虉草适应湿地环境的解剖结构和组织化学特征研究

Anatomy and histochemistry features of Phalaris arundinacea adapted to wetland environments

为研究虉草适应湿地环境的结构特征,探讨了该植物不定根、根状茎、直立茎和叶的解剖结构、组织化学及其质外体屏障结构的通透性生理。利用光学显微镜和荧光显微镜对虉草进行了解剖学和组织化学研究。结果表明:1)虉草不定根解剖结构由外而内分别为表皮、外皮层、皮层、内皮层、中央为木质部和厚壁组织;茎结构由外而内分别为角质层、表皮、周缘厚壁机械组织层、皮层、具维管束厚壁机械组织层和髓腔。2)不定根具栓质化和木质化内皮层和外皮层组成的屏障结构;茎具角质层、栓质化和木质化周缘厚壁组织层和厚壁组织层;根状茎具内、外皮层,直立茎仅具外皮层。3)虉草体内气腔包括不定根中通气组织,茎皮层气腔和髓腔,及叶鞘气腔。虉草的机械组织结构、屏障结构和气腔是其适应湿地环境的重要结构特征,该研究为今后选择湿地生态修复的植物物种提供依据。

Reed canarygrass(Phalaris arundinacea)is a perennial herb adapted to wetland environments.The current work explores the anatomy and histochemistry of the adventitious roots,stems(rhizomes and culms),leaves and the permeability of apoplastic barriers of reed canarygrass.The anatomy and histochemistry of P.arundinacea were studied using an optical microscope and fluorescent microscope.Sections were stained with Sudan red 7B(SR7B)for suberin lamellae,with berberine hemisulfate-aniline blue(BAB)for casparian bands and lignified cell walls,phloroglucinol-HCl(Pg)for lignin and berberine hemisulfate-potassium thiocyanate for apoplastic permeability.Concentrated sulfuric acid digestion(AD)was used to detect the wavy casparian bands in young rhizomes and culms.The adventitious roots had a primary structure comprising epidermis,exodermis,cortex,endodermis and vascular cylinder with sclerenchyma;the stems comprised a cuticle,epidermis,peripheral mechanical ring,exodermis,cortex,endodermis,sclerenchyma ring with vascular bundles and pith cavity.The apoplastic barriers consisted of adventitious roots with a suberized and lignified endodermis and an exodermis,stems possessed a cuticle,suberized and lignified peripheral mechanical ring and a sclerenchyma ring,and rhizomes with endodermis and exodermis,culms only with exodermis.The air space consisted of pith cavities and cortical cavities in the stems,and aerenchyma in roots and leaves.This research revealed that reed canarygrass has the key constitutive,structural and histochemical features in roots and stems that allow it to grow in wetlands,be protected against oxygen leakage from aerenchyma,with-stand seasonal flooding and consequently,widely distributed.The anatomical structures and histochemical features of these perennial,rhizomatous grasses enhance our awareness of the biology of this species in native Asian and North American invaded habitats to select species for the restoration of degraded wetland of the Jianghan Floodplain and Three Gorges Reservoir Region of the Yangtze River.