低氧胁迫下24-表油菜素内酯对黄瓜幼苗叶片光合特性及多胺含量的影响

Effects of exogenous 24-epibrassinolide on the leaf photosynthetic characteristics and polyamines content of cucumber seedlings under hypoxia stress

采用1/2Hoagland营养液培养,研究了低氧胁迫下24-表油菜素内酯(EBR)对黄瓜幼苗叶片光合特性及多胺含量的影响.结果表明:低氧胁迫下黄瓜幼苗的净光合速率(Pn)、气孔导度(gs)、蒸腾速率(Tr)、胞间CO2浓度(Ci)显著下降,而叶绿素含量显著提高,幼苗生长受抑;低氧胁迫显著提高了黄瓜幼苗叶片的腐胺(Put)、亚精胺(Spd)、精胺(Spm)、多胺(PAs)含量和Put/PAs,但降低了(Spd+Spm)/Put.低氧胁迫下,外源EBR不仅显著提高了黄瓜幼苗的Pn、gs、Tr及叶绿素含量,也显著提高了黄瓜幼苗叶片的游离态Spm、结合态Spd、Spm及束缚态Put、Spd、Spm含量,促进了PAs的进一步积累,且降低了Put/PAs,提高了(Spd+Spm)/Put.可见,外源EBR调节了黄瓜幼苗内源多胺含量及形态的变化,维持了较高的光合性能,促进了叶面积和干物质量的显著增加,缓解了低氧胁迫对黄瓜幼苗的伤害.

A water culture experiment with 1/2 Hoagland solution was carried out to study the effects of exogenous 24-epibrassinolide （EBR） on the leaf photosynthetic characteristics and polyamines （PAs） content of cucumber seedlings under hypoxia stress. Under the stress, the leaf net photosynthetic rate （Pn）, stomatal conductance （gs）, transpiration rate （Tr）, and intercellular CO2 concentration （Ci） decreased significantly while the chlorophyll content was in adverse, and the seedling growth was inhibited. Hypoxia stress increased the leaf Put, Spd, and Spm contents and Put/PAs ratio significantly, but decreased the （Spd＋Spm）/Put. Under the stress, exogenous EBR not only increased the Pn, gs, Tr, and chlorophyll content significantly, but also increased the contents of free Spm, conjugated Spd and Spm, and bound Put, Spd, and Spm significantly. Meanwhile, the PAs content and （Spd＋Spm）/Put ratio were further increased, and the Put/PAs ratio decreased. The results suggested that exogenous EBR could regulate the formation and form transformation of PAs in cucumber seedling leaf, made the leaf keep a higher photosynthetic performance, promote the increase of leaf area and dry mass, and alleviate the damage of hypoxia stress.