|Rajeevan M S, - EMORY UNIV|
Submitted to: Society of America Plant Growth Regulator Proceedings
Publication Type: Proceedings
Publication Acceptance Date: August 6, 1994
Publication Date: N/A
Interpretive Summary: Flowering is one of the most critical processes in a plant's life, yet it is one of the least understood. Although the physiology of flowering has been well characterized in the last 50 years, there is very little known about the chemistry of the process or the genes that control it. In many of these studies the Japanese morning glory has been used as a model for floral induction since it requires only one 16h dark period to initiate flowers. The present work describes the identification of a gene product from morning glory that may represent one of the earliest genes expressed in response to floral induction. This gene (called S34) was isolated and characterized; its expression was highest in the older leaves and younger cotyledons of induced plants. Although its expression in shoot tips where flowers will ultimately be initiated was independent of induction, it still may be associated with floral initiation because its expression could be greater in the apical region where the early changes associated with flowering take place. Such a situation would be masked by the preponderance of non-apical tissues in the shoot tips. The identification and isolation of a gene potentially associated with flowering could lead to manipulation of this process in important fruits, vegetables and grains and could have significant impact on our ability to grow crops that resist frost because of early flowering or can be grown at different lattitudes because of eliminating light dependence on flower initiation, just to name a few examples.
Technical Abstract: A small (175 bp) cDNA clone (S34) was isolated by subtractive hybridization using a 1.6-fold excess of RNA from vegetative tips. By northern analysis S34 hybridized with two RNAs (1.2 kb and 750 b), the smaller of which was undetectable after a more stringent wash. Surprisingly, expression of S34 was not noticeably different between flowering and vegetative shoot tips. More detailed examination of S34 expression revealed an unusual pattern of organ specificity in which the abundance of S34 RNA decreased in the order: cotyledons older leaves younger leaves shoot tips roots. In all cases S34 expression was independent of photoperiodic induction. Southern hybridization of S34 with restriction-digested morning glory genomic DNA detected numerous bands under low stringency wash conditions and 1-3 bands under high stringency.