Auxin-Glucose Conjugation Protects the Rice (Oryza sativa L.) Seedlings Against Hydroxyurea-Induced Phytotoxicity by Activating UDP-Glucosyltransferase Enzyme

Abstract

Hydroxyurea (HU) is the replication stress known to carry out cell cycle arrest by inhibiting ribonucleotide reductase (RNR) enzyme upon generating excess hydrogen peroxide (H2O2) in plants. Phytohormones undergo synergistic and antagonistic interactions with reactive oxygen species (ROS) and redox signaling to protect plants against biotic and abiotic stress. Therefore, in this study, we investigated the protective role of Indole-3-acetic acid (IAA) in mitigating HU-induced toxicity in rice seedlings. The results showed that IAA augmentation improved the growth of the seedlings and biomass production by maintaining photosynthesis metabolism under HU stress. This was associated with reduced H2O2 and malondialdehyde (MDA) contents and improved antioxidant enzyme [superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), and peroxidase (POD)] activity that was significantly affected under HU stress. Furthermore, we showed that the HU stress-induced DNA damage leads to the activation of uridine 5′-diphosphate-glucosyltransferase (UGT), which mediates auxin homeostasis by catalyzing IAA-glucose conjugation in rice. This IAA-glucose conjugation upregulates the RNR, transcription factor 2 (E2F2), cyclin-dependent kinase (CDK), and cyclin (CYC) genes that are vital for DNA replication and cell division. As a result, perturbed IAA homeostasis significantly enhanced the key phytohormones, such as abscisic acid (ABA), salicylic acid (SA), cytokinin (CTK), and gibberellic acid (GA), that alter plant architecture by improving growth and development. Collectively, our results contribute to a better understanding of the physiological and molecular mechanisms underpinning improved growth following the HU + IAA combination, activated by phytohormone and ROS crosstalk upon hormone conjugation via UGT.

Physiological and Transcriptomic Analyses Reveal the Mechanisms of Compensatory Growth Ability for Early Rice after Low Temperature and Weak Light Stress

“…After the restoration of suitable temperature and light, GA 3 can affect rice plant height by activating cell division in meristematic tissue and promoting cell elongation [ 38 , 39 ]. IAA and CTK act synergistically in a variety of cellular and physiological processes, such as cell expansion and apical dominance [ 40 , 41 ]. From the end of stress, we tracked the changes in GA 3 , ABA, IAA, and ZR concentrations.…”

Auxin Application at the Flowering Stage of Rice Alleviates the Negative Impact of Heat Stress on Spikelet Fertility and Yield Attributes

“…In addition, high leaf temperature substantially affects the RuBisCo enzyme activation process [49], which interrupts photosynthesis [50]. The augmentation of IAA influenced the growth and biomass production of rice seedlings through the stability of the photosynthesis process under heat stress conditions [51]. In this study, stomatal conductance significantly decreased under heat stress, while reciprocally influenced under the auxin application.…”

Effect of Abiotic Signals on the Accumulation of Saponarin in Barley Leaves in Hydroponics Under Artificial Lights

“…The antioxidant enzyme activities for APX and CAT were conducted following the method by Kantharaj et al 41 The fresh YBL sample (100 mg, fresh weight) was rapidly frozen in liquid nitrogen and then homogenized with 200 μL of extraction buffer consisting of 50 mM HEPES and 0.1 mM EDTA for APX and potassium phosphate buffer for CAT. The extract was centrifuged at 12 000 rpm for 15 min at 4 °C, and the supernatant was measured for the activity.…”