生物结皮中优势蓝藻胞外多糖对几种荒漠草本植物种子萌发的影响

蓝藻是荒漠生物结皮的重要组成。选取生物结皮中的优势蓝藻(具鞘微鞘藻(Microcoleus vaginatus)、眼点伪枝藻(Scytonema ocellatum)、地木耳(Nostoc commune)),通过提取其胞外多糖,研究了不同蓝藻胞外多糖对荒漠植物种子萌发的影响。结果表明:具鞘微鞘藻、眼点伪枝藻的胞外多糖对粗枝猪毛菜(Salsola subcrassa)的种子萌发表现为低浓度抑制、高浓度促进作用,地木耳的胞外多糖仅在高浓度时对粗枝猪毛菜的种子萌发具有促进作用(p<0.05);具鞘微鞘藻胞外多糖对小花荆芥(Nepeta micrantha)种子萌发无明显的影响作用,但眼点伪枝藻和地木耳对小花荆芥种子萌发具有抑制作用。具鞘微鞘藻、眼点伪枝藻和地木耳胞外多糖对琉苞菊(Hyalea pulchella)种子萌发具有明显的抑制作用。藻种胞外多糖组分的差异和不同种子的生物学特性差异可能是造成不同藻种胞外多糖对种子萌发产生不同影响的主要原因。

Influence of Exopolysaccharides from Dominant Cyanobacteria in Microbiotic Crusts on Seed Germination of Several Desert Herbaceous Plants

Desert cyanobacteria are important component in microbiotic crusts. Several dominant cyanobacteria species, including Microcoleus vaginatus, Scytonema ocellatum, and Nostoc commune were selected to extract ex-polysaccharides (EPS) and their effects on seed germination of desert plants were investigated. The results indicated that low concentration EPS of M. vaginatus, and S. ocellatum inhabited seed germination of Salsola subcrassa, whereas high concentration EPS promoted seed germination of S. subcrassa. EPS of N. commune showed significant effects on seed germination of S. subcrassa with high concentration (p<0.05). EPS of M. vaginatus showed no obvious effects on seed germination of Nepeta micrantha, however, EPS of S. ocellatum, and N. commune had negative effects on seed germination of N. micrantha. EPS of M. vaginatus, S. ocellatum, and N. commune inhabited seed germination of Hyalea pulchella. EPS of the different cyanobacteria had different effect on seed germination, which could be explained by the differences of composition content of EPS and biological character of different seed.