Putative paternal factors controlling chilling tolerance in Korean market-type cucumber (Cucumis sativus L.)

• Previously, inheritance of chilling injury in cucumber has been reported as maternal and nuclear controls.
• We have found a new paternal inheritance pattern of chilling injury in cucumber.
• Nuclear control of chilling injury was also suggested in the progenies.

Chilling temperatures (<10 °C) may cause damages in cucumber plants (Cucumis sativus L.) during winter and early spring seasons. Inheritance of chilling injury in U.S. processing cucumber is controlled by cytoplasmic (maternally) and nuclear factors. To understand inheritance of chilling injury in Korean market-type cucumber, reciprocal crosses between chilling tolerant (CT1) and susceptible (CT4) lines produced F1 (CT1 × CT4) and F1 (CT4 × CT1) progenies. Reciprocal F2 (CT1 × CT4) and F2 (CT4 × CT1) populations were subsequently derived. Seedlings in the first true leaf stage were subjected to 4 °C for 8 h (08:00 to 16:00) and damage level was assessed visually using 1 (no damage) to 5 (severe damage) rating scale. Means of damage rating for reciprocal F1 (CT1 × CT4) and F1 (CT4 × CT1) progenies were 1.1 and 1.1, respectively. This indicates that tolerance for chilling stress at 4 °C in this germplasm is dominant. However, means of damage for F2 (CT1 × CT4) progenies and F2 (CT4 × CT1) progenies were 3.2 and 1.2, respectively. These data indicate that genetic control of chilling injury in these progenies is paternal. Based on the data, we hypothesize that line CT1 possesses a dominant nuclear factor that conditions chilling tolerance in both reciprocal F1s and a paternal factor(s) that lead chilling tolerance only in F2 (CT4 × CT1). These putative nuclear and paternal genetic factors are designated as Ch-1 and Ch-p, respectively.