Functional analysis of lactate dehydrogenase during hypoxic stress in Arabidopsis

Abstract

During waterlogging conditions plants switch from aerobic respiration to anaerobic fermentation to cope with the lack of available oxygen. Plants have two main fermentation pathways: ethanol and lactic acid fermentation. In this paper we carry out a functional analysis of the Arabidopsis lactate dehydrogenase gene, LDH1. Our results indicate that LDH1, like some other anaerobic genes, is expressed in a root-specific manner and is affected by a variety of abiotic stresses (hypoxia, drought, cold) and mechanical wounding. Functional analysis of LDH1 was carried out using transgenic Arabidopsis overexpressing the gene (35S promoter) and a T-DNA knockout line. Overexpression of LDH1 resulted in improved survival of low oxygen stress conditions in roots but not in shoots. Increased lactic acid fermentation also resulted in significantly higher activities of pyruvate decarboxylase (PDC). Knockout mutants of LDH1 showed reduced survival under low oxygen conditions and PDC activity levels were not changed compared with the wild type. Our data suggest that there is an interdependency between the lactic and ethanol fermentation pathways and that lactic acid fermentation may play a role in stimulating ethanol fermentation and improving plant survival. We show also that Arabidopsis plants are able to exude lactate efficiently into the medium, preventing it accumulating to toxic levels in the cells.

Ecophysiological and biochemical behavior in young plants of Parkia gigantocarpa Ducke subjected to waterlogging conditions

“…The high activity of LDH (Figure 10), and consequently, the signaling mechanism is required to initiate or promote the activity of ADH in the stimulation of ethanolic fermentation, by consuming more protons than lactic, increasing the cytosolic pH survivability of plants subjected to waterlogged conditions (Dolferus et al, 2008), which explains the results obtained in this study.…”

The Low-Oxygen-Induced NAC Domain Transcription Factor ANAC102 Affects Viability of Arabidopsis Seeds following Low-Oxygen Treatment

“…Overexpression of PDC, considered to be rate limiting in ethanol fermentation, has been shown to increase Arabidopsis survival Ismond et al, 2003). Increased root survival was also observed in LACTATE DEHYDROGENASE (LDH)-overexpressing Arabidopsis lines (Dolferus et al, 2008). Altering the expression of ALANINE AMINO-TRANSFERASE, which controls the Ala fermentation pathway, did not affect tolerance to low oxygen in Arabidopsis Miyashita et al, 2007).…”

Submergence Confers Immunity Mediated by the WRKY22 Transcription Factor in Arabidopsis

“…Multiple signaling pathways are triggered transcriptionally in response to flooding (Klok et al, 2002;Fukao and Bailey-Serres, 2008;Hattori et al, 2009). Functional studies of plant flooding and the effects of low oxygen have mainly focused on altering the expression of the genes encoding the enzymes for fermentation and glycolysis (Ellis et al, 1999;Kürsteiner et al, 2003;Bieniawska et al, 2007;Dolferus et al, 2008). Transcriptomic studies have revealed that expression of huge numbers of genes (;10% genes assayed) is altered upon flooding (Klok et al, 2002;Liu et al, 2005;Kreuzwieser et al, 2009;van Dongen et al, 2009;Hsu et al, 2011), suggesting that global transcriptional regulatory networks play important roles in response to flooding.…”