Department of Biological Sciences > Faculty & Staff > Plant Sciences > Thomas L. Sims

Representative Publications

T.L. Sims & T. P. Robbins. (2008) “Gametophytic Self-Incompatibility”, in Petunia: A Model System for Comparative Research . Tom Gerats and Judith Stommer, eds. Spring, NY. Chpt 7, pp 1-22. (in press).

T.L. Sims. (2007) Mechanisms of S-RNase-based Self-Incompatiblity. CAB Reviews: Perspectives in
Agriculture, Veterinary Science, Nutrition and Natural Resources 2 No 058.

T. L. Sims (2005) Pollen recognition and rejection in different self-incompatibility systems. in Recent Research Developments in Plant Molecular Biology 2 31-62.

T.L. Sims and M. Ordanic. (2001) Identification of a S-Ribonuclease binding protein in Petunia hybrida. Plant Molecular Biology 47 771-783.

W.S. Grayburn and T.L. Sims (1998) "Anchored Oligo dT primers for automated dye terminator DNA sequencing" Biotechniques 25 340-346.

K.R. Clark, J.J. Okuley and T.L. Sims (1995) "Complete nucleotide sequence of the S1-RNase gene of Petunia hybrida" Plant Physiology 107 307-308.

Sims T.L. (1994) Molecular genetics of gametophytic self-incompatibility in Petunia hybrida. In: Genetic control of self-incompatibility and reproductive development in flowering plants. EG Williams, AE Clarke, and RB Knox, eds. Kluwer Academic Publishers, Dordrecht. pp 19-41. 

Clark KR and Sims TL (1994) The S-ribonuclease gene of Petunia hybrida is expressed in nonstylar tissue, including immature anthers. Plant Physiology 106: 25-36. 

Sims TL (1993) Genetic Regulation of Self-Incompatibility. CRC Critical Reviews in Plant Sciences 12: 129-167 

Clark KR, Okuley JJ, Collins PD and Sims TL (1990) Sequence variability and developmental expression of S-alleles in self-incompatible and pseudo-self-compatible petunia. The Plant Cell 2: 815-826

Research Interests

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My research combines molecular and classical genetics to investigate cell-cell interactions during the gametophytic self-incompatibility response of Petunia hybrida. Self-incompatibility, a genetic barrier to inbreeding in higher plants, represents a distinct case of cell-cell interaction that is amenable to molecular dissection. The essence of this barrier is the ability--mediated by the S, or self-incompatibility locus--to discriminate self pollen from non-self pollen. Pollen tubes expressing an S-allele recognition specificity identical to that expressed in the style cease growth in the upper third of the style, whereas pollen tubes lacking S-alleles in common with the style grow normally and effect fertilization. According to current models of gametophytic self-incompatibility, pollen tubes expressing (presumed) S-linked proteins are recognized as incompatible by stylar-expressed S-alleles. Following recognition, an inhibition response involving ribonuclease activity of the stylar-expressed S-RNase acts to retard further growth of incompatible pollen tubes. As yet, neither the molecular basis of S-allele recognition, nor the nature of developmental programming governing S-locus expression in pollen and styles is understood. The long term goal of our research is to understand the molecular basis for recognition events functioning in self-incompatibility. Our approach has been to clone S-locus genes encoding style and pollen recognition factors, then seek to understand how these factors interact.