Exploring Chara as a model system to study the function of homeobox genes in macroalgae

Abstract

Chara is a multicellular green algae belonging to the family Characeae. Our literature survey showed that land plants might have evolved from the Charophyceans algae. In the present investigation, we aimed to establish Chara as a model system to study the evolutionary origin of land plants. Because Chara exhibits apical cell mediated growth, and also shows the presence of plasmodesmatal connections between nodal and internodal cells, a characteristic of intracellular communication in higher plants. Homeobox gene KNOX is shown to have multipurpose role in the maintenance of shoot apical meristem in higher plants. Hence, an attempt has also been made to identify and isolate the homeobox gene in Chara, which may provide insights into the apical cell mediated growth of Chara development. In this study, sterile cultures of Chara zeylanica have been established in our lab. Germination protocol of Chara oospores has also been standardized followed by the optimization of growth of germinated sporelings aseptically. Based on the phylogenetic analysis of rbcL and 18S sequences, the species has been successfully identified and routinely cultured in the lab. Both morphological and histological observations are made and documented for our study. Since, our overall interest was to understand the role of KNOX genes in Chara, in this attempt, conserved homeodomain sequence from Chara zeylanica has been isolated and sequence verified. Isolation of full length sequence of KNOX is presently in progress.