3rd Global Summit on Plant Science August 07-09, 2017 Rome, Italy

Biography:

Leon Daniel van Rensburg is a soil physicist lecturing soil and water management at the University of the Free State, South Africa. He established and maintained a vibrate post-graduate research team, which currently consisted of 2 post-doctoral fellows, 4 doctoral students and 8 master students. The team focus mainly on soil and water management off dryland, irrigation as well as natural field and they published in the last 6 years about 45 scientific articles. He is leading two projects of national importance for South Africa, viz. (i) Management guidelines for technology transfer to reduce salinisation of irrigated land with precision agriculture funded by the Water Research Commission and (ii) the soil water balance of the Ghaap Platue as influenced by open cast mining funded by Sishen Iron Ore Company (Anglo American Kolomela). Both projects are scheduled for five years.

Abstract:

Biography:

Arooran Kanagendran is following his PhD in Plant Ecophysioogy at the Estonian University of Life Sciences, Estonia under the supervision of Professor Ülo Niinemets. His main research interests are in terpene molecular biology and emission in higher plants. He did his masters in Molecular Biology at the University of Hertfordshire, UK

Abstract:

Statement of the Problem: Ozone is a phytotoxic compound often encountered at increased levels in the atmosphere. However, the immediate and longer-term impact of ozone exposure on plant volatile release is poorly understood. Methodology & Theoretical Orientation: Tobacco (Nicotiana  tabacum cv. Wisconsin) leaves were exposed to acute ozone doses of 0 (control), 400, 600, 800, and 1000 ppb for 30 min and we studied the effects of ozone exposure on ozone uptake, gas exchange properties, emission of lipoxygenase pathway (LOX) volatiles, mono- and sesquiterpenes, and expression of a monoterpene synthase. Findings: foliage net assimilation rate and stomatal conductance to water vapor, were curbed with the severity of ozone exposure. Ozone exposure enhanced emissions of LOX volatiles dominated by hexanal, and also altered the emission blend of foliage monoterpenes dominated by limonene and foliage sesquiterpenes dominated by α-caryophyllene compared with control leaves. A relative expression of a monoterpene synthase gene, camphene synthase, was downregulated immediately after exposure to 400, 600, and 800 ppb ozone but it was upregulated at 1000 ppb of ozone. A time-delay analysis of camphene synthase gene expression and product emission indicated that with a 3-hour delay, the emissions and gene expression were highly correlated, suggesting that there was a time-lag of at least 3 h from signal transduction and gene expression to formation of the terpene synthase protein. Conclusion & Significance: This study reveals foliage emission of LOX in response to acute ozone exposure was quantitatively related to the severity of ozone exposure. However, the stress dose vs. emission relationship was not observed for mono-and sesquiterpene emissions. There was a time-delay of minimum 3 h from signal transduction to formation of the terpene synthase protein for monoterpene synthases but further studies are needed to gain insight into how TPS genes are regulated upon acute ozone stress.

Biography:

Plants constantly encounter a wide range of diseases, leading to tremendous crop losses. Plant bacterial wilt (BW), caused by Ralstonia solanacearum, is a deadly and complex soil-borne vascular disease of many agronomically important crops worldwide. Control for this disease via traditional practices has been very ineffective. To gather important information and resources potentially useful for disease control, our researches aim to gain insights into molecular mechanisms and signaling pathways involved in the interactions among plants, R. solanacearum and biocontrol agents. Through systematic genomic screening, we currently focus on studying the functions and the involved mechanisms of a group of plant and R. solanacearum genes which play crucial roles in plant-pathogen interactions. In addition, resources have been collecting from tentative biocontrol agents, including bacteriophages and symbiotic fungi.

