Production of branches from unsuccessful primary germ tubes of conidia of Erysiphe graminis f. sp. tritici on wheat leaves
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Confusion exists regarding nomenclature and possible significance of outgrowths produced by conidial primary germ tubes (PGT) of Erysiphe graminis f. sp. tritici Em. Marchai on wheat leaves. Production of these outgrowths has been taken as a criterion of successful host-parasite relationship. However, such outgrowths have been observed to have developed from 12.3 % of the unsuccessful PGT on a resistant wheat and 9.2 % of the unsuccessful PGT on a susceptible wheat.
It is proposed that these outgrowths may be called PGT branches which may develop whether the penetration by PGT is successful or not. In case the PGT penetration is successful, then such a PGT branch may be called a secondary hypha. These branches from unsuccessful PGT may also produce host responses in the form of halos in the host cell-walls or may also penetrate the host cells successfully and produce apparently healthy (normal) haustoria. Both PGT branches and the secondary hyphae may be called functional when they produce either host responses in the form of halos or penetrate successfully and produce haustoria, or produce both halos and haustoria.
KeywordsHost Cell Host Response Germ Tube Wheat Leave Resistant Wheat
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