Characterization of the effect of heat stress on maternal and embryonic tissues of maize (<i>Zea mays L.</i>) kernels using scanning electron microscopy (SEM)

Commuri, P. D.; Jones, Robert J.

doi:10.1017/s0424820100162909

Cited by 2 publications

(7 citation statements)

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“…Dissection of a subsample of these kernels revealed, however, that the apparent increase in kernel size was due mainly to increased growth of the pericarp. This response during and after exposure to HTT has been reported previously for the single cross hybrid A619 × W64A (Cheikh and Jones, 1995; Commuri, 1997; Commuri and Jones, 1996).…”

Section: Resultssupporting

confidence: 85%

High Temperatures during Endosperm Cell Division in Maize: A Genotypic Comparison under In Vitro and Field Conditions

Commuri¹,

Jones

2001

Crop Science

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126

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High temperature during endosperm cell division reduces grain yield of maize (Zea mays L.). The objective of the study was to determine if there were differences in tolerance of two inbred lines (B73 and Mo17) to exposure to brief high temperature treatments (HTTs). Beginning 5 d after pollination (DAP), kernels were exposed to a continuous 35°C temperature for either 4 or 6 d. The effects of HTTs on kernel development, ultrastructure, and sink capacity were evaluated under both in vitro and field conditions. In B73, the 4 and 6 d HTT reduced final kernel dry weights >40 to 60% under in vitro and 79 to 95% under field conditions, compared with the controls. The HTT‐induced reduction in kernel mass was due mainly to reduction in starch granule number, since by 16 DAP the endosperm cell number had recovered and was not significantly different from the controls. In contrast, in Mo17 both the number of endosperm cells and starch granules were reduced by >45 to 80% by the 4 and 6 d HTT imposed under the two growing conditions. Hence, these data and kernel ultrastructure evidence confirm that kernel development is more tolerant to high temperature in B73 than in Mo17. The difference appears to be due mainly to the ability of B73 to maintain a higher kernel sink capacity after exposure to HTT during endosperm cell division. Exploiting the differential response of these genotypes appears to be a viable approach to further elucidate the physiological basis for heat tolerance during early kernel development.

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Section: Resultssupporting

confidence: 85%

High Temperatures during Endosperm Cell Division in Maize: A Genotypic Comparison under In Vitro and Field Conditions

Commuri¹,

Jones

2001

Crop Science

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126

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“…As observed earlier (Cheikh & Jones 1995; Commuri & Jones 1996), maize kernels grown in vitro at the control temperature (25 ºC) reached maximum dry matter accumulation by 31 DAP. However, 4 and 6 d high‐temperature treatments reduced kernel mass by 40 and 77%, and increased kernel abortion by three‐ and 12‐fold, respectively (Table 1).…”

Section: Resultssupporting

confidence: 81%

“…1). Closer examination revealed that, as previously reported (Chiekh & Jones 1995; Commuri & Jones 1996), the endosperm was divided into two lobes due to intrusion of the enlarged embryo. Kernels exposed to high temperatures for 6 d were oblong and the kernel cavity appeared to be partially filled with the endosperm tissue (Fig.…”

Section: Resultssupporting

confidence: 78%

“…2C) which indicates that cell expansion may be less sensitive to elevated temperatures. In fact, this was shown to be the case with the pericarp tissue of maize kernels exposed to high temperature (Chiekh & Jones 1995; Commuri & Jones 1996). Thus, the degree reduction in peripheral endosperm cell division activity was dependent on the duration of the high‐temperature treatment.…”

Section: Resultsmentioning

confidence: 95%

“…To our knowledge, a similar type of ultrastructural characterization of maize kernels exposed to high temperature has not been reported to date. Recently, we observed that in maize kernels exposed to high temperature, the growth of the pericarp was stimulated whereas the embryos were malformed (Commuri & Jones 1996). The objective of the present study was to characterize the effects of high temperature (continuous 35 ºC) for 4 and 6 d during the endosperm cell division stage on the ultrastructure of maize kernel component tissues by using light microscopy, SEM and transmission electron microscopy (TEM).…”

Section: Introductionmentioning

confidence: 99%

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Ultrastructural characterization of maize (Zea mays L.) kernels exposed to high temperature during endosperm cell division

Commuri

Jones

1999

Plant Cell & Environment

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This study reports the ultrastructural changes in maize endosperm that result from exposure to high temperature during cell division. Kernels were grown in vitro at 25 ºC continuously (control) and at 5 d after pollination (DAP) subsamples were transferred to continuous 35 ºC for either 4 or 6 d. The 4 d treatment reduced kernel mass by 40% and increased kernel abortion three-fold. The 6-d high-temperature treatment resulted in a 77% reduction in kernel mass and a 12-fold increase in kernel abortion. Evaluation of the kernels at 11 DAP using scanning and transmission electron microscopy revealed that the reduced kernel mass and/or abortion was associated with the disruption of cell division and amyloplast biogenesis in the periphery of the endosperm. This was further confirmed by the presence of an irregular-shaped nucleus, altered size of the nucleolus, highly dense nucleoplasm, and a decrease in the number of proplastids and amyloplasts. Thus, the endosperm cavity was not filled, the total number of endosperm cells was reduced by 35 and 70%, and the number of starch granules was decreased by 45 and 80% after exposure to 4 and 6 d of high-temperature treatments, respectively. This also resulted in a 35-70% reduction in total starch accumulation. KI/I 2 staining and light microscopy revealed that starch accumulation in the peripheral endosperm cells was reduced more severely than in the central zones. However, the scanning electron micrographs of cells from the central endosperm showed that the number and the size of apparently viable amyloplasts were reduced and isolated granules were smaller and/or showed enhanced pitting. These ultrastructural data support the hypothesis that high temperature during endosperm cell division reduces kernel sink potential and subsequently mature kernel mass, mainly by disrupting cell division and amyloplast biogenesis in the peripheral and central endosperm.Key-words: Zea mays L.; amyloplast number; cell division; corn; high temperature; kernel morphology; kernel sink potential; kernel ultrastructure. INTRODUCTIONIn many of the world's maize-producing areas, high temperature is a common abiotic stress and is a major cause of decreased grain yield (Dale 1983). The thermal optimum for grain development in maize (Zea mays L.) has been shown to be between 27 and 32 ºC (Keeling & Greaves 1990; Teixiera & Jones, unpublished results). However, an average temperature of 32 ºC or more during reproductive development is common across many parts of the USA corn belt (Thompson 1968). High temperature, especially during the endosperm cell division is highly detrimental to the subsequent starch deposition and the grain yield (Jones, Gengenbach & Cardwell 1981;Jones, Ouattar & Crookston 1984;Jones, Roessler & Ouattar 1985). Elevated temperature (35 ºC) even for 3-4 d during this stage can reduce kernel mass at maturity and may even result in kernel abortion (Jones et al. 1984;Cheikh & Jones 1994). In cereal grains, kernel sink capacity is an important physiological determinant of the ...

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Characterization of the effect of heat stress on maternal and embryonic tissues of maize (Zea mays L.) kernels using scanning electron microscopy (SEM)

Cited by 2 publications

References 4 publications

High Temperatures during Endosperm Cell Division in Maize: A Genotypic Comparison under In Vitro and Field Conditions

High Temperatures during Endosperm Cell Division in Maize: A Genotypic Comparison under In Vitro and Field Conditions

Ultrastructural characterization of maize (Zea mays L.) kernels exposed to high temperature during endosperm cell division

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