Intercellular Distribution of Glutathione Synthesis in Maize Leaves and Its Response to Short-Term Chilling

Abstract

To investigate the intercellular control of glutathione synthesis and its influence on leaf redox state in response to short-term chilling, genes encoding g-glutamylcysteine synthetase (g-ECS) and glutathione synthetase (GSH-S) were cloned from maize (Zea mays) and specific antibodies produced. These tools were used to provide the first information on the intercellular distribution of g-ECS and GSH-S transcript and protein in maize leaves, in both optimal conditions and chilling stress. A 2-d exposure to low growth temperatures (chill) had no effect on leaf phenotype, whereas return to optimal temperatures (recovery) caused extensive leaf bleaching. The chill did not affect total leaf GSH-S transcripts but strongly induced g-ECS mRNA, an effect reversed during recovery. The chilling-induced increase in g-ECS transcripts was not accompanied by enhanced total leaf g-ECS protein or extractable activity. In situ hybridization and immunolocalization of leaf sections showed that g-ECS and GSH-S transcripts and proteins were found in both the bundle sheath (BS) and the mesophyll cells under optimal conditions. Chilling increased g-ECS transcript and protein in the BS but not in the mesophyll cells. Increased BS g-ECS was correlated with a 2-fold increase in both leaf Cys and g-glutamylcysteine, but leaf total glutathione significantly increased only in the recovery period, when the reduced glutathione to glutathione disulfide ratio decreased 3-fold. Thus, while there was a specific increase in the potential contribution of the BS cells to glutathione synthesis during chilling, it did not result in enhanced leaf glutathione accumulation at low temperatures. Return to optimal temperatures allowed glutathione to increase, particularly glutathione disulfide, and this was associated with leaf chlorosis.

Arabidopsis GLUTATHIONE REDUCTASE1 Plays a Crucial Role in Leaf Responses to Intracellular Hydrogen Peroxide and in Ensuring Appropriate Gene Expression through Both Salicylic Acid and Jasmonic Acid Signaling Pathways

“…This is consistent with the roles of glutathione in redox homeostasis, heavy metal resistance, cold acclimation, and metabolite conjugation and transport (Cobbett et al, 1998;May et al, 1998;Kocsy et al, 2000;Wagner et al, 2002;Gomez et al, 2004).…”

Cold Nights Impair Leaf Growth and Cell Cycle Progression in Maize through Transcriptional Changes of Cell Cycle Genes

“…Also, the transcript level of the large subunit of the Rubisco gene was similar in both control and treated leaves (data not shown). In contrast, severe cold stress, particularly occurring during the photoperiod, causes profound perturbation of chloroplast development and may lead to cell death (Allen and Ort, 2001;Gomez et al, 2004). Nevertheless, our treatment resulted in a 20% decrease of final length of leaf 4 (Table I; P , 0.001, n 5 12).…”

“…Severe cold (chilling stress) impairs chloroplast function, thereby reducing photosynthetic capacity (Allen and Ort, 2001), and may result in cell death (Gomez et al, 2004); prolonged chilling stress eventually may arrest growth. Interestingly, even before visible chilling effects occur, suboptimal temperature inhibits leaf growth (Ben-Haj-Salah and Tardieu, 1995).…”

Structure of Soybean Serine Acetyltransferase and Formation of the Cysteine Regulatory Complex as a Molecular Chaperone

“…Plants subjected to low temperature accumulate hydrogen peroxide and the activities of reactive oxygen species detoxification enzymes require enhanced glutathione synthesis, which places increased demands on the sulfur assimilation and cysteine synthesis pathways (75)(76)(77)(78)(79)(80)(81). Thus, CRC formation may allow OASS to act as a molecular chaperone of SAT activity in plants when the demand for sulfur assimilation and cysteine production increases in response to low temperatures.…”