Physiological performance and expression of isozymes in maize seeds subjected to water stress

Abstract

Early characterization of genotypes, through the previous assessment of physiological quality of their seeds and their enzymatic systems, can provide parameters capable of aiding in the selection of new maize cultivars tolerant to water stress. Thus, this study was aimed at assessing seed performance of five different maize lines subjected to four different water stress levels. The physiological quality of seeds germinated under the osmotic potentials of 0.0, -0.3, -0.6 and -0.9 MPa was assessed by germination test, number of strong normal seedlings and T50, as well as by the expression of the isozymes superoxide dismutase (SOD), catalase (CAT), glutamate oxaloacetate transaminase (GOT), esterase (EST), malate dehydrogenase (MDH), alcohol dehydrogenase (ADH), and of heat-resistant proteins. The osmotic potential of -0.9 MPa affected the physiological quality and vigor of seeds of all maize lines assessed. The highest values for the germination percent, in the lowest osmotic potentials assessed, were found in the seeds of line 63. However, seeds of line 91 were superior in regard to vigor. Increased expression of the enzymes SOD and CAT, considered as enzymes of the antioxidant system, was observed in seeds of lines 44 and 91. Thus, line 91 was considered as promising for tolerance to water stress.

Heat-resistant protein expression during germination of maize seeds under water stress

“…In line 91, an increase of low molecular weight bands was observed under water stress conditions. This was also observed by Abreu et al (2014), who used seed root protrusions as a material for protein extraction. In this study, they also found that lines 91 and 64 responded to water stress conditions with an increase and decrease in catalase enzyme activity, respectively (Abreu et al, 2014).…”

“…This was also observed by Abreu et al (2014), who used seed root protrusions as a material for protein extraction. In this study, they also found that lines 91 and 64 responded to water stress conditions with an increase and decrease in catalase enzyme activity, respectively (Abreu et al, 2014). Under prolonged hydration conditions, LEA proteins can act as antioxidant molecules (Caramelo and Iusem, 2009).…”

“…Small polymorphisms for heat-resistant proteins were found by Abreu et al (2014), when studying heat-resistant protein extraction in protruded seeds under water stress conditions. Albuquerque et al (2009) also found a reduction in band intensity of heat-resistant protein in seeds soaked for a longer time, near the root protrusion.…”

“…Seeds were produced during the 2011/2012 harvest, in the experimental area of UFLA Agriculture Department. The seeds had previously been classified according to water stress tolerance (Abreu et al, 2014). Line 64 was classified as low tolerant and line 91 classified as tolerant to water stress.…”

Genes related to high temperature tolerance during maize seed germination

“…When studying tolerance to low temperature during germination of seeds from six maize lines (44,54,57,63,64, and 91) Silva-Neta et al (2014) found that there was a change in SOD expression in seeds from strain 63, which are tolerant to low temperatures, following seed imbibition for 24 h at 25°C, and that in most strains SOD expression was highest in seeds imbibed for 48 h at 25°C. Abreu et al (2014) studied tolerance to drought in seeds from five maize lineages (44, 54, 63, 64, and 91) and observed high SOD activity in hydric potential control (0MPa). As this was reducing hydric potential, a reduction in band intensity was observed for lineages 63, 54, and 64, which did not occur in the lineages 91 and 44.…”