γ-氨基丁酸调控高温胁迫下茄子种子萌发的生理特性及相关基因表达OA

[Objective]Effect of γ-aminobutyric acid(GABA)treatment on eggplant seed germination under high temperature was studied.[Methods]Under high temperatures,GABA in the concentrations of 0,0.5,1,3,or 5 mmol·L-1 was added to observe'Bulika'eggplant seed germination.With threshold temperature for germination determined,physiological characteristics,endogenous hormone secretion,and relevant gene expressions of the germinating seeds treated by GABA at varied concentrations were monitored.[Results]The highest temperature the seeds could tolerated was found to be 38℃.To maximize the temperature effect below the threshold,37℃was selected for the experimentation.Since 0.5 mmol·L-1 GABA raised the seed germination rate at 37℃by 138.81%in 6 d,the addition level was applied for the subsequent experiments.With the GABA treatment under heat stress,the seed germination potential and indicators were improved,the hypocotyls lengthened,the proline,soluble sugar,and protein contents enhanced,the superoxide dismutase(SOD),peroxidase(POD),and catalase(CAT)activities elevated,and the malondialdehyde(MDA)and hydrogen peroxide(H2O2)accumulations reduced over control.In addition,the endogenous hormones Gibberellin3(GA3),gibberellin1(GA1),gibberellin7(GA7),jasmonoy-L-isoleucine(JA-Ile),and salicylic acid(SA)rose significantly,abscisic acid(ABA)and indoleacetic acid(IAA)declined,and jasmonic acid(JA)remained high compared to CK in 3 d.The expressions of GA synthesis genes(i.e.,GA20ox2 and GA3ox1),signaling factors(i.e.,GID1-a,GID1-b,and GID1-c),and ABA degradation genes(i.e.,CYP707A1 and CYP707A2)were upregulated,while the GA degradation genes(i.e.,GA2ox1 and GA2ox2)and negative regulator Della downregulated.Meanwhile,the ABA synthesis genes(i.e.,NCED1 and NCED2)and signaling factors(i.e.,ABI5 and SnRK2.3)were inhibited.[Conclusion]Treating the eggplant seeds with 0.5 mmol·L-1 of GABA stimulated germination and enhanced heat tolerance to 37℃through a synergy of multi-pathways.Theoretically,the application could help accelerate eggplant seedling operation.