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Chen F.B.,Sichuan Agricultural University | Chen F.B.,Fuling Agricultural Science Institute of Chongqing | Yang K.C.,Sichuan Agricultural University | Zhou G.F.,Fuling Agricultural Science Institute of Chongqing | And 5 more authors.
Philippine Agricultural Scientist | Year: 2011

Fifteen inbred lines of tuber mustard were used to determine their genetic diversity by using simple sequence repeat (SSR) markers and seven inbred lines (male) and eight sterile male inbred lines (female) were crossed to obtain 56 hybrids. Heterosis and combining ability were analyzed among these hybrids. We detected 80 pairs of SSR primers amplifying 637 bands among the parents, with an average of 8.0 and ranging from 3 to 13. The genetic distances between the male lines and the male sterile lines ranged from 0.25 to 0.40, with an average of 0.33. Fifteen accessions were classified into two clusters based on genetic distance. The combining ability analysis showed that five significant positive relative effects and 24 significant positive relative effects were found in general combining ability (GCA) and specific combining ability (SCA) analyses, respectively. Thirty-six hybrids showed significant positive effects in high-parent heterosis, indicating that heterosis in stem yield among parents was evident in tuber mustard. Because heterosis of stem yield in tuber mustard among the parents was associated with GCA and SCA, attention should be paid to both GCA and SCA in breeding for tuber yield heterosis. The correlation coefficients of genetic distance between stem yield, high-parent heterosis and SCA were all small and not significant. Further study is necessary to determine whether or not genetic distance could be used to predict heterosis and SCA in stem yield of tuber mustard.


Chen F.B.,Fuling Agricultural Science Institute of Chongqing | Yang K.C.,University of Sichuan | Zhou G.F.,Fuling Agricultural Science Institute of Chongqing | Fan Y.H.,Fuling Agricultural Science Institute of Chongqing | And 4 more authors.
International Journal of Agriculture and Biology | Year: 2011

Tuber mustard (Brassica juncea var. tumida Tsen & Lee), a variation in the species B. juncea belonging to the Cruciferae family, is an agriculturally and economically important crop cultivated along the Yangtze River in China. In this study the karyotypic characteristics of tuber mustard has been investigated by examining metaphase chromosome spreads obtained from root tip. The results showed that the karyotype formula of tuber mustard was 2n=2x=36=18 m (2SAT)+12sm+6st. The total haploid length of the species was 27.85 μm. The chromosome lengths ranged from 1.47 μm to 2.10 μm with an average of 1.73. The relative lengths of chromosomes ranged from 5.28 to 7.54. The ratio between the longest chromosome and the shortest chromosome was 1.43. The arm ratio ranged from 1.12 to 4.21. The karyotypic asymmetry of tuber mustard was 70.10%, of which belonged to "2A". We can differentiate tuber mustard and the other species in brassica juncea by their karyotype characteristics. These results may help to carry out germplasm protection, research and improving tuber mustard in future. © 2011 Friends Science Publishers.


Fang P.,Yangtze Normal University | Chen F.-B.,Yangtze Normal University | Yao Q.-L.,Yangtze Normal University | Yang K.-C.,University of Sichuan | And 5 more authors.
Genetic Resources and Crop Evolution | Year: 2013

