Abstract
Leaf primordia of the lam-1 mutant of Nicotiana sylvestris grow normally in length but remain bladeless throughout development. The blade initiation site is established at the normal time and position in lam-1 primordia. Anticlinal divisions proceed normally in the outer L1 and L2 layers, but the inner L3 cells fail to establish the periclinal divisions that normally generate the middle mesophyll core. The lam-1 mutation also blocks formation of blade mesophyll from distal L2 cells. This suggests that LAM-1 controls a common step in initiation of blade tissue from the L2 and L3 lineage of the primordium. Another recessive mutation (fat) was isolated in N. sylvestris that induces abnormal periclinal divisions in the mesophyll during blade initiation and expansion. This generates a blade approximately twice its normal thickness by doubling the number of mesophyll cell layers from four to approximately eight. Presumably, the fat mutation defines a negative regulator involved in repression of periclinal divisions in the blade. The lam-1 fat double mutant shows radial proliferation of mesophyll cells at the blade initiation site. This produces a highly disorganized, club-shaped blade that appears to represent an additive effect of the lam-1 and fat mutations on blade founder cells.
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Selected References
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- Freeling M. A conceptual framework for maize leaf development. Dev Biol. 1992 Sep;153(1):44–58. doi: 10.1016/0012-1606(92)90090-4. [DOI] [PubMed] [Google Scholar]
- Hake S., Vollbrecht E., Freeling M. Cloning Knotted, the dominant morphological mutant in maize using Ds2 as a transposon tag. EMBO J. 1989 Jan;8(1):15–22. doi: 10.1002/j.1460-2075.1989.tb03343.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Smith L. G., Greene B., Veit B., Hake S. A dominant mutation in the maize homeobox gene, Knotted-1, causes its ectopic expression in leaf cells with altered fates. Development. 1992 Sep;116(1):21–30. doi: 10.1242/dev.116.1.21. [DOI] [PubMed] [Google Scholar]
- Smith L. G., Hake S. The Initiation and Determination of Leaves. Plant Cell. 1992 Sep;4(9):1017–1027. doi: 10.1105/tpc.4.9.1017. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Szymkowiak E. J., Sussex I. M. The internal meristem layer (L3) determines floral meristem size and carpel number in tomato periclinal chimeras. Plant Cell. 1992 Sep;4(9):1089–1100. doi: 10.1105/tpc.4.9.1089. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Vollbrecht E., Veit B., Sinha N., Hake S. The developmental gene Knotted-1 is a member of a maize homeobox gene family. Nature. 1991 Mar 21;350(6315):241–243. doi: 10.1038/350241a0. [DOI] [PubMed] [Google Scholar]
- Wang X. D., de Boer P. A., Rothfield L. I. A factor that positively regulates cell division by activating transcription of the major cluster of essential cell division genes of Escherichia coli. EMBO J. 1991 Nov;10(11):3363–3372. doi: 10.1002/j.1460-2075.1991.tb04900.x. [DOI] [PMC free article] [PubMed] [Google Scholar]