Syed's Learn Microbiology

Bacterial Blight Causative Agent : Bacterial blight is primarily caused by Xanthomonas oryzae in rice and Xanthomonas campestris in other crops. Commonly affects rice, but can also impact other crops, such as beans and various vegetables. Bacterial blight Transmission : Spread through contaminated water, soil, tools, and infected plant material. Bacteria can survive in plant debris, facilitating disease persistence in fields.    Domain : Bacteria    Phylum : Proteobacteria    Class : Gammaproteobacteria    Order : Xanthomonadales    Family : Xanthomonadaceae    Genus : Xanthomonas    Species : Xanthomonas oryzae (in rice) and Xanthomonas campestris (in other crops) Within Xanthomonas oryzae , there are two significant pathovars: Xanthomonas oryzae pv. oryzae : Causes bacterial leaf blight in rice. Xanthomonas oryzae pv. oryzicola : Causes bacterial leaf streak ...

Botrytis Blight (Gray Mold)   Caused by the fungus Botrytis cinerea , a necrotrophic pathogen, meaning it kills host tissue  to feed on it    Botrytis cinerea has a broad host range, affecting over 200 plant species, including grapes, strawberries, tomatoes, lettuce, beans, roses, and many ornamental plants.    Domain : Eukaryota    Kingdom : Fungi    Phylum : Ascomycota    Subphylum : Pezizomycotina    Class : Leotiomycetes    Order : Helotiales    Family : Sclerotiniaceae    Genus : Botrytis    Species : Botrytis cinerea   Disease Cycle : Spores : Botrytis cinerea produces spores (conidia) that are easily dispersed by wind, water, and physical contact. These spores land on plant surfaces and require moisture for germination. Infection : The fungus infects plant tissues through wounds, cuts, or natural openings like stom...

  Citrus Greening (Huanglongbing)                Caused by the bacterium Candidatus Liberibacter , primarily Candidatus Liberibacter asiaticus (most common), africanus , and americanus . Domain : Bacteria Phylum : Pseudomonadota (formerly Proteobacteria) Class : Alphaproteobacteria Order : Rhizobiales Family : Rhizobiaceae Genus : Candidatus Liberibacter Species : Candidatus Liberibacter asiaticus (most widespread and virulent species) Candidatus Liberibacter africanus (found mainly in Africa) Candidatus Liberibacter americanus (less common, found in parts of Brazil). Transmission : The primary vector is the Asian citrus psyllid ( Diaphorina citri ), which transmits the bacterium while feeding on the sap of citrus trees. Once a tree is infected, the bacterium moves through the phloem, affecting the plant's ability to transport nutrients. Pathogenicity of Citrus Greening (HLB): Intra...

Awl Nematodes (Dolichodorus spp.) Plant Disease  Dolichodorus spp., commonly known as awl nematodes, are plant-parasitic nematodes.    Kingdom : Animalia    Phylum : Nematoda    Class : Secernentea    Order : Dorylaimida    Family : Longidoridae    Genus : Dolichodorus Distribution: Found in sandy soils of tropical, subtropical, and temperate regions. Commonly associated with turfgrasses , agricultural crops , and nursery plants Host Plants: Wide Host Range : Awl nematodes can infect a variety of plants, including: Crops : Corn, soybeans, potatoes, and vegetables. Turfgrasses : Golf courses and lawns. Ornamentals : Many nursery and garden plants. Symptoms in Plants: Stunted Growth : Infected plants often show poor growth due to the nematode feeding on the root tips. Wilted or Yellowing Leaves : Plants may wilt or develop yellow le...

Aster Yellows (Phytoplasma Disease) Aster yellows is caused by phytoplasmas, which are specialized bacteria that lack cell walls and live in the phloem of plants. Caused by Candidatus Phytoplasma asteris. Taxonomy: Kingdom : Bacteria Phylum : Tenericutes Class : Mollicutes Order : Acholeplasmatales Family : Acholeplasmataceae Genus : Candidatus Phytoplasma Species : Candidatus Phytoplasma asteris        Shape : Pleomorphic (varied shapes, but often round or elongated). Size : Very small, ranging from 200-800 nm in diameter, making them smaller than most bacterial cells. Lack of Cell Wall : Unlike many bacteria, phytoplasmas lack a rigid cell wall and are instead bound by a flexible plasma membrane. Transmission: Insect Vectors : Primarily spread by leafhoppers ( Macrosteles quadrilineatus and others). The phytoplasma is transmitted from plant to plant through feeding by infected le...