Heat Stress Effects on Protein Accumulation of Maize Endosperm

Abstract

and Jones, 1999;Commuri and Jones, 2001; Duke and Doehlert, 1996; Engelen-Eigles et al., 2000; Heat stress is a major factor limiting crop yield in many agricultural Singletary et al., 1994). The extent of damage caused regions. During the early stage of kernel development, heat stress is particularly detrimental to subsequent dry matter accumulation since it by heat stress depends on the time of exposure in relacauses disruption of cell division, sugar metabolism, and starch bio-tion to the stage of kernel development (Gibson and synthesis in the endosperm. The effects of heat stress on protein accu- Paulsen, 1999). By exposing maize kernels to heat stress mulation, however, is less well understood. Therefore, the objective of during the lag phase (starting at 5 DAP), cell division this study was to determine the mechanisms by which heat stress decreases and ultimately the number of endosperm cells and starch protein accumulation and alters composition of developing maize (Zea granules are severely reduced (Commuri and Jones, 1999; mays L.) kernels. In this study, maize ears were heat stressed for 2 and Engelen-Eigles et al., 2000), which is also associated with 4 d at continuous 35؇C starting at 5 d after pollination (DAP). Endosperms a reduction in cytokinin levels (Cheikh and Jones, 1994). were analyzed for the relative proportion of each Osborne protein solubil-Starch metabolism is particularly repressed, which apity class fraction and for individual zein proteins. The 2-and 4-d heat pears to be due to a reduction of the activity of ADP stress (DHS) treatment caused a 20 and 48% reduction in kernel final dry weight, respectively, and protein content was similarly reduced. glucose pyrophosphorylase and soluble starch synthaseSpecifically, zein content was reduced by an average of 53%, but zein (Commuri, 1997). These findings are in agreement with composition was only mildly affected. The concentrations of glutelin those of Duke and Doehlert (1996), Keeling et al. (1994), and albumin plus globulin tended to increase throughout most of 4- Singletary et al. (1994), andWilhelm et al. (1999), who DHS kernel development. L-[ 35 S]-methionine incorporation in theshowed that, even when maize kernels are exposed to zein fraction was delayed by the 4 DHS when compared to control heat stress at later developmental stages (e.g., the linear and 2-DHS treated kernels. Therefore, we concluded that heat stress fill period), there is a significant repression in starch during early stages of endosperm development repressed zein accumubiosynthesis because of the reduction in the activity of lation at the synthesis level. In contrast, later in development, zein these two enzymes. accumulation appeared to be repressed mainly by protein degradation, Maize protein accumulation seems less susceptible to which appears to be a part of the natural progression of kernel development since there was no apparent significant effect of heat stress heat stress (Bhullar and Jenner, 1985;Wilhelm et al., 1999) treatments on this process. and w...

Maize Production in a Changing Climate

“…During this stage heat stress affects cell division, sugar metabolism and starch biosynthesis, reducing subsequent dry matter accumulation within kernels (Commuri and Jones, 2001;Engelen--Eigles et al, 2000;Monjardino et al, 2005). The duration of the grain filling process (ca.…”

Evaluation of Maize Hybrids for Tolerance to High Temperature Stress in Central Punjab

“…The activation state of RUBISCO decreases at 32.5 0 C (Crafts-Brander and Salvucci, 2002) with almost complete inactivation at 45 o C and plant dies at 54 o C (Smith, 1996 andSteven et al 2002). Heat shock affects the endosperm development in maize and reduces grain yield due to interruption in cell division, aberrant sugar metabolism and starch biosynthesis (Monjardino et al, 2005). Therefore this current study was planned to explore the variation and to determine the target traits conferring heat stress tolerance in maize hybrids.…”

High temperature effects on photosynthate partitioning and sugar metabolism during ear expansion in maize (Zea mays L.) genotypes

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