scholarly journals MicroRNA Zma-miR528 Versatile Regulation on Target mRNAs during Maize Somatic Embryogenesis

2021 ◽  
Vol 22 (10) ◽  
pp. 5310
Author(s):  
Eduardo Luján-Soto ◽  
Vasti T. Juárez-González ◽  
José L. Reyes ◽  
Tzvetanka D. Dinkova

MicroRNAs (miRNAs) are small non-coding RNAs that regulate the accumulation and translation of their target mRNAs through sequence complementarity. miRNAs have emerged as crucial regulators during maize somatic embryogenesis (SE) and plant regeneration. A monocot-specific miRNA, mainly accumulated during maize SE, is zma-miR528. While several targets have been described for this miRNA, the regulation has not been experimentally confirmed for the SE process. Here, we explored the accumulation of zma-miR528 and several predicted targets during embryogenic callus induction, proliferation, and plantlet regeneration using the maize cultivar VS-535. We confirmed the cleavage site for all tested zma-miR528 targets; however, PLC1 showed very low levels of processing. The abundance of zma-miR528 slightly decreased in one month-induced callus compared to the immature embryo (IE) explant tissue. However, it displayed a significant increase in four-month sub-cultured callus, coincident with proliferation establishment. In callus-regenerated plantlets, zma-miR528 greatly decreased to levels below those observed in the initial explant. Three of the target transcripts (MATE, bHLH, and SOD1a) showed an inverse correlation with the miRNA abundance in total RNA samples at all stages. Using polysome fractionation, zma-miR528 was detected in the polysome fraction and exhibited an inverse distribution with the PLC1 target, which was not observed at total RNA. Accordingly, we conclude that zma-miR528 regulates multiple target mRNAs during the SE process by promoting their degradation, translation inhibition or both.

2017 ◽  
Vol 17 (1) ◽  
pp. 9
Author(s):  
Yosi Zendra Joni ◽  
Riry Prihatini ◽  
Darda Efendi ◽  
Ika Roostika

<p>Somatic embryogenesis is a technique for regenerating embryos derived from somatic cells of various plant species. This technique along with the utilization of plant growth regulator (PGR) might benefit for mass propagation and improvement of plant species through biotechnological tools. The study aimed to determine the effect of different plant growth regu-lators, namely 6-benzyladenine (BA) and thidiazuron (TDZ) on the embryogenic callus induction as well as casein hydrolysate and malt extract on the somatic embryo development of mangosteen. The explants used were in vitro young stems of mangosteen clone Leuwiliang. This study consisted of two experiments, namely induction of embryogenic callus and formation of somatic embryo. The first experiment was arranged as factorial in a completely randomized design with BA (0 and 0.7 mg l-1) as the first factor and TDZ (0, 0.1, 0.5 and 1.0 mg l-1) as the second factor. The second experiment consisted of four treatments, i.e. casein hydrolysate and malt extract at the rate of 500 and 1,000 mg l-1. The results showed that the best medium for embryogenic callus induction was MS supplemented with 0.1 mg l-1 TDZ, which resulted semifriable calli. Casein hydrolysate and malt extract could not induce the formation of somatic embryos. After two times subcultures on the same MS medium supplemented with 0.5 mg l-1 TDZ and 0.7 mg l-1 BA, a total of 33.8 somatic embryos per explant was induced. The successful somatic embryogenesis would support mangosteen breeding and in vitro mass propagation program.</p>


1988 ◽  
Vol 66 (9) ◽  
pp. 1734-1742 ◽  
Author(s):  
Pierre R. Fobert ◽  
David T. Webb

