Nandy et al., Cell Dev Biol 2013, 2:2 DOI: 10.4172/2168-9296.1000117 Volume 2 • Issue 2 • 1000117 Cell Dev Biol ISSN: 2168-9296 CDB, an open access journal Open Access Research Article Over-expression of Arginine Decarboxylase Gene in Tapetal Tissue Results in Male Sterility in Tomato Plants Soumen Nandy, Ranjita Sinha and Manchikatla V Rajam* Plant Polyamine, Transgenic and RNAi Research Laboratory, Department of Genetics, University of Delhi South Campus, India Abstract Homeostasis of cellular Polyamines (PAs) is very important for proper growth and development of living organisms. Development of male sex organ and gametophyte in plants is a complex process involving many known and unknown pathways. PAs are actively involved in the development of anther and pollen. In the present study, oat arginine decarboxylase (ADC) gene has been over-expressed in tapetum of tomato using tapetum-specifc TA29 promoter to perturb the PA homeostasis in order to see its implication on male fertility. Tapetum-specifc ADC over- expression resulted in PA accumulation, mainly in free and bound fractions in the anther of transgenics. Transgenic lines displayed abnormal pollen and tapetum development. Pollen grains were aborted and distorted in morphology and tapetum showed premature degeneration in ADC transgenics. These transgenics failed to set seeds, but cross pollination with normal pollen from wild type plants restored the seed setting indicating that s ADC over-expression did not affect female fertility. ADC over-expression also did not affect the growth and morphology of transgenics. The present study suggests that the excess of PAs in anther is lethal for pollen and tapetum development and over- expression of ADC gene can be an effective approach for the engineering of male sterility in plants. *Corresponding author: MV Rajam, Plant Polyamine, Transgenic and RNAi Research Laboratory, Department of Genetics, University of Delhi South Campus, Benito Juarez Road, New Delhi 110021, India, Fax: 91-1124112437; E-mail: rajam.mv@gmail.com Received May 23, 2013; Accepted May 24 2013; Published May 27, 2013 Citation: Nandy S, Sinha R, Rajam MV (2013) Over-expression of Arginine Decarboxylase Gene in Tapetal Tissue Results in Male Sterility in Tomato Plants. Cell Dev Biol 2: 117. doi:10.4172/2168-9296.1000117 Copyright: © 2013 Nandy S, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Keywords: Polyamine; Arginine decarboxylase; Tapetum; Pollen development; Male sterility; Transgenic plants; Solanum lycopersicum Introduction Polyamines (PAs), the low molecular weight, poly-cationic nitrogenous compounds are widely distributed in all the organisms. Putrescine (Put), Spermidine (Spd) and Spermine (Spm) are major PAs and they have been implicated in regulation of several important physiological and molecular processes including cell division, growth and development, fower and fruit development, stress responses, membrane integrity, senescence, stabilization of DNA, gene expression and many other cellular functions [1-6]. In animals and fungi, the essential Put, the precursor of the higher PAs, Spd and Spm is synthesized directly from ornithine by the enzyme Ornithine Decarboxylase (ODC). Plants and bacteria have an alternative route to the production of Put from arginine, which is catalyzed by Arginine Decarboxylase (ADC). Additional reactions convert Put into Spd and Spm. Tese steps are catalyzed by Spd and Spm synthases, which add propylamino group generated from S-adenosylmethionine (SAM) by SAM decarboxylase (SAMDC). Diamine oxidase (DAO) and Polyamine Oxidase (PAO) are involved in the degradation of diamines (Put) and PAs (Spd and Spm), respectively [2]. Pollen represents the entire male gametophyte. Its potential uses in genetic transformation and breeding programs have encouraged researchers to study pollen development in depth [7-9]. In fowering plants, development and maturation of pollen takes place in anthers. It starts with the meiosis of Pollen Mother Cells (PMC) to make haploid tetrad in the locule of anther. Haploid tetrad then gets released as uninucleate microspores [9] with the help of callase, an enzyme produced by tapetum. Tapetum is the innermost and most nutritive sporophytic tissue of the anther [10]. Further in the development process, uninucleate microspores undergo asymmetric division and forms bicellular pollen with a larger vegetative cell and a smaller generative cell [9]. Maturation of pollen grain is the fnal process in pollen development. A number of changes take place in the cytoplasm, including the deposition of reserve material and dehydration of the pollen grain. In addition, several changes occur at the surface of the pollen wall such as the deposition of substances involved in pollen- pistil interaction. Various changes also occur in the nourishing layer of the anther, i.e., the tapetum to support the pollen maturation [11]. Tapetum provides various nutrients, enzymes and other molecules for the pollen development. During late pollen developmental stage, tapetum undergoes Program Cell Death (PCD) mediated degeneration (apoptosis) and releases the nutrients into anther locule. Te signifcance of the tapetum in pollen development is evident from the facts that any abnormality in this tissue directly afects the male fertility of the plant [10]. In addition, timely apoptotic degeneration of the tapetum is also crucial for male fertility as abolition of apoptosis or premature PCD mediated degeneration [12,13] of tapetum results in male sterility. Tis indispensable involvement of tapetum in pollen development, encouraged the study of various tapetum- specifc genes, promoters [14,15] and also elucidation of the functioning of tapetum [16-20]. Furthermore, various strategies, viz. expression of cytotoxic gene in tapetum, tapetum-specifc down-regulation of genes involved in pollen development, abolition of PCD-mediated degeneration of tapetum, etc. have been adopted to genetically engineer male sterility in crops [21-25]. PAs are well associated with the anther and male gametophyte development. Te necessity of the PAs for pollen maturation, germination and tube growth has been examined by various experiments using PAs and their inhibitors in in vitro germination and also ex-vivo applications [26-29]. It has also been observed that decrease in PA levels in foral organs causes male sterility [25,29,30,31]. Interestingly, elevated levels of PAs are also seen to be associated with abnormal stamen development [32,33], pollen degeneration [34] and delayed C e l l & D e v e l o p m e n t a l B i o l o g y ISSN: 2168-9296 Cell & Developmental Biology