Exogenous Gamma-Aminobutyric Acid Application Induced Modulations in the Performance of Aromatic Rice Under Lead Toxicity

Umair Ashraf; Sammina Mahmood; Shakeel Ahmad Anjum; Rana Nadeem Abbas; Fahd Rasul; Javed Iqbal; Zhaowen Mo; Xiangru Tang

doi:10.3389/fpls.2022.933694

Exogenous Gamma-Aminobutyric Acid Application Induced Modulations in the Performance of Aromatic Rice Under Lead Toxicity

Front Plant Sci. 2022 Jul 22:13:933694. doi: 10.3389/fpls.2022.933694. eCollection 2022.

Authors

Umair Ashraf^{1

2}, Sammina Mahmood¹, Shakeel Ahmad Anjum³, Rana Nadeem Abbas³, Fahd Rasul³, Javed Iqbal⁴, Zhaowen Mo^{2

5}, Xiangru Tang^{2

5}

Affiliations

¹ Department of Botany, Division of Science and Technology, University of Education, Lahore, Pakistan.
² Department of Crop Science and Technology, College of Agriculture, South China Agricultural University, Guangzhou, China.
³ Department of Agronomy, University of Agriculture, Faisalabad, Pakistan.
⁴ Department of Agricultural Engineering, Khawaja Fareed University of Engineering and Information Technology, Rahim Yar Khan, Pakistan.
⁵ State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Agriculture, South China Agricultural University, Guangzhou, China.

Abstract

Gamma-aminobutyric acid (GABA) is a non-protein amino acid and has a multi-functional role in abiotic stress tolerance. A pot experiment was conducted to assess the role of exogenous gamma-aminobutyric acid (GABA) application to modulate the growth, yield, and related physio-biochemical mechanisms in two aromatic rice cultivars, that is, Guixiangzhan (GXZ) and Nongxiang 18 (NX-18), under Pb toxic and normal conditions. The experimental treatments were comprised of Ck: without Pb and GABA (control), GABA: 1 mM GABA is applied under normal conditions (without Pb), Pb + GABA: 1 mM GABA is applied under Pb toxicity (800 mg kg^-1 of soil), and Pb= only Pb (800 mg kg^-1 of soil) is applied (no GABA). The required concentrations of GABA were applied as a foliar spray. Results revealed that Pb stress induced oxidative damage in terms of enhanced malondialdehyde (MDA), electrolyte leakage (EL), and H₂O₂ contents, while exogenous GABA application improved leaf chlorophyll, proline, protein and GABA contents, photosynthesis and gas exchange, and antioxidant defense under Pb toxicity in both rice cultivars. Moreover, glutamine synthetase (GS) and nitrate reductase (NR) activities were variably affected due to GABA application under Pb stress. The yield and related traits, that is, productive tillers/pot, grains/panicle, filled grain %, 1,000-grain weight, and grain yield were 13.64 and 10.29, 0.37% and 2.26%, 3.89 and 19.06%, 7.35 and 12.84%, and 17.92 and 40.56 lower under Pb treatment than Pb + GABA for GXZ and NX-18, respectively. Furthermore, exogenous GABA application in rice reduced Pb contents in shoot, leaves, panicle, and grains compared with Pb-exposed plants without GABA. Overall, GXZ performed better than NX-18 under Pb toxic conditions.

Keywords: GABA; antioxidants; lead; photosynthesis; rice.