| H2S and SO2 can act gaseous signaling molecule after nitric oxide (NO) and carbon monoxide (CO) in animals. Recently, it has been documented that H2S are involved in regulating many progress of physiological and pathological in plant (such as root organogenesis, seed germination, stomatal movement, the ripening senescence of fruits, photosynthesis, the response of stress and the senescence and death of plant). In our paper, we studied the effect of H2S donor NaHS on the programmed cell death in barley aleurone layers. Here we investigated the effects of H2S on programmed cell death (PCD) in barley (Hordeum vulgare L.) aleurone layers. The 0.25 mM NaHS markely delayed PCD in aleurone layers isolated from imbibed embryoless barley grain. H2S effectively reduced the accumulation of superoxide anion (·O2-), hydrogen peroxide (H2O2) and malondialdehyde (MDA), promoted superoxide dismutase (SOD), guaiacol peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) activity, and decreased those of lipoxygenase (LOX) in isolated aleurone layers. RT-PCR showed that H2S treatment of aleurone tissue led to enhanced transcript levels of the antioxidant genes HvSOD1, HvAPX, HvCATl, HvCAT2and cystain gene HvICY, repressed transcript levels of HvLOX (lipoxygenase gene), and of two cysteine protease genesHvEPA and HvCP3-31. H2S treatment of 20 μ gibberellic acid (GA)-treated aleurone layers also delayed the PCD process, reduced the content of superoxide anion (·02-), and increased POD activity while decreased LOX activity. These results indicated that H2S delayed the PCD of barley aleurone layers by acting as an antioxidant role.Gibberellin (GA), as a plant hormone, can accelerate the PCD in aleurne layers and promote the embryo growth. H2S inhibited the GA-induced PCD of barley aleurone layers, reduced the content of ·02-, promote the activity of POD, decrease LOX activity. These results show that H2S can act an antioxidant to delay the PCD of barley aleurone layers, and the characteristic of H2S may be a universal event.SO2 acts a gaseous signaling molecule. Plants absorb inorganic SO42- and change it to SO32-.SO32- is converted to H2S and then H2S produces cysteine. Similar to the study of NaHS, It has been shown that SO2 can significantly increase the H2S content in germinal wheat seeds under the drought or aluminum stress, indicating that SO2 may mediate the response against the stress condition and the process of seed germination.Our study of fluorescence probe showed that SO2 increased the endogenous H2S level of barley aleurone layers compared to that of control. At the same time, the result of fluorospectro photometer also detected a higher level of H2S than control aleurone layers. In our study, SO2 donor effectively alleviated PCD process in barley aleurone layers in a dose-dependent manner with optimal concentration being 0.05 mM. SO2 donor treatment significantly reduced the accumulation of hydrogen peroxide (H2O2), superoxide anion (·O2) and malondialdehyde (MDA) in aleurone layers. Besides, antioxidant enzymes such as SOD, CAT, APX, glutathione reductase (GR),and hydroperoxide lyase (HPL) were activated by SO2 donor treatment. Gene expression analysis revealed that 0.05 mM SO2 donor treatment dramatically enhanced the expression of HvSOD1, HvAPX, HvCAT2 and cystain gene HvICY, decreased the expression of HvLOX and cysteine protease geneHvEPA. NO is proved to be an important gaseous signaling molecule.It is shown that NO can enhance the seed germination and delay the PCD of GA-induced PCD of aleurone layers. A high level of NO was also detected in SO2-treated layers indicating that NO also participated in the progress of SO2 acting an antioxidant role to delay PCD of barley aleurone layers.There are a lot of P-amylase in the endosperm of barley grain. The β-amylase hydrolyzes the starch endosperm to nourish the gernimation. The study to p-amylase showed that H2Smarkedly promoted the activity of total amylase, but did’t stimulate the synthesis and secretion of α-amylaseduring the early germination of barley seeds. H2S treatment lightly increased the activity of the free form, dramatically enhanced bond form β-amylase of barley seeds. And treatment with different concentration of H2Sshowed that the enhancement of β-amylase was dose-dependent which had a gradual increase to a maximum at 0.8 mM.Bond β-amylase was most accelerated by H2Sat about 9 hours. However, H2Sdid’t activate the monomer β-amylase activity. Barley aleurone layers secrets a-amylase during the late stage of germination. The storge starch endosperm is hydrolyzed to low molecular nutrition to nurtrish embryo germination. The study to a-amylase in barley aleurone layers showed that a-amylase secretion in barley aleurone layers was significantly enhanced by H2S. The a-amylase secretionwasenhanced with the increase of H2S concentration in a range of 0.05-2.0 mM H2S donor.Similarly, the SO2 donor also increased of β-amylase activity during the early germination of barley seeds; slightly promoted free P-amylas; significantly and especially enhanced bond β-amylas at 0.8 mM when treated with 9 hours; had no effect at the monomer β-amylase activity; dramatically promoted the a-amylase secretion of barley aleurone layers in a dose-dependent manner with the ideal concentration being 1.0 mM.In a word, both H2S and SO2 can acts an antioxidant role and delayes the PCD of barley aleurone layers in late stage of barley seeds gemimation;promoted theβ-amylase activity during early stage of gernimation; enhanced the a-amylase secretion in middle period germimation. |
PDF Full Text Request