Exogenous Effects Of Trehalose On The Salt Tolerance Of Wheat

In the present study, a salt-sensitive wheat (Thiticum aestivum L.) cultivar(Luniai No. 15) was used to study the responses of salt tolerance in thegennination and the seedling stages to exogenous trehalose treatment under NaC1stress. Results were as followings:1 .Germination stageSeeds were germinated in Hoagland solution, 150 mM NaCl solution and150 mM NaC1+l 0 mM trhalose respectively. Water absorption rate, embryonicroot and coleoptile elongation, Na~ and K~ contents and ratio of Na~/K~ in theembryonic roots and coleoptiles were determined. Results were shownfollowings:1.1 Effect of exogenous trehalose on water absorption rate of the seeds undersalinity.During the first 6 h, there is no significant difference in the water absorptionrate between different treatments (p>O.OS). But after l2h, significant difference isobserved: NaC1 stress greatly decreased the water absorption rate compared withthe control and exogenous trehalose markedly increased the water absorption rateunder the same salinity. This difference became more significant with furthertreatment.1.2 Effect of exogenous trehalose on the coleoptile elongation under salinityNaC1 stress greatly inhibited the coleoptile elongation compared with thecontrol. Exogenous trhalose significantly alleviated the elongation inhibitionunder the same NaCl stress (p<0.05) and the alleviation was more obvious as the42treatemnt time.1.3Effect of exogenous trehalose on the embryonic root elongation undersalinityNaCl stress greatly inhibited the embryonic root elongation compared withthe control. Exogenous trehalose significantly alleviated the elongation inhibitionunder the same NaC1 stress.1.4 Effect of exogenous trehalose on the Nat, K7~ content and Na~[K~ ratio inthe embryonic roots and coleoptiles under salinity.NaC1 stress resulted in a obvious decrease in K~ content, a obvious increasein Na~ content and a great increase of Na~ / K~ ratio in coleoptile. Addingexogenous trehalose to salt solution significantly increased IC content, decreasedNa~ content and led to a low Na~ / K~ ratio in coleoptiles.1.5 Effect of exogenous trehalose on the activity of cL-amylase under salinity.NaC1 stress greatly decreased the activity of c~-amylase compared with thecontrol. But exogenous trehalose markedly increased the activity of (x-amylaseunder the same salinity.2.Seedling stage2.1Growth and ionic content2.1.1Effect of exogenous trehalose on the leaf osmotic potential of wheatseedlings under salinity.The leaf osmotic potential was greatly decreased by NaC1 stress comparedwith control plants. Adding trehalose to the same salt solution resulted in a furtherdecrease in the leaf osmotic potential. It suggested that exogenous trehaloseinvolved in raising osmotic adjustment of wheat seedlings under NaC1 stress.2.1.2Effect of exogenous trehalose the fresh weight and dry weight ofdifferent organs of wheat seedlings under salinity.Both NaC1 and NaC1+trehalose treatment led to a significant decrease in the43fresh weight and dry weight of roots, stem and leaves compared with controlplants and the root fresh weight was most sensitive to NaC1 stress. However, thefresh weight and dry weight of roots, stem and leaves of NaC1+trehalose-treatedplants were all significant higher than those of the same NaC1-treated plants andeffectiveness of the trehalose on the roots was the most significant. These reasultssuggested that exogenous trehalose significantly increased the fresh weight of thewheat seedlings and the roots was most sensitive to exogenous trehalose undersalinity. Similar trends in the dry weight of different organs of wheat seedlingsunder NaCI stress was obtained.2.1.3 Effect of exogenou...