Color mutations on citrus skin are a common occurrence and can serve as indicators of fruit maturation in citrus. In this study, a new early maturing navel orange cultivar, Lei Zao 1 Hao (MT), was identified as a spontaneous bud mutation from the Leibo Navel Orange (WT). To assess the differences between these two cultivars, the coloration of the fruit, the sugar content, and the levels of acid were examined throughout the ripening process. The study findings revealed that over the course of the fruit's development, the external peel color progressively turned orange. MT exacerbated the decline in H° while increasing L*, a*, and b*, and the chlorophyll level of the MT peel was continuously lower than that of WT, which coincided with a decrease in chlorophylls a and b. Compared to WT, MT had higher expression levels of genes linked to chlorophyll degradation, including CitCLH, CitNYC1, CitPPH, CitPAO, CitCAB1, and CitCAB2. The elevated expression of these genes in MT may potentially be associated with the initial color transformation process. In addition, the MT accelerated the accumulation of TSS and total sugar, especially before the 189 DAF of ripening. In short, ‘Lei Zao 1 Hao’ is a new option of navel orange available with extremely early maturity and a higher sugar content.

中文翻译：

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脐橙自发芽突变中与叶绿素降解和颜色转变相关的基因表达


柑橘果皮的颜色突变很常见，可以作为柑橘果实成熟的指标。在本研究中，一个早熟脐橙新品种雷早1号（MT）被鉴定为雷波脐橙（WT）的自发芽突变。为了评估这两个品种之间的差异，在整个成熟过程中检查了果实的颜色、糖含量和酸水平。研究结果显示，在水果的发育过程中，外部果皮的颜色逐渐变成橙色。 MT加剧了H°的下降，同时增加了L*、a*和b*，并且MT果皮的叶绿素水平持续低于WT，这与叶绿素a和b的下降相一致。与 WT 相比，MT 与叶绿素降解相关的基因表达水平较高，包括 CitCLH、CitNYC1、CitPPH、CitPAO、CitCAB1 和 CitCAB2。这些基因在 MT 中的表达升高可能与初始颜色转变过程有关。此外，MT还加速了TSS和总糖的积累，尤其是在成熟189 DAF之前。总之，‘雷早1号’是脐橙的新品种，成熟极早，含糖量较高。