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K üresel nüfus artışı ve endüstriyel kirlilik, tuz stresi ile birleştiğinde, tarımsal şartları ağırlaştıran çevresel tehditlere dönüşmektedir. Yeni fungal izolatların moleküler karakterizasyonu ve bunların tarım üzerindeki etkilerinin araştırılması, tuz stresi toleransının kontrolünde çevre dostu bir yaklaşım olabilir. Bu bağlamda mevcut çalışmada, doza bağımlı tuz (NaCl) stresi uygulanan mısır tohumlarına fungal ön muamele gerçekleştirilmiştir. Fungusun genetik bağlantıları iyi bilinen ITS barkodları kullanılarak tanımlanmış ve Trichoderma citrinoviride (T11C) türüne benzerlik gösterdiği ortaya çıkarılmıştır. Fungal uygulamanın yapıldığı stres altındaki mısır bitkilerinde, maksimum kuantum verimi (Fv/Fm), elektron transfer oranı (ETO), ve fotokimyasal kullanılmanın (qP) optimuma yakın olduğu, bununla birlikte NPQ (fotokimyasal olmayan floresans sönmesi) değerlerinin ise; ilgili gruplarda azaldığı belirlenmiştir. Ayrıca, fotosentetik pigment içeriklerinin yüksek olduğu kaydedilmiştir. T11C fungal muamelesinin, tuz stresi altındaki bitkilerde lipid oksidasyonunu düşürdüğü tespit edilmekle birlikte, mısır kök ve yapraklarında SOD, GPX, GR ve CAT aktivitelerini belirgin şekilde arttırmadığı gözlenmiştir. Yüksek tuz stresi uygulanan test gruplarında, yüksek RWC (göreceli su içeriği), çözünebilir protein ve prolinin tespiti, fungal ön muamelenin, bitkilerde artan bir osmoregülasyon kapasitesini tetiklediğini kanıtlamıştır. Devam eden çalışmalar, mısır gibi ekonomik açıdan önemli tahıllarda çoklu stres toleranslarını test etmek adına, tarımsal uygulamalarda kullanılabilecek toz halindeki mantar biyopreparatlarının geliştirilmesine yöneliktir.

The protective effect of a cytokinin benzyladenine (BA), against toxicity of paraquat (PQ), a widely used herbicide and a well-known oxidative stress inducer, was investigated in the leaves of maize. Maize leaves have been pretreated with BA at concentrations of 1, 10 and 100 microM and afterwards treated with PQ. At all concentrations tested, BA retarded PQ-induced decreases in chlorophyll, carotenoid and ascorbic acid contents. Pretreatment with 10 and 100 microM of BA significantly increased superoxide dismutase (SOD) activity after 8 h of PQ treatment but there was no significant change in SOD activity in the leaves pretreated with BA at 12 and 24 h. However, peroxidase activity significantly increased in 100 microM of BA pretreated leaves. Results indicate that pretreatment with BA reduce PQ toxicity and BA-treated plants might become more tolerant against oxidative stress.

the effects of diuron, a photosystem ii inhibiting herbicide, on lipid peroxidation, photosynthetic pigments, soluble protein, proline contents and some antioxidant enzymes in maize leaves were studied and protective effects of polyamines against diuron toxicity were investigated. Diuron significantly increased lipid peroxidation, suggesting oxidative damage in the plants and proline content, while it decreased total chlorophyll, carotenoid and soluble protein levels in the leaves during the experiments. Pretreatment with polyamines statistically decreased lipid peroxidation induced by diuron and spermine (sPm) proved to be the most effective polyamine. Also, pretreatment with polyamines significantly prevented the losses of total chlorophyll, carotenoid and soluble protein induced by diuron. on the other hand, pretreatment with polyamines significantly increased proline contents of the leaves in comparison with the leaves treated with diuron. superoxide dismutase (sod), guaiacol peroxidase (GPX) and glutathione reductase (Gr) activities increased in the leaves treated with diuron while catalase (cat) activity decreased. Pretreatment with spermidine (SPD) did not change significantly SOD activity at 24 and 72 hrs of diuron treatment but prevented the increase in sod activity induced by diuron at 48 h. however, pretreatment with sPd increased GPX activity at 24 h and GR activity at 48 and 72 hrs. CAT activity in the leaves pretreated with SPD was similar to that of the leaves treated with diuron. Pretreatment with sPm prevented the increase in sod activity induced by diuron at 48 h but significantly increased it at 72 h of diuron treatment. However, pretreatment with SPM did not significantly change GPX and GR activities during the experiments but reversed the decrease in CAT activity induced by diuron at 72 h. Pretreatment with putrescine (PUT) prevented the increase in SOD activity induced by diuron at 48 and 72 hrs while it increased GPX and GR activities at 48 h of diuron treatment. Also, the decrease in CAT activity induced by diuron at 72 h was completely prevented by Put. it can be concluded that pretreatment of maize leaves with polyamines reduced the damage produced by diuron and the protective effects of polyamines against diuron toxicity were closely associated with antioxidant system.