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However, for most of the path (from adhesion to entry into the ovary; Figure ), the anatomical arrangement of the tissues seems to be sufficient to mechanically provide a limited freedom for tube growth.
The physical and chemical features of the tissues that make direct contact with pollen tubes (lipids, water, glycosylated proteins, and so on) provide the rest of the signals [).
, Stewman and colleagues have quantified the parameters of this attraction and used them to calibrate a mathematical model that reproduces the process and enables predictions on the nature of the female attractant and the mechanisms of the male response.
See research article: Darwin referred to the rapid success of flowering plants in evolution as an 'abominable mystery'.
In a tour-de-force of proteomics, the same authors recently isolated the first proteins to be shown to be specifically involved in the attractant signal: small, defensin-like, cysteine-rich peptides called LUREs [ Ovule attraction and the chemotaxis of pollen tubegrowth.
(a) Pollen tube guidance precedes double fertilization in flowering plants.
A great deal of this success relies on the peculiar ways of sexual reproduction that they have evolved.