Histopathology of Seed-Borne Infections - Applied Research Center ...

Seed Infection by Nematodes 233largely with Marcinowski that occasionally one or two stamens of a flower may benormal while others are transformed into galls. Midha and Swarup (1974) observedthat it is the staminate tissue that is primarily involved in gall formation. Carpellategalls are also formed. On the basis of macroscopic and microscopic observations,Agarwal (1984) traced the origin of seed galls to the anther, ovary, or anther–ovarytogether (Figure 8.2A, B to F). In all, seven types of galls are identified, dividedinto three broad categories.Category 1: Staminate galls(i) single anther gall (Figure 8.2B)(ii) double anther gall(iii) triple anther gallGalls, (i) to (iii) are sessile, but since sporogenous tissue is seen in suchdeveloping galls, they are called anther galls rather than staminate galls.The basal part of primordium forming filament fails to develop after theinfection has taken place. However, when the infection is delayed or gallformation is slow, partial galls with distinct filament develop.Category 2: Carpellate galls(iv) ovary gall (Figure 8.2C)Usually these galls do not show any evidence of style–stigma differentiation.However, the normal half of the carpel of the partial ovary gallsshow well-developed feathery stigma.Category 3: Staminate–carpellate galls(v) single anther–ovary gall (Figure 8.2D)(vi) double anther–ovary gall.(vii) triple anther–ovary gall (Figure 8.2F)The development of various types of galls may take place in the same spikelet.Once a particular structure becomes infected in a spikelet, other floral parts alsocontinue to develop and can be observed as whitish, pale, and sterile structures(Figure 8.2B to F).Agarwal (1984) made an extensive study on mature infected field crop andexperimental potted plants in order to collect evidence on the types of galls producedin wheat. Out of the 1257 green galls studied, triple anther–ovary galls were predominant(74.62%), and the single anther galls were the second dominating type(11.06%).Besides the anther and ovary galls, galls are rarely formed on leaves, glumes,palea, lemma, and its awn and lodicules. In exceptional cases, as many as four orfive galls are seen in a spikelet.8.2.1.3 Histology of Developing and Mature GallsThe histology of developing galls permits identification of galls developing fromanther or ovary; therefore, a separate account is given for them.