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EditorialPlants Coping Abiotic and Biotic Stresses:A Tale of Diligent Management
1Biochimie et Physiologie Moleculaire des Plantes, Unite Mixte de Recherche CNRS-INRA, Universite Montpellier 2,Montpellier SupAgro, Place Viala, 34060 Montpellier, France2Department of Botany, University of Jammu, Jammu, Jammu and Kashmir 180-006, India3Jacob Blaustein Institute for Desert Research, BGU, 84990 Sede-Boqer Campus, Israel4Department of Microbiology and Plant Biology, University of Oklahoma, 770 Van Vleet Oval, Norman, OK 73019, USA5Signaling Pathway Research Unit, RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku,Yokohama 230-0045, Japan
Plants unlike other living forms are sessile thereby facingsevere biotic and abiotic stresses. Plants have evolved differentefficient defence responses which thrive upon a numberof intrinsic factors, such as genotypic and phenotypic con-stitutions and developmental circumstances, and extrinsicfactors like severity and duration of the stresses. Stressmanagement uses molecular and biochemical level controls,the competence, and speed, at which a stress signal isperceived and transmitted to generate stress signal moleculesand activate stress-protective mechanisms. A well-concertedaction of the plants’ competence atmorphological, physiolog-ical, biochemical, and molecular strata regulates numerousadaptive responses to biotic and abiotic stresses. Geneticmanipulations of signalling networks have been widely usedto improve plant productivity under stressful conditions.Advanced biotechnological application will enable maintain-ing agriculture in a sustainable manner. In this special issue,we present two reviews and four research papers whichaddress genomic, molecular, and physiological regulations aswell as signalling networks dealing with plant responses toabiotic and biotic factors.
Climate change, desertification, and the rise in humanpopulation have put a severe load on agriculture and are
deteriorating crop productivity. In recent years, numer-ous molecular and metabolic pathways involved in plantresponses and adaptation to various types of environmentalstresses have been identified and reported. Among hundredsof metabolic pathways identified, the role of polyaminesin stress management to enhance plant acclimation andadaptation is emerging rapidly. In this special issue, a timelyreview by P. Rangan et al. (2014) summarizes our knowledgeon biosynthesis and catabolism of polyamines and highlightsrecent progress in elucidating the functions of polyaminesin regulation of plant responses to abiotic stresses. Givena huge genetic variation among plant species, the authorsalso discuss a systematic approach based on polyamine-mediated enhancement of stress tolerance which might beused as a potential strategy for screening and identification ofnatural variants within existing crop species. The identifiedgenotypes that possess compatible allelic variants could bethen used for the improvement of stress tolerance.
Plant-microbe interactions are at the core of symbiotic,parasitic, or mutualistic plant-microbe relationships. Theseinteractions have displayed a unique way of mutualisticcommunications for a resource sharing. To shed light onthe topic, a detailed review of M. Libault (2014) explains
Hindawi Publishing CorporationBioMed Research InternationalVolume 2015, Article ID 754754, 2 pageshttp://dx.doi.org/10.1155/2015/754754
2 BioMed Research International
the unique mechanisms in using legumes to interact withbacteria. Leguminous plants have developed a mutualisticsymbiotic relationship with rhizobium (a type of soil bac-teria). Upon bacterial infection, a new root organ callednodule is developed that enables the leguminous plants toaccess a steady source of nitrogen through the fixation andassimilation of the atmospheric N
2by the symbiotic bacteria.
In return, the bacteria also get benefit from the symbioticplants that provide photosynthesis product to bacteria assource of carbon. Environmental stress or climate change,which influences the concentration of the atmospheric car-bon dioxide (CO
2), will have a significant impact on plant
photosynthesis. As a consequence, this will affect the nitrogenand carbon metabolism, leading to altered nitrogen fixationefficiency. The key regulatory mechanisms controlling car-bon/nitrogen balances with particular attention to legumenodulation are reviewed by coeditor M. Libault in his reviewarticle. In addition, readers can also get an overview aboutthe effect of the change in CO
2level on nitrogen fixation
efficiency through this review, giving rise to idea as to howwe could mitigate the impact of the change in atmosphericCO2concentration.
Besides the change in atmospheric CO2level, water
deficit is one of the major constraints for nodulation, and,as a consequence for plant productivity. This topical issue ispresented here by a research article of S. Sulieman et al. (2014).In their study, the authors assessed the growth andnodulationattributes of two soybean varieties DT2008 and Williams 82(W82), which have contrasting drought-tolerant capacity, in asymbiotic association with Bradyrhizobium japonicum underdrought and subsequent rehydration. The authors aimed tounderstand the correlation betweenN
2fixation efficiency and
differential drought-responsive phenotypes of DT2008 andW82. Their results also provide genetic resources and basisfoundation for further genomic research that would lead tobetter understanding of mechanisms involved in regulationof N2fixation in soybean under drought at molecular level.
Heavy metal pollution has been a matter of grave con-cern. Until recently, efforts have been mainly restricted tophytoremediation of soils using plant species with highmetaluptake capacity such as Brassica species. Chromium (Cr) is ahighly phytotoxic heavymetal affecting crop productivity andhuman health via entering the food chain. Phytoremediationof Cr-polluted soils has been mostly demonstrated in usingherbaceous plants, whereas use of cotton cultivars in Crphytoremediation is least explored. In the present issue,M. K.Daud et al. (2014) have shown the potentials of two transgeniccotton cultivars (J208 and Z905) and their hybrid line(ZD14) in Cr phytoremediation using a multiple biomarkerapproach. Their work showed that these cotton cultivarsand hybrid line could effectively uptake and sequestrate Crin dead parts of the plants, such as vacuole and cell wall,besides having a more highly accelerated antioxidant system.This study thus proposes a new role of cotton cultivars inphytoremediation of Cr-polluted soils.
The interactions between macro- and micronutrienthomeostases have been reported in many physiological andnutritional situations. N. Bouain et al. (2014) studied the
interaction between phosphate (Pi) and zinc (Zn) home-ostasis in two lettuce varieties. The results revealed that thevariation in Pi and Zn supplies affects the biomass andphotosynthesis as well as the dynamics of Pi transport in acontrasting manner between the two varieties, indicating agenetic basis for such physiological responses. On the basisof their results, the authors proposed a workingmodel of howPi and Zn signalling pathways are integrated into functionalnetworks to control plant growth.
Salinity is a major abiotic stress worldwide claimingagriculture lands and affecting productivity. Research paperby A. Matsui et al. (2014) investigated salt stress in Ara-bidopsis. The authors reported that the tasiRNA-ARF path-way is involved in controlling floral architecture in plantsunder drought and high salinity. The ta-siRNA biosynthesismutants and mutated ARF3-overexpressing plants showedshort stamen under drought and salt stress, which hamperedself-pollination. This study reports for the first time that atype of ta-siRNAs (tasiRNA-ARF) plays an important role inmaintaining normal stamen growth and fertilization underdrought and high salinity.
Acknowledgments
The editors would like to thank the authors for contributingtheir manuscripts to this special issue.