Expression of the malate synthase (MS) gene is activated in cotyledons of cucumber seedlings during postgerminative growth and then repressed as the cotyledons become photosynthetic. MS gene expression is subsequently reactivated in the cotyledons as they senesce a few weeks later. In situ hybridization revealed that MS RNA is distributed throughout the organ during postgerminative growth and senescence, showing that the same cells express the gene at different stages of development. MS RNA also appears in senescing leaves and petals of cucumber plants. In addition, we found that MS RNA appears in mature expanded leaves and roots when they are removed from the plant and incubated in darkness for several days, thus providing a potential experimental system for the manipulation of MS gene expression. Leaves from transgenic Nicotiana plumbaginifolia containing the cucumber MS promoter fused to the beta-glucuronidase (GUS) reporter gene accumulated GUS activity when detached, demonstrating an activation of transcription from the MS promoter following leaf excision. These results are discussed in terms of the metabolic regulation of MS gene expression.

Item Type:	Refereed Article
Keywords:	malate synthase, cucumber, senescence
Research Division:	Biological Sciences
Research Group:	Plant Biology
Research Field:	Plant Physiology
Objective Division:	Expanding Knowledge
Objective Group:	Expanding Knowledge
Objective Field:	Expanding Knowledge in the Biological Sciences
Author:	Smith, SM (Professor Steven Smith)
ID Code:	101593
Year Published:	1992
Deposited By:	Plant Science
Deposited On:	2015-06-26
Last Modified:	2015-09-24
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