Modification of nitrogen remobilization, grain fill and leaf senescence in maize (Zea mays) by transposon insertional mutagenesis in a protease gene.
A maize (Zea mays) senescence-associated legumain gene, See2beta, was characterized at the physiological and molecular levels to determine its role in senescence and resource allocation. A reverse-genetics screen of a maize Mutator (Mu) population identified a Mu insertion in See2beta. Maize plants homozygous for the insertion were produced. These See2 mutant and sibling wild-type plants were grown under high or low quantities of nitrogen (N). The early development of both genotypes was similar; however, tassel tip and collar emergence occurred earlier in the mutant. Senescence of the mutant leaves followed a similar pattern to that of wild-type leaves, but at later sampling points mutant plants contained more chlorophyll than wild-type plants and showed a small extension in photosynthetic activity. Total plant weight was higher in the wild-type than in the mutant, and there was a genotype x N interaction. Mutant plants under low N maintained cob weight, in contrast to wild-type plants under the same treatment. It is concluded, on the basis of transposon mutagenesis, that See2beta has an important role in N-use and resource allocation under N-limited conditions, and a minor but significant function in the later stages of senescence.
Donnison
Iain S
IS
Institute of Grassland & Environmental Research, Plas Gogerddan, Aberystwyth, Ceredigion SY23 3EB, Wales, UK.
Gay
Alan P
AP
Institute of Grassland & Environmental Research, Plas Gogerddan, Aberystwyth, Ceredigion SY23 3EB, Wales, UK.
Thomas
Howard
H
Institute of Grassland & Environmental Research, Plas Gogerddan, Aberystwyth, Ceredigion SY23 3EB, Wales, UK.
Edwards
Keith J
KJ
School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK.
Edwards
David
D
Plant Biotechnology Centre, Primary Industries Research Victoria, La Trobe University, Bundoora 3086, Victoria, Australia.
James
Caron L
CL
Institute of Grassland & Environmental Research, Plas Gogerddan, Aberystwyth, Ceredigion SY23 3EB, Wales, UK.
Thomas
Ann M
AM
Institute of Grassland & Environmental Research, Plas Gogerddan, Aberystwyth, Ceredigion SY23 3EB, Wales, UK.
Ougham
Helen J
HJ
Institute of Grassland & Environmental Research, Plas Gogerddan, Aberystwyth, Ceredigion SY23 3EB, Wales, UK.
D020029:Base Pairing; D002338:Carotenoids / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D002874:Chromosome Mapping; D004251:DNA Transposable Elements / Q000235:genetics*; D018744:DNA, Plant / Q000378:metabolism; D005091:Exons / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant; D007438:Introns / Q000235:genetics; D016254:Mutagenesis, Insertional; D009584:Nitrogen / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000235:genetics* / Q000378:metabolism; D010788:Photosynthesis; D018515:Plant Leaves / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012098:Reproduction; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D013997:Time Factors; D003313:Zea mays / Q000201:enzymology / Q000235:genetics* / Q000502:physiology*
D004251:DNA Transposable Elements; D018744:DNA, Plant; D012333:RNA, Messenger; D002734:Chlorophyll; D002338:Carotenoids; D010447:Peptide Hydrolases; D009584:Nitrogen