US EPA

2968706 

Journal Article 

Effects of P(SAG12)-IPT gene expression on development and senescence in transgenic lettuce 

Mccabe, MS; Garratt, LC; Schepers, F; Jordi, WJ; Stoopen, GM; Davelaar, E; van Rhijn, JH; Power, JB; Davey, MR 

2001 

1 

Plant Physiology
ISSN: 0032-0889
EISSN: 1532-2548 

Plant physiology 

127 

2 

505-516 

English 

11598225 

10.1104/pp.127.2.505 

WOS:000172144500016 

https://search.proquest.com/docview/218635157?accountid=171501
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An ipt gene under control of the senescence-specific SAG12 promoter from Arabidopsis (P(SAG12)-IPT) significantly delayed developmental and postharvest leaf senescence in mature heads of transgenic lettuce (Lactuca sativa L. cv Evola) homozygous for the transgene. Apart from retardation of leaf senescence, mature, 60-d-old plants exhibited normal morphology with no significant differences in head diameter or fresh weight of leaves and roots. Induction of senescence by nitrogen starvation rapidly reduced total nitrogen, nitrate, and growth of transgenic and azygous (control) plants, but chlorophyll was retained in the lower (outer) leaves of transgenic plants. Harvested P(SAG12)-IPT heads also retained chlorophyll in their lower leaves. During later development (bolting and preflowering) of transgenic plants, the decrease in chlorophyll, total protein, and Rubisco content in leaves was abolished, resulting in a uniform distribution of these components throughout the plants. Homozygous P(SAG12)-IPT lettuce plants showed a slight delay in bolting (4-6 d), a severe delay in flowering (4-8 weeks), and premature senescence of their upper leaves. These changes correlated with significantly elevated concentrations of cytokinin and hexoses in the upper leaves of transgenic plants during later stages of development, implicating a relationship between cytokinin and hexose concentrations in senescence. 

Biology--Botany; Arabidopsis Proteins; Cytokinins; Hexoses; Nitrogen Compounds; Plant Proteins; RNA, Plant; Chlorophyll; Alkyl and Aryl Transferases; adenylate isopentenyltransferase; SAG12 protein, Arabidopsis; Cysteine Endopeptidases; Plant Proteins -- metabolism; Nitrogen Compounds -- metabolism; Plant Proteins -- biosynthesis; Chlorophyll -- biosynthesis; Cytokinins -- biosynthesis; Lettuce -- growth & development; Arabidopsis -- metabolism; Cysteine Endopeptidases -- metabolism; Arabidopsis Proteins -- metabolism; Alkyl & Aryl Transferases -- metabolism; Chlorophyll -- metabolism; Plants, Genetically Modified; Gene Expression Regulation, Plant; Hexoses -- biosynthesis; RNA, Plant -- biosynthesis; Nitrogen Compounds -- pharmacology; Plant Leaves -- growth & development; Plant Leaves -- genetics; Genes, Reporter; Apoptosis; Lettuce -- genetics; Cysteine Endopeptidases -- genetics; Alkyl & Aryl Transferases -- genetics; Arabidopsis -- genetics; Arabidopsis Proteins -- genetics