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

Weiliang Qi; Fei Wang; Li Ma; Ze Qi; Songqing Liu; Cun Chen; Junyan Wu; Ping Wang; Cairong Yang; Yong Wu; Wancang Sun

doi:10.3389/fpls.2020.01241

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

Front Plant Sci. 2020 Aug 12:11:1241. doi: 10.3389/fpls.2020.01241. eCollection 2020.

Authors

Weiliang Qi^{1

2

3

4}, Fei Wang⁴, Li Ma^{1

2

3}, Ze Qi⁵, Songqing Liu⁴, Cun Chen⁴, Junyan Wu^{1

2

3}, Ping Wang⁴, Cairong Yang⁴, Yong Wu⁴, Wancang Sun^{1

2

3}

Affiliations

¹ College of Agronomy, Gansu Agricultural University, Lanzhou, China.
² Gansu Provincial Key Laboratory of Arid land Crop Science, Gansu Agricultural University, Lanzhou, China.
³ Key Laboratory of Crop Genetics Improvement and Germplasm Enhancement of Gansu Province, Lanzhou, China.
⁴ College of Chemistry and Life Science, Chengdu Normal University, Chengdu, China.
⁵ College of Metallurgy, Northeastern University, Shenyang, China.

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 O₂ ^- and H₂O₂ 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 O₂ ^- and H₂O₂, respectively, were produced in the root, stem, and leaf were higher than under non-cold conditions. Contents of O₂ ^- and H₂O₂ in cultivar Tianyou2238 were higher than 16NTS309, this is consistent with the phenotypic result. To understand the specific distribution of O₂ ^- in the sub-cellular, we found that in both cultivars O₂ ^- 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.

Keywords: Brassica napus; biochemical index; cold stress; cytology; physiological index; super-oxide anion (O2−).