Effects Of Hexaconazole-Cu Complex On Plant Morphology And ABA-related Gene Expression

Drought stress is a stress that severely damage plant growth and development.Triticum aestivum is a major cereal crop,so to alleviate its damage under drought stress is an important issue to be solved.Triazole not only can serve as plant growth regulator but also effectively relieve abiotic stress causing damage.In this research,the effects of hexaconazole-Cu complex on plants' stomata and roots were studied.Hormone ABA content and gene expression of key enzymes in ABA,9-cis-epoxycarotenoid dioxigenase(NCED)and ABA 8'-hydroxylase(CYP707A 1),in T.aestivum seedlings were analyzed.The results are as follows:(1)The leaves hypodermis tissue of T.aestivum and tobacco were treated by complex solutions of various concentrations for different time lengths.With the concentration of the complex increasing from 0 to 100 ?M,the stomatal apertures of both materials decreased after 1 h treatment.For T.aestivum,the average stomata was 1.06 ?m,0.96 pm,0.75 ?m,0.63 ?m,0.59 ?m and 0.55 ?m,respectively,corresponding to complex concentration of 0,20,40,60,80 and 100 ?M.The average stomata of tobaccos decreased from 2.37 to 0.90 ?m when the complex concentration increased from 0 to 100 ?M.The treatment time also depicted remarkable effect on the stomatal aperture.After treated by complex solution of 80 ?M for 9 h,the average stomata of tobacco decreased from 2.37 ?m(non-treated)to 0.94 ?m.The same trend was observed in T.aestivum,which had its average stomata decreased by 40.6%,49.1%,50.9%and 54.7%,respectively after 1,3,6 and 9 hours' treatment in complex solution 60 ?M.The changes of T.aestivum root apical were observed by scanning electron microscopy before and after the treatmet of complex solution of 60 ?M.The root apical of seedlings in the control group appeared to be sparse,short and thick,contrary to the dense and slender root apical in the treated group.No significant difference was observed on the root apical morphological top of the control group and the treated group,whereas from 5mm from the top of the root,the treated group had thicker and longer root than that of the control group.Meanwhile,hexaconazole-Cu complex inhibits wheat seedlings growth,leading to increased root weight.The root weight of complex treated seedlings is 1.42 times heavier than that of the control.(2)The effects of complex on ABA content as well as the expression of NCED and CYP707A1 by real-time quantitative PCR in seedlings of T.aestivum were studied.Under the drought condition,the expression level of NCED in seedlings of both control and treated groups were lower than those at non-treated 0 h.During the dehydration process(24 h-144 h),the expression of NCED in seedlings of control group gradually increased with time elapsing,whereas the treated group depicted decreasing NCED expression in the first stage(24-48 h),which was followed by an subsequent increasing between 96 and 144 h.The seedlings were rehydrated afterwards,and the NCED expression of both control and treated groups showed a decreasing trend with rehydration(144-192 h).For both control and treated groups,the expressions of CYP707A1 in seedlings were higher after drought than those at 0 h.For the control group,the CYP707A1 expression reached the highest level after 144 h's dehydration,and it decreased when the seedlings were hydrated.Whereas for the treated groups,the highest expression was observed at 168 hours when the seedlings had been hydrated for 24 h after 144 h's dehydration.It was worth noting that in the dehydration process,the CYP707A1 expression of control group was higher than that of the treated group,whereas it was lower comparing to that of treated group after rehydration.Meanwhile,the expression of CYP707A1 was greater than that of NCED.Under drought stress,the ABA contents of both control and treated groups were higher than that of nontreated 0 h.The highest ABA contents were achieved at 96 h,which was 4.38(control group)and 4.64(treated group)times of that at 0 h,respectively.So ABA content is an important indicator of drought tolerance.In the present study,the ABA content in the treated group was higher than that in the control group,indicating that the complex treatment had an effect on the drought tolerance of T.aestivum.(3)An electrochemical biosensor using a combination of PCR amplification techniques and gold nanoparticles/grapheme/deposited nano-gold composite(AuNPs/Gra/DpAu)was prepared,which was used to detect the CYP707A1 content in the above-treated seedlings of T.aestivum.The results were consistent with the results obtained from RT-qPCR.The results showed that the biosensor had a broad detection range of 5 orders of magnitude with a minimum detecting limitation of 13 pM,indicating the good sensitivity and specificity of the sensor.