Yang Li, Zhang Jing, He Junna, Qin Yingying, Hua Deping, Duan Ying, Chen Zhizhong, Gong Zhizhong
State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, China.
State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, China; National Center for Plant Gene Research, Beijing, China.
PLoS Genet. 2014 Dec 18;10(12):e1004791. doi: 10.1371/journal.pgen.1004791. eCollection 2014 Dec.
Although research has determined that reactive oxygen species (ROS) function as signaling molecules in plant development, the molecular mechanism by which ROS regulate plant growth is not well known. An aba overly sensitive mutant, abo8-1, which is defective in a pentatricopeptide repeat (PPR) protein responsible for the splicing of NAD4 intron 3 in mitochondrial complex I, accumulates more ROS in root tips than the wild type, and the ROS accumulation is further enhanced by ABA treatment. The ABO8 mutation reduces root meristem activity, which can be enhanced by ABA treatment and reversibly recovered by addition of certain concentrations of the reducing agent GSH. As indicated by low ProDR5:GUS expression, auxin accumulation/signaling was reduced in abo8-1. We also found that ABA inhibits the expression of PLETHORA1 (PLT1) and PLT2, and that root growth is more sensitive to ABA in the plt1 and plt2 mutants than in the wild type. The expression of PLT1 and PLT2 is significantly reduced in the abo8-1 mutant. Overexpression of PLT2 in an inducible system can largely rescue root apical meristem (RAM)-defective phenotype of abo8-1 with and without ABA treatment. These results suggest that ABA-promoted ROS in the mitochondria of root tips are important retrograde signals that regulate root meristem activity by controlling auxin accumulation/signaling and PLT expression in Arabidopsis.
尽管研究已确定活性氧（ROS）在植物发育中作为信号分子发挥作用，但ROS调节植物生长的分子机制尚不清楚。一个脱落酸（ABA）超敏感突变体abo8-1，其负责线粒体复合体I中NAD4内含子3剪接的一个五肽重复（PPR）蛋白存在缺陷，与野生型相比，其根尖积累了更多的ROS，并且ABA处理进一步增强了ROS的积累。ABO8突变降低了根分生组织活性，ABA处理可增强这种活性，添加一定浓度的还原剂谷胱甘肽（GSH）可使其可逆恢复。如低水平的ProDR5:GUS表达所示，abo8-1中生长素积累/信号传导减少。我们还发现ABA抑制多能性相关蛋白1（PLETHORA1，PLT1）和PLT2的表达，并且在plt1和plt2突变体中根生长对ABA比野生型更敏感。在abo8-1突变体中，PLT-1和PLT2的表达显著降低。在诱导系统中过表达PLT2，无论有无ABA处理，都能在很大程度上挽救abo8-1的根尖分生组织（RAM）缺陷表型。这些结果表明，ABA促进的根尖线粒体中的ROS是重要的逆行信号，通过控制拟南芥中的生长素积累/信号传导和PLT表达来调节根分生组织活性。
