BIOL 420 1st Edition Lecture 4Current LectureViruses – not living- aren’t cellular and have their own taxonomy system- doesn’t fit in any kingdomsTobacco mosaic virus – Iwanowski- Viral genome – may be single-stranded or double-stranded RNA or DNA- Capsid: protein coat with no cytoplam- Virion – genome +capsid- Tobacco mosaic virus is a single-stranded RNA virus, most plant viruses are RNA viruses- highly contagious and cause he leafs to splur. What is this? Tried filtering it, tried isolating, it wasn’t following the protocol that a bacteria would follow – realize that it was a virus. Human (animal viruses) – polio, rabies, Ebola, AIDS (HIV)- There are 2,000 known diseases caused by plant viruses- More than 600 types of plant viruses are known- $15 billion dollars in crop losses annually- transmitted Viral life cycles- Lytic enzyme will destroy most DNA and virus takes completely over DNA and lysogenic life cycles - Unlike animal viruses, plant viruses do not generally enter plant host cell through cell membrane (plant cells have cell walls)These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Plants lack motility and behavior patterns that animals demonstrate so rare to have wind-borne, food borne, contact type pathogens- Plant viruses usually require a vector (aphids, leafhoppers, whiteflies, with biting and sucking mouthparts) to be transmitted- All virus needs a host and needs a bacteriophage- Viruses are measured at the 10^9 – that’s how small they arePlant viruses can also be transmitted by:- Nematodes: live in the soil, the affect the root system, can be a mode of transmission bygoing through the roots- Harvest operations: cutting the crop from one plant to another plant- Vegetative propagation - Can be spread by vector – an insect that is sucking up the virusmerViroids: lack a capsid, don’t even have a protein coat. Cause different plant diseases. Plant viral RNA usually able to act directly as mRNA when it is in the cytoplasm of the plant cellSymptoms of plant viral infections- Chlorotic coloration- Tissue necrosis- Leaf roll- CankerDNA Plant Viruses (3 Types) (most are RNA)- Geminiviruses: exists as 2 subunits to the viral structureExamples: bean golden mosaic disease, corn streak, others- Badnaviruses: Examples: diseases of bananas, sugarcanes, and raspberries- Caulimoviruses – affect cauliflower, blueberries, and carnations- Systemic plant viral infectionsViruses move from cell to cell through plasmodesmata of cell wallVectors usually introduce virus into the sieve tubes of phloemSlow movement through phloem, 1 cm per dayEven slower through parynchema cells of leaf, 8-10 cells per dayAnimals viruses can move through circulatory systemHost resistance to plant pathogens MOVE TO UNIT 3Do plants have immune systems?- Hypersensitivity response (HR)- Systemic acquired resistance (SAR)- Posttranscriptional Gene Silencing (PTGS) Viroids – small, lack capsids- 1971 Theodor Diener- Spindle disease in potatoes- Coconut cadang-cadang killed millions of coconut trees in Philipines Photosynthetic Prokaryotes (Cyanobacteria)Prokaryotic cell structure- Lack nucleus but have a nuclear region (DNA)- Nucleoid (DNA)- Circular chromosome- Ribosomes - Plasmids- Cell membrane – phospholipid bilayer- Plasma membrane – electron transport chain- Cell wall – peptidoglycan- Some have a capsule – just another wall for protection- If it the cell has a flagella – then it is able to move - Pili: in sexual reproduction & asexual (binary fission) Eubacteria Morphology (true bacteria)Bacillus (rods), coccus (circles), spirillium (spirals)Prokaryotic organisms- Archaea- Cyanobacteria- Eubacteria – many are plant pathogensCyanobacteria – blue/green bacteria/mass that grows around the summer in water etc- Have a cell wall, plasma membrane, plays a critical role in the life on earth by the way they evolved. - Photosynthetic- Thylakoids stack of coin-like structure with chlorophyll- StromatolitesImportance- First photosynthetic organisms- Origin of atmospheric oxygen- Among first living things on Earth- Many fix nitrogenPlanktonic cyanobacteria- Gas vesicles- Heterocyst: nitrogen fixing cell- Akinetes: resistance to drying out, heating spores and survive tough environments. Thickcovering on their cell wall (capsule) -Trichodesmium-Anabeana – not considered multicellular, don’t have tissues and organs -Oscillatoria: fillamentus, each rectangular would be a cell. It can grow really long and oscillates through water.-Stromatolites: secreting minerals, growing in stool-like structures. -Calothrix-NostocSymbiotic cyanobacteria- Origin of chloroplastsSome bacteria are related in plants by the diseases they share. Some of the diseases are described in different ways.Eubacteria Plant PathogensMany wilts, blights, soft rots are caused by bacteriaSymptoms of bacterial infections (plants)- Spots on stems, leaves, fruits or flowersExamples: Pseudomonas: wide spread bacteria, grows everywhere. Can feed on strange carbon sources and soapLeaf spots, banana wilt, olive galls Xanthomonas - Wilts- Soft rotsExamples- Fire blight – apples and pears- Soft rot of potatoes and carrotsCaused by ErwiniaHelpful Eubacteria- Nitrogen fixing eubacteria- Example: Rhizobium – symbiotic with legumes – close with lagune family (beans and their relatives). Millions of the bacteria infected the plant with tumors, parasyetic that gets nutrients from other plants but fixes nitrogen (mutualism to the beam and the bacteria mer)- In soil.Archaea- Not known to cause disease- Can grow in hot springs and salty environment - Low levels of oxygen and are still