The genus Prunus contains many fruits used in the human diet, which exhibit a variety of different flavors. However, publications on the diversity of carotenoid profiles and sequestering structures in Prunus fruits are limited. In this study, carotenoids and their associated sequestering structures in mature fruits of four Prunus species, including peach [Prunus persica (L.) Batschi], nectarine [Prunus persica (L.) Batschi var. nucipersica], plum (Prunus salicina L.), and apricot (Prunus armeniaca L.) were investigated. HPLC-PAD analysis revealed that mature fruits all accumulated carotenoid esters, while their profiles and levels differed significantly. Transcription analysis suggested a positive correlation between carotenogenic genes and carotenoid profiles. Transmission electron microscopy (TEM) analysis revealed a common globular chromoplast in Prunus. However, the number and size of plastids and plastoglobules varied between species. Noticeably, the white-flesh Ruiguang 19 nectarine contained plastids similar to chromoplasts, except with smaller plastoglobules. In addition, it seemed like a lipid-dissolved β-carotene form in apricot fruits, which is more effectively absorbed by humans than the solid-crystalline form. Moreover, the lowest transcriptions of plastid-related genes were found in Friar plum, and GLK2 and OR genes were presumed to be associated with the largest chromoplasts observed in apricot. We investigated the correlations among carotenoid accumulation, plastid characteristics and gene transcription and found that chromoplast development is likely more important in determining carotenoid accumulation than carotenogenic transcription in Prunus fruits. This study presents the first report on the diversity of carotenoid sequestering structures in Prunus fruits and suggests some crucial genes associated with diversity.

中文翻译：

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四种李属成熟果实中类胡萝卜素组成，螯合结构和基因转录的多样性。

李属包含人类饮食中使用的许多水果，其表现出多种不同的风味。但是，有关李子果实中类胡萝卜素分布和螯合结构多样性的出版物有限。在这项研究中，类胡萝卜素及其相关的螯合结构存在于四种李属的成熟果实中，包括桃[Prunus persica（L.）Batschi]，油桃[Prunus persica（L.）Batschi var。）。nucipersica]，李子（Prunus salicina L.）和杏子（Prunus armeniaca L.）被调查。HPLC-PAD分析表明，成熟果实均积聚了类胡萝卜素酯，而它们的特征和水平却有显着差异。转录分析表明类胡萝卜素基因与类胡萝卜素谱之间呈正相关。透射电子显微镜（TEM）分析显示在李属中常见的球状色细胞。但是，质体和质球的数量和大小在物种之间有所不同。值得注意的是，白肉瑞光19油桃含有与色体相似的质体，但质体球较小。另外，在杏果实中似乎是脂质溶解的β-胡萝卜素形式，与固态晶体形式相比，人类更有效地吸收了β-胡萝卜素。此外，质体相关基因的转录最低见于Friar李子中，并且GLK2和OR基因被认为与杏中观察到的最大的质体有关。我们调查了类胡萝卜素积累之间的相关性，质体特征和基因转录，发现在确定类胡萝卜素积累方面，色质的发展可能比李子果实中的类胡萝卜素转录更为重要。这项研究提出了关于李子果实中类胡萝卜素螯合结构多样性的第一份报告，并提出了一些与多样性相关的关键基因。