PtomtAPX, a mitochondrial ascorbate peroxidase, plays an important role in maintaining the redox balance of Populus tomentosa Carr

Abstract

Plant mitochondria are important energy-producing structure and ROS are generated as byproducts. APX is one enzyme of the AsA-GSH cycle to reduces H2O2 to water. We identified both PtomtAPX and PtosAPX are located in mitochondria of Populus tomentosa Carr. PtomtAPX is specifically targeted to mitochondria, while PtosAPX is dual targeted to both chloroplast and mitochondria. The expression of PtomtAPX in mitochondria was 60-fold that of PtosAPX by ELISA and qPCR analysis. Under high light stress, the expression levels of PtosAPX increased, while that of PtomtAPX only slightly changed. Compared to the WT, the antisense transgenic PtomtAPX cell lines showed slowed growth, smaller cells impaired mitochondria in MS medium under normal growth. RNA-seq results showed 3121 genes significantly altered expression in the antisense cells, and most of them are important for mitochondrial function, particularly in oxidative phosphorylation. Our findings demonstrates a mitochondrial location for one APX isoform, and provide valuable insight into the mechanism which ROS balance is modulated by AsA-GSH cycle in mitochondria.

Identification and Characterization of the APX Gene Family and Its Expression Pattern under Phytohormone Treatment and Abiotic Stress in Populus trichocarpa

“…Previous studies have identified seven APX genes in Populus trichocarpa [53], In this study, 11 PtrAPX genes have been identified encoding seven cytosolic isoforms, and four chloroplastic isoforms. Among the PtrAPXs genes located in chloroplast, PtrAPX1 and PtrAPX5 are dual-targeted to chloroplasts and/or mitochondria, consistent with the findings that PtosAPX and AtsAPX are dual-targeted to these two organelles [9,30].…”

“…Moreover, PtrAPX1 located in chloroplasts and/or mitochondria was stongly induced by high salinity in leaves (Figure 9). A previous study showed that PtomtAPX is dual targeted to both chloroplast and mitochondria of Populus tomentosa Carr, and showed the same expression pattern under salt stress [30]. Based on the present phylogenetic reconstruction (Figure 1), cytosolic PtrAPX6 is homologous to OsAPX2, and the relative expression level or PtrAPX6 in roots was increased approximately 16-fold at 3 and 6 h under salt stress.…”

“…PtomtAPX and PtosAPX located in mitochondria of Populus tomentosa Carr were identified. PtosAPX is dual targeted to both chloroplast and mitochondria, while PtomtAPX is specifically targeted to mitochondria and plays an important role in maintaining the redox balance [30]. As an important component of the ROS antioxidant system, the molecular characteristics of PtrAPX genes and their functions require detailed investigation.…”

Chloroplast Thylakoidal Ascorbate Peroxidase, PtotAPX, Has Enhanced Resistance to Oxidative Stress in Populus tomentosa

“…Using AsA as a substrate, the activity of the enzyme PtotAPX was measured under different concentration gradients of other substrates. Compared to the results shown by Yin et al [ 28 ], PtotAPX has a greater affinity for AsA ( Table 1 ). Taken together, these results indicate that PtotAPX could utilize lower concentrations of AsA to scavenge H 2 O 2 .…”

Mitochondria: Key Organelles Accelerating Cell Wall Material Accumulation in Juice Sacs of Pummelo (Citrus grandis L. Osbeck) Fruits during Postharvest Storage

“…On the other hand, mitochondria are also an important site for reactive oxygen species (ROS) synthesis [58][59][60]. positively correlated with xylem lignification [22] and cellulose accumulation in plants growing in salt stress conditions [61].…”