scholarly journals Activation of rape (Brassica napus L.) embryo during seed germination. V. The first zones of ultrastructural changes and their expansion

2014 ◽  
Vol 56 (1) ◽  
pp. 77-91 ◽  
Author(s):  
Mieczysław Karaś

In the germinating rape embryo the columella and basal part of hypocotyl undergo earliest activation. Its first ultrastructural symptom is the appearance of numerous ER vesicles after 3-6 h of seed swelling. Their number is the highest in the external layers of the columella and decreases in basipetal direction. Dermatogen cells in the basal zone of the hypocotyl contain the greatest amount of ER structures, whereas decreasing amounts are found in both directions along the embryo axis and centripetally. Further changes in the ER spread in a similar order. The vesicles merge and form a tubular and plate-like ER. Then, they disappear and are replaced by tubular and vesicular forms. The changes in the ER are gradually followed by ultrastructural symptoms of activation of mitochondria, plastids and dictyosomes. The highest number of ER structures and other organelles accumulate in root cells shortly before piercing of the seed coat. After germination their amount decreases and remains almost stable.

2019 ◽  
Vol 67 (18) ◽  
pp. 5085-5095 ◽  
Author(s):  
Zahid Hussain ◽  
Muhammad Ali Khan ◽  
Farasat Iqbal ◽  
Muhammad Raffi ◽  
Fauzia Yusuf Hafeez

2020 ◽  
Vol 18 (5) ◽  
pp. 1153-1168 ◽  
Author(s):  
Yungu Zhai ◽  
Kaidi Yu ◽  
Shengli Cai ◽  
Limin Hu ◽  
Olalekan Amoo ◽  
...  

2016 ◽  
Vol 44 (2) ◽  
pp. 435-444
Author(s):  
Imen GLAIED GHRAM ◽  
Hatem BELGUITH ◽  
Maha BEN MUSTAPHA ◽  
Issam HIMILA ◽  
Balkiss BOUHAOUALA ◽  
...  

Lipases catalyze the hydrolysis of ester bonds in triacylglycerides, generating glycerol and free fatty acids. These enzymes are encoded by extremely complex gene families, and appear to fulfil many different biological functions. Although they are present in all types of organisms, available information on plant lipases is still very limited, as compared to their bacterial and animal counterparts. A full-length clone, BnLIP, encoding a putative lipase, has been isolated by PCR amplification of Brassica napus genomic DNA, with oligonucleotide primers derived from the sequence of an Arabidopsis thaliana homologue. The clone included an open reading frame of 1581 bp encoding a polypeptide of 526 amino acids, with a calculated molecular mass of 59.5 kDa. Analysis of the deduced protein sequence, sequence alignment with homologous proteins from related plant species, and a phylogenetic analysis revealed that the BnLIP protein belongs to the ‘classical’ GxSxG-motif lipase family. RT-PCR assays indicated that the BnLIP gene is expressed specifically, but only transiently, during seed germination: the lipase mRNA was not present at detectable levels in ungerminated seeds, was detected only three days after seed imbibition, but its levels decreased rapidly afterwards. No expression was observed in roots, stems or leaves of adult plants. This expression pattern suggests that BnLIP is one of the lipases involved in the hydrolysis of triacylglycerides stored in rapeseed seeds, ultimately providing nutrients and energy to sustain seedling growth until photosynthesis is activated.


2015 ◽  
Vol 6 ◽  
Author(s):  
Sophie Brunel-Muguet ◽  
Philippe D'Hooghe ◽  
Marie-Paule Bataillé ◽  
Colette Larré ◽  
Tae-Hwan Kim ◽  
...  

Botany ◽  
2009 ◽  
Vol 87 (6) ◽  
pp. 616-625 ◽  
Author(s):  
Leonid Akhov ◽  
Paula Ashe ◽  
Yifang Tan ◽  
Raju Datla ◽  
Gopalan Selvaraj

The yellow seed characteristic in Brassica napus  L. is desirable because of its association with higher oil content and better quality of oil-extracted meal. YN01-429 is a yellow-seeded canola-quality germplasm developed in Canada arising from several years of research. Seed-coat pigmentation is due to oxidized proanthocyanidins (PA; condensed tannins) derived from phenylpropanoids and malonyl CoA. We found PA accumulation to be most robust in young seed coats (20 d post anthesis; dpa) of a related black-seeded line N89-53 and only very little PA in YN01-429, which also contained much less extractable phenolics. The flavonol content, however, did not show as great a difference between these two lines. Furthermore, sinapine, a product of the general phenylpropanoid metabolism, was present at comparable levels in the embryos of both lines. Dihydroflavonol reductase (DFR) activity that commits phenolics to PA synthesis was lower in YN01-429 seed coats. The results of Southern blot and in silico analyses were indicative of two copies of the DFR gene in B. napus. Both copies were functional in YN01-429, ruling out homeoallelic repression or silencing, but together they showed very low expression levels (17-fold fewer transcripts) relative to DFR activity in N89-53 seed coats. These results collectively suggest that YN01-429 differs in regulatory circuits that impact the PA synthesis branch much more than the flavonol synthesis branch in the seed coats and such circuits do not impinge upon general phenylpropanoid metabolism in the embryos.


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