Teddies Talks Biology - Issue 9

(continued)

Stem Rust Fungus: A Plant Pathogen

The stem rust fungus attacks the parts of the plant that are above ground. Spores that land on green wheat plants form a pustule that invades the outer layers of the stalk. • The hypha secretes enzymes that digest plant tissue - the nutrients are absorbed into the fungus. • The hyphae branch to form a mycelium.

Infected plants produce fewer tillers and set fewer seed, and in cases of severe infection the plant may die. • Absorbs nutrients from the plant, reducing yield • Pustules break the epidermis making it harder to control transpiration - increased water loss • Mycelium grows into the vascular tissue - absorbing water and nutrients • Weakens stem

Spores are carried by wind to the cereal host where they germinate and the germ tubes pene- trate into the plant. The spore needs water to germinate

Plasmodium and Malaria

The Plasmodium parasite (a Protoctist) is transmitted by mosquito vector - the bite of a female Anopheles mosquito. The infection happens both ways - the female mosquito picks up malaria as well as giving it while anticoagulants prevent blood from clotting.

• Malaria parasite transmitted to per- son from infected female Anopheles mosquito • Parasites travel to the liver • Next stage of malarial parasites re- leased into blood where they invade RBCs • Parasites reproduce asexually and burst out of RBCs and destroy them - happens every 48 - 72 hours • Malarial parasite transmitted to a mosquito taking a meal where it can be transmitted to another person

Malaria causes flu - like symptoms caused by parasite bursting out of red blood cells • Symptoms include: fever, sweating, shaking, muscle pains, headaches. • Long term damage to liver and reduction in number of RBCs • This leads to weakness, anaemia and death • When in the human body, it is mostly hidden from the immune system by hiding in liver cells and RBCs.

Teddies Talks Biology I Issue 9 I June 2021

5