Protoporphyrinogen Oxidase–Overexpressing Transgenic Rice is Resistant to Drought Stress

Abstract

Transgenic rice (Oryza sativa L. ‘Dongjin’) lines, AP37 and MX, overexpressing Arabidopsis thaliana and Myxococcus xanthus protoporphyrinogen oxidase (PPO), respectively, were examined for their physiological responses and tolerance mechanism to drought stress. AP37 and MX lines were previously confirmed to be resistant to PPO inhibitors. Transgenic AP37 and MX plants showed significantly improved drought tolerance, as indicated by higher water content, lower leaf injury, less oxidative damage, and more favorable redox balance compared to wild‐type (WT) plants. The magnesium‐protoporphyrin IX (Mg‐Proto IX) content of WT and the transgenic lines did not vary significantly with the drought treatments, but MX lines had higher Mg‐Proto IX methyl ester (ME) content after 90 h of drought treatment compared to WT and AP37. In addition, the expression of most genes involved in porphyrin biosynthesis, particularly in the chlorophyll branch, such as glutamyl‐tRNA reductase, glutamate‐1‐semialdehyde aminotransferase, protoporphyrinogen oxidase 1, Fe‐chelatase2, H‐subunit of Mg‐chelatase, and I‐subunit of Mg‐chelatase, was up‐regulated in the transgenic plants, and this up‐regulation was higher in AP37 than in MX. Overall, the AP37 transgenic line was found to show better drought tolerance than the MX transgenic line.

Specific ABA‐independent tomato transcriptome reprogramming under abiotic stress combination

“…It has been suggested that ROS, produced by porphyrin mediators, function as signaling molecules within the stress response pathway. Thus, it has been previously postulated that the ROS increase activates the stress response network, ultimately leading to the downregulation of genes associated with porphyrin metabolism and chlorophyll metabolism inhibition (Karami et al., 2023; Yun et al., 2013).…”

Physiological and transcriptome analyses for assessing the effects of exogenous uniconazole on drought tolerance in hemp (Cannabis sativa L.)

“…1 a–d). Many genes involved in porphyrin biosynthesis, such as those for glutamyl-tRNA reductase, protoporphyrinogen oxidase, and the Mg chelatase subunit, are regulated to provide better drought tolerance in plants 28 . Glutamyl-tRNA reductase, a key enzyme in plant porphyrin biosynthesis, affects Mg chelatase and enzymes involved in Chl synthesis 29 .…”

A comprehensive analysis of transcriptomic data for comparison of plants with different photosynthetic pathways in response to drought stress

“…PPO as the last enzyme in the tetrapyrrole biosynthetic pathway is crucial for the biosynthesis of chlorophyll and heme. ferrochelatase (FC) and magnesium chelatase (composed of three subunits CHLD, CHLH, and CHLI) convert the PPO product (protoporphyrin IX (Proto IX)) into Fe-Proto IX and Mg-Proto IX, respectively [ 41 ].…”

“…It has been suggested that ROS, which are generated by porphyrin mediators, act as signaling molecules in the stress response pathway. Their levels increase, activating the stress response network, ultimately leading to the down-regulation of genes involved in porphyrin metabolism [ 41 ]. On the other hand, the accumulation of ROS under stress leads to lipid peroxidation and consequently the destruction of chlorophyll.…”