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5.44.5Antioxidative Defense,SuppressedNitric Oxide Accumulation,andSynthesis of Protective Proteins inRoots and Leaves Contribute to theDesiccation Tolerance of theResurrection Plant HaberlearhodopensisKatya Georgieva,Gergana Mihailova,Liliana Gigova,Antoaneta V.Popova,Maya Velitchkova,Lyudmila Simova-Stoilova,Mt Sgi-Kazr,Helga Zelenynszki,Katalin Solymosi and dm SoltiSpecial IssueDesiccation/Salinity Tolerance and the Crosstalk ThereinEdited byProf.Dr.Jill M.Farrant and Dr.Mariam AwliaArticlehttps:/doi.org/10.3390/plants12152834Citation:Georgieva,K.;Mihailova,G.;Gigova,L.;Popova,A.V.;Velitchkova,M.;Simova-Stoilova,L.;Sgi-Kazr,M.;Zelenynszki,H.;Solymosi,K.;Solti,.AntioxidativeDefense,Suppressed Nitric OxideAccumulation,and Synthesis ofProtective Proteins in Roots andLeaves Contribute to the DesiccationTolerance of the Resurrection PlantHaberlea rhodopensis.Plants 2023,12,2834.https:/doi.org/10.3390/plants12152834Academic Editors:Jill M.Farrant,Mariam Awlia and Dayong ZhangReceived:19 May 2023Revised:27 July 2023Accepted:28 July 2023Published:31 July 2023Copyright:2023 by the authors.Licensee MDPI,Basel,Switzerland.This article is an open access articledistributedunderthetermsandconditions of the Creative CommonsAttribution(CC BY)license(https:/creativecommons.org/licenses/by/4.0/).plantsArticleAntioxidative Defense,Suppressed Nitric Oxide Accumulation,and Synthesis of Protective Proteins in Roots and LeavesContribute to the Desiccation Tolerance of the ResurrectionPlant Haberlea rhodopensisKatya Georgieva1,*,Gergana Mihailova1,Liliana Gigova1,Antoaneta V.Popova2,Maya Velitchkova2,Lyudmila Simova-Stoilova1,Mt Sgi-Kazr3,4,Helga Zelenynszki3,4,Katalin Solymosi5and dm Solti31Institute of Plant Physiology and Genetics,Bulgarian Academy of Sciences,Academic Georgi Bonchev Str.,Building 21,1113 Sofia,Bulgaria;gmihailovabio21.bas.bg(G.M.);(L.G.);lsimovamail.bg(L.S.-S.)2Institute of Biophysics and Biomedical Engineering,Bulgarian Academy of Sciences,Academic GeorgiBonchev Str.,Building 21,1113 Sofia,Bulgaria;popovabio21.bas.bg(A.V.P.);mayavbio21.bas.bg(M.V.)3Department of Plant Physiology and Molecular Plant Biology,Institute of Biology,ELTE Etvs LorndUniversity,Pzmny Pter Stny 1/C,H-1117 Budapest,Hungary;sagi.kazar.matettk.elte.hu(M.S.-K.);helga.zelenyanszkittk.elte.hu(H.Z.);adam.soltittk.elte.hu(.S.)4Doctoral School of Biology,Institute of Biology,ELTE Etvs Lornd University,Pzmny Pter Stny 1/C,H-1117 Budapest,Hungary5Department of Plant Anatomy,Institute of Biology,ELTE Etvs Lornd University,Pzmny Pter Stny1/C,H-1117 Budapest,Hungary;katalin.solymosittk.elte.hu*Correspondence:katyabio21.bas.bg or ;Tel.:+359-2-979-2620Abstract:The desiccation tolerance of plants relies on defense mechanisms that enable the protectionof macromolecules,biological structures,and metabolism.Although the defense of leaf tissuesexposed to solar irradiation is challenging,mechanisms that protect the viability of the roots,yetlargely unexplored,are equally important for survival.Although the photosynthetic apparatusin leaves contributes to the generation of oxidative stress under drought stress,we hypothesizedthat oxidative stress and thus antioxidative defense is also predominant in the roots.Thus,weaimed for a comparative analysis of the protective mechanisms in leaves and roots during thedesiccation of Haberlea rhodopensis.Consequently,a high content of non-enzymatic antioxidantsand high activity of antioxidant enzymes together with the activation of specific isoenzymes werefound in both leaves and roots during the final stages of desiccation of H.rhodopensis.Among others,catalase and glutathione reductase activity showed a similar tendency of changes in roots and leaves,whereas,unlike that in the leaves,superoxide dismutase activity was enhanced under severe butnot under medium desiccation in roots.Nitric oxide accumulation in the root tips was found to besensitive to water restriction but suppressed under severe desiccation.In addition to the antioxidativedefense,desiccation induced an enhanced abundance of dehydrins,ELIPs,and sHSP 17.7 in leaves,but this was significantly better in roots.In contrast to leaf cells,starch remained in the cells ofthe central cylinder of desiccated roots.Taken together,protective compounds and antioxidativedefense mechanisms are equally important in protecting the roots to survive desiccation.Sincedrought-induced damage to the root system fundamentally affects the survival of plants,a betterunderstanding of root desiccation tolerance mechanisms is essential to compensate for the challengesof prolonged dry periods.Keywords:antioxidant enzymes;drought stress;non-enzymatic antioxidants;nitric oxide;photosyn-thesis;protective proteins;root anatomyPlants 2023,12,2834.https:/doi.org/10.3390/plants12152834https:/ 2023,12,28342 of 221.IntroductionIn the 21st century,evidence becomes clear on climate change,the primary challengefor humankind presently and in the future.Since extremities in the weather such as pro