In the present study, analyses of SSR molecular markers were performed to investigate the genetic diversity of 133 tuber mustard cultivars. Eighty-one pairs of SSR primers from a total of 600 in Brassica produced stable amplified bands. In addition, 810 bands were detected among the cultivars, and 724 of those were polymorphic (89.38 %). The average number of bands per locus was 10.0 with a range from 5 to 16. Shannon's information index for each SSR locus varied from 0.52 to 3.72, with an average of 2.74. The coefficients of genetic similarity in the SSR marker patterns among the 133 cultivars ranged from 0.77 to 0.91, with an average of 0.85. The cluster analysis showed that the cultivars could be classified into six clusters when the genetic similarity was 0.83, with 90.23 % of the cultivars included in Clusters 5 and 6. Principal component analysis was carried based on the SSR data. The results showed that the first three principal components could explain the genetic variation with 85.47, 0.67, and 0.61 %, and the 133 cultivars could be divided into six clusters according to the nearest phylogenetic relationship. It was indicated that the similarity was high and the genetic diversity was narrow among the 133 mustard tuber cultivars. 360 individuals from 24 cultivars were analyzed to reveal the genetic structure and genetic diversity within cultivars. A total of 925 alleles were detected in the 24 cultivars. Estimates of the mean number of alleles 'A', the effective allelic number 'Ae', the observed heterozygosity 'Ho', and expected heterozygosity 'He' were 6.0, 3.6, 0.64, and 0.37, respectively. An obvious genetic deviation from Hardy-Weinberg expectation was observed both among and within cultivars and a considerable genetic variation was revealed within rather than among cultivars. It is necessary to broaden the genetic basis of the breeding germplasm in tuber mustard. Based on their geographical distributions, the tuber mustard cultivars in this study can be divided into up-Yangtze river, mid-Yangtze river, and down-Yangtze river groups. Genetic diversity was highest in mid-Yangtze river group, followed by up-Yangtze river group, and then down-Yangtze river group. It was presumed that the origin center or genetic diversity center of tuber mustard was mid-Yangtze river, and the crop was transmitted along the Yangtze river in both directions. © 2012 Springer Science+Business Media Dordrecht.


Liu Y.,Chongqing University | Yin Y.-P.,Chongqing University | Wang Z.-K.,Chongqing University | Luo Y.-L.,Chongqing University | Luo Y.-L.,Fuling Agricultural Science Institute of Chongqing
Agricultural Sciences in China | Year: 2012

Five commonly-used reference genes: ACT (actin), UBE (ubiquitin-conjugating enzyme), RPL2 (ribosomal protein L2), BRP II (RNA polymerase II subunit), and NADH (nicotinamide adenine dinucleotide) were examined using geNorm software as reference genes for RT-qPCR. Among the tested reference genes, ACT and UBE were the most stable in all samples. In parallel, expression analysis of nitrilases in Brassica juncea var. tumida, was performed to preliminarily investigate the molecular interactions between nitrilase and clubroot development at 10, 15, 20, 25, 30, and 40 d postinoculation (dpi) with a suspension of resting spores of Plasmodiophora brassicae. The results showed that different gene expressions of nitrilases were regulated during the initial periods of clubroot development. The expression level of BjNIT1 increased sharply from 20 to 40 dpi in infected roots while there were no remarkable changes in healthy roots. From 15 to 30 dpi, the expression levels of BjNIT2 and BjNIT4 in infected roots were lower than those in non-infected roots. Finally, BjNIT2 in treatment was down approximately to control at 40 dpi. Our results suggest that BjNIT1, which promoted overproductions of auxin, might be involved in P. brassicae infection of B. juncea. © 2012 Chinese Academy of Agricultural Sciences.


Luo Y.,Chongqing University | Luo Y.,Fuling Agricultural Science Institute of Chongqing | Yin Y.,Chongqing University | Liu Y.,Chongqing University | And 5 more authors.
European Journal of Plant Pathology | Year: 2013

Mustard clubroot, caused by Plasmodiophora brassicae, is one of the most serious diseases affecting Brassica juncea var. tumida Tsen, a mustard plant which is the raw material of a traditional fermented food manufactured in the Chongqing Municipality, P. R. China. We used suppression subtractive hybridization (SSH) to better understand the interaction between B. juncea var. tumida and P. brassicae, and the complex regulation of resistance mechanisms occurring in B. juncea var. tumida after infection by P. brassicae. A total of 1,842 different gene clones were selected from the forward subtracted library (using diseased roots as tester and healthy roots as driver), and 224 positive spots were identified following cDNA array dot blotting. Elimination of polyA tails and sequences shorter than 100 bp generated 196 high-quality gene sequences with an average length of 332 bp. Bioinformatic analysis showed that these 196 sequences represented 173 unigenes, comprising 14 contigs and 159 singlets. Of these, 146 ESTs (84.4 % of the total) were significantly similar to known sequences in plants, the remaining 23 (13.3 % of the total) were of P. brassicae origin. We used quantitative reverse transcription-PCR to analyze the six genes most likely to be involved in disease resistance or the stress response to evaluate the efficiency of SSH, and the results showed that our library data is reliable. Further study of these genes might be helpful for breeding resistance of mustard plants to P. brassicae. © 2013 KNPV.

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