PLANT OMICS


Gene expression analysis in response to combined salt and boron (B) stresses in a tolerant maize landrace


Wilson Huanca-Mamani*, Marcelo Vargas Ortiz, Steffany Cárdenas-Ninasivincha, Gerardo Acosta-Garcia, Elizabeth Bastías

Laboratorio de Biología Molecular de Plantas, Depto. Producción Agrícola. Fac. Cs. Agronómicas, Universidad de Tarapacá, Chile
Laboratorio de Fisiología Vegetal, Depto. Producción Agrícola. Fac. Cs. Agronómicas. Universidad de Tarapacá, Chile
Departamento de Ingeniería Bioquímica, Instituto Tecnológico de Celaya, Av. Tecnológico y A. García Cubas S/N, Col. Alfredo V. Bonfil C.P. 38010, Celaya, Gto. México


Abstract

To understand the molecular stress response in maize plants to high salt and boron (B) stress, we focused on the transcript accumulation of six stress-related genes in Lluteño maize, a sweet corn landrace from the Lluta valley (northern Chile). This landrace is tolerant to salt and B stress. A randomized complete block design with four replications was used. Seedlings of Lluteño maize and maize hybrid B73 were exposed to 150 mM NaCl and 20 ppm B in nutrient solution for 120 hrs, then root and leaf samples were collected and Na+ and B content were determined. Transcript accumulation of three salt stress-related genes SOS1, NHX2 and HKT1 and three B stress-related genes BOR1, BOR2 and PIP1;2 were determined in roots and leaves of Lluteño maize using RT-PCR and real-time PCR at 3 and 96 h after treatment with 150 mM NaCl and/or 20 ppm B. The results indicated that combined salt and B stress caused changes in physiological parameters. The damage was more severe in B73 than in Lluteño maize, confirming that this landrace behaves as a plant tolerant to these stresses. Regulation of stress-related genes under combined stress was different under individual stresses. The ability of Lluteño maize to survive and thrive in soil with high salinity and B concentration is probably based on a decrease in membrane water permeability, preventing salt and B uptake from the roots through down-regulation of BOR1, BOR2 transporters and PIP1;2 aquaporin. The increased water transport is mediated by the up-regulation of the PIP1;2 in leaves, allowing cellular water conservation, and the retrieval of Na+ from xylem through up-regulation of HKT1;1 transporters in roots and leaves.

Pages 80-88 | Full Text PDF| doi: 10.21475/poj.11.02.18.pne1144
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Metabolomics analysis of mangosteen (Garcinia mangostana Linn.) fruit pericarp using different extraction methods and GC-MS

Siti Farah Mamat, Kamalrul Azlan Azizan, Syarul Nataqain Baharum, Normah Mohd Noor, Wan Mohd Aizat*

Institute of Systems Biology (INBIOSIS), Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor, Malaysia

Abstract
Garcinia mangostana Linn. (mangosteen) reportedly contains several bioactive metabolites which have been used in various traditional disease treatment, nutritional supplement and skincare products. However, reports detailing its characterization and metabolite content are still scarce. Most of the earlier reports only focused on the extraction of specific metabolites such as xanthones and anthocyanins, rather than a comprehensive metabolome profile. In this study, global metabolomics approach using gas chromatography-mass spectrometry (GC-MS) analysis was conducted to profile the metabolite content of mangosteen fruit pericarp harvested at the final stage of ripening (dark purple stage). Five different extraction methods, which vary in their solvent mixtures, solvent ratios, with or without sonication were compared, aimed to maximize metabolite detection from the mangosteen tissue. The results showed that the method using a combined solvent mixture of methanol/chloroform/water (3:1:1 v/v ratio) with sonication has consistent reproducibility amongst biological replicates and successfully yielded the highest number of metabolites compared to the other methods. By combining the results of different extraction methods, we tentatively identified a total of 73 metabolites comprising of sugars (49.32%), alcohols (9.59%), sugar acids (8.22%), organic acids (6.85%), phenolic acids (5.48%), aromatic compounds (2.74%) and aldehyde (1.37%). This finding provides an overview of the metabolite content of mangosteen pericarp and comprehensive assessment of extraction methods for an untargeted metabolomics approach of this beneficial fruit. 


