Krzyżowanie wsteczne

Krzyżowanie wsteczne (ang. backcrossing) – metoda stosowana w genetyce oraz w hodowli roślin i zwierząt polegająca na krzyżowaniu heterozygotycznego potomka (F1, F2, .. Fn) z jedną z homozygotycznych form rodzicielskich (P). Efektem krzyżowania wstecznego jest krzyżówka genetyczna zwana pokoleniem wstecznym (BC).

Np. krzyżując formy rodzicielskie otrzymuje się heterozygotycznego mieszańca-F1, który następnie w wyniku krzyżowania wstecznego z jedną z form rodzicielskich daje pierwsze pokolenie wsteczne. Jeśli do takiej krzyżówki użyta zostanie forma rodzicielska, która jest homozygotą recesywną, to taką krzyżówkę nazywamy krzyżówką testową.

Zastosowanie

Dzięki tej metodzie hodowli można wprowadzić określony gen jednej formy rodzicielskiej na tło genetyczne formy drugiej. Krzyżowanie wsteczne stosuje się w hodowli odmian wieloliniowych i w hodowli heterozyjnej, np. w celu uzyskania odmian dziedzicznie odpornych na patogeny wykorzystujących zarówno odporność bierną (oporność), jak i czynną. Krzyżowanie wsteczne pozwala na:

  • wprowadzenie cech determinowanych genami dominującymi
  • wprowadzenie cech determinowanych genami recesywnymi

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