• Journal of Life Science
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• v.25 no.1
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• pp.37-43
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• 2015

We have investigated the effects of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC), indole-3-acetic acid (IAA) and methyl jasmonate (MeJA) on the development of aerenchyma in the primary root of maize (Zea mays). Because plant hormones affected the longitudinal organization of the primary root, we need an indicator to direct the positions for comparison between control and hormone-treated roots. Therefore, the zones of the maize primary root were categorized as PR25, PR50 and PR75, where each value indicates the relative position between the root tip (PR0) and the base (PR100). Aerenchyma was not observed at PR25 and PR50 and rarely found at PR75 in the cortex of control roots. The aerenchymal area at PR75 increased in the presence of the ethylene precursor ACC or a natural auxin IAA. On the other hand, MeJA differentially acted on non-submerged and submerged roots. Exogenously applied MeJA suppressed the aerenchyma formation in non-submerged roots. When the primary root was submerged, aerenchymal area expanded prominently. The submergence-induced aerenchyma formation was amplified with MeJA. Lateral root primordia have been known to inhibit aerenchymal death of surrounding cells. All the three hormones stimulating aerenchyma formation as described above did not restore the inhibition caused by lateral root primordia, suggesting that the inhibitory step regulated by lateral root primordia can be located after hormonal signaling steps.

• Korean Journal of Weed Science
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• v.9 no.2
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• pp.97-102
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• 1989

1. IAA showed no significant growth of root primordia and then lateral root emerged at 2 days after IAA treatment. BA treatment, however, strongly inhibited the formation of root primordia and a few lateral roots, if any, emerged about 5 days after treatment. 2. Treatment of BA and Indol-B on the water retaining ability sampled 1, 3, 5 days after chemical treatment was apparent on the soybean sprouts sampled 5 days after treatment while the difference among the treatments was negligible when sampled 1 and 3 days after treatment. 3. BA stimulated ABA content in the hypocotyl while inhibited ABA content in the root of soybean sprouts. ABA may relate with water retaining ability. 4. Soaking the soybean seeds to several seed disinfectant chemical solution had no effect on the growth and elongation of soybean sprouts. 5. It can be recommended that container of soybean sprouts should be shut tight during growing period except irrigation because the ethylene accumulation in the container may stimulate hypocotyl swelling and inhibit length of soybean sprouts.

• Molecules and Cells
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• v.26 no.6
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• pp.611-615
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• 2008

DNA methylation is an epigenetic mechanism for gene silencing. In Arabidopsis, MET1 is the primary DNA methyltransferase that maintains CG DNA methylation. Plants having an overall reduction of MET1 activity, caused by a met1 mutation or a constitutively expressed MET1 antisense gene, display genome hypomethylation, inappropriate gene and transposon transcription, and developmental abnormalities. However, the effect of a transient reduction in MET1 activity caused by inhibiting MET1 expression in a restricted set of cells is not known. For this reason, we generated transgenic plants with a MET1 antisense gene fused to the DEMETER (DME) promoter (DME:MET1 a/s). Here we show that DME is expressed in leaf primordia, lateral root primoridia, in the region distal to the primary root apical meristem, which are regions that include proliferating cells. Endogenous MET1 expression was normal in organs where the DME:MET1 a/s was not expressed. Although DME promoter is active only in a small set of cells, these plants displayed global developmental abnormalities. Moreover, centromeric repeats were hypomethylated. The developmental defects were accumulated by the generations. Thus, not maintaining CG methylation in a small population of proliferating cells flanking the meristems causes global developmental and epigenetic abnormalities that cannot be rescued by restoring MET1 activity. These results suggest that during plant development there is little or no short-term molecular memory for reestablishing certain patterns of CG methylation that are maintained by MET1. Thus, continuous MET1 activity in dividing cells is essential for proper patterns of CG DNA methylation and development.

• Korean Journal of Plant Taxonomy
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• v.38 no.1
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• pp.51-61
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• 2008

Leaves are indeterminate organs and possess a lot of genes which is involved in establishing leaf polarities. These polarities are regulated relatively early during leaf development and defined relative to the factors intrinsic to the primordia and interactions with the shoot apical meristem (SAM). Recently, several genes that control the polarity of lateral organs have been identified. Our genetic study of deformed root and leaf1 (drl1) mutant, which produces narrow, filament‐like leaves and defective meristems, revealed that DRL1 is involved in the regulation of SAM activity and leaf polarity. The DRL1 gene was found to encode a novel protein showing homology to Elongator‐associate protein (EAP) of yeast KTI12. The amino acid sequence of DRL1 is universally conserved in prokaryotes and eukaryotes. DRL1 and the plant DRL1 homologs clearly formed a monophyletic clade, suggesting the evolutionary conservation of DRL1 homologs was maintained in the genomes of all land plants.