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Host infection and flower formation by the parasite Tristerix aphyllus (Loranthaceae)

1985; Canadian Science Publishing; Volume: 63; Issue: 3 Linguagem: Inglês

10.1139/b85-072

1480-3305

James D. Mauseth, Gloria Montenegro, Alan M. Walckowiak,

Plant tissue culture and regeneration

Tristerix aphyllus is able to invade its host as follows. As a seed germinates, the tip of the radicle swells and attaches to the host, forming a haustorium. Slender multiseriate filaments are produced that can pass through the stomata and enter the host. Additionally, the haustorium forms a layer of cells that slide radially from the center of the haustorium. Because the cells adhere to the host surface, they tear the cuticle and epidermis away as they slide, thereby exposing inner layers of the host to invasion by filaments of cells produced by the haustorium. After invasion, the seed and embryo die and fall away, and T. aphyllus exists purely as an endophyte. To produce flowers, certain filaments of T. aphyllus, lying just below the host epidermis, proliferate forming nodules of callus. Within these nodules, up to 10 adventitious floral buds arise, either exogenously or endogenously. These have an apical meristem, a short axis, and three to six leaf primordia. By an unknown mechanism, the nodule is able to kill and break open the host hypodermis and epidermis; when this happens, one or several of the buds (which become dormant after formation) resume growth and emerge through the broken host epidermis.