Abstract:

Bacterial wilt (BW) caused by Ralstonia solanacearum (Rs) is a devastating disease of many crops, and breeding for durable resistance is urgent and important for disease control. Tomato cultivar Hawaii 7996 (H7996) is currently the most stable resistance source for BW control. Although various BW-resistance-associated quantitative trait loci (QTLs) have been mapped on H7996 chromosomes, the involved molecular mechanisms and the gene identities remain undetermined. Our studies showed that H7996 possesses strong PTI responses, and the major QTL associated with the H7996 resistance against Rs phylotype I strains, namely Bwr12, is involved in PTI. Functional genetic and gene expression analyses further revealed positive roles of Bwr12-A and Bwr12-B in PTI and defense against distinct pathogens. Transient expression assay suggested that 12g520 localizes on the plasma membrane of Nicotinana benthamiana (Nb), while 12g550 might localize on the cell membrane, nucleus or be secreted to the apoplast. Overexpression of 12g550 in transgenic Nb increased H₂O₂ accumulation and resistance to Rs and Pectobacterium carotovorum subsp. carotovorum (Pcc). In addition, 12g520 might not interact with SlSERK3A, SlSERK3B, and SlFLS2 under normal conditions. These results along with future studies are projected to shed light on H7996 defense mechanisms.

Biography:

Federica Della Rovere investigated the mechanisms affecting the initiation and development of adventitious roots in planta and in vitro systems, with a special interest in the genetic control affecting this organogenic process and in particular the definition of stem cell niche of the apical root meristem in Arabidopsis. Another interest is about the somatic embryogenic process in numerous species, and the genetic and hormonal control involved in xylogenesis.

Abstract:

Adventitious roots (ARs) are post-embryonic roots formed in planta by tissues of the primary root in secondary vascular structure and by tissues of the aerial organs. Indole-3-acetic acid (IAA), and its natural precursor indole-3-butyric acid (IBA) (1), control AR formation in planta and in vitro, however IBA roles have to be elucidated. Arabidopsis thin cell layers (TCL) consist of stem inflorescence tissue external to the vascular system and 10mM IBA applied with 0.1mM Kinetin induce AR formation from stem TCL (2,3). In the Arabidopsis transversal stem cuttings, it has been hypothesized that the induction of AR formation by exogenous IBA occurs by an interaction with the endogenous IAA content (4), but there is no information about the interaction between the two auxins in the TCLs. In Arabidopsis seedlings it has been demonstrated that IBA is sufficient to stimulate IAA transport because PIN-FORMED1 (PIN1) IAA-efflux carrier, AUXIN RESISTANT1 (AUX1) and LIKE AUXIN RESISTANT3 (LAX3) IAA-influx carriers are active also in the presence of IBA alone (5). The WEAK ETHYLENE-INSENSITIVE2/ANTHRANILATE SYNTHASE  alpha1 (WEI2/ASA1) and WEI7/ANTHRANILATE SYNTHASE beta1 (ASB1), are genes involved in IAA-biosynthesis and required for AR formation in Arabidopsis seedlings (5). It is unknown whether the same genes are involved in AR-formation by TCLs. The aim of the research was to determine the endogenous levels of IBA and IAA at the onset of the culture in Arabidopsis TCLs. Another aim was to understand whether IBA alone was able to induce AR formation in TCL, whether the IAA transport by PIN1, LAX3, and AUX1 was affected, whether an IBA conversion into IAA was needed, and whether an IAA biosynthesis by WEI2/ASA1 and WEI7/ASB1 was also involved. Results indicate that IBA induced AR-formation by conversion into IAA, with this process involving nitric oxide formation and activity, and by positively affecting IAA-transport and ASA1/ASB1-mediated IAA-biosynthesis. 

Biography:

Hee-Jong Koh has his expertise in rice genetics and breeding for higher yield and better quality. He developed several mutants on morphological and quality traits, and cloned genes responsible for the mutant phenotypes. He has also studied natural variation in yield-related and quality traits demonstrating selection models for better genotypes in rice breeding programs. Recently, he edited a book “Current technologies in plant molecular breeding” published by Springer Verlag.

