Roy Sujit, Das Kali Pada
Protein Chemistry laboratory, Department of Chemistry, Bose Institute, Kolkata, India.
PLoS One. 2017 Jan 3;12(1):e0169294. doi: 10.1371/journal.pone.0169294. eCollection 2017.
Abscisic acid (ABA) acts as an important plant hormone in regulating various aspects of plant growth and developmental processes particularly under abiotic stress conditions. An increased ABA level in plant cells inhibits DNA replication and cell division, causing plant growth retardation. In this study, we have investigated the effects of ABA on the growth responses of some major loss-of-function mutants of DNA double-stand break (DSB) repair genes in Arabidopsis during seed germination and early stages of seedling growth for understanding the role of ABA in the induction of genome instability in plants. A comparative analysis of ABA sensitivity of wild-type Arabidopsis and the knockout mutant lines related to DSB sensors, including atatm, atatr, the non-homologous end joining (NHEJ) pathway genes, and mutants related to homologous recombination (HR) pathway genes showed relatively enhanced sensitivity of atatr and HR-related mutants to ABA treatment. The expression levels of HR-related genes were increased in wild-type Arabidopsis (Col-0) during seed germination and early stages of seedling growth. Immunoblotting experiments detected phosphorylation of histone H2AX in wild-type (Col-0) and DSB repair gene mutants after ABA treatment, indicating the activation of DNA damage response due to ABA treatment. Analyses of DSB repair kinetics using comet assay under neutral condition have revealed comparatively slower DSB repair activity in HR mutants. Overall, our results have provided comprehensive information on the possible effect of ABA on DNA repair machinery in plants and also indicated potential functional involvement of HR pathway in repairing ABA induced DNA damage in Arabidopsis.
脱落酸（ABA）作为一种重要的植物激素，在调节植物生长和发育过程的各个方面发挥着作用，尤其是在非生物胁迫条件下。植物细胞中ABA水平的升高会抑制DNA复制和细胞分裂，导致植物生长迟缓。在本研究中，我们研究了ABA对拟南芥中一些DNA双链断裂（DSB）修复基因功能缺失突变体在种子萌发和幼苗生长早期阶段生长反应的影响，以了解ABA在诱导植物基因组不稳定中的作用。对野生型拟南芥和与DSB传感器相关的敲除突变体系（包括atatm、atatr）、非同源末端连接（NHEJ）途径基因以及与同源重组（HR）途径基因相关的突变体进行ABA敏感性比较分析，结果表明atatr和HR相关突变体对ABA处理的敏感性相对增强。在种子萌发和幼苗生长早期阶段，野生型拟南芥（Col-0）中HR相关基因的表达水平有所增加。免疫印迹实验检测到ABA处理后野生型（Col-0）和DSB修复基因突变体中组蛋白H2AX的磷酸化，表明ABA处理导致DNA损伤反应的激活。在中性条件下使用彗星试验分析DSB修复动力学，结果显示HR突变体中的DSB修复活性相对较慢。总体而言，我们的研究结果提供了关于ABA对植物DNA修复机制可能影响的全面信息，也表明HR途径可能在修复拟南芥中ABA诱导的DNA损伤中发挥作用。
