• Journal of Plant Biology
• /
• 제31권4호
• /
• pp.289-298
• /
• 1988

The pattern of elongation in the developing hypocotyl of Glycine max shows that the elongation generally proceeds from base to the cotyledonary node in acropetal diredtion, although earlier elongation takes place through the entire hypocotyl. Because the differentiation of the vascular cambium in the hypocotyl advances also acropetally, it can be seen that the acropetal wave of hypocotyl elongation is associated with the acropetal differentiation of the cambium in the hypocotyl elongation is associated with the acropetal differentiation of the cambium in the hypocotyl elongation is associated with the acropetal differentiation of the cambium in the hypocotyl. The elongation of procambial cells occurs not only during active elongation but also after cessation of elongation of the hypocotyl. In tangential view, the procambium of the hypocotyl in early stage has homogeneous structure composed of short cells. Subsequently, these procambial cells elongate actively and then become elongated long cells. These long cells eventually become fusiform initials, while some of elongated long cells are transversely divided and then converted into ray initials. The characteristics of the vascular cambium are entirely acquired some time after hypocotyl elongation is completed, and the transitin from procambium to vascular cambium in the hypocotyl is a rather gradual process.

• Journal of Plant Biology
• /
• 제34권4호
• /
• pp.274-281
• /
• 1991

The relationship between elongation of hypocotyl and its vascular transition was studied with seedling of Glycine max. the hypocotyl elongation proceeded acropetally from the base of hypocotyl toward the cotyledonary node. The vascular transition did not occur in the basal region of the hypocotyl, which did not nearly elongate, with exarch radial vascular bundles. However, the vascular transition was almost completed at the middle part of the hypocoty, more or less elongated, with endarch collateral vascular bundles. Such bundles also appeared in the uppermost region of the hypocotyl, in which the elongation was the most striking. These results suggested that the vascular transition was related to the hypocotyl elongation and that the transition of primary vascular system in Glycine max seedling was established by rather rapid process. Our observations of the serial sections from root to hypocotyl revealed that the vascular system through the root-hypocotyl-cotyledon was a unit, to which one of the epicotyl that did not participate in transition was superimposed.

• Molecules and Cells
• /
• 제45권4호
• /
• pp.243-256
• /
• 2022

Transcriptional regulation, a core component of gene regulatory networks, plays a key role in controlling individual organism's growth and development. To understand how plants modulate cellular processes for growth and development, the identification and characterization of gene regulatory networks are of importance. The SHORT-ROOT (SHR) transcription factor is known for its role in cell divisions in Arabidopsis (Arabidopsis thaliana). However, whether SHR is involved in hypocotyl cell elongation remains unknown. Here, we reveal that SHR controls hypocotyl cell elongation via the transcriptional regulation of XTH18, XTH22, and XTH24, which encode cell wall remodeling enzymes called xyloglucan endotransglucosylase/hydrolases (XTHs). Interestingly, SHR activates transcription of the XTH genes, independently of its partner SCARECROW (SCR), which is different from the known mode of action. In addition, overexpression of the XTH genes can promote cell elongation in the etiolated hypocotyl. Moreover, confinement of SHR protein in the stele still induces cell elongation, despite the aberrant organization in the hypocotyl ground tissue. Therefore, it is likely that SHR-mediated growth is uncoupled from SHR-mediated radial patterning in the etiolated hypocotyl. Our findings also suggest that intertissue communication between stele and endodermis plays a role in coordinating hypocotyl cell elongation of the Arabidopsis seedling. Taken together, our study identifies SHR as a new crucial regulator that is necessary for cell elongation in the etiolated hypocotyl.