Abstract:

Starch biosynthesis is one of the most important pathways that determine both grain quality and yield in rice (Oryza sativa L.). Sugary endosperm, sugary-1 (sug-1), is a mutant trait for starch biosynthesis. Plants carrying sug-1 produce grains that accumulate water-soluble carbohydrates instead of starch, even after maturity. Although this trait confers improved digestibility and enhanced nutritional merits, sugary endosperm rice has not been commercialized due to the severely wrinkled grains and subsequent problems in milling. We performed chemical mutagenesis on the Korean japonica cultivar Hwacheong, and identified a mild sugary mutant, sugary-h (sug-h). Grains of the sug-h mutant were translucent and amber-colored, and the endosperm appeared less wrinkled than sug-1, whereas the soluble sugar content was high. These characteristics confer greater marketability to the sug-h mutant through normal procedures in hulling and milling of rice grains. Genetic analyses indicated that the sug-h mutant phenotype was controlled by complementary interaction of two recessive genes, Isoamylase1 (OsISA1), which was reported previously, and Starch branching enzyme IIa (OsBEIIa), which was newly identified in this study. These results extend our knowledge of the mechanism of starch biosynthesis in rice endosperm, and facilitate the breeding of sugary endosperm rice for better digestibility

Biography:

Hee-Jong Koh has his expertise in rice genetics and breeding for higher yield and better quality. He developed several mutants on morphological and quality traits, and cloned genes responsible for the mutant phenotypes. He has also studied natural variation in yield-related and quality traits demonstrating selection models for better genotypes in rice breeding programs. Recently, he edited a book “Current technologies in plant molecular breeding” published by Springer Verlag.

Abstract:

Starch biosynthesis is one of the most important pathways that determine both grain quality and yield in rice (Oryza sativa L.). Sugary endosperm, sugary-1 (sug-1), is a mutant trait for starch biosynthesis. Plants carrying sug-1 produce grains that accumulate water-soluble carbohydrates instead of starch, even after maturity. Although this trait confers improved digestibility and enhanced nutritional merits, sugary endosperm rice has not been commercialized due to the severely wrinkled grains and subsequent problems in milling. We performed chemical mutagenesis on the Korean japonica cultivar Hwacheong, and identified a mild sugary mutant, sugary-h (sug-h). Grains of the sug-h mutant were translucent and amber-colored, and the endosperm appeared less wrinkled than sug-1, whereas the soluble sugar content was high. These characteristics confer greater marketability to the sug-h mutant through normal procedures in hulling and milling of rice grains. Genetic analyses indicated that the sug-h mutant phenotype was controlled by complementary interaction of two recessive genes, Isoamylase1 (OsISA1), which was reported previously, and Starch branching enzyme IIa (OsBEIIa), which was newly identified in this study. These results extend our knowledge of the mechanism of starch biosynthesis in rice endosperm, and facilitate the breeding of sugary endosperm rice for better digestibility

Biography:

Jiayan Ye foucs on the study of  plants volatile emission and regulation by the biotic stresses. She tries to establish a quantitative dose-response model of the induced volatile emission  from a wide range of plants by the exogenous  treatment of the MeJA treatment, fungus infection and insect infestation

Abstract:

Past studies have focused on the composition of essential oil of Ocimum basilicum leaves, but data on composition and regulation of its aerial emissions, especially floral volatile emissions are scarce. We studied the chemical profile, within-flower spatial distribution (sepals, petals, pistils with stamina and pedicels), diurnal emission kinetics and effects of exogenous methyl jasmonate (MeJA) application on the emission of floral volatiles by dynamic headspace collection and identification using gas chromatography-mass spectrometry (GC-MS) and proton transfer reaction mass spectrometry (PTR-MS). We observed more abundant floral emissions from flowers compared with leaves. Sepals were the main emitters of floral volatiles among the flower parts studied. The emissions of lipoxygenase compounds (LOX) and monoterpenoids, but not sesquiterpene emissions, displayed a diurnal variation driven by light. Response to exogenous MeJA treatment of flowers consisted of a rapid stress response and a longer-term acclimation response. The initial response was associated with enhanced emissions of fatty acid derivatives, monoterpenoids, and sesquiterpenoids without variation of the composition of individual compounds. The longer-term response was associated with enhanced monoterpenoid and sesquiterpenoid emissions with profound changes in the emission spectrum. According to correlated patterns of terpenoid emission changes upon stress, highlighted by a hierarchical cluster analysis, candidate terpenoid synthases responsible for observed diversity and complexity of released terpenoid blends were postulated. We conclude that flower volatile emissions differ quantitatively and qualitatively from leaf emissions, and overall contribute importantly to O. basilicum flavor, especially under stress conditions.

