Teliospore Production Research Articles

Floret Development and Teliospore Production in Bunt-Infected Wheat, in Planta and in Cultured Spikelets

Greening of the infected ovaries was correlated with the onset of teliosphore formation in the ovary, and as sporulation continued, the greening intensified. The possible involvement of hormones in the abnormal morphological alterations of the infected florets is discussed. Excised wheat spikelets infected with Tilletia controversa were successfully grown in liquid culture media containing sucrose, glutamine, salts, and minor organic factors. Varying the composition of the medium affected sporulation in the ovaries, and the highest sporulation occurred at 3 g L −1 of glutamine

Improved bunt inoculation of wheat utilizing adventitious shoots

A procedure is described of injecting inoculum of dwarf or common bunt at the bases of the internodes of wheat. Physical stimulation by wounding of the intercalary meristem located above the nodes resulted in the formation of adventitious shoots. If inoculum of dwarf or common bunt is injected at the time of stimulation, the spike of the resulting shoot is usually infected. This procedure shortened the period between teliospore germination and production of sori, gave a high infection rate, and induced several infected spikes on one primary stem.

Basidiospore formation and self-fertility in Puccinia mesnieriana

The microcyclic Puccinia mesnieriana is very common in Israel on indigenous Rhamnus palaestina , and also occurs on other Rhamnus species. Teliospore germination and basidiospore production, including the implicated nuclear behaviour, are described. Single basidiospore inoculation of R. palaestina results in the development of telia and proves that the rust can be self-fertile. The fungus is presumably correlated with the widespread P. coronata and represents an outcome of a prolonged regressive evolution. Both traits, the short life cycle and self-fertility, enhance adaptation of the fungus to sub-optimal ecologic conditions.

Light and scanning electron microscopy of the telial, pycnial, and aecial stages of Melampsora lini

Urediospore infection by Melampsore lini on stems or leaves of Linum usitatissimum produced uredia which quickly converted from urediospore to teliospore production. The telium was composed of a palisade of laterally united, sessile, prismatic teliospores (ca. 50 × 6 μm) positioned between the epidermis and the stem cortex. Teliospores were induced to germinate by subjecting telia to a series of freeze–thaw and wet–dry cycles. Germination began after 6–10 such cycles and continued until 20–24 cycles had been performed. Teliospores germinated apically to form basidia and smooth, ovate to elliptical basidiospores (ca. 6 × 5 μm). Basidiospore germlings penetrated directly through the host epidermis and formed intercellular and intracellular hyphae. The haploid intracellular structures formed were irregular and hypha like, often septate, and occasionally grew into adjacent host cells. Several morphological variants of intracellular hyphae were observed; all such structures were distinct from the more specialized dikaryotic haustoria derived from either dikaryotic aeciospore or urediospore infections. Development of pycnia occurred primarily in the substomatal cavities of leaves. Flexuous hyphae extended through stomata; concomitantly, pycniospores produced in chains from a palisade of pycniosporophores exuded through the stomata onto the leaf surface in droplets of honeydew. Pycniospores were smooth, ellipsoidal, and ca. 3 × 1.5 μm. Caeomoid aecia developed on both sides of flax leaves and on stems. Short irregular chains of aeciospores alternating with smaller wedge-shaped intercalary cells were produced from sporogenous hyphae at the base of aecia. Mature aeciospores were globose to ovate (ca. 16 × 13 μm) and were densely ornamented with smooth, cog-like verrucae.

Production of teliospores by some races of Puccinia graminis f. sp. tritici in detached wheat and barley leaves

Five races of Puccinia graminis f. sp. tritici cultured on wheat and barley leaves in two nutrient solutions were studied for teliospore formation by subjecting them to varying treatments of temperature and light. The early appearance as well as a high percentage of teliospore formation occurred in 100 ppm benzimidazole solution on wheat or barley leaves kept at 30°C and 500 footcandles of light. The feasibility of maintaining and multiplying races of Puccinia graminis f. sp. tritici in continuous cultures on detached leaves depends on various factors, the most important being the onset of the teliostage of the fungus. The appearance of the teliospore denotes the culmination of the sporophytic or repeating stage of the wheat rusts. In this paper, some factors that influence the production of teliospores by certain races of Puccinia graminis tritici in detached leaves are discussed.

Aphanocladiutn album, a fungus inducing teliospore production in rusts

SUMMARYThe hyphomycetous fungus Aphanocladiutn album can grow over and around uredia of the rusts Puccinia coronata, P. hordei, P. graminis f.sp. avenae and P. recondita f.sp. triticina when host plants are kept under very humid conditions, but not on such plants not infected with rusts; uredia are adversely affected and telia develop in their vicinity.Plants inoculated with these rusts and with five isolates of A. album (one from a dead insect) showed: (1) much earlier development of telia on detached and non‐detached rusted leaves inoculated with A. album than on corresponding leaves not thus inoculated; (2) telial induction by A. album in some isolates of rust species which hitherto had rarely or never produced telia; (3) precocious telial formation, in comparison with controls, when A. album spores were sprayed on leaves as much as 3 days before and 9 days after rust inoculation, and occasionally after uredia had already matured. As affected leaves remained green until the whole leaf became moribund, senescence is apparently not the factor inducing telia formation.The normal‐appearing teliospores of some isolates were induced to germinate, whereas others did not. Rhamnus palaestina inoculated with basidiospores of one isolate of A. album‐treated P. coronata f.sp. avenae produced pycnia and fertile aecia.The importance of A. album as a working tool in rust research and as a possible means for biological control of rust epiphytotics is discussed.

Production of Teliospores and Uredospores of Puccinia Graminis on Berberis Cretica in Nature

The black stem rust occurs annually on the cereals in Greece and sometimes it is very severe. The alternate host of this rust is Berberis cretica which is the only species of the family Berberidaceae growing wild in this country. Its habitat is on mountains from 800 m. to subalpine regions, in Macedonia, Thessaly, Euboea, Attica, Laconia, and Crete. Berberis cretica is annually attacked by P. graminis; however, so far it has not been proved that it plays an indispensable part in the life cycle of the black stem rust. If the bush formation of this alternate host on the mountain tops is really a source of inoculum for the cereals in the plains, then a program of eradication would have to be considered. This problem however is not answered in the present paper. Instead an interesting fact is recorded, namely, the finding of teliospores and urediospores of black stem rust on the alternate host. In this connection I desire to give due recognition for guidance to my honored Professor Frank D. Kern of the Pennsylvania State College, U. S. A. The infection of B. cretica by P. graminis has been known for a long time. Stakman (1923) was one of the first to mention it. Politis (1929) also found B. cretica infected by the black stem rust of cereals. On the contrary, in west and south Asia Minor the same barberry, which forms more or less extensive formations on the mountains above the tree zone, i.e. over 1500 m., has not been found to be attacked. On the leaves the infection consists of yellowish spots one or more on each leaf, in the middle of which first pycnia and then aecia are produced. On the diseased fruits the at-

Production of Teliospores and Uredospores of Puccinia Graminis on Berberis Cretica in Nature

Production of Teliospores and Uredospores of Puccinia Graminis on Berberis Cretica in Nature