Srivignesh Sundaresan

Aims: The study's objective is to develop lignosulfonate-based nanocarriers as a UV protectant for agrochemical delivery Place and Duration of Study: Department of Nano Science & Technology, Tamil Nadu Agricultural University, Coimbatore. The research was carried out between March 2021 and January 2022. Methodology: We demonstrate a straightforward approach for the solvent – anti-solvent conversion of lignosulfonate macromolecules from black liquor derived from the paper pulping industry to nanocarriers. Due to the amphiphilic nature of lignin, nanoparticles are generated by self-assembly. To create lignin nanoparticles, a drop-by-drop solvent exchange approach has been used. The lignosulfonate solution was prepared using solvents such as ethanol and tetrahydrofuran, and then water was added as an antisolvent, resulting in the creation of nanoparticles by self-assembly. The hydrophobic portion of lignin creates the particle's core, while the hydrophilic hydroxyl groups form ...

Background The KNOTTED1-LIKE HOMEOBOX PROTEIN1 ( KD1 ) gene is highly expressed in flower and leaf abscission zones (AZs). RNA-antisense silencing of KD1 was shown to delay tomato pedicel and petiole abscission, induced by flower or leaf removal, respectively. KD1 was found to regulate flower pedicel abscission via alteration of auxin gradient through the flower AZ (FAZ), and disruption of the auxin response at the early stages of the abscission process. The present work was aimed to further understand how KD1 regulates signaling factors and regulatory genes involved in the delay of pedicel abscission using the silenced KD1 lines. For this purpose we performed a large scale transcriptome profiling of the FAZ at various time points after flower removal, using a customized AZ-specific microarray. Results The results highlighted a differential expression of regulatory genes in the FAZ of KD1 -silenced plants compared to the wild type (WT). These genes were controlled by KD1 before and ...

A laboratory study was undertaken to determine the effects of a nano-emulsion carrying hexanal, an enhanced freshness formulation (EFF), as a post-harvest dip technology to minimize the post-harvest losses and to extend the shelf life of bananas. The banana fruits were harvested at three maturities (95%, 85%, and 75%), dipped or not dipped in the EFF, and studied under both ambient and reduced temperature storage conditions. During the experiments, the fruit’s physical, physiological, and biochemical parameters were periodically evaluated. The treated fruit had lower physiological loss of weight and higher firmness throughout the study period, regardless of maturity level at the start. Treated fruit had higher total soluble solids and total sugars, and less acidity indicating improved fruit quality during storage, in addition to an extended shelf life. High resolution imaging using scanning electron microscopy showed that EFF-treated fruit exhibited well maintained structural lentic...

Abscission of plant organs is a key process during plant life cycle and prerequisite factor involved in limiting the spread of disease, shedding of un-pollinated flowers and facilitates dispersal of seeds. In an agricultural context, abscission may become a major limiting factor for crop productivity. The organs abscise at a specific position called Abscission zone (AZ) and it is one of the prime traits to be manipulated during the crop improvement process towards the selection of reduced abscission lines. The tomato abscission polygalacturonase (TAPG) genes are abscission induced polygalacturonases and specifically induced in the AZ, which plays a major role in AZ separation. The current study had accentuated to identify the entire polygalacturonase gene families in tomato AZs, through AZ specific customized microarray. The results revealed that TAPG1, 2, 5, 7 and TPG6, PS2 genes were specifically induced and continuously overexpressed linearly along with abscission progression in tomato flower AZ. Similarly, the same set of genes were up-regulated upon abscission induction at the early hours (24 h) in the leaf AZ, indicating potential involvement in organ abscission. Our study provides new insights for the regulation of the early events in the process of tomato organ abscission and a novel trait for molecular breeding.

The Tomato Hybrid Proline-rich Protein () gene was specifically expressed in the tomato () flower abscission zone (FAZ), and its stable antisense silencing under the control of an abscission zone (AZ)-specific promoter, , significantly inhibited tomato pedicel abscission following flower removal. For understanding the THyPRP role in regulating pedicel abscission, a transcriptomic analysis of the FAZ of -silenced plants was performed, using a newly developed AZ-specific tomato microarray chip. Decreased expression of in the silenced plants was already observed before abscission induction, resulting in FAZ-specific altered gene expression of transcription factors, epigenetic modifiers, post-translational regulators, and transporters. Our data demonstrate that the effect of silencing on pedicel abscission was not mediated by its effect on auxin balance, but by decreased ethylene biosynthesis and response. Additionally, silencing revealed new players, which were demonstrated for the fir...

Abscission of organs from the plant is initiated by changes in the auxin gradient across the abscission zone (AZ) which sensitizes the AZ to ethylene. Changes in gene expression have been correlated with the ethylene-mediated execution of abscission, but there has been little study of the molecular and biochemical basis of the role of auxin depletion. After excising flowers or leaves from tomato (Solanum lycopersicum Mill.) inflorescences, leading to rapid pedicel or petiole abscission, respectively, we examined transcriptome changes in the flower and leaf AZs. Microarray analysis using the Affymetrix Tomato GeneChip revealed changes in expression, occurring prior to and during pedicel or petiole abscission, of many genes with possible regulatory functions. They included a range of auxin-related transcription factors (TFs) such Aux/IAA genes, ethylene biosynthesis related and ethylene signal transduction related genes. IAA application after flower or leaf removal, which prevented pe...

