Action of Multiple Rice β-Glucosidases on Abscisic Acid Glucose Ester

Abstract

Conjugation of phytohormones with glucose is a means of modulating their activities, which can be rapidly reversed by the action of β-glucosidases. Evaluation of previously characterized recombinant rice β-glucosidases found that nearly all could hydrolyze abscisic acid glucose ester (ABA-GE). Os4BGlu12 and Os4BGlu13, which are known to act on other phytohormones, had the highest activity. We expressed Os4BGlu12, Os4BGlu13 and other members of a highly similar rice chromosome 4 gene cluster (Os4BGlu9, Os4BGlu10 and Os4BGlu11) in transgenic Arabidopsis. Extracts of transgenic lines expressing each of the five genes had higher β-glucosidase activities on ABA-GE and gibberellin A4 glucose ester (GA4-GE). The β-glucosidase expression lines exhibited longer root and shoot lengths than control plants in response to salt and drought stress. Fusions of each of these proteins with green fluorescent protein localized near the plasma membrane and in the apoplast in tobacco leaf epithelial cells. The action of these extracellular β-glucosidases on multiple phytohormones suggests they may modulate the interactions between these phytohormones.

Isolation and Characterization of Extracellular Vesicles from Arabidopsis thaliana Cell Culture and Investigation of the Specificities of Their Biogenesis

“…The presence of ESM1 in callus-derived vesicles suggests the retention of plant exosome loading mechanisms and potentially underscores their involvement in glucosinolate biosynthesis in callus cultures. Moreover, our analysis identified proteins, including heat shock 70 kDa protein, myrosinase 2, vegetative storage protein 1, polygalacturonase inhibitor 1, and beta-glucosidase isoforms, that are associated with defense and immune responses to both biotic and abiotic stresses [55][56][57]. Our findings are consistent with those of EVs originating from Arabidopsis apoplastic fluid.…”

Transcriptomic and metabolomic analyses reveal the potential mechanism of waterlogging resistance in cotton (Gossypium hirsutum L.)

“…The phenylpropanoid biosynthesis pathway, popularly known to regulate under hypoxia and waterlogging conditions ( Zhang et al., 2017 ; Yu et al., 2020 ), revealed a higher expression of peroxidases (EC: 1.11.1.7) and beta glucosidases (EC: 3.2.1.21) ( Figure 2E ). This is a clear indication of ROS scavenging and activation of the plant defense system, hormone production, and cell wall lignification ( Kongdin et al., 2021 ). In the glycolysis pathway, phosphofructokinase (EC: 2.7.1.11), alcohol dehydrogenase (EC: 1.1.1.1), and pyruvate decarboxylase-2 (EC: 4.1.1.1) genes were significantly expressed in CJ1831072 than in CJ1831056 ( Figure 2F ).…”

Transcriptome profiling shows a rapid variety-specific response in two Andigenum potato varieties under drought stress

“…BGlu enzymes have been associated with the activation of ABA by hydrolyzing ABA glucose ester (ABA-GE) to convert it to free active ABA. In Oryza sativa , Os4Glu9, Os4Glu10, Os4BGlu11, Os4BGlu12, and Os4BGlu13 belong to a group of beta glucosidase enzymes that act on ABA-GE ( Kongdin et al., 2021 ). The coding sequence of Soltu.DM.01G028100 was similar to GLU12 , suggesting that the tolerant variety may not only respond to drought by synthesising ‘new’ ABA, but also by activating pre-existing ABA in the leaf.…”