Anatomical and histochemical studies of the somatic embryogenesis of Syagrus oleracea from immature inflorescences

Abstract Anatomical and histochemical studies were carried out during the somatic embryogenesis of Syagrus oleracea (Mart.) Becc. from immature inflorescences. Immature rachillas were inoculated on Murashige and Skoog medium with 4.52 μM 4-amino-3,5,6-trichloropicolinic acid (Picloram) and 2,4-diclorophenoxyacetic acid. Auxin concentrations were gradually reduced for the formation of somatic embryos, while for plantlet regeneration, embryos were inoculated on a medium without growth regulator. After 270 days, two types of embryogenic calluses were observed in explants under the effect of Picloram: nodular, with a smooth surface and those without definite shape, with an irregular surface, both presenting a meristematic zone with polysaccharide content. Callus progression to the differentiation stage allowed for the conversion of somatic embryos, some with a well-defined protoderm and procambial bundles. The histochemical analysis of the somatic embryos did not identify the presence of polysaccharide and protein reserves, which emphasizes the necessity for optimization of the maturation conditions.

摘要：本研究针对以食用散尾葵（Syagrus oleracea (Mart.) Becc.）未成熟花序为外植体的体细胞胚胎发生过程，开展了解剖学与组织化学分析。将未成熟小穗轴接种于添加了4.52 μM 4-氨基-3,5,6-三氯吡啶羧酸（毒莠定，Picloram）与2,4-二氯苯氧乙酸的MS培养基（Murashige and Skoog medium）中。为诱导体细胞胚胎形成，研究中逐步降低培养基中生长素的浓度；而在幼苗再生阶段，将体细胞胚接种于不含生长调节剂的培养基。培养270天后，在毒莠定处理的外植体中观察到两类胚性愈伤组织：一类为表面光滑的结节状愈伤组织，另一类为表面不规则、无明确形态的愈伤组织，两类均含有具多糖成分的分生组织区。愈伤组织进入分化阶段后，可发育为体细胞胚，其中部分体细胞胚具有清晰的原表皮层与原维管束束。对体细胞胚的组织化学分析未检测到多糖与蛋白质储备，这凸显了优化体细胞胚成熟培养条件的必要性。