# Environmental Regulation of 2-Acetyl-1-pyrroline Biosynthesis in Fragrant Rice: From Metabolic Pathways to Sustainable Quality Management

## TL;DR

This paper explores how environmental factors and farming practices influence the production of the aromatic compound 2-acetyl-1-pyrroline in fragrant rice, aiming to improve sustainable quality management.

## Contribution

The study integrates metabolic pathways and environmental regulation to propose strategies for stable aroma trait development in fragrant rice under climate change.

## Key findings

- Environmental factors like moderate drought and optimal temperatures enhance 2-AP accumulation through stress-responsive pathways.
- Agronomic practices such as nitrogen and potassium fertilization promote 2-AP synthesis by increasing precursor availability.
- Challenges include the yield-aroma trade-off and incomplete understanding of molecular mechanisms affecting aroma formation.

## Abstract

The market value of fragrant rice is largely defined by the presence and intensity of its aroma, which is primarily attributed to volatile compound 2-acetyl-1-pyrroline (2-AP). The biosynthesis of 2-AP is chiefly governed by recessive alleles of the badh2 gene. Nevertheless, 2-AP accumulation is also profoundly shaped by environmental factors and agronomic management. Field practices—such as balanced nitrogen and potassium fertilization, supplementation with trace elements, and application of plant growth regulators like methyl jasmonate—promote 2-AP synthesis by increasing precursor availability and enhancing the activity of key enzymes. Additionally, tillage systems, alternate wetting and drying irrigation, optimal planting density, and harvest timing significantly affect aroma quality. Abiotic stresses, including moderate drought, salinity, optimal temperatures around 25 °C, and low light during grain filling, can also stimulate 2-AP accumulation, often through shifts in proline metabolism and activation of stress-responsive pathways involving GABA and methylglyoxal. Despite the promise of these strategies, several challenges persist, such as the common trade-off between yield and aroma intensity, complex genotype-by-environment interactions, and incomplete elucidation of the molecular mechanisms involved. Moving forward, integrating multi-omics analyses with smart agriculture technologies will be essential to unravel the regulatory networks underlying aroma formation and to advance the breeding of high-yielding fragrant rice varieties with stable aroma traits under changing climate scenarios.