Location: Forage and Range Research
Title: Assessment of chilling injury and molecular marker analysis in cucumber cultivars (Cucumis sativus L.) Authors
|Ali, Asjad -|
|Yang, Eun Mi -|
|Bang, Sun Woong -|
|Chung, Sang-Min -|
Submitted to: Korean Society of Horticulture Science Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 1, 2014
Publication Date: November 17, 2014
Citation: Ali, A., Yang, E., Bang, S., Chung, S., Staub, J.E. 2014. Assessment of chilling injury and molecular marker analysis in cucumber cultivars (Cucumis sativus L.). Korean Society of Horticulture Science Journal. 32:227-234. Interpretive Summary: Low temperatures limit plant growth and can cause significant economic losses in vegetable crop species worldwide. Temperatures near freezing disrupt plant growth in cold-sensitive plants causing stunting and injury. In fact, plant exposure to non-freezing temperatures below 12 degrees C (~40 degrees F) often causes chilling injury in many tropical and sub-tropical plants, especially when grown in temperate climates. For instance, cotton, rice, corn, tomato, and cucumber are not considered chilling tolerant. Such species suffer a loss of productivity due to the disruption of photosynthesis (changing light energy to carbohydrates for useable energy for plant functions). Moreover, chilling temperatures (above 0 degrees C) often affects cell membranes and enzyme activity. Chilling resistance is an important trait that is not present in modern U.S. processing cucumber cultivars. Chilling temperatures (0-12 degrees C) often cause severe economic damage to cucumber foliage and fruit during field and greenhouse production. The chilling tolerance of several U.S. processing (pickling) type cucumbers has been characterized, but little is known regarding chilling response in other market types (e.g. fresh market types). Although Asian, European, and U.S.A. cucumber market types are genetically different, and chilling tolerance has been reported in Korean cucumber germplasm, the strength of their response compared to chilling tolerant U.S. processing cucumber types is not known. Therefore, a study was designed to compare the chilling response of several previously identified susceptible and tolerant U.S. and Asian (Korean, Japanese, and Chinese) cucumber lines at the seedling stage to determine if any tolerances were greater than U.S. cultivars. The sensitivity to chilling of Korean cultivar Nacdongchungjang and Chinese cultivar Dongguan was equal to, but no better than the U.S. cultivars examined. These results indicate that Asian cultivars do not possess genes for chilling tolerance that is better than U.S. cultivars, and that genes from Asian cucumber are not required to improve U.S. cucumber germplasm. Thus, recent progress made in the development of U.S. chilling tolerant cucumber lines by the USDA does not have to consider Asian chilling tolerant genes for cultivar improvement. This shortens the time of release of U.S. chilling tolerant USDA cucumber lines for use by seed companies in their plant improvement efforts, and thus improves the capacity of U.S. cucumber growers.
Technical Abstract: The responses to chilling temperature of 12 Korean cucumber varieties were compared to those of two U.S.A. (previously determined cold tolerant NC76 and 'Chipper'), and Chinese and Japanese germplasms. Seedlings of each entry were exposed to 4 degrees C (Experiment 1) and 1 degree C (Experiments 2 and 3) at the first true leaf stage for eight and nine hours, respectively, under 80% relative humidity (RH) and 149 umoles.m-2.sec-1 photosynthetic photon flux (PPF). The chilling response [damage rating (DR)] of each accession was based on visual ratings (1 to 5) after treatment, where 1 = no damage, 2 = slight, 3 = moderate, 4 = advanced, and 5 = severe damage. Predictably the cumulative average DR of chilling tolerant line NC76 and 'Chipper' after chilling was 1 and 1.1, respectively. Korean 'Nacdongchungjang' was most sensitive to chilling temperatures [DR = 2.3] when compared to the other entries examined. The sensitivity to chilling of 'Nacdongchungjang' was followed by Chinese 'Dongguan' [DR = 1.7]. In contrast, 'Saeronchungjang' (DR = 1) and 'Janghyungnachap' (DR = 1) were the most chilling tolerant of the Korean accessions examined and equivalent to the response of line NC76 and 'Chipper'. Nevertheless, chloroplast type genotyping of these accessions with known chilling-linked sdCAPS genomic markers revealed genotypic differences between chilling tolerant lines (NC76 and 'Chipper') and all Korean lines examined.