Tilletia indica: cytology and teliospore formation in vitro and in immature kernels

Abstract

In teliospores of Tilletia indica Mitra meiosis occurred at germination, followed by a series of mitoses in teliospores, promycelia, or both, resulting in promycelia with numerous haploid nuclei. Primary sporidia initially were single, monokaryotic cells. After abstriction cell division occurred, but each cell stayed monokaryotic. Mycelia isolated from incipiently infected wheat caryopses formed teliospores on potato sucrose agar after 2–3 weeks and continued to do so for about 2 years. Nuclear stages of the fungus in culture and host tissue were demonstrated with haematoxylin, HCl–Giemsa, and (or) the Feulgen nucleal reaction. During formation of teliospores in vitro, conjugately associated nuclei of sporogenous mycelia migrated to probasidial initials which formed at right angles to the parent hypha. The dikaryotic probasidia usually were subtended by Y-shaped septa. Karyogamy was not seen, but circumstantial evidence suggested that it occurred during very early stages of probasidial development because even immature teliospores were monokaryotic. The process of teliospore formation and the concomitant changes in nuclear condition were easily observed in cultures, but in vivo the gelatinoid nature of the mycelium in the host tissue made this much more difficult. Moreover, some stages of teliospore formation observed in vitro were not seen in soral sections and presumably did not form in son on the host.

Pathogenic and genetic variability in Tilletia indica monosporidial culture lines using universal rice primer-PCR

“…On germination, the diploid (2N) nucleus in teliospore undergoes meiosis followed by several mitotic divisions to produce haploid (1N) nuclei. When a teliospore germinates, a promycelium (basidium) emerges and produces as many as 180 primary sporidia (basidiospores) (Bansal et al 1983;Fuentes-Davila and Duran 1986;Gill et al 1993). Each primary sporidium contains a single haploid nucleus.…”

Immunological characterization of Karnal bunt resistance by differential response of pathogen restriction in a dual culture system

“…The behavior of the causal organism of KB disease as regards to structural and nuclear changes prior to host penetration and after establishment in the host is not clearly understood (Davila & Duran 1986;Aujla et al 1987). For understanding the disease progression and response to pathogen, a number of plant pathogenic fungi have been cultured on calluses derived from their host plants (Helgeson 1983;Daub 1986).…”

Completion of the sexual cycle and demonstration of genetic recombination in Ustilago maydis in vitro

“…Mating and formation of forced diploids in some Ustilaginales can be induced in vitro (Day and Jones 1968;Puhalla 1969;Harrison and Sherwood 1994), but attempts to obtain teliospores in vitro have been unsuccessful. In vitro formation of teliospores has been reported in Tilletia indica (Fuentes-Davila and Duran 1986) and in T. controversa (Trione et al 1989), but the evidence provided was exclusively morphological, and the structures observed may have been chlamydiospores, as reported for aged cultures of Ustilago maydis (Kusch and Schauz 1989). Accordingly it is generally accepted (Banuett 1995) that the plant is obligatorily required to provide elements necessary for the completion of the sexual cycle by these pathogens.…”