Biography:

Minkyun Kim is professor in Seoul National University, Republic of Korea

Abstract:

Among the many miRNAs involved in plant stress responses, miR399 is well known to be involved in controlling phosphate homeostasis by down-regulating the expression of PHO2, which encodes the ubiquitin-conjugating E2 enzyme, UBC24, in Arabidopsis. In this study, to understand the expression of the rice OsmiR399 genes under abiotic stress conditions, the expression of the eleven OsmiR399 (a-k) genes was studied by analyzing the levels of their precursor transcripts (pre-miRNAs) in the roots and shoots of rice seedlings subjected to the stress-responsive phytohormone abscisic acid (ABA). We found that the OsmiR399 genes showed different patterns in pre-miRNA accumulation. In particular, OsmiR399b, OsmiR399d, OsmiR399e, and OsmiR399f showed high and steady accumulation in both the roots and shoots regardless of ABA treatments. However, OsmiR399c and OsmiR399k showed ABA-induced expression in the whole plant body or aerial part of the rice seedlings. In addition, to test the possibility that the putative rice PHO2 ortholog of Arabidopsis, also known as LEAF TIP NECROSIS 1 (LTN1), might be down-regulated by the multiple OsmiR399s with certain sequence divergences, four different lines of transgenic rice plants that overexpress either the constitutively expressed OsmiR399s (OsmiR399d and OsmiR399f) or the ABA-inducible OsmiR399s (OsmiR399c and OsmiR399k) were produced and the levels of OsmiR399 pre-miRNAs and LTN1 transcripts were analyzed. A significant decrease in the accumulation of LTN1 transcripts and an increase in the OsmiR399 pre-miRNAs levels were found in all of the transgenic plants. Based on these results, we concluded that LTN1 is down-regulated by multiple OsmiR399 genes in rice.

Biography:

Ju-Kon Kim, Professor in Graduate School of International Agricultural Technology, Seoul National University, is the Director of Crop Biotechnology Institute, where he worked since 2013. He obtained his PhD on Plant Molecular Biology in 1992 at Cornell University of USA. Current research is concentrated on discovering novel genes for drought tolerance of rice with special attention to crop biotechnology by integrating genomics and phenomics approaches, characterizing key regulators in stress tolerance.

Abstract:

Drought, a common environmental constraint, induces a range of physiological, biochemical and molecular changes in plants, and can cause severe reductions in crop yield. Consequently, understanding the molecular mechanisms of drought tolerance is an important step towards crop biotechnology. Here, we report that the rice (Oryza sativa) homeodomain-leucine zipper class IV transcription factor gene, Rice outermost cell-specific gene 10 (Roc10), enhances drought tolerance and grain yield by increasing lignin accumulation in ground tissues. Overexpression of Roc10 in rice significantly increased drought tolerance at the vegetative stages of growth and promoted both more effective photosynthesis and a reduction in water loss rate, compared with non-transgenic controls or RNAi transgenic plants. Importantly, Roc10 overexpressing plants had a higher drought tolerance at the reproductive stage of growth and a higher grain yield compared with the controls under field-drought conditions. Roc10 is mainly expressed in outer cell layers including the epidermis and the vasculature of the shoots, which coincides with areas of cell wall lignification. Roc10 overexpression elevated the expression levels of lignin biosynthetic genes in shoots, with a concomitant increase in the accumulation of lignin, while the overexpression and RNAi lines showed opposite patterns of lignin accumulation. We identified downstream target genes of Roc10 by performing RNA-seq and chromatin immunoprecipitation (ChIP)-seq analyses of shoot tissues. Roc10 was found to directly bind to the promoter of PEROXIDASEN/PEROXIDASE38, a key gene in lignin biosynthesis. Together, our findings suggest that Roc10 confers drought stress tolerance by promoting lignin biosynthesis in ground tissues.

