柑橘春梢叶片Ⅰ–型气孔保卫细胞程序性死亡的研究

 柑橘叶片Ⅰ–型气孔器是在叶片发育早期形成的具有6 ~ 8 个副卫细胞和较大保卫细胞的一 类气孔器。以‘稻叶温州蜜柑’（Citrus unshiu）、‘春见’C. reticulata ×（C. reticulata × C.sinensis）]、‘卡 拉卡拉’红肉脐橙（C. sinensis）、‘HB 柚’（C. grandis）和‘玫瑰橙’（C. sinensis）等5 个柑橘品种不同 发育阶段的春梢叶片为材料，采用本实验室改良的临时装片法和常规石蜡切片法，研究其发育过程中的 Ⅰ–型气孔保卫细胞程序性死亡及其对表皮结构变化的影响。结果表明：叶片发育过程中，气孔密度呈单 峰变化，并在2/3 伸展叶龄时达到峰值。春梢叶片发育后期，‘稻叶温州蜜柑’、‘春见’和‘HB 柚’的 Ⅰ–型气孔保卫细胞退化率较低。‘玫瑰橙’和‘卡拉卡拉’红肉脐橙的Ⅰ–型气孔保卫细胞几乎全部退化。 DAPI 染色显示发生退化的保卫细胞核内染色质凝集并产生核固缩，进一步形成凋亡小体，初步表明细胞 发生程序性死亡。发生程序性死亡的保卫细胞内原生质凝聚，细胞逐步萎缩，气孔逐渐变小并最终关闭 或消失。Ⅰ–型保卫细胞程序性死亡使‘卡拉卡拉’红肉脐橙和‘玫瑰橙’成熟叶片中气孔器内开口分布 与‘稻叶温州蜜柑’的趋于一致。

Studies on Programmed Cell Death of Type-Ⅰ Stomatal Guard Cells on Spring Leaves of Citrus

The Type-Ⅰstomatal complex of citrus leaf forms at early developmental stage and consists of 6–8 subsidiary cells and two big stomatal guard cells. In this report，programmed cell death （PCD）of Type-Ⅰstomatal guard cells and its role in modification of surface structure during leaf expansion were studied with modified temporary slides preparation method and conventional paraffin section technique，which were conducted on spring leaves of different developmental stages in five citruscultivars，including‘Inaba Wase’（Citrus unshiu），‘Harumi’tangorC. reticulata ×（C. reticulata × C. sinensis）]，‘Cara Cara’navel orange（C. sinensis），‘HB’pummelo（C. grandis）and‘Meigui Cheng’ （C. sinensis）. Results showed that stomatal density of lower epidermis presented a unimodal distribution during leaf development，with a peak at two-thirds expanded stage. Degeneration rates of Type-Ⅰstomatal apparatus were low in spring leaves of‘Inaba Wase’，‘Harumi’tangor and‘HB’pummelo at late developmental stage. However，Degeneration ranges of Type-Ⅰstomatal apparatus were very high in spring leaves of ‘Cara Cara’navel orange and‘Meigui Cheng’，with almost all Type-Ⅰstomatal guard cells degenerated at matured stage in both cultivars. With DAPI staining，nuclear pyknosis with chromatin condensation，followed by formation of apoptotic bodies，was generally observed in degenerated Type-Ⅰ stomatal guard cells，suggesting that cells underwent PCD. PCD of Type-Ⅰstomatal guard cells resulted in closure or disappear of Type-Ⅰstomata through shrinkage of the guard cells. And as Type-Ⅰstomatal guard cells underwent PCD，distribution of size of stomatal inner pores in‘Cara Cara’navel orange and ‘Meigui Cheng’both became similar to that of‘Inaba Wase’.