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Abstract：
In autumn and spring, citrus leaves with a Ponkan (Citrus reticulata Blanco cv. Ponkan) genetic background (Harumi, Daya, etc.) are prone to abnormal physiological chlorosis. The effects of different degrees of chlorosis (normal, mild, moderate and severe) on photosynthesis and the chlorophyll metabolism of leaves of Citrus cultivar (Harumi) were studied via field experiment. Compared with severe chlorotic leaves, the results showed that chlorosis could break leaf metabolism balance, including reduced chlorophyll content, photosynthetic parameters, antioxidant enzyme activity and enzyme activity related to chlorophyll synthesis, increased catalase and decreased enzyme activity. In addition, the content of chlorophyll synthesis precursors showed an overall downward trend expected for uroporphyrinogen III. Furthermore, the relative expression of genes for chlorophyll synthesis (HEMA1, HEME2, HEMG1 and CHLH) was down-regulated to some extent and chlorophyll degradation (CAO, CLH, PPH, PAO and SGR) showed the opposite trend with increased chlorosis. Changes in degradation were more significant. In general, the chlorosis of Harumi leaves might be related to the blocked transformation of uroporphyrinogen III (Urogen III) to coproporphyrinogen III (Coprogen III), the weakening of antioxidant enzyme system activity, the weakening of chlorophyll synthesis and the enhancement in degradation.
摘要：
在秋天和春天，柑橘叶子带有Ponkan（柑橘类植物Blancocv。Ponkan）遗传背景（Harumi，Daya,等。)容易发生异常的生理萎黄。不同程度的萎黄病的影响（正常，温和,中度和重度）通过田间试验研究了柑橘品种（Harumi）叶片的光合作用和叶绿素代谢。与重度褪绿相比，结果表明，黄化病可以打破叶片代谢平衡，包括叶绿素含量降低，光合参数，抗氧化酶活性和与叶绿素合成相关的酶活性，过氧化氢酶增加，酶活性降低。此外,对于尿卟啉原III，叶绿素合成前体的含量显示出总体下降趋势。此外，叶绿素合成基因(HEMA1，HEME2，HEMG1和CHLH)的相对表达在一定程度上下调，叶绿素降解(CAO，CLH,PPH,PAO和SGR）表现出相反的趋势，萎黄病增加。降解的变化更显著。总的来说,Harumi叶片的萎黄病可能与尿卟啉原III（UrogenIII）向猪卟啉原III（CoprogenIII）的转化受阻有关，抗氧化酶系统活性的减弱，叶绿素合成的减弱和降解的增强。
