Study On Effects Of Nitric Oxide Fumigation On Cottony Softening Of Postharvest Wax Apple

Wax apple（Syzygium samarangense）is the characteristic fruit resources with excellent quality.High metabolism rates of wax apple fruits reflect fast consumption of energy and rapid depletion of reserves such as carbohydrates and organic acids,so that its senescence is quick after harvest.The phenomenon of cottony softening in pulp after harvest will occur in short term,The cottony softening of fruits is a main reason causing postharvest losses,and has become a limiting factor in market distribution of wax apple fruit.we constructed 10 small-RNA libraries in the NO treatment group（0 d,2 d,4 d,8 d,12 d）and the control group（0d,2d,4d,8d,12d）using the illumine Hiseq 2500 platform and se50 of sequencing strategy.Conjoint analysis of mi RNA,mRNA and physiological indexes to study wax apple provide insight to cottony softening influence by NO.The results were as follows: We identified 314 known miRNAs belonging to 64 miRNA families and 44 novel miRNAs among the 10 libraries.NO treatment could influence wax apple mRNA of polygalacturonase（PG）,pectin methylesterase（PME）and cellulase（Cx）expression pattern in postharvest.The bnamiR167 d and osa-miR167 d showed high expiession levels and target gene（PG）were negatively correlated.Study phenylpropanoid metabolism of lignin monomer synthetic pathway find that exogenous NO induces significant changes lignin synthesis of wax apple fruit during storage,which the transcript levels of CA,CCoAOMT,F5H and C3H genes in NO-treated fruit remained at significantly higher levels compared to the control fruit.However,the profiles of PAL,POD,4CL and CAD genes were lower in the NO group than in the control.NO treatment can maintained energy charge at a high level in the storage period.We found that NO teatment could affect the activity of Ca²⁺-ATPase and H+-ATPase maintaining the normal physiological function of mitochondria,while affecting the activity of succinate dehydrogenase（SDH）and cytochrome oxidase（CCO）regulating tricarboxylic acid cycle（TCA）and oxidative phosphorylation.The miR477,miR530,miR156,miR858 target gene be predicted can regulate the energy metabolism.Reactive oxygen is the main production pathway by oxidative phosphorylation.NO treatment could inhibit the rise of reactive oxygen by increase the activity of superoxide dismutase（SOD）and catalase（CAT）during the storage period,however,not find miRNA regulate reactive oxygen metabolism related enzymes.The miRNAs may regulate the metabolism of reactive oxygen by affecting the lavonoids,glutathione etc to reducing substances synthesis,and may by regulating the relevant transcription factors influence wax apple active oxygen metabolism.The postphysiology regulation is very complex process.The miRNA can regulate genes transcription by influence transcription factors expression.We found that 69 mi RNAs target genes are predicted regulating transcription factors.The miRNA could influence the gene transcription by regulating transcription factors,meanwhile transcription factors can also affect the transcription of miRNA precursors to regulate miRNAs expression level.Therefore miRNAs,transcription factors and mRNA formed a co-regulatory network,regulation postharvest physiology of wax apple.NO treatment can regulate the cell wall metabolism,energy metabolism,active oxygen metabolism by miRNAs,transcription factors and mRNA forming a co-regulatory network to regulate cottony softening process.