Response to abscisic acid application and hormone profiles in spring Brassica napus seed in relation to secondary dormancy

2004 ◽  
Vol 82 (11) ◽  
pp. 1618-1624 ◽  
Author(s):  
Robert H Gulden ◽  
Sheila Chiwocha ◽  
Suzanne Abrams ◽  
Ian McGregor ◽  
Allison Kermode ◽  
...  

The plant hormone abscisic acid (ABA) has been implicated in the inception and maintenance of seed dormancy, while gibberellins promote dormancy breakage and germination in some species. We investigated whether osmotic stress induced secondary dormancy in Brassica napus L. is associated with changes in ABA sensitivity and metabolism, as well as changes in gibberellin levels. Seeds of two genotypes, one with low dormancy potential (LDP) and one with high dormancy potential (HDP) for secondary dormancy, were exposed to a dormancy-inducing osmotic treatment for up to 4 weeks and then germinated in the presence of increasing ABA concentrations. Even at relatively high concentrations of supplied ABA, germination of LDP seed was not inhibited, while relatively low ABA concentrations inhibited the germination of HDP seed after osmotic treatment. Fluridone was highly effective in suppressing secondary dormancy development in HDP seed, but had no effect on germinability in LDP seed. Despite the lack of differences in nonosmotically treated seed, ABA and ABA-glucose ester accumulated to higher levels, and gibberellin A1 accumulated to lower levels, in HDP relative to LDP seed by the end of the osmotic treatment. Our findings indicate an association among ABA sensitivity, biosynthesis and accumulation, and secondary dormancy potential in B. napus seed.Key words: abscisic acid (ABA), Brassica napus, fluridone, induced dormancy, osmotic stress, sensitivity.


1997 ◽  
Vol 150 (4) ◽  
pp. 414-419 ◽  
Author(s):  
Jeroen A. Wilmer ◽  
Johannes P.F.G. Helsper ◽  
Linus H.W. van der Plas


2021 ◽  
Vol 12 ◽  
Author(s):  
Xueyuan Li ◽  
Sjur Sandgrind ◽  
Oliver Moss ◽  
Rui Guan ◽  
Emelie Ivarson ◽  
...  

Difficulty in protoplast regeneration is a major obstacle to apply the CRISPR/Cas9 gene editing technique effectively in research and breeding of rapeseed (Brassica napus L.). The present study describes for the first time a rapid and efficient protocol for the isolation, regeneration and transfection of protoplasts of rapeseed cv. Kumily, and its application in gene editing. Protoplasts isolated from leaves of 3–4 weeks old were cultured in MI and MII liquid media for cell wall formation and cell division, followed by subculture on shoot induction medium and shoot regeneration medium for shoot production. Different basal media, types and combinations of plant growth regulators, and protoplast culture duration on each type of media were investigated in relation to protoplast regeneration. The results showed that relatively high concentrations of NAA (0.5 mg l−1) and 2,4-D (0.5 mg l−1) in the MI medium were essential for protoplasts to form cell walls and maintain cell divisions, and thereafter auxin should be reduced for callus formation and shoot induction. For shoot regeneration, relatively high concentrations of cytokinin were required, and among all the combinations tested, 2.2 mg l−1 TDZ in combination with auxin 0.5 mg l−1 NAA gave the best result with up to 45% shoot regeneration. Our results also showed the duration of protoplast culture on different media was critical, as longer culture durations would significantly reduce the shoot regeneration frequency. In addition, we have optimized the transfection protocol for rapeseed. Using this optimized protocol, we have successfully edited the BnGTR genes controlling glucosinolate transport in rapeseed with a high mutation frequency.



2011 ◽  
Vol 47 (No. 3) ◽  
pp. 114-122 ◽  
Author(s):  
S.H. Ardebili ◽  
M.E. Shariatpanahi ◽  
R. Amiri ◽  
M. Emamifar ◽  
M. Oroojloo ◽  
...  

