Reviews of related Literatures. Dwarf Bunt

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1 Reviews of related Literatures Dwarf Bunt Dwarf bunt (DB) originated in Near East but only in high elevation areas or in mountain regions which have persistent winter snow cover and the disease presents in very limited areas of winter wheat planting in the Americas, Europe and West Asia. Dwarf bunt is caused by Tilletia contraversa Kühn is closed to Common bunt (CB) caused by T. leavis Kuhn and T. tritica (Bjerk.) Wint. (Goates, 1996). Both are important wheat diseases that affect economic loss, especially in the Western USA. The impact from dwarf bunt is not because of the yield losses, though they can be severe, but by the prohibition of wheat importation into the People s Republic of China which reports no dwarf bunt in their country (Trione, 1982; Goates 1996). Before 1935, DB was thought to be a race of CB but it was finally distinguished by Young that DB cannot be controlled by seed treatments that effectively control CB (Young, 1935), and does not infect by seed inoculation (Goates, 1996). In addition, DB germinates at a much lower temperature than CB. Classification Kindom: Fungi Division: Basidiomycotina

2 Class: Ustilaginomycetes Order: Tilletiales Family: Tillertiaceae Genus: Tilletia Species: Tilletia contraversa (Pascoe et al., 2009) While the similarity to common bunt has caused controversies about the origin of dwarf bunt, even the scientific name of the disease is controversial. The disease was first identified by Kühn as Tilletia contraversa but this was likely a spelling error because Kühn used controversa in later publications, and the Latin derivation of controversa is more sensible than contraversa. It has often been spelled controversa since Recently, however, pathology taxonomists have reverted the accepted name back to the original contraversa (Goates 1996; Pascoe et al., 2009). Frequently, the disease is simple abbreviated TCK for Tilletia contraversa Kühn. Teliospore germination The process of germination is start by growing of promycelium or basidium through the spore s wall that extend to the outside in various lengths, long on agar or in high moisture condition, but short in soil; then the promycelium form filliform primary

3 sporidia (basidiospores) at the tip of the promycelium. Two mating types of primary sporidia pair to opposite mating types making up the H-body that then produce infection hyphae, vegetative hyphae or secondary sporidia of allantoids or filiform type. The secondary basidiospores then germinate to produce infection hyphae, vegetative hyphae or addition allantoids or filiform sporidia. Three to eight weeks of low temperature, about 3-8 ºC, and high humidity is required for teliospore germination and development of hyphae capable of infecting tillering seedlings. This stable condition can be found in high elevation areas with long snow cover in the end of winter, so this is the reason why dwarf bunt is only a problem on winter wheat in very limited areas. For laboratory experiments, incubating on soil extract agar at 5 ºC with continuous low light from fluorescent bulb is recommended (Goates, 1996). Infection and disease cycle Teliospores remaining near the soil surface will germinate if environmental conditions are appropriate and possibly infect winter wheat seedlings by infection hyphae when it starts to tiller. Fungus hyphae will invade through stomata and grow systemically inside the plant eventually reaching the ovary then forming a sorus filled with teliospores instead of producing a wheat kernel (Goates, 1996). The relationship between virulence genes and resistance genes during the signaling process of infection is not well understood.

4 Hosts The primary host plant of dwarf bunt is winter wheat (Triticum aestivum L.), but it also occurs on numerous grasses as determined after artificial inoculation (Goates, 1996). These native grasses that are alternative hosts may provide a source of inoculum even when resistant cultivars prevent teliospore production in wheat fields. Their role in development of new races of the disease is also unclear. Artificial inoculation of spring wheat cultivars, such as Chinese Spring, grown under winter sewing conditions indicates that they are generally susceptible to the disease and only normally escape under spring sowing conditions. Adventitious infection of native grasses is thought to minimal, however. Wheat Growth regions Although wheat is grown primarily as a temperate-zone, cool-season crop, it thrives in many regions around the world. Each types of wheat also requires specific conditions for the best growth and development. Wheat is a worldwide grain that has an importance as a major food consumed by people through the world. Many types of food are made from wheat including; breads, noodles, spaghetti and macaroni, crackers, cakes and cookies. Each kind of food made from the different market class of wheat that meets the need of product s texture.

5 Types of wheat The earliest domesticated wheat was einkorn which is a diploid wheat, but wheat that is commonly planted at present is tetraploid and hexaploid. Three species of wheat that commonly grown are: - Triticum aestivum (Hexaploid) consists of hard red winter, hard red spring, soft red winter, hard white and soft white. - T. aestivum ssp. compactum (Hexaploid) includes club wheat. - T. durum (Tetraploid) which includes durum and red durum. Three sets of words used in describing types of wheat by their characters are hard/soft, which refer to kernel hardness, or resistance to crushing; red/white, which refers to the presence of phenolic coloring in the pericarp; and winter/spring, which refers to the season of planting. Winter wheat is planted in the autumn and harvested the next summer, this type requires vernalization for the development of heads, while spring wheat is planted in spring and ready to harvest in late summer or autumn (Atwell, 2001). PK Functions for Microsoft Excel Eight pharmacokinetic (PK) functions developed to simplify pharmacokinetic calculations by Microsoft Excel worksheets consisted of Cmax, tmax, ElimRateConstant, Half_life AUC0_t, AUC0_inf, AUMC0_t and AUMC0_inf,. This helps user easily work on

6 their calculation without remember mathematical formulae for less human errors in working. Half-life calculation calculates by regression of the semi-logarithmic concentration versus time data. Half life tells how long it takes to reduce the concentration or amount by half of initial concentration (Usansky, n.d.). Half-life is usually used in pharmacokinetics to examine the elimination of a drug. It is also used in radiochemistry to explain the radioactive decay of isotopes. However, it frequently is useful in biological situations to explain the decay of viability of seeds or spores over time.