——它是表明香蕉將很快不可食用的警告標(biāo)記——代表了死亡的組織。
Bernhard Kraeutler及其同事報(bào)告說,，香蕉在紫外線照射下發(fā)出藍(lán)光,，而在死亡斑點(diǎn)周圍顯示出亮藍(lán)色的光暈,。這組作者指出，這種熒光藍(lán)色是由葉綠素分解造成的,。葉綠素是植物葉子的顏料,，也是光合作用的關(guān)鍵。這組作者證明了當(dāng)葉綠素在香蕉中分解的時(shí)候,，這種化合物產(chǎn)生了熒光分子,，讓香蕉在紫外線下發(fā)出藍(lán)光。這組作者證明了這些殘留的熒光分子在變老的組織中積累,，而且讓它出現(xiàn)了藍(lán)色冷光,，他們還提出，這種色彩化可能成為一種發(fā)現(xiàn)凋亡和正在死亡的植物細(xì)胞的工具,。這組作者說,，一些吃水果的動(dòng)物可能適應(yīng)了這種藍(lán)色熒光光暈，把它作為食物成熟的標(biāo)記,。（生物谷Bioon.com）
生物谷推薦原始出處：
PNAS September 8, 2009, doi: 10.1073/pnas.0908060106
Fluorescent chlorophyll catabolites in bananas light up blue halos of cell death
Simone Mosera,b, Thomas Müllera,b, Andreas Holzingerc, Cornelius Lützc, Steffen Jockuschd, Nicholas J. Turrod,1 and Bernhard Kr?utlera,b,1
aInstitute of Organic Chemistry and
bCentre for Molecular Biosciences, University of Innsbruck, A-6020 Innsbruck, Austria;
cInstitute of Botany, University of Innsbruck, A-6020 Innsbruck, Austria; and
dDepartment of Chemistry, Columbia University, New York, NY 10027
Breakdown of chlorophyll is a major contributor to the diagnostic color changes in fall leaves, and in ripening apples and pears, where it commonly provides colorless, nonfluorescent tetrapyrroles. In contrast, in ripening bananas (Musa acuminata) chlorophylls fade to give unique fluorescent catabolites (FCCs), causing yellow bananas to glow blue, when observed under UV light. Here, we demonstrate the capacity of the blue fluorescent chlorophyll catabolites to signal symptoms of programmed cell death in a plant. We report on studies of bright blue luminescent rings on the peel of very ripe bananas, which arise as halos around necrotic areas in ‘senescence associated' dark spots. These dark spots appear naturally on the peel of ripe bananas and occur in the vicinity of stomata. Wavelength, space, and time resolved fluorescence measurements allowed the luminescent areas to be monitored on whole bananas. Our studies revealed an accumulation of FCCs in luminescent rings, within senescing cells undergoing the transition to dead tissue, as was observable by morphological textural cellular changes. FCCs typically are short lived intermediates of chlorophyll breakdown. In some plants, FCCs are uniquely persistent, as is seen in bananas, and can thus be used as luminescent in vivo markers in tissue undergoing senescence. While FCCs still remain to be tested for their own hypothetical physiological role in plants, they may help fill the demand for specific endogenous molecular reporters in noninvasive assays of plant senescence. Thus, they allow for in vivo studies, which provide insights into critical stages preceding cell death.
