Honors Theses

Date of Award


Document Type

Undergraduate Thesis



First Advisor

Sarah Liljegren

Relational Format



The fruit are an integral plant organ that function to nurture and disperse seeds. Â Using the model species Arabidopsis thaliana, the genetic mechanisms underlying fruit development have been carefully studied. Â The Arabidopsis fruit originates from the female reproductive organ, the gynoecium, which consists of two carpels that develop into the ovary with a style and stigma. Â Proper formation of the fruit relies on a functional floral meristem and on the specification of boundary regions that arise between the carpel walls and a medial replum. Â Two genes known to affect both the development of organ boundaries in the flower as well as meristem maintenance are SHOOT MERISTEMLESS (STM) and the ARABIDOPSIS THALIANA HOMEOBOX GENE1 (ATH1). Â STM and ATH1 encode transcription factors from the homeodomain family. Â Combined mutations in the STM and ATH1 genes blur the boundaries formed between the floral organs and the underlying stem. To explore the functions of STM and ATH1 during fruit development, I analyzed the size and structure of stm, ath1, and stm ath1 mutant fruit compared to wildtype. Since STM is essential for maintenance of the stem cell population in shoot meristems, I expected that the size of stm single and stm ath1 double mutant fruit would be reduced. Â If the STM and ATH1 genes also have redundant roles in boundary formation in the fruit, I expected to see possible alterations in the structure of double mutant fruit. Â To quantify fruit growth defects of the single and double mutants compared to wildtype fruit, I measured the length and width of fruit, and determined the number of carpels present. I found that the majority of stm ath1 flowers did not produce a fruit and that the size of the stm ath1 double mutant fruit present was severely reduced. Furthermore, the double mutant flowers exhibited a diverse array of unusual carpel-derived structures, some of which may be related to defects in boundary formation. My results indicate that the STM and ATH1 genes have redundant functions during fruit development.

Included in

Biology Commons



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