Thermal Environment During Endosperm Cell Division in Maize: Effects on Number of Endosperm Cells and Starch Granules¹

Abstract

Reductions in kernel mass are observed when corn (Zea mays L.) kernels are grown in vitro or when unfavorable temperature occurs during endosperm cell division. We investigated the possibility that a decreased number of endosperm cells or a decreased number of starch granules is responsible for the reduced kernel mass in such environments. Three‐day‐old kernels of the single cross hybrid A619 ✕ W64A were placed in culture on a denned medium at 15, 30, and 35 °C, and their growth was compared with kernels from ears developed in the field or greenhouse. Kernels cultured at 30°C attained a final mass of 164 mg compared with 274 mg for field‐grown controls. At 30°C, endosperm cell division ceased approximately 10 days earlier, and the final number of cells was reduced by 34%. Final kernel mass was reduced by 49 and 78% when kernels were cultured at 15 and 35°C, respectively, compared with those grown at 30°C. At 35°C, the rate and duration of cell division in the endosperm, and the number of endosperm cells were severely reduced. In contrast, the rate of cell division decreased in kernels cultured at 15°C, but the duration was prolonged, and the number of endosperm cells formed was not affected. However, the number of starch granules initiated at 15 and 35°C was reduced by 70 and 97%, respectively. Final kernel mass was highly correlated with the number of endosperm cells (r=0.85,p≤0.01) and starch granules formed (r=0.76, p≤0.01). These data suggest that thermal regulation of the number of endosperm cells, starch granules, or both are mechanisms by which final kernel mass may be mediated. The reduction in mass of in vitro compared with field‐ or greenhouse‐grown kernels appears to be due mainly to a decline in the number of endosperm cells formed.

Physicochemical characterization of starch from hexaploid triticale (X TriticosecaleWittmack) genotypes

“…However, the lower starch contents in substituted triticales suggest that the sowing temperature would probably not have been the most appropriate for their vernalization and maturation, affecting the enzymatic synthesis and accumulation of total carbohydrates and starch. High growing temperatures adversely affect starch accumulation in barley (MacLeod & Duffus, 1988), corn (Jones, Roessler, & Ouattar, 1985;Tester, South, Morrison & Ellis, 1991) and wheat (Chowdhury & Wardlaw, 1978;Liu et al, 2011;Tester et al, 1995), leading to reduction in starch accumulation and grain size. Hurkman et al (2003) observed that high temperatures during grain filling of wheat caused a decrease in starch content primarily due to the reduction in the duration of starch accumulation.…”

Effect of High Temperature at Ripening Stage on the Reserve Accumulation in Seed in Some Rice Cultivars

“…6). In maize kernels, Jones et al (1985) reported that, starch granules per endosperm and per cell were reduced by a high temperature. Further studies are needed on the fine structural changes of translocation or accumulation system in some cereal crops.…”

Abscisic Acid Inhibition of Endosperm Cell Division in Cultured Maize Kernels

“…Randomly selected control kernels were transferred at 8 and 11 DAP to ABA-containing medium. Kernels were sampled from each treatment at 5, 9, and 12 d after start of culture (10,14,and 17 DAP). In study 4, the effect of ABA concentration in the medium was determined.…”

“…Both cell division and cell expansion may be important in determining the storage capacity of the kernel. Water or I temperature stress during early kernel development decreases the number of endosperm cells and starch granules (5,14,18,19) and also decreases dry matter accumulation (18,28). Since ABA accumulates in plant tissues subjected to water deficit and other types of stress, it is plausible that the effects of water deficit on kernel development may be due, in part, to elevated levels of ABA in the kernel.…”