柑橘油胞凹陷病组织结构特征的研究

Histological Characterization of Rind Oil Spotting Disease in Citrus

以4个柑橘品种奉节脐橙(Citrus sinensis Osbeck cv.Fengjie navel orange)、纽荷尔脐橙(C.sinensis Osbeck cv.Newhall navel orange)、红橘(C.reticulata Blanco cv.Red tangerine)和太田椪柑(C.reticulata Blanco cv.Ota ponkan)为试验材料,采用石蜡切片技术,对果皮油胞凹陷病从轻到重的发展过程进行了研究,了解果皮油胞凹陷病各阶段的果皮组织结构特征。结果表明,果皮油胞凹陷病始于黄皮层内4～7层细胞带,受害部位细胞变扁,原生质体收缩位于细胞中央,但表皮细胞仍排列整齐、紧密;受害部位都始于两油胞之间,受害细胞层有多种形式,有的与果皮表面平行,有的为块状,沿着黄皮层延伸,在正常细胞层之间形成明显的受害区;中期细胞变得狭长,原生质体在细胞壁周围缩成薄薄的一层;后期病害到达表皮细胞,造成胞质降解,但油胞仍然完好;末期油胞上部细胞破裂,部分油胞受到伤害,向内凹陷。

In the present paper, the dynamic process of rind oil spotting disease in citrus from light to severe was investigated on four varieties, viz.Citrus sinensis Osbeck cv.Fengjie navel orange, C.sinensis Osbeck cv.Newhall navel orange, C.reticulata Blanco cv.Red tangerine and C.reticulata Blanco cv.Ota ponkan through paraffin section in order to find out histological characteristics at different stages of the rind oil spotting disease.Results showed that rind oil spotting disease initiated from the forth to seventh cell layers of the flavedo.The affected cells became flattened and the protoplast retracted and located in the center of cell.However, the epidermal cells still arranged regularly and densely.Affected cell layers initiated between the two oil lands in different manners.They were massive or in parallel with peel, extended along with the flavedo, and formed obvious injured region between normal cells.Affected cells tended to be narrow and long at the middle stage.The protoplast of such cells were restricted to a thin peripheral layer around the cell walls.The cytoplasm of affected cells degraded and reached the epidermis across the flavedo at the late stage.Meanwhile, the oil glands remained intact.Apical cells of oil glands broke, and some of them got impairment and depressed towards the apical region.