Question

Trichoderma harzianum has proved a useful microorganism for
A. Gene transfer in higher plants
B. Biological control of soil-borne plant pathogens
C. Bioremediation of contaminated soils
D. Reclamation of wastelands

Answer 1

Hint:- Kingdom Fungi comprises some of the most diverse organisms which are often closely associated with organisms of the other kingdoms. Known for their pivotal role as decomposers, they are distributed all over the globe, from dead matter to soils to aquatic bodies to deserts to other plants/animals.

Complete Answer:-Fungi’s means of nutrition may be parasitic (harmful for the host), mutualistic (beneficial for host & fungi), commensalism (harmless for the host) or even saprophytic (feed on dead & decaying substance). These associations ultimately exist to serve their nutritional needs as they are heterotrophic. Kingdom Fungi encompass Phyla Ascomycota, Chytridiomycota, Glomeromycota, Zygomycota and Basidiomycota.

Among the Ascomycetes (familiarly called sac fungi) are Trichoderma harzianum which are ironically also famous fungicides. They are recognised biological control agents (BCA) which are natural agents used as substitutes for chemical products that serve the purpose of pest control.

Upon application, Trichoderma harzianum enhances the growth, development, nutrient uptake, immunity and yield of the crops. However, time taken for the application of such BCA to prove effective can be long, hence improved strains/formulations that accurately identify strains, modify the physiological & genetic makeup and manipulate the environment have been developed.

Therefore, the correct answer is option (B). Biological control of soil-borne plant pathogens.

Note:- In recent times, Trichoderma species have also been identified to possess bioremediation and biodegradation qualities due to their ability to tolerate and degrade toxic substances. This causes ambiguity between options B and C, however, since they have been long established as BCA, option B is more accurate.