Modification of nitrogen remobilisation, grain fill and leaf senescence in maize (Zea mays L.) by transposon insertional mutagenensis in a protease gene

Donnison, I. S., Gay, A. P., Thomas, Howard, Edwards, K. J., Edwards, D., James, C. L., Thomas, A. M., Ougham, H. J. (2007). Modification of nitrogen remobilization, grain fill and leaf senescence in maize (Zea mays) by transposon insertional mutagenensis in a protease gene. New Phytologist, 173 (3), 481-494. Sponsorship: BBSRC RAE2008

A maize (Zea mays) senescence-associated legumain gene, See2?, 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 See2?. 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 ? 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 See2? 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.

Peer reviewed