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Type: Journal article
Title: α-Amylase and programmed cell death in aleurone of ripening wheat grains
Other Titles: alpha-Amylase and programmed cell death in aleurone of ripening wheat grains
Author: Mrva, K.
Blesing, M.
Mares, D.
Citation: Journal of Experimental Botany, 2006; 57(4):877-885
Publisher: Oxford Univ Press
Issue Date: 2006
ISSN: 0022-0957
Statement of
Kolumbina Mrva, Meredith Wallwork and Daryl J. Mares
Abstract: Late maturity α-amylase (LMA) in wheat is a genetic defect that may result in the accumulation of unacceptable levels of high pI α-amylase in grain in the absence of germination or weather damage. During germination, gibberellin produced in the embryo triggers expression of α-Amy genes, the synthesis of α-amylase and, subsequently, cell death in the aleurone. LMA also involves the aleurone and whilst LMA appears to be independent of the embryo there is nevertheless some evidence that gibberellin is involved. The aim of this investigation was to determine whether the increase in α-amylase activity in LMA-prone genotypes, like α-amylase synthesis by aleurone cells in germinating or GA-challenged grains, is followed by aleurone cell death. Programmed cell death was seen in aleurone layers from developing, ripe and germinated grains using confocal microscopy and fluorescent probes specific for dead or living cells. Small pockets of dying cells were observed distributed at random throughout the aleurone of ripening LMA-affected grains and by harvest-ripeness these cells were clearly dead. The first appearance of dying cells, 35 d post-anthesis, coincided with the later part of the ‘window of sensitivity’ in grain development in LMA-prone wheat cultivars. No dead or dying cells were present in ripening or fully ripe grains of control cultivars. In germinating grains, dying cells were observed in the aleurone adjacent to the scutellum and, as germination progressed, the number of dead cells increased and the affected area extended further towards the distal end of the grain. Aside from the obvious differences in spatial distribution, dying cells in 20–24 h germinated grains were similar to dying cells in developing LMA-affected grains, consistent with previous measurements of α-amylase activity. The increase in high pI α-amylase activity in developing grains of LMA-prone cultivars, like α-amylase synthesis in germinating grains, is associated with cell death, providing further evidence for the involvement of gibberellin in the LMA response.
Keywords: Aleurone layer; cell viability; germination; late maturity α-amylase; wheat
RMID: 0020060024
DOI: 10.1093/jxb/erj072
Appears in Collections:Agriculture, Food and Wine publications

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