TRANSCRIPTOME ANALYSIS OF THE TOMATO FLOWER AND LEAF ABSCISSION ZONES, USING A CUSTOMIZED ABSCISSION ZONE MICROARRAY Sundaresan, S1, 2, Philosoph-Hadas, S1, Riov, J1, Kochanek, B1, Mugasimangalam, R3 and Meir, S1 )srivignesh@volcani.agri.gov.il) 1 Agricultural Research Organization (ARO), The Volcani Center, Bet-Dagan, Israel 2 The Robert H. Smith Faculty of Agriculture, Food & Environment, The Hebrew University of Jerusalem, Rehovot, Israel 3 Genotypic Technology Private Limited, Bangalore, India Organ abscission is initiated by decreased auxin activity and increased ethylene production in the abscission zone (AZ). We used a new approach to reveal the transcriptomic changes in tomato flower and leaf AZs (FAZ and LAZ, respectively), by designing a customized AZ-specific microarray chip. The chip includes transcripts from the Next Generation Sequencing (NGS) of RNA isolated from tomato AZs at various times during abscission, SOL genomics network database, and NCBI. The results show t...

Abscission is a highly regulated process of cell separation, by which plants are able to shed their organs. Abscission is initiated by decreased auxin activity and increased ethylene production, as well as increased sensitivity to ethylene in the abscission zone (AZ) cells. In the present study we used a new approach to identify novel transcripts in tomato (Solanum lycopersicum) flower and leaf AZs (FAZ and LAZ, respectively) at various stages of abscission, by designing a customized AZ-specific microarray chip. This chip was based on 176,026 probes, including transcripts from the Next Generation Sequencing (NGS) of RNA isolated from tomato AZs at various times during abscission and public domain data bases (NCBI-RefSeq, SOL genomics network). Both sense and antisense probes were included for all the transcripts. The results are deposited at the following databases: AMADID ID - 043310; NCBI GEO ID - GSE45355 (for FAZ), and GSE45356 (for LAZ). As expected, several auxin-related genes...

Plant organ abscission is initiated by changes in the auxin gradient across the abscission zone (AZ), which sensitizes it to ethylene. Changes in gene expression were correlated with the ethylene-mediated execution of abscission, but the molecular and biochemical basis of the role of auxin depletion was hardly studied. After excising flowers or leaves from tomato (Solanum lycopersicum Mill.) inflorescences, leading to rapid pedicel or petiole abscission, respectively, we examined transcriptome changes in the flower and leaf AZs. Microarray analysis using the Affymetrix Tomato GeneChip revealed changes in expression, occurring prior to and during pedicel or petiole abscission, of many genes with possible regulatory functions. They included auxin-related transcription factors (TFs) such as Aux/IAA genes, ethylene biosynthesis and signal transduction related genes. IAA application after flower or leaf removal, which prevented pedicel or petiole abscission, respectively, diminished thes...

Ethylene enhances flower abscission in various systems. The pH-sensitive, intracellularly trapped dye, 2',7'-bis-(2-carboxyethyl)-5(and-6)-carboxyfluorescein (BCECF) acetoxymethyl (AM) ester derivative was used, combined with confocal microscopy, to characterize the pH regulation in the flower abscission zone (AZ) following ethylene treatment. A specific and gradual increase in the cytosolic pH of AZ cells was observed during the natural abscission process of flower organs in Arabidopsis thaliana and wild rocket (Diplotaxis tenuifolia). This increased or inhibited alkalinization, paralled acceleration by ethylene or inhibition by 1-methylcyclopropene (1-MCP) of flower organ abscission, respectively in wild rocket. Similarly, 1-MCP pretreatment of tomato explants abolished the pH increase induced in AZ cells by flower removal, as well as the abscission of the remaining pedicels. Also, delayed alkalinization was observed in the flower organ AZs of Arabidopsis mutants showing d...

Abscission of organs from the plant is initiated by changes in the auxin gradient across the abscission zone (AZ) which sensitizes the AZ to ethylene. Changes in gene expression have been correlated with the ethylene-mediated execution of abscission, but there has been little study of the molecular and biochemical basis of the role of auxin depletion. After excising flowers from tomato ( Solanum lycopersicum Mill.) inflorescences, leading to rapid pedicel abscission, we examined transcriptome changes in the flower AZ. Microarray analysis using the Affymetrix Tomato GeneChip revealed changes in expression, occurring prior to and during pedicel abscission, of many genes with possible regulatory functions. They included a range of auxin-related transcription factors (TFs) such as seven AUX/IAA genes, supporting the suggestion that auxin depletion is an important mediator of the abscission response. In addition, several ethylene-related and other TFs showed transient up-regulation just ...

In vivo changes in the cytosolic pH of abscission zone (AZ) cells were visualized using confocal microscopic detection of the fluorescent pH-sensitive and intracellularly trapped dye, 2',7'-bis-(2-carboxyethyl)-5(and-6)-carboxyfluorescein (BCECF), driven by its acetoxymethyl ester. A specific and gradual increase in the cytosolic pH of AZ cells was observed during natural abscission of flower organs in Arabidopsis thaliana and wild rocket (Diplotaxis tenuifolia), and during flower pedicel abscission induced by flower removal in tomato (Solanum lycopersicum Mill). The alkalization pattern in the first two species paralleled the acceleration or inhibition of flower organ abscission induced by ethylene or its inhibitor 1-methylcyclopropene (1-MCP), respectively. Similarly, 1-MCP pre-treatment of tomato inflorescence explants abolished the pH increase in AZ cells and pedicel abscission induced by flower removal. Examination of the pH changes in the AZ cells of Arabidopsis mutant...