• 한국작물학회지
• /
• 제41권6호
• /
• pp.634-639
• /
• 1996

근래에 육성된 한국산 녹두품종에 대하여 용도상 분류 기준이 되는 하배축신장성과 주요 성분함량을 조사하여 품종 육성의 기초 자료로 활용하고자 수행하였던 바 그 결과를 요약하면 다음과 같다. 1. 하배축 신장성이 큰 품종은 4234-697과 금성녹두였으며 남평녹두는 중간정도, 선화녹두는 작았다. 2. 파종 후 치상온도가 높을수록 하배축 신장은 양호하였는데 고온에서는 파종직 후부터 급속한 신장을 나타냈다. 3. 냉장고에 저장한 종자의 하배축신장성은 상온에 저장한 종자보다 하배축신장성이 양호하였다. 4. 종자크기와 하배축신장성과는 품증에 따라 각각 다른 상관정도를 보였으나 유의성은 인정되지 않았다.

• 한국작물학회지
• /
• 제37권1호
• /
• pp.68-77
• /
• 1992

대두재배에 있어서 단위면적당 주수를 결정하기 때문에 수량에 직접적인 영향을 미치는 것으로 알려진 출아ㆍ입묘에 대한 기초연구의 일환으로 한국 대두 장려 품종들에 대한 하배축신장성 및 출아에 대한 조사를 하였던 바 그 결과를 요약하면 다음과 같다. 1. 하배축신장은 파종 후 3.0-3.5일 사이에 가장 왕성하였으며 하배축신장성이 ＆apos;양호＆apos;한 품종은 은하콩, 장경콩, 보광콩, 등 3품종이었고, ＆apos;중＆apos; 품종은 남해콩, 단경콩, 단엽콩, 밀양콩, 덕유콩, 팔달콩, 망운조생, 남해콩, 새알콩, 등 9품종 이었고 ＆apos;불량＆apos;했던 품종은 광교, 백운콩, 장백콩 등 3품종이었다. 2. 같은 품종에 있어서 종자크기별 하배축신장은 종자크기와는 반대로서 소립, 중립 및 대립 순으로 종자크기가 작을수록 오히려 하배축신장이 양호하였다. 3. 100입중과 하배축신장성과의 관계는 r=-0. 2506$^{**}$ 으로 100입중이 클수록 하배축신장성은 오히려 저조하였다. 4. 처리온도가 높을수록 하배축신장은 양호하였고, 낮을수록 저조하였는데 우리나라 대두의 하배축신장에는 30-35$^{\circ}C$가 적온이었다. 또한 처리온도 $25^{\circ}C$에서 특이하게 하배축신장이 억제되었던 품종은 발견할 수 없었다. 5. G $A_3$는 처리농도가 높을수록 하배축신장을 촉진하였고, ABA, Kinetin및 BA는 처리농도가 높을수록 하배축신장을 억제하여 서로 상반되는 .반응을 보였는데 그 정도는 하배축신장이 큰 품종에 비해 작은 품종에서 뚜렷하였다. 6. 습윤ㆍ고온처리에 의한 종자노후화 정도는 하배축신장이 양호하였던 품종이 불량하였던 품종보다 노후화 속도가 느려 습윤ㆍ고온처리를 하였을 때도 하배축신장이 뚜렷하게 컸다.

• Journal of Plant Biology
• /
• 제11권1호
• /
• pp.22-26
• /
• 1968

Hypocotyl segments of shade-grown soybean sprouts(var. Kumdo) were floated in solutions of various substances at physiological levels and grown for either 24 hours at 28$^{\circ}C$ or 72 hours at $25^{\circ}C$. Increased length of the segments beyond 20mm (the original length) was obtained as a measure of the present studies. At the room temperature, Ca and DNP strongly inhibited elongation of the hypocotyl segments, whereas K, IAA, GA and EDTA in general promoted it. There were, however, no such differences in the effects at relatiely low temperature. This indicated that the elongation process not only involves stretching of wall materials, but also does synthesis of the materials. Ca was found to be antagonistic to the promotive action of GA in the elongation, and the IAA action involves metabolic energy. EDTA seemed to act as a widely known chelator removing Ca already existed in the hypocotyl tissue, thus shwoed a promotion in the elongation.

