Kentaro Ishimaru

University of Tsukuba, Tsukuba, Ibaraki, Japan

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Publications (3)11.16 Total impact

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    ABSTRACT: To develop a new system for inducible male sterility without any modification of the floral architecture in tobacco plants, a mutated ethylene receptor gene Cm-ERS1/H70A was fused either to the tobacco Nin88 promoter known to function mainly in the tapetum and microspore or to the CaMV 35S promoter known to be a constitutive promoter. The fusion genes pNin88::Cm-ERS1/H70A and p35S::Cm-ERS1/H70A were introduced in tobacco plants, which generated two independent transformants. Transformants with 35S::Cm-ERS1/H70A produced less normal pollen and had modified floral architecture while those with Nin88::Cm-ERS1/H70A produced less normal pollen without modification of floral architecture. Histological observations of anthers at stage 2 showed that tapetum degeneration in NH70A #8 and H70A #2 transformants occurred later than in wild types, strongly indicating that the expression of the mutated gene was involved in this delay. These results suggest that the tapetum-specific expression of a mutated ethylene receptor gene is a potential strategy for inducing male sterility in transgenic plants.
    Plant Cell Reports 10/2006; 25(9):936-41. · 2.94 Impact Factor
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    ABSTRACT: A major concern about genetically modified crops is transgene flow through pollen dispersal. We previously demonstrated that overexpression of the mutated melon ethylene receptor genes Cm-ETR1/H69A or Cm-ERS1/H70A induces pollen abortion and altered flower architecture, resulting in sterility or reduced fertility in transgenic tobacco plants. To investigate the stability of these traits, three transgenic tobacco lines in which Cm-ETR1/H69A or Cm-ERS1/H70A confer sterility or reduced fertility were grown in a greenhouse with environmental conditions that changed, depending on the outside conditions. During the growth of the plants, the temperature ranged from 31°C at the beginning of September to 17°C at the beginning of November. The light provided was natural sunlight. The first group of plants flowered in late September, and the second group flowered in late October. The wild-type plants showed the homostyly type of floral architecture, whereas, three transgenic lines showed the heterostyly type. The floral architecture was stable during the different flowering periods. Pollen production was significantly reduced in two transgenic lines and completely aborted in one transgenic line, and these traits were also stable during the different flowering periods. These results suggest that the sterility or reduced fertility induced by the expression of mutated melon ethylene receptor genes in transgenic tobacco plants is stable under varying environmental conditions.
    Plant Science 09/2006; 171(3):355-9. · 4.11 Impact Factor
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    ABSTRACT: To investigate the role of an ethylene receptor gene in plant reproduction, we introduced a mutated melon ethylene receptor gene, Cm-ETR1/H69A, into tobacco plants and generated 11 independent transformants. In 5 of the 11 transformants, the flower longevities were longer than that of the wild type, indicating that the transformants had a reduced sensitivity to ethylene than the wild type. The seed yields of these transformants were lower than those of the wild-type plants. The reduced seed yields were mainly caused by abnormal stamen development, modification of floral architecture, and reduced pollen production. Filament elongation was reduced in the transformants, resulting in the heterostyly type of floral architecture. Histological observation of anthers at several developmental stages showed that in transgenic plants, tapetum degeneration occurred later than in the wild type. These results suggest that stamen development is related to ethylene sensitivity.
    Plant Science 11/2005; · 4.11 Impact Factor