Physiological and Biochemical Mechanisms and Cytology of Cold Tolerance in Brassica napus

Abstract

Cold damage has negatively impacted the yield, growth and quality of the edible cooking oil in Northern China and Brassica napus L.(rapeseed) planting areas decreased because of cold damage. In the present study we analyzed two Brassica napus cultivars of 16NTS309 (highly resistant to cold damage) and Tianyou2238 (cold sensitive) from Gansu Province, China using physiological, biochemical and cytological methods to investigate the plant's response to cold stress. The results showed that cold stress caused seedling dehydration, and the contents of malondialdehyde (MDA), relative electrolyte leakage and O 2 − and H 2 O 2 were increased in Tianyou2238 than 16NTS309 under cold stress at 4°C for 48 h, as well as the proline, soluble protein and soluble sugars markedly accumulated, and antioxidant enzymes of peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) were higher in 16NTS309 compared with in Tianyou2238, which play key roles in prevention of cell damage. After exposure to cold stress, the accumulation of the blue formazan precipitate and reddish brown precipitate indicated that O 2 − and H 2 O 2 , respectively, were produced in the root, stem, and leaf were higher than under noncold conditions. Contents of O 2 − and H 2 O 2 in cultivar Tianyou2238 were higher than 16NTS309, this is consistent with the phenotypic result. To understand the specific distribution of O 2 − in the sub-cellular, we found that in both cultivars O 2 − signals were distributed mainly in cambium tissue, meristematic cells, mesophyll cytoplasm, and surrounding the cell walls of root, stem, leaves, and leaf vein by morphoanatomical analysis, but the quantities varied. Cold stress also triggered obvious ultrastructural alterations in leaf mesophyll of Tianyou2238 including the damage of membrane system, destruction of chloroplast and swelling of mitochondria. This study are useful to provide new insights about the physiological and biochemical mechanisms and cytology associated with the response of B. napus to cold stress for use in breeding cold-resistant varieties.

Phosphoproteomics of Cold Stress-Responsive Mechanisms in Rhododendron Chrysanthum

“…The SOD was signi cantly enhanced under cold stress (Fig. 6), which is in agreement with the cold stress-increased SOD activity in rice [23]and rapeseed [24]. In addition, cold stress signi cantly enhanced the CAT activity(Fig.…”

Phosphoproteomics of Cold Stress-Responsive Mechanisms in Rhododendron Chrysanthum

“…As we know, in response to oxidative stress, plant tissues would increase the activity of SOD to reduce the reactive oxygen species level and generate H 2 O 2 [8]. The SOD was signi cantly enhanced under cold stress (Figure 6, Supplementary Table S1 and Supplementary Table S2), which is in agreement with the cold stress-increased SOD activity in rice [23]and rapeseed [24]. In addition, cold stress signi cantly enhanced the catalase (CAT) activity(Figure 2B),which is supposed to break down H 2 O 2 into water and oxygen [25].…”

Genome-Wide Identification and Analysis of the Ascorbate Peroxidase (APX) Gene Family of Winter Rapeseed (Brassica rapa L.) Under Abiotic Stress

“…Our previous studies have shown that the expression of peroxisome pathway genes in different cold-resistant varieties of B. rapa differs under cold stress, and these differentially expressed genes are closely related to cold resistance (Ma et al, 2019a;Qi et al, 2020). This study further analyzed the expression of the APX gene family under cold stress.…”

“…Growth cones are considered to be the most direct site for sensing temperature changes and stresses, while roots (root length and root diameter) can show great variation in pots. Studies have shown that cold stress causes significant changes in phenotype and gene expression in rapeseed leaves and growth cones (Ma et al, 2019a;Qi et al, 2020). Therefore, leaf and growth cone sites were used for this project study.…”

“…RNA-seq library (SRP211768) was derived from roots of B. rapa cultivars "Longyou-7" (ultra-cold resistance) and "Tianyou-2" (weakly coldresistance) under freezing stress (22 °C as a control, and −4 °C for 6 h) 3. RNA-seq library was derived from leaves of B. napus cultivars "NTS-309" (strong cold resistance) and "Tianyou-2238" (weakly cold-resistant) under cold stress (25 °C as a control and 4 °C for 48 h) (Qi et al, 2020). 4.…”