We report here a detailed analysis of the proteome adjustments that accompany chromoplast differentiation from chloroplasts during bell pepper (Capsicum annuum) fruit ripening. While the two photosystems are disassembled and their constituents degraded, the cytochrome b₆f complex, the ATPase complex, and Calvin cycle enzymes are maintained at high levels up to fully mature chromoplasts. This is also true for ferredoxin (Fd) and Fd‐dependent NADP reductase, suggesting that ferredoxin retains a central role in the chromoplasts’ redox metabolism. There is a significant increase in the amount of enzymes of the typical metabolism of heterotrophic plastids, such as the oxidative pentose phosphate pathway (OPPP) and amino acid and fatty acid biosynthesis. Enzymes of chlorophyll catabolism and carotenoid biosynthesis increase in abundance, supporting the pigment reorganization that goes together with chromoplast differentiation. The majority of plastid encoded proteins decline but constituents of the plastid ribosome and AccD increase in abundance. Furthermore, the amount of plastid terminal oxidase (PTOX) remains unchanged despite a significant increase in phytoene desaturase (PDS) levels, suggesting that the electrons from phytoene desaturation are consumed by another oxidase. This may be a particularity of non‐climacteric fruits such as bell pepper that lack a respiratory burst at the onset of fruit ripening.

中文翻译：

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甜椒果实的叶绿体分化

我们在这里报告了在青椒（Capsicum annuum）果实成熟期间伴随叶绿体从叶绿体分化的蛋白质组调节的详细分析。当两个光系统分解并且它们的成分降解时，细胞色素b ₆f复合物，ATPase复合物和Calvin循环酶维持在高水平直至完全成熟的染色体。铁氧还蛋白（Fd）和依赖Fd的NADP还原酶也是如此，这表明铁氧还蛋白在色质体的氧化还原代谢中保持着核心作用。异养质体的典型代谢酶的数量显着增加，例如氧化戊糖磷酸途径（OPPP）以及氨基酸和脂肪酸的生物合成。叶绿素分解代谢和类胡萝卜素生物合成的酶大量增加，支持色素重组以及色细胞的分化。质体编码的蛋白质大多数下降，但质体核糖体和AccD的组成丰度增加。此外，尽管八氢番茄红素去饱和酶（PDS）含量显着增加，但质体末端氧化酶（PTOX）的数量保持不变，这表明来自八氢番茄红素去饱和的电子被另一种氧化酶消耗。这可能是非更年期的水果（例如灯笼椒）的一种特殊情况，这种水果在成熟后就不会出现呼吸爆发。