Pages 89-97 | Full Text PDF| Supplementary Data| doi: 10.21475/poj.11.02.18.pne1191
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In silico identification of agriculturally important molecule(s) for defense induction against bacterial blight disease in Soybean (Glycine max)

Saril Mamgain, Shalini Dhiman, Rajesh Kumar Pathak, Mamta Baunthiyal*

Department of Biotechnology, Govind Ballabh Pant Institute of Engineering & Technology, Pauri Garhwal-246194, Uttarakhand, India

Abstract
The productivity of Glycine max (Soybean), one of the economically important crops of India, is seriously affected by bacterial blight disease which is mainly caused by Psedomonas syringae. The disease results in significant yield losses in Soybean crops. Since no proven resistant source is available against bacterial blight, the only option remaining is to utilize biotechnological strategies which could lead to inhibition of pathogenic proteins of the Psedomonas syringae responsible for disease progression. Phytoalexins are well known to inhibit bacterial growth and trigger defense response against diseases in crop plants. The present study was conducted to identify the molecules which could inhibit the growth and development of bacteria. A few proteins were selected from literature analysis viz., Ornithine carbamoyl transferase 2, phaseolotoxin-insensitive, avirulence protein AvrRpt2, HarpinHrpZ, Sensor protein GacS, and Translation initiation factor IF-3 of Psedomonas syringae as possible molecular target of phytoalexins. The molecular modeling of these proteins were done by using their amino acid sequence on Phyre2 and I-TASSER tool followed by model validation through energy minimization and Ramachandran plot analysis. Subsequently molecular docking was performed using some selected phytoalexins produced by members of Brassicaceae, Fabaceae, Solanaceae, Vitaceae and Poaceae family with each modeled protein structure by AutoDock vina. Based on the molecular docking study, we identified efficient defense molecules, which can be used for the development of agrochemicals for protection of G. max against infection of Psedomonas syringae.

Pages 98-105 | Full Text PDF| doi: 10.21475/poj.11.02.18.1238
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Mining and characterization of Allium cepa expressed sequence tags (ESTs) encoding receptor-like kinases (RLKs)

Satyabrata Nanda

Centre for Biotechnology, Siksha ‘O’ Anusandhan University, Bhubaneswar, India
Present address: State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, P.R. China


Abstract
Plant receptor-like kinases (RLKs) are comprised of a large family of kinases having multitudinous functions. Onion (Allium cepa), an important bulbous plant, has almost no reports on RLKs and their role in onion plant growth and defense responses. In the present work, mining of the transcript database ‘dbEST’ has been performed to obtain the expressed tags of A. cepa. Subsequently, the consensus sequence assembling carried out by CAP3 program resulted in 4175 number of contigs. Consecutive rounds of BLAST searches resulted in identification of 4 highly homologous contigs with the previously reported plant RLKs. Further structural characterizations by MEME, Prosite and SOPMA supported the identified contigs to be putative RLKs. All four putative RLKs (AcCon13, AcCon183, AcCon383, and AcCon1738) possessed 9 out of 11 canonical kinase sub-domains, the signature protein-kinase domain, and the ATP binding sites. Phylogenetic analysis along with previously reported plant RLKs revealed that the identified contigs belong to different RLK sub-families.


Pages 106-112 | Full Text PDF| doi: 10.21475/poj.11.02.18.1250
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Expression analysis of host defense responses against the 8K (KDa) cysteine-rich viral silencing suppressor protein in Nicotiana benthamiana

Aminallah Tahmasebi*, Alireza Afsharifar, Ahmad Heydari, Mohammad Mehrabadi

Plant Virology Research Center, College of Agriculture, Shiraz University, Shiraz, Iran
Firoozabad Center for Higher Education, Iran
Department of Entomology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran

Abstract
Potato mop-top virus (PMTV) encodes the 8K cysteine-rich viral suppressor of RNA silencing. To gain an insight into N. benthamiana defense mechanisms against 8K suppressor protein, we expressed two 8K suppressors from Peruvian isolates in Nicotiana benthamiana and assessed the expression of its defense genes involved in autophagy (ATG6, ATG2 and ATG7, AGO1), salicylic acid (SA) (ICS1, NPR1 and PR1) and jasmonic acid (JA) (OPR3, COI1 and PDF1.2) pathways. To do this, the 8K cDNAs of two Peruvian PMTV isolates were cloned in pGWB17 vector with a C-terminal myc tag and N-terminal 35S promoter using Gateway technology. Agrobacterium cultures harboring PMTV 8K were syringe infiltrated into the abaxial side of N. benthamiana leaves. The expression levels of defense genes were examined in N. benthamiana leaves infiltrated with P1 8K, P11 8K and the control constructs at 2 and 5 days post infiltration in response to PMTV 8Ks using q-PCR technique. Our results showed that the expression levels of ATG6, ATG2, ATG7, ICS1, OPR3, NPR1, PR1, COI1 and PDF1.2 were increased in response to both 8K suppressors. However, the transcript level of Argonaute1 (AGO1) was decreased in response to both 8K suppressors compared with the control. These results indicated that 8K suppressor proteins can alter the expression of autophagy, SA and JA signaling pathway genes in N. benthamiana. Taken together, it seems that despite the 8K role in virus pathogenicity, it can also induce host defense responses to modulate plant-virus interactions and fine-tune host-virus coexistence.

Pages 113-119 | Full Text PDF| doi: 10.21475/poj.11.02.18.1295



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