The Effects Of Abaand H₂O₂ On SHSPs And Antioxident Defense Enzymes Induced By The Combination Of Drought And Heat Stress In Maize

In order to determine the effects of H₂O₂ and ABA on small heat shock protein (sHSPs) and antioxidant defense enzymes induced by the combination of drought and heat stress in maize (Zea mays L.) leaves and roots, Zheng dan 958 and ABA deletion mutant vp5 maize plants as experimental materials were used in this study. Fristly, through primer designing and RT-PCR analyzing, selected out sHSPs that induced by the combination of drought and heat stress. Secondly, ABA inhibitor tungstate (T) and H₂O₂ scavenger KI(I) were used to analyse the influences of H₂O₂ and ABA on sHSPs and antioxidant defense enzymes genes expression induced by the combination of drought and heat stress in maize leaves and roots by RT-PCR. Finally, the expression of sHSP26 was analysed by western blot. The detailed research results are as follows.1,Searching out all of maize sHSPs gene sequences published in NCBI database GenBank. Fristly, sHSPs gene sequences with different families were compared and analysised by Dnaman software; Then, primers in its conservative districts were designed by Oligo6.0 software. In the end, sHSPs genes induced by combined drought and heat stress were selected out by RT-PCR, which incluced sHSP16.9,sHSP17.2,sHSP17.4,sHSP17.5,sHSP22 and sHSP26. In addition, the four antioxidant defense enzymes such as catalase 1( CAT1),cytolic ascorbate peroxidase ( cAPX),glutathione reductase 1 ( GR1) and superoxide dismutase 4 (SOD4) primers were also designed.2,The results of pretreatment with ABA inhibitor T and H₂O₂ scavenger KI showed that: (1) The six sHSPs genes expression in maize leaves were all inhibited by T more or less, but only sHSP16.9,sHSP17.2,sHSP17.5 and sHSP22 were slightly inhibited in maize roots. The expression of four antioxidant defense enzymes gene SOD4, GR1, CAT1 and cAPX were all significantly inhibited by T both in maize leaves and roots. (2) Compared with vp5 maize plant that without 100μM ABA pretreatment, the pretreatment significantly increased the four enzymes genes expression in leaves and roots, but only slightly increased the six sHSPs genes expression in maize leaves and sHSP17.2 expression in roots. (3) The pretreatment with KI significantly inhibited the genes expression of four antioxidant defense enzymes both in maize leaves and roots and slightly inhibited the genes expression of six sHSPs in maize leaves, but only slightly inhibited the genes expression of sHSP16.9,sHSP17.2,sHSP17.5,sHSP22 and sHSP26 in maize roots.3,The results of sHSP26 expression analysed by western blot showed that, sHSP26 was significantly inhabited by T and KI in maize leaves, but T was almostly no influence to sHSP26 expression and KI only slightly inhabited sHSP26 expression in maize roots.These results supplied the basis for further researching the mechanisms of plant response to stress and gene cloning, and also offered important scientific evidences to reveal the mechanism of plants tolerant to combination stress.