Hoang Hai Ha, Sechet Julien, Bailly Christophe, Leymarie Juliette, Corbineau Françoise
UR5-EAC 7180 CNRS, PCMP, UPMC Univ Paris 06, Boîte courrier 156, Bat C, 4 place Jussieu, F-75005, Paris, France.
Plant Cell Environ. 2014 Jun;37(6):1393-403. doi: 10.1111/pce.12239. Epub 2013 Dec 12.
Germination of primary dormant barley grains is promoted by darkness and temperatures below 20 °C, but is strongly inhibited by blue light. Exposure under blue light at 10 °C for periods longer than five days, results in a progressive inability to germinate in the dark, considered as secondary dormancy. We demonstrate that the inhibitory effect of blue light is reinforced in hypoxia. The inhibitory effect of blue light is associated with an increase in embryo abscisic acid (ABA) content (by 3.5- to 3.8-fold) and embryo sensitivity to both ABA and hypoxia. Analysis of expression of ABA metabolism genes shows that increase in ABA mainly results in a strong increase in HvNCED1 and HvNCED2 expression, and a slight decrease in HvABA8'OH-1. Among the gibberellins (GA) metabolism genes examined, blue light decreases the expression of HvGA3ox2, involved in GA synthesis, increases that of GA2ox3 and GA2ox5, involved in GA catabolism, and reduces the GA signalling evaluated by the HvExpA11 expression. Expression of secondary dormancy is associated with maintenance of high embryo ABA content and a low HvExpA11 expression. The partial reversion of the inhibitory effect of blue light by green light also suggests that cryptochrome might be involved in this hormonal regulation.
初级休眠大麦籽粒的萌发在黑暗和20°C以下的温度条件下会得到促进，但会受到蓝光的强烈抑制。在10°C的蓝光下暴露超过五天，会导致在黑暗中逐渐丧失萌发能力，这被视为二次休眠。我们证明，蓝光的抑制作用在缺氧条件下会增强。蓝光的抑制作用与胚脱落酸（ABA）含量的增加（3.5至3.8倍）以及胚对ABA和缺氧的敏感性增加有关。对ABA代谢基因表达的分析表明，ABA的增加主要导致HvNCED1和HvNCED2表达的强烈增加，以及HvABA8'OH-1的轻微下降。在所检测的赤霉素（GA）代谢基因中，蓝光降低了参与GA合成的HvGA3ox2的表达，增加了参与GA分解代谢的GA2ox3和GA2ox5的表达，并降低了通过HvExpA11表达评估的GA信号传导。二次休眠的表达与高胚ABA含量的维持和低HvExpA11表达有关。绿光对蓝光抑制作用的部分逆转也表明，隐花色素可能参与了这种激素调节。