Biography:

Shuai Li is currently working as a junior researcher at the Estonian University of Life Sciences. His research focuses on the impact of abiotic stress such as ozone, heat stress on the emissions of volatile organic compound (VOC) from leaves and flowers. 

Abstract:

Exposure to acute ozone (O₃) concentrations results in elicitation of key stress volatiles methanol, products of lipoxygenase (LOX) pathway and methyl salicylate (VOC), but it is unclear how different ozone doses later the timing and rate of elicitation of emissions of different stress volatiles, and how priming responses can modify the magnitude and kinetics of stress volatile emissions in short and long term. Our work reveals that methanol and LOX product emissions were induced rapidly after O₃ exposure, but no MeSA emission and lower LOX emissions were detected in plants first pre-exposed to lower O₃ concentration, and the maximum emission rates and the total amount of emissions of LOX products and both methanol emission bursts were quantitatively correlated with stomatal O₃ uptake, but elicited MeSA emissions did not depend on O₃ dose. Timing of elicitation was only moderately altered by O₃ dose with LOX emissions elicited earlier in the most severe treatment and secondary emission elicited later for O₃-priming treatment. The stomatal closure due to darkness and pre-exposure to low-level ozone protect leaves against high-level ozone-induced injury in Phaseolus vulgaris, suggesting the important implications for understanding plant response to O₃ in natural environments where both light and ozone concentrations strongly vary during the day and among the days, and could drive ecological success of different sensitive groups in response to environmental changes.

Biography:

Marilena Ronzan is a PhD student in Botany at the University La Sapienza in Rome, specialized in the response of plants to Arsenic and Cadmium contamination. In her Master Thesis she studied the response of the hyperaccumulator fern pteris vittata to the presence of Cadmium alone or combined with As (Ronzan et al., 2016).Her PhD project is focused on the hormonal response, in particular of auxin and jasmonates, in Oryza sativa and Arabidopsis thaliana after exposure to As and Cd.

She is interested in understanding the response of plants to a frequent cause of soil and water contamination in order to find solutions to prevent or at least reduce the effect of such elements in plant production and their presence in the food chain. 

Abstract:

Cadmium (Cd) and arsenic (As) soil and water contamination is a frequent cause of stress for plants, especially for the cereal crop Oryza sativa. The root is the first organ to respond to the presence of these toxic elements and often to be severely damaged. In general, plant response to abiotic stress involves phytohormones which in turn coordinate arrays of plant growth and developmental programs (1). Indole-3-acetic acid (IAA) is a key regulator of many aspects of plant growth and development, especially for the maintenance of the quiescent centre (QC) cells in the root apex (2). Jasmonic acid (JA), a lipid derived phytohormone, is an important plant growth regulator with versatile functions in the development and in the response to environmental stress (3). Sun and coworkers reported in   Arabidopsis thaliana plants a relation between IAA and Jasmonates (JAs), methyl-jasmonate (MeJA) in particular. (4). IAA and JA have been suggested to interact in the presence of abiotic stress, but the effects of this interaction needs further investigation. The aim of this research was to understand the crosstalk between auxin and JAs in the presence of As and Cd. For this purpose, we carried out different experiments using the JA biosynthetic mutant coleoptile photomorphogenesis 2 (Cpm2) (3). Morphological and histological analyses of wild type (ssp. japonica, cv. Nihonmasari) and Cpm2 plants were carried out after exposure to As and/or Cd. Furthermore, IAA-sensitive OsDR5::GUS plants (5), treated with As and/or Cd and different MeJA concentrations, were analyzed. qRT-PCR analyses of the expression of some JAs biosynthetic genes after exposure to As and/or Cd were carried out. All together the results suggest that As and Cd interfere with auxin and JAs during root formation in rice.