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Clubroot disease has spread explosively in recent years, posing a serious threat to cruciferous crop production. Take rapeseed for example, according to the statistics, until year 2022 the incidence of the clubroot has exceeded 1.33 million hectares in China. Breeding for resistant cultivars is considered as the most efficient and economical way to prevent clubroot disease spreading. However, the current CR cultivars mostly used CR loci of PbBa8.1 or CRb. Due to the complexity and diversity of Plasmodiophora brassicae from different locations, resources for resistant germplasm need to be explored. In this study, 14 clubroot-resistant Chinese cabbages were characterized using different clubroot pathogens and molecular markers for known CR loci. We found that among them, five materials, DG117, ZS105, SG01, SR06 and JQ07 did not contain CRb locus, and their disease resistance were stronger than Huashuang5R/Huayouza5R. At last, KL02 containing the CRb locus showed stronger resistance to PbXM (strain from Xinmin) than 409R, therefore it may contain other novel loci leading to better resistance. These six Chinese cabbage resources can be considerd as new resistance resources and could be utilized in future breeding work for CR Brassica napus. [ABSTRACT FROM AUTHOR]

To study the drought tolerance of Brassica juncea, quality of 150 local varieties of B. juncea was investigated in Yunnan Province. The aboveground and underground parts of the plants were studied under drought stress with different degrees. Results showed that B. juncea was tolerant to drought, and had wide range of quality variations. The variation coefficient of oleic acid and erucic acid was more than 1, and the varieties tested were roughly grouped into 3 categories according to quality characteristics. The medium and severe drought could significantly affect growth of shoot and root system, especially the root system. Under medium drought, drought tolerance had significant positive correlations with oil content and extremely long fatty acids (erucic acid and arachidonic acid), but had significant negative correlation with 5 long-chain fatty acids (stearic acid, palmitic acid, oleic acid, linoleic acid and linolenic acid). Under severe drought condition, drought tolerance had no relevance with quality traits. Meanwhile, drought resistance of the same variety was different under different degree of drought. Oil content had extremely significant positive correlation with long chain fatty acids. The oil content was negatively correlated with the content of long chain fatty acids and protein. The very long chain fatty acids had a significant negative correlation with long chain fatty acids. Eight varieties with strong comprehensive drought resistance were screened out. [ABSTRACT FROM AUTHOR]

Clubroot is one of the most serious disease in oilseed rape. To explore the resistant molecular mechanism of the interaction between Plasmodiophora brassicae and Brassica napus during early infection, gene differential expression analysis of the clubroot - resistant rapeseed line ZHE - 226 ( R) and clubroot - susceptible line 10159 ( S) were performed by RNA - seq. A total of 809 and 1082 genes were commonly up - and down - regulated at 0, 12, 48, 72h post - inoculation (hpi) time points in R line. Pattern recognition receptors (PRRs), chiti-nase, R gene,WRKY transcription factor, salicylic acid (SA) and jasmonic acid(JA) were involved in the early response to clubroot infection in lines of R and S, but showed different expression patterns. Compared to S line, most of the PRRs genes were down - regulated, R genes were up - regulated and SA genes were down - regulated in earlier stage but up -regulated at 72hpi in R line. Chitinase,WRKY and JA related genes were both induced in R and S lines. These results showed that PTI -mediated by PRRs was significantly induced in S line, but played a small role in R line. ETI - mediated by R gene and resistance signal pathway - mediated by SA played great role in clubroot resistance. This research provided a better understanding of the resistance genes of B. napus in response to P. brassicae, and assistance for clubroot - resistant breeding. [ABSTRACT FROM AUTHOR]

To evaluate new drought resistant germplasm, 24 DH lines from hybrid of Brassica napus and Brassica juncea were planted under 2 conditions of drought stress at 3 stages (seedling, flowering and podding stages) and normal irrigation in Kunming, Yunnan Province. In this area, the rainfall is approximately 60mm in the whole growth season for rapeseed. The identification criteria for drought-resistance were yield, 4 yield-related agronomic traits and five quality traits and different evaluation methods were compared by drought resistance index method, gray relevancy method and cluster analysis. The result showed that the drought resistance of the most hybrids was stronger than that of the conventional B. napus, especially at podding and seedling stage. 10 strong drought-resistant materials were screened, and 2 materials with both strong resistance and high yield were found. The drought-resistance correlation coefficient analysis of 3 growth stages showed that the drought resistance at seedling stage was correlated to flowering stage, and podding stage showed a poor correlation to seedling or flowering stage. Drought stress at any growth stage could seriously affect the fresh weight, plant height, oleic acid content and erucic acid content. Yield was affected by the drought stress most seriously at the flowering stage, and next at the seedling stage. The drought-resistance had significant positive correlation to fresh weight at seedling, flowering and podding stages. The drought-resistance had significant positive correlation to plant height at flowering stage. [ABSTRACT FROM AUTHOR]

Drought tolerance was identified using 58 interspecific hybrids from Bassica juncea and Brassica napus. The object was to improve the drought tolerance of B. napus cuhivar. Traits of drought tolerance included individual plant yield, main inflorescence yield and seed quality under drought stress in field. Subordinate function values method, cluster analysis and gray relevancy method were involved. Result showed significant correlations on both branch number and effective pod number to drought tolerance. Seed number per pod or 1 000 -seed weight showed low correlation to drought tolerance. Under water stress, three traits of the main inflorescence were significant at 1% level among drought -resistance and drought -susceptible lines. These three traits were oil content, 1 000 - seed weight and protein content of main inflorescence. Among them, oil content and 1 000 - seed weight in tolerance lines increased under drought, while protein content decreased. The correlation between three traits and single plant yield was greater than 50%. These three traits could be applied in preliminary selection for drought tolerance materials. Using the traits and methods above, these 3 lines 2007M004, 2007M018 and 2007M027 were selected for high drought tolerance with average subordinate function values of at least 0. 413. [ABSTRACT FROM AUTHOR]

A seed-specific Fad2 gene expression cassette, which is free-marker gene and with sense and antisense structure, was constructed by using the promoter and terminator of rape seed storage protein cruciferin gene. Transgenic rape plants without selection marker genes were obtained by Agrobacterium-mediated transformation. The oleic acid content of transgenic plant seeds is 83.9%, which is nearly the same as that of Brassica napus with double Fad2 mutation (85%). The result of RT-PCR analysis shows that the raising of oleic acid content may be due to the degradation of Fad2 mRNA induced by co-transformation of sense-antisense Fad2 gene. These transgenic plants with high oleic acid trait grew normally and without the disadvantageous agronomic traits such as weak cold resistance, tardy development, death of buds and low rate of seed setting caused by Fad2 inactivation in mutant Brassica napus plants. This work would serve as a good base for breeding of more lines with high oleic acid content.