Samkumar Amos, Karppinen Katja, McGhie Tony K, Espley Richard V, Martinussen Inger, Jaakola Laura
Department of Arctic and Marine Biology, UiT The Arctic University of Norway, Tromsø, Norway.
The New Zealand Institute for Plant and Food Research Ltd., Palmerston North, New Zealand.
Front Plant Sci. 2022 Jul 22;13:969934. doi: 10.3389/fpls.2022.969934. eCollection 2022.
Light spectral quality is known to affect flavonoid biosynthesis during fruit ripening. However, the response of fruits to different light conditions, when ripening autonomously from the parent plant (detached), has been less explored. In this study, we analyzed the effect of light quality on detached and naturally ripening (attached) non-climacteric wild bilberry ( L.) fruits accumulating high amounts of anthocyanins and flavonols. Our results indicated contrasting responses for the accumulation of phenolic compounds in the berries in response to red and blue light treatments. For detached berries, supplemental blue light resulted in the highest accumulation of anthocyanins, while naturally ripening berries had elevated accumulation under supplemental red light treatment. Both red and blue supplemental light increased the expression levels of all the major structural genes of the flavonoid pathway during ripening. Notably, the key regulatory gene of anthocyanin biosynthesis, , was found to express fivefold higher under blue light treatment in the detached berries compared to the control. The red light treatment of naturally ripening berries selectively increased the delphinidin branch of anthocyanins, whereas in detached berries, blue light increased other anthocyanin classes along with delphinidins. In addition, red and far-red light had a positive influence on the accumulation of flavonols, especially quercetin and myricetin glycoside derivatives, in both ripening conditions. Our results of differential light effects on attached and detached berries, which lacks signaling from the mother plant, provide new insights in understanding the light-mediated regulatory mechanisms in non-climacteric fruit ripening.
众所周知，光的光谱质量会影响果实成熟过程中的类黄酮生物合成。然而，当果实从母株上自主成熟（脱离母株）时，其对不同光照条件的反应却鲜有研究。在本研究中，我们分析了光质对脱离母株自然成熟（附着于母株）的非跃变型野生越橘果实中酚类化合物积累的影响，这些果实积累了大量的花青素和黄酮醇。我们的结果表明，在红色和蓝光处理下，浆果中酚类化合物的积累呈现出不同的反应。对于脱离母株的浆果，补充蓝光导致花青素积累量最高，而自然成熟的浆果在补充红光处理下积累量增加。在成熟过程中，补充红光和蓝光均提高了类黄酮途径所有主要结构基因的表达水平。值得注意的是，与对照相比，在蓝光处理下，脱离母株的浆果中花青素生物合成的关键调控基因表达量高出五倍。对自然成熟的浆果进行红光处理选择性地增加了花青素的飞燕草素分支，而在脱离母株的浆果中，蓝光除了增加飞燕草素外，还增加了其他类别的花青素。此外，在两种成熟条件下，红光和远红光对黄酮醇的积累都有积极影响，尤其是槲皮素和杨梅素糖苷衍生物。我们关于附着和脱离母株的浆果对光的不同反应的结果，这些浆果缺乏来自母株的信号，为理解非跃变型果实成熟过程中光介导的调控机制提供了新的见解。
