Histopathology 



Detailed infection studies were conducted by Wilson 

 et al. (1945) and Neill and Hyde (1939). Infections 

 occurred at the base of the stigma in ovaries within 1 

 week of fertilization (Wilson et al. 1945). Hyphae 

 invaded the inner epidermis, nucellus, and embryo 

 sac. Within 9 days, conidia were produced between 

 inner epidermis and outer integument and appeared on 

 the surface. The endosperm and embryo filled with 

 hyphae. The resulting grains were as long as healthy 

 seeds but thinner. Hyphae invaded the embryo and 

 endosperm when infections occurred after the embryo 

 was differentiated into scutellum, plumule, radicle, 

 and endosperm. 



Neill and Hyde (1939) observed greater ramification 

 and degradation of endosperm and embryonic tissues 

 than Wilson et al. (1945), who observed extensive 

 invasion of both embryonic and endosperm tissues. 

 Wilson et al. (1945) observed hyphal penetration 

 through the epithelial and aleurone layers, while Neill 

 and Hyde ( 1939) reported that G. temulenta did not 

 appear to penetrate cells of the aleurone layer. Sys- 

 temic infections beyond the seed were not observed 

 (Cunningham 1940, 1941; Neill and Hyde 1942; 

 Wilson etal. 1945). 



Fungal Genetics and Physiology 



G. temulenta is heterothallic — it requires genetic 

 exchange between two different mating types for 

 sexual reproduction and subsequent production of 

 apothecia (Griffiths 1958). G. temulenta has two 

 mating types that are identical in all morphological 

 features. Within each apothecium half of the as- 

 cospores are of each mating type, arbitrarily called "a" 

 and "b." Apothecia will develop only after mating 

 types a and b come into contact with one another and 

 undergo fusion. 



Conidia produced following infection from an 

 ascopore of one mating type will produce only conidia 

 of that mating type. Genetic exchange between types 

 can occur through transfer of macroconidia from one 

 infected seed to another or through transfer of micro- 

 conidia, which can develop on the seed in spring after 

 the seed has overwintered. A conjugation tube — a 

 device to exchange genetic information — can form 

 between pairs of macroconidia even before either 

 conidium germinates (Wilson et al. 1945). As ex- 



pected from the heterothallic requirement of G. 

 temulenta, relatively few infected seeds produce 

 apothecia. 



The vegetative hyphae are uninucleate. Chromosome 

 number in G. temulenta is n=15, and mitotic chromo- 

 somes range in size from 0.25 to 1.0 urn. (Griffiths 

 1959b). In the microconidiophores the nucleolus is 

 lacking, RNA is low, and the level of RNA depends 

 on the level in the subtending cells (Griffiths 1959a). 

 Microconidia have not been observed to germinate 

 and produce a vegetative mycelium but can serve a 

 sexual function (Griffiths 1958). 



Little is known about variability in virulence of G. 

 temulenta. Sproule and Faulkner (1974) reported 

 variation in aggressiveness among strains of G. 

 temulenta. Wright and Sproule ( 1969) reported that 

 disease ranking of clones was the same when mixed 

 blind seed isolates from The Netherlands or the 

 British Isles were used. 



Little is known about the physiology of G. temulenta. 

 A cold conditioning period of about 8 weeks is 

 required to induce the apothecial phase. The metabolic 

 pathways or mechanism associated with the induction 

 have not been investigated. 



Toxicity 



Prillieux and Delacroix (1892a) and Prillieux (1897) 

 described toxic properties associated with infection of 

 rye by the asexual stage of the blind seed fungus, 

 Endoconidium temulentum (anamorph of G. 

 temulenta). Consumption of bread made from the 

 flour induced dizzyness, faintness, vertigo, and an 

 intensive stuporous state lasting for several days. 

 Dogs, pigs, and poultry that consumed the bread 

 became depressed, numb, and refused to eat or drink 

 for 24 hours. The symptoms in humans and animals 

 differed from those produced after ingestion of ergot 

 (Claviceps purpurea) or darnal (Lolium temulentum) 

 (Prillieux and Delacroix 1892a, Prillieux 1897). This 

 is the only known report of toxicity from seed infected 

 with G. temulenta. 



Cunningham ( 1958) conducted trials in which sheep 

 were fed seed infected with G. temulenta. No abnor- 

 mal symptoms or effects were observed. 



