Effects of Nutrients on Self-Inhibition of Germination of Conidia of Glomerella cingulata

Abstract

SUMMARYThe percentage germination of suspensions of washed conidia of Glomerella cingzclata decreased with increasing concentrations of the conidia in distilled water. With 30 conidia/mm.2 greater than 90 yo germination was obtained, whereas the conidia from the same batch gave less than 3 yo germination when there were 3000 conidia/mm.2. This inhibition of germination of crowded conidia was nullified by adequate amounts of peptone; but aeration by shaking had no influence, so that oxygen lack was ruled out as a factor in the inhibition. Various adsorbents, ion exchange resins, vitamins and germination stimulating chemicals were ineffective in inducing germination of crowded conidia. Czapek-Dox mineral solution, Hoagland's mineral solution and Czapek-Dox glucose solution gave respectively 10, 30 and 40% germination of crowded conidia. The germination of conidia was improved by repeated washing with distilled water. Addition of various mineral salts and trace elements (Mg, Fe, Mn, Bo, Zn, Mo, Cu) were relatively ineffective or toxic. Glucose, or mannitol did not induce germination. Peptone and phenylalanine were most effective in promoting the germination of crowded conidia, but only in massive doses. Bimodal response of germination of conidia to added nutrients was noticed. Since the conidia germinated, when present at low concentrations in redistilled water without added nutrients, the conidia could not be considered as nutritionally deficient. The beneficial effect of nutrients in promoting the germination of crowded conidia may be due to inactivation of inhibitory metabolites from the conidia.

A destructive new disease of Syzygium samarangense in Thailand caused by the new species Pestalotiopsis samarangensis

“…Ten-days-old sporulating cultures of Pestalotiopsis strains on PDA (25ºC, day light) were flooded with CzapekDox nutrient solution (Lingappa & Lingappa, 1965), and the mycelia were scraped using a spatula. The conidiomata were crushed using a glass rod.…”

The Nature of Self-Inhibition of Germination of Conidia of Glomerella cingulata

“…The percentage germination of conidia of Glmnerella cingulata has been found inversely proportional to concentration of conidia (Lingappa & Lingappa, 1965). Washed conidia do not germinate on laboratory media when dispersed in amounts greater than 8000/mm.2, but they do germinate readily in redistilled water when there are less than 100 conidia/mm.2 It follows that the conidia are not nutritionally deficient.…”

“…We found previously that the washed conidia of Glomerella cingulata did not germinate in water under crowded conditions ( 3000/mm.2 ; Lingappa & Lingappa, 1965). Germination of crowded conidia was not increased by aeration but by the addition of peptone, or of amino acids.…”

“…The cultivation and germination procedures were the same as mentioned previously (Lingappa & Lingappa, 1965); the concentration of sucrose in the potato sucrose medium was 506% (w/v), not 8*5% (w/v) as there reported. For germination studies, conidia from culture slopes were washed three times by suspension in water and centrifugation.…”

Occurrence of leaf blotch disease (<i>Botryosphaeria</i> Sp.) in <i>Ficus religiosa</i> in Sri Lanka

“…on water agar medium was flooded with Czapek-Dox nutrition solution (Lingppa and Lingppa, 1965), and the mycelia were scraped using a spatula. The ascomata were crushed using a glass rod.…”