Microbes and Plant Diseases

Candida cultures can be obtained on  Sabouraud’s agar. Other media used to culture fungi are cornmeal agar and Czapek-Dox medium.

Mitis-Salivarius-Bacitracin agar (MSA) with 20% sucrose and 0.2 U bacitracin/ml is a selective medium for streptococcus mutans. Bacitracin present in the medium suppresses the growth of most non-S.mutans colonies.

Interferons are a family of host-coded proteins produced by cells on induction by viral inducer. Interferon does not act on virus, but it renders other host cells refractory to virus. Interferons (IFNs) are natural cell-signaling proteins produced by the cells of the immune system of most vertebrates in response to challenges, such as viruses, parasites and tumour cells.

Aspergillus causes opportunistic infection in immunocompromized patients and debilitated hosts like HIV, diabetes and other immunocomprmised. Other opportunistic fungal infection in diabetes is candidiasis.

Stripe disease of wheat is caused by cochliobolus sativus. Wheat’s false eyespot disease is caused by Hymenula cerealis.

Sheath brown rot disease of rice is caused by Pseudomonas fuscovaginae, symptoms appearing at seedling and later stages include discoloration and rotting of sheath. After transplanting, infected seedlings initially show yellow-brown discolorations on their lower leaf sheaths. Later the discolorations turn gray-brown to dark brown. Ultimately, rot results in death of the infected seedlings.

In maize, Stewart's disease is caused by Erwinia stewartii and Holcus spot disease is caused by Pseudomonas syringae.

Early blight of tomato and potato disease is caused by Alternaria solani. Phytophthora infestans causes the Late blight of potato disease.Stem black rust of wheat is caused by Puccinia graminis fungus.Loose smut of wheat is caused by fungi, Ustilago species like-U. tritici, U. segatum.

Agrobacerium rhizogenes in apple causes Hairy root disease.

In carrot, Cottony rot disease is caused by the fungal species- Sclerotinia sp. (S. minor, S. sclerotiarum).

Dry rot disease is caused by Ashbya gossypii and Nematospora coryli in citrus.

In coffee, warty berry disease is caused by Botrytis cinerea.

Xanthomonas campestris causes fucous blight disease in beans.

In apple, Kernel blight disease is caused by bacteria- Pseudomonas syringae pv. syringae and Basal glume rot is caused by bacteria- Pseudomonas syringae pv. atrofaciens. Anthracnose, Dwarf bunt and Leaf rust are caused by fungal pathogens- Collectotrichum cereale, Tilletia controversa and Puccinia hordei respectively, in apple.

In apple, Diplocarpon mali and Marsonia coronaria cause ‘Marsonia blotch’ disease, Mucor piriformis causes the Mucor rot disease and Nectria galligena causes Canker disease.