ABSTRACT
Aim: To develop new Trichoderma strains, capable of removing toxic heavy metal ions from polluted environments, via protoplast fusion.Methodology: Trichoderma parental strains (T. viride and T. koningii) along with their ten fusants (Tk+Tv 1, Tk+Tv 2, Tk+Tv 3, Tk+Tv 4, Tk+Tv 5, Tk+Tv 6, Tk+Tv 7, Tk+Tv 8, Tk+Tv 9 and Tk+Tv 10) were obtained from the Department of Plant Pathology, Junagadh Agricultural University, Junagadh. The strains obtained by protoplast fusion were examined for their ability to remove toxic heavy metal ions, especially zinc ion. Fourier-transform infrared spectroscopy (FTIR) was conducted to detect the zinc uptake mechanism of Trichoderma parental and their fusant strains. Results: FTIR results demonstrated the Zn ion uptake capacity of fusant strains was found to be higher than that of the parental strains (12.8 to 10.7 mg g-1 on a dry weight basis at 1300 ppm). The highest Zn ion mobility observed was 62.1 mg. kg-1 and the highest Zn ion mobility observed per strain was 12.4% in Tk+Tv 3, followed by 11.86 % in Tk + Tv 7, 11.84% in Tk + Tv 9 and 11.28% in Tk + Tv 10. Parental and fusant strains Tk + Tv 3, Tk + Tv 8 and Tk + Tv 10 confirmed the involvement of different functional groups for different concentrations of zinc during adsorption by the fungus. Interpretation: FTIR results identified greater metal removal capacity in the fusant strains, particularly for soil Zn ion. Zinc tolerance was higher in the fusant strains than in the parental strains. Thus, protoplast fusion is an effective and feasible method for constructing new strains that can be used for bioremediation of contaminated environments.
ABSTRACT
Aim: The present study aimed to investigate the phosphate solubilization potential of agriculturally important fungi, i.e., Aspergillus sp. isolated from the rhizosphere of healthy plants in Abha city, Saudi Arabia.Methodology: Sixteen Aspergillus sp. isolated and tested for phosphate solubilization potential were identified by 5.8S-ITS region sequencing and characterized by 11 ISSR-PCR markers. Finally, the highest phosphate solubilization potential isolates were used in field experiments on cucumber and tomato plants. Results: All Aspergillus niger isolates showed 96–100% similarity to A. niger strains available at GenBank database, Isolate ASAB-5 was most efficient at solubilizing phosphate on Pikovskaya’s medium, with a solubilization index of 2.67, and 235.22 mg l-1 of solubilized phosphate. ISSR-PCR markers revealed is total 142 bands in all isolates, with about 32.3% showing monomorphism and 67.6% polymorphism. Based on genetic similarity and intraspecies variability, the Aspergillus isolates were grouped into two different clusters with about 67.9% genetic similarity. The results of field experiments showed no significant difference between seeds treated with culture filtrate or conidial suspension of ASAB-5; however, both differed remarkably from untreated seeds. Interpretation: The current study confirms the existence of several useful phosphate solubilizing fungi in plants, which may serve as potential biological fertilizers. They are safer than chemical fertilizers and increase the bioavailability of soil phosphates for plants