We investigated the role of AtbZIP62, an uncharacterized Arabidopsis bZIP TF, in oxidative, nitro-oxidative and drought stress conditions using reverse genetics approach. We further monitored the expression of AtPYD1 gene (orthologous to rice OsDHODH1 involved in the pyrimidine biosynthesis) in atbzip62 knock-out (KO) plants in order to investigate the transcriptional interplay of AtbZIP62 and AtPYD1. The atbzip62 KO plants showed significant increase in shoot length under oxidative stress, while no significant difference was recorded for root length compared to WT. However, under nitro-oxidative stress conditions, atbzip62 showed differential response to both NO-donors. Further characterization of AtbZIP62 under drought conditions showed that both atbzip62 and atpyd1-2 showed a sensitive phenotype to drought stress, and could not recover after re-watering. Transcript accumulation of AtbZIP62 and AtPYD1 showed that both were highly up-regulated by drought stress in wild type (WT) plants. Interestingly, AtPYD1 transcriptional level significantly decreased in atbzip62 exposed to drought stress. However, AtbZIP62 expression was highly induced in atpyd1-2 under the same conditions. Both AtbZIP62 and AtPYD1 were up-regulated in atnced3 and atcat2 while showing a contrasting expression pattern in atgsnor1-3. The recorded increase in CAT, POD, and PPO-like activities, the accumulation of chlorophylls and total carotenoids, and the enhanced proline and malondialdehyde levels would explain the sensitivity level of atbzip62 towards drought stress. All results collectively suggest that AtbZIP62 could be involved in AtPYD1 transcriptional regulation while modulating cellular redox state and photosynthetic processes. In addition, AtbZIP62 is suggested to positively regulate drought stress response in Arabidopsis.

我们使用逆向遗传学方法研究了AtbZIP62（一种未鉴定的拟南芥bZIP TF）在氧化，硝基氧化和干旱胁迫条件下的作用。为了研究AtbZIP62和AtPYD1的转录相互作用，我们进一步监测了atbzip62敲除（KO）植物中AtPYD1基因的表达（与参与嘧啶生物合成的水稻OsDHODH1同源）。该atbzip62 KO植株在氧化应激下芽长显著增加，而没有显著差异记录根长比WT。但是，在硝基氧化应激条件下，atbzip62对两个NO供体均表现出不同的反应。AtbZIP62在干旱条件下的进一步表征表明atbzip62和atpyd1-2均表现出对干旱胁迫敏感的表型，并且在重新浇水后无法恢复。AtbZIP62和AtPYD1的转录本积累表明，它们在野生型（WT）植物中均受到干旱胁迫的高度上调。有趣的是，AtPYD1转录水平显著下降atbzip62暴露于干旱胁迫。然而，AtbZIP62表达高度诱导在atpyd1-2相同的条件下。两者都是AtbZIP62和AtPYD1表达上调在atnced3和atcat2而示出了在对比表达模式atgsnor1-3。记录的CAT，POD和PPO样活性增加，叶绿素和总类胡萝卜素的积累以及脯氨酸和丙二醛水平的提高将解释atbzip62对干旱胁迫的敏感性水平。所有结果共同表明，AtbZIP62可能参与AtPYD1转录调控，同时调节细胞的氧化还原状态和光合过程。此外，建议AtbZIP62积极调节拟南芥中的干旱胁迫响应。