Many plants increase in freezing tolerance upon exposure to low non-freezing temperatures, a phenomenon known as cold acclimation. Cold acclimation in Arabidopsis involves rapid cold-induced expression of the inducer of C-repeat/dehydration-responsive element-binding factor (CBF) expression (ICE) transcriptional activators followed by expression of the CBF; subsequently, CBF-targeted genes that increase freezing tolerance. Here, we present evidence for a CBF cold-response pathway in non-heading Chinese cabbage (Brassica campestris ssp. chinensis L. Makino). We show that non-heading Chinese cabbage encodes ICE1-like gene BrICE1 that bracket an open reading frame of 1,491 bp encoding a protein with a potential bHLH domain, which accumulates rapidly in response to low temperature followed closely by expression of the BrCBF gene, an ortholog of the Arabidopsis CBF3-like gene, and then BrCOR14 gene, an ortholog of the Arabidopsis CBF-targeted COR15b gene. An alignment of the later two genes from Arabidopsis, Brassica napus revealed the presence of conserved CANNTG core element and AP2 domain in BrCBF and a CCG core element in BrCOR14. In addition, BrCBF and BrCOR14 showed increased expression induced by low temperature as well as salt and drought, but not by ABA stress which are similar to those of Arabidopsis. We conclude that components of the CBF cold-response pathway are highly conserved in non-heading Chinese cabbage.

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Changes in ascorbic acid content and antioxidant enzyme activities were investigated in non-heading Chinese cabbage (Brassica campestris ssp. chinensis Makino) leaves of 'Wutacai' and 'Erqing' exposed to excess copper (Cu). Cu treatment reduced the fresh weight of shoot and root by 57% and 46% in 'Wutacai', and 60 and 54% in 'Erqing', respectively.

Cytoplasmic male sterility (CMS) is an important factor to observe heterosis in Brassica rapa. Although several studies have documented the rearrangements of mitochondrial DNA and dysfunction in the mitochondria have been observed in most types of CMS, the basis of the molecular mechanisms involved in these processes and other effects on CMS remain unclear. In this study, suppression subtractive hybridization was performed in the flowers of an alloplasmic Polima CMS system from B. rapa ssp. chinensis to identify genes that are differentially expressed between fertile and sterile plants. A total of 443 clones were isolated (156 were upregulated in fertile buds, and 287 were upregulated in sterile ones). Real-time RT-PCR further demonstrated the credibility of SSH. Among these genes, many membrane protein genes (LTP12, PIP2A, and GRP14) were inhibited in the sterile male line. Mitochondrial membrane potential (MMP) assay was then performed. Results showed that the sterile MMP was unstable and failed to create a potential difference; thus, mitochondrial dysfunction occurred. Moreover, abnormal microtubules and photosynthetic pathways were found in sterile male cells. Unstable MMP, nutritional deficiency, and abnormal microtubules were the causes of Polima CMS in Brassica campestris. H2O2, MDA, and O(2-), accumulated as byproducts of energy metabolism disorder in sterile male cells.

It studies the changes of endogenous hormones and polyamines in cytoplasmic male sterile non-heading Chinese cabbage (Brassica campestris L. ssp. chinensis Makino var. communis Tsen et Lee). Results showed that the microspore was prone to being sterile when there were lack of IAA, GA and polyamines, especially Put and abundant with ZRs and ABA in the anther. The imbalance of IAA/ZRs also easily caused the anther sterile.