Co-functioning of 2AP precursor amino acids enhances 2-acetyl-1-pyrroline under salt stress in aromatic rice (Oryza sativa L.) cultivars

N Renuka; Vitthal T Barvkar; Zahid Ansari; Chunfang Zhao; Cailin Wang; Yadong Zhang; Altafhusain B Nadaf

doi:10.1038/s41598-022-07844-7

Co-functioning of 2AP precursor amino acids enhances 2-acetyl-1-pyrroline under salt stress in aromatic rice (Oryza sativa L.) cultivars

Sci Rep. 2022 Mar 10;12(1):3911. doi: 10.1038/s41598-022-07844-7.

Authors

N Renuka¹, Vitthal T Barvkar¹, Zahid Ansari², Chunfang Zhao³, Cailin Wang³, Yadong Zhang⁴, Altafhusain B Nadaf⁵

Affiliations

¹ Department of Botany, Savitribai Phule Pune University, Pune, 411007, Maharashtra, India.
² The University Polytechnic, Aligarh Muslim University, Aligarh, 202002, India.
³ Institute of Food Crops, Jiangsu Academy of Agricultural Sciences, Jiangsu Rice Engineering Research Centre, National Centre for Rice Improvement (Nanjing), Nanjing, 210014, China.
⁴ Institute of Food Crops, Jiangsu Academy of Agricultural Sciences, Jiangsu Rice Engineering Research Centre, National Centre for Rice Improvement (Nanjing), Nanjing, 210014, China. zhangyd@jaas.ac.cn.
⁵ Department of Botany, Savitribai Phule Pune University, Pune, 411007, Maharashtra, India. abnadaf@unipune.ac.in.

Abstract

Aromatic rice (Oryza sativa) fetches a premium price due to the pleasant aroma. The major aroma compound 2-acetyl-1-pyrroline (2AP) has been found to be enhanced under stress. This condition can be considered to study the genes, precursors, enzymes, and metabolites involved in elevated levels of 2AP biosynthesis. In the present study, 100 mM salt treatment was given to two aromatic rice cultivars Ambemohar-157 (A-157) and Basmati-370 (B-370) at the vegetative stage (VS₃). After salt treatment, in the leaves, 2AP contents were elevated by 2.2 and 1.8 fold in A-157 and B-370, respectively. Under these elevated 2AP conditions, the precursor amino acids (glutamate, putrescine, ornithine, and proline), their related genes, enzymes, and metabolites (methylglyoxal and γ-aminobutyric acid (GABA) related to 2AP biosynthesis were analyzed. In addition, agronomic characters were also studied. It was observed that the proline content was enhanced in both the cultivars by 29% (A-157) and 40% (B-370) as compared to control. The Δ¹-pyrroline-5-carboxylate synthetase (P5CS) enzyme activity was increased in salt-treated plants leaf tissue by 31% (A-157) and 40% (B-370) compared to control. The P5CS gene expression was enhanced by A-157 (1.8 fold) and B-370 (2.2 fold) compared to control, putrescine content in A-157 and B-370 decreased by 2.5 and 2.7 fold respectively as compared to control. The ornithine decarboxylase (ODC) activity was enhanced in A-157 (12%) and B-370 (35%) over control. Further, ODC gene expression was enhanced in both the cultivars A-157 (1.5 fold) and B-370 (1.3 fold). The diamino oxidase (DAO) enzyme activity was increased by 28% (A-157) and 35% (B-370) respectively over control. The GABA content marginally increased over control in both the cultivars namely, A-157 (1.9%) and B-370 (9.5%). The methylglyoxal levels were enhanced by 1.4 fold in A-157 and 1.6 fold in B-370. Interestingly, the enhancement in 2AP in the vegetative stage also helped to accumulate it in mature grains (twofold in A-157 and 1.5 fold in B-370) without test weight penalty. The study indicated that the ornithine and proline together along with methylglyoxal contribute towards the enhancement of 2AP under salt stress.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Amino Acids / metabolism
Ornithine / metabolism
Oryza* / metabolism
Proline / metabolism
Putrescine / metabolism
Pyrroles
Pyruvaldehyde / metabolism
Salt Stress
gamma-Aminobutyric Acid / metabolism

Substances

Amino Acids
Pyrroles
gamma-Aminobutyric Acid
Pyruvaldehyde
Proline
Ornithine
2-acetyl-1-pyrroline
Putrescine