Eggplant (Solarium melongena L.) cotyledons grown on Murashige and Skoog medium with naphthaleneacetic acid formed callus, roots, and somatic embryos. Low levels of naphthaleneacetic acid (0.1 – 0.5 mg L−1) favoored rhizogenesis, intermediate levels (1.0 – 5.0 mg L−1) favoured embryogenesis, and high levels (10 – 50 mg L−1) favoured callogenesis. Addition of polyamines or their precursors did not induce morphogenesis on medium containing no growth regulator, nor did it affect embryogenesis on medium containing naphthaleneacetic acid, except at the highest concentrations tested, which were inhibitory. Enzyme-activated inhibitors of putrescine synthesis significantly reduced embryogenesis and stimulated rhizogenesis. α-Difluoromethylornithine was more potent in inhibiting embryogenesis and stimulating rhizogenesis than was α-difluoromethylarginine. α-Difluoromethylarginine did not inhibit growth and α-difluoromethylornithine stimulated growth. Addition of putrescine with α-difluoromethylornithine restored embryogenesis to control levels and reduced rhizogenesis. Competitive inhibitors of polyamine synthesis had nonspecific effects. Compared with seedling cotyledons, expiants grown on 5.0 mg naphthaleneacetic acid per litre contained slightly less free soluble putrescine and about the same amount of spermidine. At day 8, free putrescine and spermidine levels were higher in explants grown on naphthaleneacetic acid than in those grown on medium containing no growth regulator. Addition of α-difluoromethylornithine greatly reduced the putrescine and spermidine titres of the explants. Application of putrescine with α-difluoromethylornithine dramatically increased putrescine titres but not spermidine titres. Although the results suggest a role for polyamines in eggplant somatic embryogenesis, they do not support the hypothesis that polyamines act as auxin- or cytokinin-like growth regulators or as second messengers for auxin in this system.


1984 ◽  
Vol 100 (3) ◽  
pp. 281-286 ◽  
Author(s):  
A. I. Toorop ◽  
H. M. A. Meijs-Roelofs ◽  
P. Kramer ◽  
W. J. de Greef

ABSTRACT Steroid concentrations were studied in ovarian tissue obtained by means of unilateral ovariectomy during a 10-day period preceding first ovulation. Furthermore, the levels of progesterone were measured in this period in the serum of simultaneous intact control rats. Ovarian concentrations of testosterone and oestradiol were at about 70 and 15 fmol/mg ovary respectively from 10 to 4 days before first ovulation; they clearly increased to a maximum of 170 and 120 fmol/mg ovary during the last 1–3 days before first ovulation. Ovarian concentrations of 5α-reduced androgens (i.e. androsterone and 5α-androstane-3α, 17β-diol) were high (up to 2500 fmol/mg ovary) from 7 to 4 days before first ovulation, whereas low levels (500–750 fmol/mg ovary) were present during the last 3 days before ovulation. Both ovarian and serum concentrations of progesterone were constantly low (at 500–1000 fmol/mg ovary and at 17–32 nmol/l respectively) from 10 days to 1 day before first ovulation. An inverse correlation was observed between the ovarian content of 5α-reduced androgens and that of oestradiol, which is in agreement with the existence of a prepubertal shift in pathways of steroid production; this shift seems to take place between 4 and 3 days before first ovulation. Changes in ovarian steroids on the day of the first pro-oestrus were fully comparable to those at pro-oestrus in adults: relatively high levels of ovarian testosterone and oestradiol, reaching values of 339 and 711 fmol/mg ovary respectively during the morning, an increase in progesterone (from 986 to > 40 000 fmol/mg ovary) first observed at 14.00 h and a decline, observed at 17.00 h, in ovarian testosterone and oestradiol concentration, resulting in values of 9 and 3 fmol/mg ovary respectively at 21.00 h. J. Endocr. (1984) 100, 281–286


2008 ◽  
Vol 13 (4) ◽  
pp. 363 ◽  
Author(s):  
R. MA ◽  
S. PULLI

Rye is an important crop in Northern and Eastern Europe. However, the application of various biotechnologies in rye breeding has been limited duo to its recalcitrant in tissue culture. In order to improve somatic tissue effi ciency, key factors affecting somatic embryogenesis and reproducible green plant regeneration of rye (Secale cereale L.) were evaluated and optimised. In this study, a total 27 rye genotypes including 10 spring and 17 winter genotypes were involved in the investigation. Genotype, culture medium, sugar, gel agent and auxin infl uenced somatic embryogenesis of immature embryo signifi cantly. One-two weeks cold pretreatment of young embryo enhanced somatic embryogenesis and green plant regeneration. In culture of immature embryos, infl orescences and leaf segments of the seedlings, explants signifi cantly infl uenced the culture effi ciency. Highest embryogenic callus yield resulted from rye immature embryo as explant compared to young infl orescence and leaf segment of seedling. Developmental stage of embryo played an important role in somatic embryogenesis. Late spherical coleoptile stage (embryo size 0.5–1mm in length) was optimal developmental stage of immature embryo for culture. Morphogenetic potential of embryogenic callus decreased with an increasing number of subcultures, and this ability could be maintained in vitro for a maximum of 8 months of culturing.;


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