Turnover of Glycerolipid Metabolite Pool and Seed Viability.

Xiao-Long Hu,Xiao-Mei Yu,Hong-Ying Chen,Wei-Qi Li

doi:10.3390/ijms19051417

Abstract

Hydration–dehydration cycles can frequently cause stress to seeds, but can also be used to improve germination. However, the molecular basis of the stress caused is poorly understood. Herein, we examine the effects of hydration–dehydration cycles on seed viability and profile the membrane glycerolipid molecular species. We find that seed viability was not affected during the first two cycles, but significantly decreased as further cycles were applied, until all viability was lost. The abundances of seven glycerolipid classes increased and decreased through hydration and dehydration, respectively, but the phosphatidic acid and diacylglycerol abundances changed in the opposite sense, while total glycerolipid contents remained constant. This suggests that during hydration–dehydration cycles, turnover of glycerolipid metabolite pools take place, while no significant lipid synthesis or degradation is involved. As further hydration–dehydration cycles occurred, lipid unsaturation increased, plastidic lipids decreased, and phosphatidylserine acyl chains lengthened. The latter two could be lethal for seeds. Our findings reveal a novel model of membrane lipid changes, and provide new insights into the responses of seeds to hydration–dehydration cycles.

Highlights

Seeds are not able to germinate without sufficient water under natural conditions [1,2]
VaniadbiDavliniItGandybtD.iDaJl.iGfMGttyeoDclra.oGSfatncei.cntr2eou0ann1m8tnte,sub1n9mcet,osrxbucoeolrfduohlfbdyhldboyrlcdoakcrtakipotiplnoal–nasd–stitdedidehhbybyidiodorgrgaaeettniniooeennssiisccsyy[c[1c1l1le1e]s,]s,(sF(osFiogtihguteuhreerree2rs)2eu. )sl.tuslstsupspuoprpteodrtseededsseleodsisnlg5oosthfine1i4gr their and DGDG contents could block plastid biogenesis [11], so the results supported seeds losing their viability after a number of hydration–dehydration cycles (Figure 2)
The double bond index (DBI) value represents the degree of lipid unsaturation [40,41]

Summary

Introduction

Seeds are not able to germinate without sufficient water under natural conditions [1,2]. Sporadic rainfall and evaporation can cause seeds to experience hydration–dehydration cycles before germination [3,4]. )sl.tuslstsupspuoprpteodrtseededsseleodsisnlg5oosthfine1i4gr their and DGDG contents could block plastid biogenesis [11], so the results supported seeds losing their viability after a number of hydration–dehydration cycles (Figure 2). We thecorenfvoerretepderspfoercmifiecadllcyoirnrteola3t4io:6nPaAnaulynsdeesr ofrfe1e4zimngolceocnudliatironsps e[c3i9e]s, isno gwreouppersfoArmanedd cBo(rFreilgautiroen8) and foundatnhaalyts1es3omnothlec3u4l:6arMsGpDecGieasnwd PeAre, annedgoantivtheely34c:6orDrGelDatGedan, dbuPtAtchoen3te4n:6tsm(exoclleucduinlagrtshpeeCcsiesedws)e, re not This suangdgefosutsntdhnaetgtautrinveovcoerrreolcactiuornrsed(r b=e−t0w.6e6e8nfotrh3e41:63MmGoDleGcualnadr PspAeacniedsrin= −g0r.o7u72pfsoAr 3a4n:6dDBG.DOGnlayndMGDG, DGDGPA, P).ATh, iasnsdugDgeAstGedhthaartb3o4r:63M4:G6 DmGoalencduDlaGrDsGpeccoiuelsd (bFeicgounrveerSt2ed), sapnedcif3ic4a:l6lyMinGtoD34G:6aPnAddDurGinDg G can be converted into 34:6 PA under freezing conditions [39], so we performed correlation analyses on the 34:6 MGDG and PA, and on the 34:6 DGDG and PA contents (excluding the C seeds), and found negative correlations (r = −0.668 for 34:6 MGDG and PA and r = −0.772 for 34:6 DGDG and PA). The bars with asterisks are significantly different (* p < 0.05, ** p < 0.01)

Membrane Lipids Became More Unsaturated during Dehydration

Hydration–Dehydration Cycles and Sampling Scheme

Findings

Seed Germination