Premium
Nitrate Reductase Activity in Heat (Drought) Tolerant and Intolerant Maize Genotypes 1
Author(s) -
Pal U. R.,
Johnson R. R.,
Hageman R. H.
Publication year - 1976
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1976.0011183x001600060009x
Subject(s) - nitrate reductase , biology , nitrite reductase , poaceae , seedling , horticulture , enzyme , botany , biochemistry
The objective of this work was to determine if stability of enzyme activity under heat stress might be associated with differences in heat or drought tolerance in corn ( Zea mays L.) inbreds in the seedling stage. Three heat (drought) tolerant and three intolerant inbreds that had been field evaluated were obtained from Pioneer Hi‐Bred International, Inc. and were used to test the effect of assay temperature on three cytoplasmic enzymes [nitrate reductase (NR), glyceraldehyde‐phosphate dehyrogenase (NAD), and ribonuclease] and two chloroplastic enzymes [nitrite reductase and glyceraldehyde‐phosphate dehydrogenase (NADP+) (phosphorylating)]. Only NR and trite reductase exhibited a differential genotypic temperature response. NR (in vivo and in vitro) from three tolerant and one intolerant inbreds was inhibited less at 40 to 45 C than the other two intolerant inbreds. This is consistent with field evaluation of these genotypes during vegetative development. When all inbreds were grown at 40/21 C day/night temperature for 19 days, four inbreds (three tolerant and one intolerant with anomalous NR sensitivity to high temperature) accumulated proportionately more dry weight than the two intolerant inbreds. In vitro and in vivo (with NO 3 ‐ in the infiltration medium) assays of the temperature‐treated seedlings showed no differential genotypic effect. However, the in vivo (without NO 3 ‐ in the infiltration medium) activity declined in a manner consistent with growth response, suggesting involvement of a “metabolic” NO 3 ‐ pool. Although maintenance of NR activity under temperature stress is associated with heat or drought tolerance during the vegetative stage, the simplest selection criterion may be plant growth rate in response to temperature stress.