Mechanisms of tolerance differences in cucumber seedlings grafted on rootstocks with different tolerance to low temperature and weak light stresses

Abstract

Stresses of low temperature and weak light are major environmental limiters for horticultural production in greenhouses in northern China during winter and early spring. Grafting is regarded as a promising approach to enhance cucumber tolerance to these environmental stresses. However, it is still unclear why cucumber plants grafted on different rootstocks usually exhibit different tolerance. The responses of cucumber (Cucumis sativus L. cv. 'Xintaimici') seedlings that were grafted on three rootstock cultivars ('Kilameki' , 'Tielizhen' , and 'Figleaf gourd') to low temperature (5 °C) and weak light (100 µmol m -2 s -1 ) were investigated in this study. The results showed that, compared to ungrafted seedlings, the electrolytic relative leakage rate and malondialdehyde (MDA) content were significantly reduced in grafted cucumber, especially in 'Figleaf gourd' . Seedlings grafted on 'Figleaf gourd' had the highest proline content, as well as activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX), followed by 'Tielizhen' and 'Kilameki' . Relative expression of Cu/Zn-SOD, Mn-SOD, and CAT mRNAs was consistent with activities of the corresponding enzymes, and higher levels were found in grafted seedlings, especially in 'Figleaf gourd' . APX activities and the relative expression of APX were also stimulated in grafted seedlings, although their changes were not completely consistent. All evidence indicated that the differences in rootstock-mediated tolerance improvement in cucumber were mainly attributed to the different stimulation of antioxidative defense systems under low temperature and weak light stresses.

Response of Photosynthesis and Chlorophyll Fluorescence Parameters of Castanopsis kawakamii Seedlings to Forest Gaps

“…The Y values under the weak light condition were lower than in control groups (Table 5). This was in accordance with weak light stress reducing the chlorophyll fluorescence characteristics [2,3].…”

“…Long-term light intensity is significantly lower than the light saturation points for plants. Thus, weak light stress is produced, which may affect plant growth [2,3]. These changes play an important role in plant adaptation to variations in light conditions.…”

Intergeneric grafting for enhanced growth, yield and nutrient acquisition in greenhouse cucumber during winter

“…Cucumber is a thermosensitive crop and temperature below 18°C may diminish its growth and production (Papadopoulos, 1994;Li et al, 2015a). In the present study, cucumber plants (both grafted and non-grafted) experienced suboptimal temperatures for a considerable period, especially during early growth stage (Fig.1).…”

“…The damage caused by abiotic stresses such as low temperatures may vary with species, and the extent of changes in cellular components can be related to degree and magnitude of low temperatures exposure (Lee et al, 2002). Further, different rootstocks may have different impressions and implications on shoot performance (Li et al, 2015a). Depending on location and purpose different rootstock genotypes of the commonly used species like pumpkin, squash, figleaf gourd, bottle gourd etc.…”

Vegetable Grafting: A Surgical Approach to combat biotic and abiotic stresses- A review

“…So, the higher activity of lipoxygenase in fig leaf gourd has proven better response to low temperature stress and may provide broad insight into stress response mechanism. Li et al (2015) at Shangdong Agricultural University, China studied the effect of low temperature on change in electrolyte leakage rate in un-grafted and grafted cucumber cv. Xintaimici onto different rootstocks like Kilameki, Tielizhen and figleaf gourd having different tolerance level and observed lowest electrolyte leakage in cucumber grafted onto figleaf gourd which was at par with cucumber grafted on Tielizhen.…”