[植物演化] 花青素是早期演化來對抗環境壓力的...嗎？ 20191021 PNAS

Plasmodesmata
Oct 21, 2019
2 min read

Auronidins are a previously unreported class of flavonoid pigments that challenges when anthocyanin biosynthesis evolved in plants

Helge Berland, Nick W. Albert, Anne Stavlanda, Monica Jordheim, Tony K. McGhie, Yanfei Zhou, Huaibi Zhang, Simon C. Deroles, Kathy E. Schwinn, Brian R. Jordan, Kevin M. Davies, and Øyvind M. Andersen

Abstract

Anthocyanins are key pigments of plants, providing color to flowers, fruit, and foliage and helping to counter the harmful effects of environmental stresses. It is generally assumed that anthocyanin biosynthesis arose during the evolutionary transition of plants from aquatic to land environments. Liverworts, which may be the closest living relatives to the first land plants, have been reported to produce red cell wall-bound riccionidin pigments in response to stresses such as UV-B light, drought, and nutrient deprivation, and these have been proposed to correspond to the first anthocyanidins present in early land plant ancestors. Taking advantage of the liverwort model species Marchantia polymorpha, we show that the red pigments of Marchantia are formed by a phenylpropanoid biosynthetic branch distinct from that leading to anthocyanins. They constitute a previously unreported flavonoid class, for which we propose the name “auronidin,” with similar colors as anthocyanin but different chemistry, including strong fluorescence. Auronidins might contribute to the remarkable ability of liverworts to survive in extreme environments on land, and their discovery calls into question the possible pigment status of the first land plants.

未曾被鑑定出的色素 - Auronidins，挑戰了花青素演化的傳統概念

摘要

花青素是植物重要的色素，他不只提供花、草以及葉子顏色，也幫助植物對抗環境壓力。大多數的說法都頃向花青素的生合成是在植物脫離水生成位陸生的時期演化出來的。苔類植物，也許是最靠近第一個陸生植物的物種，曾經被報導會在環境壓力（如紫外線B、乾旱以及營養缺乏）下，生合成可以附著在細胞壁上的紅色蓖麻毒素色素。而這個現象也曾經被推論可能是可以對應第一個在早期陸生植物祖先中的花青素。利用苔類植物中的模式植物地錢，我們展示了這個地錢所生成的紅色色素，是經由有別於花青素生合成路徑的，苯丙烷生合成路徑分支而生成。他們包含了一個之前未成報導過的類黃酮分類的色素，我們將它命名為"auronidin"。意義為與花青素有相似顏色但是有不同的化學特性，包含了可以釋放出很強烈的螢光。Auronidins可能為台類植物能夠在各種陸地上嚴苛的環境下生存，貢獻了不少。而發現他們這類的色素，對於第一個陸生植物所能生成的色素型態，提出了一個質問。