• 통합자연과학논문집
• /
• 제1권1호
• /
• pp.24-31
• /
• 2008

Brassinosteroids (BRs) are a special class of plant steroid hormones that are essential for normal growth and development. Part of confusion is whether BRs are unique to plants, because they have overlapping physiological roles with other better-studied hormones and with physiological responses caused by light. In systems designed to assay for cytokinins, the effects of BRs vary. We measured hypocotyl length for testing the ability of brassinolide (BL) to rescue double mutant between det2 and the photoreceptor null mutant phytochrome B (phyB). PHYB involved in controlling hypocotyl elongation in increased concentration of BL whereas phyBdet2 double mutant just partially rescue to phyB in white and red light indicated the involvement of BRs in PHYB regulated cell elongation. BRs regulated hypocotyl growth was delayed by BAP, a cytokinin treatment but inhibitory effects of BAPs on hypocotyl growth was slightly recovered by BL. The result indicated that the mode of action of BR and cytokinin is independent or sequential in the downstream light-regulated response control on hypocotyl elongation and also light modulated the action of BR and cytokinin in some extent.

• Journal of Plant Biology
• /
• 제27권2호
• /
• pp.43-50
• /
• 1984

Effects of IAA on the elongation and cell wall hlysocidase activities were investigated in excised rape (Brassica napus L. cv. Yongdang) hypocotyl segments. IAA promoted the elongation of rape hypocotyl segments. In rape hypocotyls, the first 10-mm segments from the hook exhibited maximal elongation and the capacity of elongation was gradually decreased with increasing distance of each 10-mm from the hook. A good correlation has been obtained between the magnitude of endogenous growth and the activities of $\alpha$, $\beta$-glucosidase and $\alpha$, $\beta$-galactosidase. However, exogenous application of IAA did not seem to enhance the tissue with IAA resulted in acidification of the incubation medium. From these data, we can conclude that IAA seems to enhance elongation of the tissue segments, at least in part, by releasing hydrogen ion into cell wall, some of which may participate in the cell wall extension process, but does not seem to trigger the activation of $\alpha$, $\beta$-glucosidase and $\alpha$, $\beta$-galactosidase.

• Journal of Plant Biology
• /
• 제32권4호
• /
• pp.305-312
• /
• 1989

Developmental anatomy was conducted in order to elucidate the differentiating pattern of fascicular cambial initials in the hypocotyl of Ricinus communis. The homogeneous procambium with relatively short cells in early stage is transformed into a heterogeneous structure with long and short cells in late stage in tangential view. Fusiform and ray initials are gradually originated from the long and short cells of the procambium in hypocotyl in later stage respectively. Fusiform initials are not shorter than procambial cells because of the successive elongation of vascular meristematic cells. Therefore, the distinction between procambium and fascicular cambium is not made from comparison with their cell length. The characteristics of the fascicular cambium are gradully acquired at or just after completion of hypocotyl elongation.

• Journal of Plant Biology
• /
• 제32권4호
• /
• pp.323-330
• /
• 1989

This work was carried out to elucidate effects of endogenous and exogenous IAA transport on adventitious root formation in Phaseolus vulgaris hypocotyl cuttings. For inverted or normal incubation in distilled water, the adventitious root is always formed at the morphological base but not at the morphological apex. For inverted incubation, in both distilled water and certain chemical solution, the root formation is retarded more at the first stage (0-24 hr) than at the second stage (24-48 hr). When p-chlorophenoxyisobutyric acid (PCIB) was applied to the cuttings at the first stage, theroot formation was inhibited more than at the second stage. Treatment of 2,3,5-triiodobenzoic aicd (TIBA)markedly inhibited the adventitious root formation in Phaseolus vulgaris hypocotyl cuttings. This inhibition influenced the root according to the applied stage and period. Therefore, the root formation is more related to the stage of root primordium formation than to the stage of root elongation from the primordium. Inhibition of auxin transport oraction by TIBA or PCIB could also be reversed when hypocotyl cuttings are incubated in exogenously applied IAA solution.