两种外源化学物影响PEG胁迫对水稻根系的伤害

研究过氧化氢内源消除剂和交替氧化酶专一性抑制剂影响渗透胁迫对水稻根系的伤害。结果表明:PEG 6000胁迫抑制了水稻幼根的生长,降低了相对含水量、增加了H₂O₂含量,并导致细胞死亡。用5 mmol·L^-1二甲基硫脲(过氧化氢内源消除剂,dimethylthiourea,DMTU)预处理水稻幼根能明显降低PEG胁迫下水稻幼根过氧化氢的含量,缓解细胞死亡和相对含水量的降低,但对水稻根的生长影响较小。在PEG胁迫下,用1 mmol·L^-1水杨基氧肟酸(交替氧化酶专一性抑制剂,salicylhydroxamic acid,SHAM)预处理水稻幼根能显著降低水稻幼根的生长和相对含水量,并增加水稻幼根的过氧化氢含量和细胞的死亡程度。这说明DMTU能缓解PEG胁迫对水稻根系伤害,而SHAM加剧了PEG胁迫对水稻根系伤害。

Effects of two exogenous chemical substances on the osmotic stress-induced damages to rice roots

The effects of the scavenger of H₂O₂ and specific inhibitor of alternative oxidase on the osmotic stress-induced damages to rice roots were studied. The results showed that PEG 6000 inhibited the growth of rice roots,decreased the relative water content,inceased the H₂O₂ content,and caused cell death. Pretreatment with 5 mmol·L^-1 dimethylthiourea(DMTU),a scavenger of H₂O₂,significantly decreased the increment in the H₂O₂ content and partially alleviated the root cell death and the decrease of the relative water content induced by PEG 6000. However,DMTU had little effect on the growth of rice roots exposed to PEG stress. Under the PEG-induced stress,pretreatment with 1 mmol·L^-1 salicylhydroxamic acid(SHAM),a specific inhibitor of alternative oxidase,significantly decreased the growth of rice roots and relative water content,but increased the levels of H₂O₂ content and cell death. The results suggested that DMTU could alleviate the osmotic stress-induced damages to rice roots,whereas SHAM could intensify those damages.