Plant Microbiology

Question 1

How many estimated species are there in the Kingdom Fungi?

Answer 1

Approximately 1.5 million species are estimated to belong to the Kingdom Fungi.

Question 2

What are the general characteristics of fungi?

Answer 2

Fungi are heterotrophic, eukaryotic organisms that lack chlorophyll. They are usually filamentous and spore-bearing, with a cell wall composed of chitin and glucan.

Question 3

Name some examples of fungi belonging to Kingdom Fungi.

Answer 3

Yeasts, moulds, and mushrooms are examples of organisms belonging to the Kingdom Fungi.

Question 4

What are the different lifestyles of plant-associated fungi?

Answer 4

Plant-associated fungi include symbiotic types like endophytes and mycorrhizae, as well as pathogenic types that may be obligate or facultative parasites.

Question 5

How are fungi classified based on morphology?

Answer 5

Fungi are classified based on macroscopic features (colony morphology, color), microscopic structures (mycelium, reproductive structures), and secondary metabolites.

Question 6

What is the universal barcode used for fungal taxonomy?

Answer 6

The Internal Transcribed Spacer (ITS), including ITS1, ITS2, and the intervening 5.8S region of nrDNA, is the universal barcode used for fungi.

Question 7

What are some benefits of mycorrhizal fungi for crops?

Answer 7

Mycorrhizal fungi improve nutrient acquisition, water absorption, drought tolerance, and resistance to biotic stresses in plants.

Question 8

How do ascomycetes cause diseases in plants?

Answer 8

Ascomycetes cause diseases such as leaf spots and powdery mildews on agricultural crops, impacting yield and food safety.

Question 9

Describe the life cycle of basidiomycetes.

Answer 9

Basidiomycetes reproduce sexually with basidiospores and basidia, and they include important pathogens like rusts and smuts.

Question 10

What is a key concern in fungal disease management?

Answer 10

Fungicide resistance in fungal populations is a significant concern, driven by disease pressure and improper fungicide use.

Question 11

What are nematodes?

Answer 11

Nematodes are small, non-segmented, worm-like organisms with transparent cylindrical bodies that taper at both ends. They can be up to a few millimeters long and are the most abundant group of multicellular animals on earth.

Question 12

How do nematodes impact agriculture?

Answer 12

Plant parasitic nematodes cause significant losses in agricultural production, ranging from 5-20%. They damage roots, reduce nutrient uptake, and can make plants more susceptible to other diseases.

Question 13

What are some diseases caused by nematodes?

Answer 13

Nematodes cause diseases such as filariasis, elephantiasis, hookworm, and pinworm in humans. In plants, they contribute to diseases like root-knot nematodes and cyst nematodes.

Question 14

How do plant parasitic nematodes feed?

Answer 14

Plant parasitic nematodes use a stylet to pierce plant cell walls and feed on the cytoplasmic contents. This feeding method directly damages roots and can lead to nutrient loss and increased susceptibility to other pathogens.

Question 15

What role do nematodes play in soil ecosystems?

Answer 15

Free-living soil nematodes play a crucial role in nutrient mineralization and cycling, with millions of individuals per square meter in soil, contributing to biological processes.

Question 16

How do beneficial nematodes contribute to agriculture?

Answer 16

Beneficial nematodes enhance soil quality by improving nutrient cycling and can control plant pests and parasitic nematodes, thus supporting sustainable crop production.

Question 17

What are the different feeding types of nematodes?

Answer 17

Nematodes can be classified based on their feeding types, including ectoparasites (using stylets externally) and endoparasites (entering plant tissues).

Question 18

Describe the life cycle of plant parasitic nematodes

Answer 18

Plant parasitic nematodes have a life cycle consisting of egg, juvenile stages (J1 to J4), and adult stages. This cycle can take 2-4 weeks to complete.

Question 19

What are the feeding lifestyles of plant parasitic nematodes?

Answer 19

Plant parasitic nematodes can be ectoparasites (e.g., dagger nematodes), endoparasites (e.g., root knot nematodes), or semi-endoparasites (e.g., reniform nematodes), each affecting plants differently.

Question 20

How can nematode infestations be managed in agriculture?

Answer 20

Nematode infestations can be managed through various methods including resistant/tolerant crop cultivars, crop rotation, chemical treatments, and biological control using antagonistic fungi or bacteria.

Question 21

What role do beneficial plant-associated bacteria play in agriculture?

Answer 21

Beneficial bacteria like rhizobia (Rhizobium spp.) fix nitrogen in legume roots, enhancing nitrogen availability and promoting plant growth.

Question 22

How do certain bacteria contribute to plant disease suppression?

Answer 22

Bacteria such as Bacillus spp. and Pseudomonas spp. produce secondary metabolites and enzymes that inhibit pathogen growth or induce systemic resistance (ISR) in plants.

Question 23

What is induced systemic resistance (ISR)?

Answer 23

ISR involves physiological changes in plants induced by plant growth promoting rhizobacteria (PGPR), like Bacillus spp. and Pseudomonas spp., enhancing resistance against diseases like Fusarium wilt.

Question 24

How do plant pathogenic bacteria affect crops?

Answer 24

Plant pathogenic bacteria disrupt plant hormones, causing symptoms such as stunting, galls, and defoliation. They produce toxins and virulence factors that aid in infection and disease development.

Question 25

What are common symptoms caused by plant pathogenic bacteria?

Answer 25

Symptoms include soft rots (e.g., caused by Pectobacterium spp.), leaf spots (e.g., Xanthomonas spp.), and wilts (e.g., Ralstonia solanacearum), impacting a wide range of crops.

Question 26

How do bacteria spread among plants?

Answer 26

Bacteria can spread through windblown soil particles, water (rain splash, irrigation), insects, and human activities, contributing to disease dissemination.

Question 27

What are effective strategies for managing bacterial diseases in crops?

Answer 27

Management includes using pathogen-free seeds, crop rotation, sanitation practices, resistant cultivars, and sometimes chemical control with bactericides.

Question 28

What are examples of serious bacterial diseases affecting crops?

Answer 28

Fire blight (Erwinia amylovora) affecting apples and pears, and Pierce’s disease (Xylella fastidiosa) affecting various crops, are significant threats requiring strict quarantine measures.

Question 29

How do viruses impact plants?

Answer 29

Viruses hijack plant cells to replicate, leading to symptoms like mosaic patterns, ringspots, mottling, and necrosis, affecting growth, yield, and quality.

Question 30

What are common modes of virus transmission?

Answer 30

Viruses transmit through vectors (insects, nematodes), vegetative propagation, and mechanical means (sap transmission), influencing their spread and management strategies.