Revisiting the role of delta-1-pyrroline-5-carboxylate synthetase in drought-tolerant crop breeding

The delta-1-pyrroline-5-carboxylate synthetase (P5CS) gene exercises a protective function in stressed plants. However, the relationship between proline accumulation caused by P5CS and abiotic stress toler-ance in plants is not always clear, as P5CS overexpression has been reported to repress plant growth under normal conditions in several reports. We re-evaluated the role of P5CS in drought-tolerant rice breeding by expressing the AtP5CS1 and feedback-inhibition-removed AtP5CS1 (AtP5CS1F128A) genes under the regulation of an ABA-inducible promoter to avoid the potential side effects of P5CS overexpres-sion under normal conditions. ABA-inducible AtP5CS1 and AtP5CS1F128A increased seedling growth in a nutrient solution (under osmotic stress) and grain yield in pot plants. However, the evidently deleterious effects of AtP5CS1 on grain quality, tiller number, and grain yield in the field indicated the unsuitability of P5CS for drought-tolerance breeding.(c) 2022 Crop Science Society of China and Institute of Crop Science, CAAS. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd.

Automated summary

The P5CS gene plays a protective role in stressed plants, but overexpression of P5CS may inhibit plant growth. By expressing AtP5CS1 and AtP5CS1F128A genes under the regulation of an ABA-inducible promoter, it was found that seedling growth and grain yield of rice can be increased, but it has detrimental effects on grain quality, tiller number, and grain yield.