Location: Forage and Range ResearchTitle: Putative paternal factors controlling chilling tolerance in Korean market-type cucumber (Cucumis sativus L.) Author
Submitted to: Scientia Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/12/2014
Publication Date: 10/2/2014
Citation: Ali, A., Yang, E., Staub, J.E., Chung, S. 2014. Putative paternal factors controlling chilling tolerance in Korean market-type cucumber (Cucumis sativus L.). Scientia Horticulturae. 167:145-148. Interpretive Summary: Chilling injury (C1) in plants manifests itself not only as plant wilting, but also in disruption of photosynthesis changing light energy into carbohydrates for use by the plant for growth and development. More specifically, chilling injury can result in surface lesions (bruises) in leaves and fruit, plant water loss, and internal fruit discoloration. Cucumber plants and fruit are sensitive to chilling temperatures between 1-12 degrees C (-34-40 degrees F). Chilling temperatures after field planting of cucumbers can decrease cucumber seedling germination and emergence, which often results in lower yields depending on intensity and duration. A considerable part of the U.S. and Korean cucumber production is performed in the greenhouse, especially in the southeastern U.S. The relatively high heating requirement during the winter season for avoidance of chilling injury adds significantly to the cost of Korean cucumber production. Thus, the availability of chilling tolerant germplasm would decrease production costs and increase managerial flexibility to cucumber greenhouse production operations. Both U.S. and Korean cucumbers have been evaluated for chilling tolerance and there are some differences in their response of chilling temperatures at the seedling stage. However, it is not known whether the genes controlling their response to chilling is the same. Therefore, genetic analyses were designed to determine the inheritance of Korean cucumber and compare it to genes controlling chilling response in U.S. and Korean cucumber is different. Thus, different breeding strategies must be used to improve cucumber lines for improved chilling tolerance. This information provides cucumber breeders with information to improve their efficiency and effectiveness in the development of chilling tolerant lines and hybrids. Such changes in cucumber breeding will allow for more rapid development of chilling tolerant cucumber cultivars, thus allowing for their more rapid introduction into the market place, which will consequently increase the productivity of the U.S. cucumber grower.
Technical Abstract: Chilling temperatures (<10 degrees C) may cause damage to Korean market-type cucumber (Cucumis sativus L.) plants during winter and early spring growing seasons. Inheritance to chilling 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 (CT4) and susceptble (CT1) lines produced F1 (CT1 x CT4) and F1 (CT4 x CT1) progenies from which reciprocal F2 (CT1 x CT4) and F2 (CT4 x CT1) population were subsequently derived. Seedings in the first true leaf stage were subjected to 4 degrees C for 8 (08:00 to 16:00) hours (immediate and constant) and damage was thereafter assessed visualy using a 1 (no damge) to 5 (severe damage) rating scale. Both reciprocal F1 populations were tolerant of exposure to the chilling temperature regime imposed, where mean damage rating for F1 (CT1 x CT4) and F1 (CT4 x CT1) progeny was 1.1. This indicates that tolerance for chilling at 4 degrees C in this germplasm is dominant. However, mean damage among F2 (CT1 x CT4) progeny was 3.2 and among F2 (CT4 x CT1) progeny damage was 1.2. These data indicate that genetic control of chilling injury in these progeny is paternal. Based on the data presented in this study, 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 x CT1). These putative nuclear and paternal genetic factors are designated as Ch-1 and Ch-p, respectively.