High Antioxidant Activity Facilitates Maintenance of Cell Division in Leaves of Drought Tolerant Maize Hybrids

Abstract

We studied the impact of drought on growth regulation in leaves of 13 maize varieties with different drought sensitivity and geographic origins (Western Europe, Egypt, South Africa) and the inbred line B73. Combining kinematic analysis of the maize leaf growth zone with biochemical measurements at a high spatial resolution allowed us to examine the correlation between the regulation of the cellular processes cell division and elongation, and the molecular redox-regulation in response to drought. Moreover, we demonstrated differences in the response of the maize lines to mild and severe levels of water deficit. Kinematic analysis indicated that drought tolerant lines experienced less impact on leaf elongation rate due to a smaller reduction of cell production, which, in turn, was due to a smaller decrease of meristem size and number of cells in the leaf meristem. Clear differences in growth responses between the groups of lines with different geographic origin were observed in response to drought. The difference in drought tolerance between the Egyptian hybrids was significantly larger than between the European and South-African hybrids. Through biochemical analyses, we investigated whether antioxidant activity in the growth zone, contributes to the drought sensitivity differences. We used a hierarchical clustering to visualize the patterns of lipid peroxidation, H2O2 and antioxidant concentrations, and enzyme activities throughout the growth zone, in response to stress. The results showed that the lines with different geographic region used different molecular strategies to cope with the stress, with the Egyptian hybrids responding more at the metabolite level and African and the European hybrids at the enzyme level. However, drought tolerance correlated with both, higher antioxidant levels throughout the growth zone and higher activities of the redox-regulating enzymes CAT, POX, APX, and GR specifically in leaf meristems. These findings provide evidence for a link between antioxidant regulation in the leaf meristem, cell division, and drought tolerance.

Inter‐relationship between photosynthetic efficiency, Δ13C, antioxidant activity and sugarcane yield under drought stress in field conditions

“…In general, drought stress increased the antioxidant enzymes APX and CAT and lipid peroxidation, mainly in the intense growth development stage. Similar results were found in drought-stressed sugarcane (Cia et al, 2012;Patade, Bhargava, & Suprasanna, 2011;Santos et al, 2015) and maize (Avramova et al, 2017), and salt-stressed sugarcane (Gomathi & Rakkiyapan, 2011). During the intense growth stage, RB72454, RB855113 and RB855536 varieties showed the highest CAT and APX activity, which indicated that these plants were under oxidative stress induced by strong photoinhibition.…”

“…Probably, these responses and the low of the chlorophyll degradation under drought stress may be associated to better plants water status this variety, promoted by size its root system. In the studies with sugarcane (Cia et al, ) and maize (Avramova et al, ) grown under drought stress also were found lower lipid peroxidation in the varieties considered more tolerant to drought.…”

The reduction in maize leaf growth under mild drought affects the transition between cell division and cell expansion and cannot be restored by elevated gibberellic acid levels

“…Our kinematic analysis showed that the cell division rate and the cell cycle duration were not significantly affected by mild drought, and also at the transcript level, no differential expression of cell cycle‐related genes was observed at the DZ. However, effects on cell division rate and down‐regulation of cell cycle genes have been observed in other studies that examined the effect of drought in the maize leaf (Avramova et al ., , ), indicating that the significance of differential expression of cell cycle genes might depend on the applied drought stress or additional environmental changes between different growth chambers. Alternatively, our high‐resolution analysis and the alignment of the samples according to the position of the TZ1 might explain some of the differences.…”

Structure Annotation and Quantification of Wheat Seed Oxidized Lipids by High-Resolution LC-MS/MS

“…In plants, lipid oxidation is not a phenomenon restricted to seed aging; instead, it plays a role in many processes, like photooxidative stress (Broin and Rey, 2003), drought-induced leaf damage (Avramova et al, 2017), and metal-induced root damage (Feigl et al, 2015). Also, numerous studies in the fields of microbiology (Imlay, 2013) and medicine (Ames et al, 1993) link lipid oxidation to biological questions of great relevance, like pathogen defense, aging, and cardiovascular diseases.…”