The effect of 2,4-dichlorophenoxyacetic acid (2,4-D) applied at high concentrations for a short time was investigated as a novel stress for induction of microspore embryogenesis for the first time. Brassica napus L. cvs. Topas and Hyola 420 were used as model plants for testing this hypothesis. Microspores were subjected to 2,4-D at 4 concentrations (15, 25, 35 and 45 mg/l) for 15–45 min while the classical heat shock was used as the control treatment. Among 2,4-D treatments in Topas, the highest yield of torpedo-stage embryos was achieved at 15 mg/l 2,4-D for 30 min while more normal plantlets were produced when 2,4-D (25 mg/l for 30 min) was applied to the microspores. In Hyola 420 the results showed a lower number of embryos and normal plantlets at all concentrations of 2,4-D. Although Hyola 420 was almost equally embryogenic as Topas after heat shock treatment, large differences between genotypes (concerning embryogenic response) occurred after 2,4-D treatment. However, the mean number of embryos and regenerants was higher in heat shock as compared to 2,4-D induced stress (one magnitude of order). According to the results obtained, 2,4-D can be introduced as a new stress for induction of embryogenesis in microspores similarly like in zygotic and somatic cells. This novel stress is very important for plant species whose microspores are extremely sensitive to classical stresses.



1998 ◽  
Vol 17 (1) ◽  
pp. 19-23 ◽  
Author(s):  
J. A. Wilmer ◽  
S. R. Abrams ◽  
J. P. F. G. Helsper ◽  
L. H. W. van der Plas


2009 ◽  
Vol 89 (4) ◽  
pp. 613-619 ◽  
Author(s):  
S Gruber ◽  
K Emrich ◽  
W Claupein

Secondary dormancy is the major reason for seed persistence of canola (Brassica napus L.) in the soil. Volunteers emerging from the soil seed bank can lead to unwanted gene dispersal. More than 40 B. napus canola cultivars were tested for secondary dormancy under laboratory conditions. All cultivars were classified into groups of low, medium, and high dormancy by performing a cluster analysis. The results suggest that secondary dormancy is a cultivar-specific trait. Additionally, inter-year variation in dormancy indicates that it seems to be influenced by a set of environmental factors. Among years, classification of cultivars based on relative rank was more robust than classification based on absolute dormancy values. The classification of cultivars by their dormancy level would allow farmers to select and grow low-dormancy cultivars. Knowledge about the relative secondary dormancy of the currently grown cultivars could help growers and breeders lower canola seed bank persistence. Key words: Brassica napus, cluster analysis, genotype, secondary dormancy, soil seed bank





2017 ◽  
Vol 27 (3) ◽  
pp. 217-230 ◽  
Author(s):  
Elias Soltani ◽  
Sabine Gruber ◽  
Mostafa Oveisi ◽  
Nader Salehi ◽  
Iraj Alahdadi ◽  
...  

AbstractThis study investigated the induction and loss of dormancy in oilseed rape (Brassica napus). Twenty genotypes were preliminary screened; from these, two genotypes, RGS003 and Hayola 308, which possess high potential for dormancy induction (HSD) and medium potential to induce secondary dormancy (MSD), were selected. The stratification of seeds at alternating temperatures of 5–30°C (in dark) significantly relieved secondary dormancy, but dormancy was not fully released. The ψb(50) values were −1.05 and −1.06 MPa for the MSD and the HSD before dormancy induction. After inducing dormancy, the ψb(50) values for the MSD and the HSD were increased to −0.59 and −0.01 on day 0 stratification at 20°C. The hydrothermal time (θHT) value was low for one-day stratification for HSD in comparison with other stratification treatments. Water stress can induce dormancy (if the seeds have the genetic potential for secondary dormancy) and warm stratification (in dark) can only reduce the intensity of dormancy. The seeds with a high potential of dormancy induction can overcome dormancy at alternating temperatures and in the presence of light. It can, therefore, be concluded that a portion of seeds can enter the cycle of dormancy ↔ non-dormancy. The secondary dormant seeds of B. napus cannot become non-dormant in darkness, but the level of dormancy may change from maximum (after water stress) to minimum (after warm stratification). It seems that the dormancy imposed by the conditions of deep burial (darkness in combination with water stress and more constant temperatures) might be more important to seed persistence than secondary dormancy induction and release. The dormancy cycle is an important pre-requisite in order to sense the depth of burial and the best time for seed germination.



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