Original Research ARTICLE
Nexus between spermidine and floral organ identity and fruit/seed set in tomato
- 1Purdue University, United States
- 2University of Georgia, United States
- 3Beltsville Agricultural Research Center, Agricultural Research Service (USDA), United States
Polyamines (PAs) constituting putrescine (Put), spermidine (Spd) and spermine (Spm) are ubiquitous in all organisms and play essential roles in the growth and developmental processes in living organisms, including plants. Evidences obtained through genetic, biochemical and transgenic approaches suggest a tight homeostasis for cellular PA levels. Altered cellular PA homeostasis is associated with abnormal phenotypes. However, the mechanisms involved for these abnormalities are not yet fully understood, nor is it known whether cellular ratios of different polyamines play any role(s) in specific plant processes. We expressed a yeast spermidine synthase gene (ySpdSyn) under a constitutive promoter CaMV35S in tomato and studied the different phenotypes that developed. The constitutive expression of ySpdSyn resulted in variable flower phenotypes in independent transgenic lines, some of which lacked fruit and seed set. Quantification of PA levels in the developing flowers showed that the transgenic plants without fruit and seed set had significantly reduced Spd levels as well as low Spd/Put ratio compared to the transgenic lines with normal fruit and seed set. Transcript levels of SlDELLA, GA-20oxidase-1 and GA-3oxidase-2, which impact gibberellin (GA) metabolism and signaling, were significantly reduced in bud tissue of transgenic lines that lacked fruit and seed set. Thus, we opine that PAs, particularly Spd, impact floral organ identity and fruit set in tomato involving GA metabolism and signaling. Further, we suggest that a nexus exists between PA ratios and developmental programs in plants.
Keywords: Polyamine, Seed-set, Parthenocarpy, gibberellin, Trasgenic, Tomato
Received: 14 Mar 2019;
Accepted: 24 Jul 2019.
Copyright: © 2019 Handa, Nambeesan and Mattoo. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Prof. Avtar K. Handa, Purdue University, West Lafayette, United States, email@example.com