OsAHT1 Plays a Negative Role in ABA Signal Transduction Pathway

Shin, Yeon Ji 부산대학교 대학원 2025 국내석사

ABA-HYPERSENSITIVE BTB/POZ PROTEIN 1 (AHT1) has been reported as a negative regulator in ABA-mediated inhibition of germination in Arabidopsis. Abscisic acid (ABA) plays a crucial role in plant stress responses and seed germination. To determine whether the ABA signaling pathway mediated by AHT1 is functionally conserved between Arabidopsis and rice, we have isolated a rice homologue of Arabidopsis AHT1 (AtAHT1) in Oryza sativa L., and named it OsAHT1. OsAHT1 showed 64.46% identity with AtAHT1 at the amino acid level, and possessed a BTB/POZ domain, which is commonly shared by CRL3 substrate receptors. The expression of OsAHT1 was upregulated by treatment of ABA and ABA-related stresses. Compared with ataht1 mutant, OsAHT1 overexpression in the ataht1 background led to enhancement of seedling growth and germination in the presence of ABA. These results demonstrate that OsAHT1 is involved in attenuating ABA sensitivity in Arabidopsis. Furthermore, the protein interaction assays between OsAHT1 and OsCUL3 showed that OsAHT1 binds directly to OsCUL3, suggesting its involvement in the ubiquitin-proteasome pathway, which regulates protein stability and downstream signaling in ABA responses. Taken together, we suggest that OsAHT1 functions as a substrate receptor of CRL3 complex and a negative regulator in ABA signaling. This research may ultimately lead to the generation of rice varieties better suited to cope with environmental challenges, offering significant potential for improving rice productivity and advancing sustainable agriculture.

ABA 신호전달에 관여하는 새로운 유전자들의 분리 및 기능분석

이지연 동아대학교 대학원 2012 국내석사

ABA 신호전달에 관여하는 새로운 유전자들의 분리 및 기능분석 식물생명공학과 이지연 지도교수 남재성 식물세포는 외부로부터의 자극을 다양하게 받으며 그 자극에 인지하는 거대한 네트워크를 가지고 있다. 애기장대에서 예를 들면 400여개 이상의 membrane에 결합된 receptor-like protein kinases(RLKs)가 있다. RLK는 식물발달과정과 생물학적 스트레스, 비생물학적 스트레스를 조절하는 신호전달 구성요소이며 병원체에 대한 방어와 자가세포사멸 조절의 중요한 역할을 하는 것으로 추측된다. 그러나 아직까지 기능적으로 많이 밝혀지지 않은 상태이다. 애기장대에서 RLK는 extracellular domain에 cystein-rich repeats를 가지고 있으며, cysteine-rich RLKs(CRKs)는 병원균 공격에 의해 유전자 발현이 유도되어 식물방어반응의 가능성을 제시하고 있다. 본 연구에서도 ABA를 공급한 배지에서 CRK28/29유전자가 없으면 발아가 억제되는 것을 확인하였다. 일반적으로 ABA는 종자의 발아를 억제하므로, 야생형의 CRK28/29유전자는 ABA 신호전달에 음성적인 조절자(negative regulator)로 기능을 함으로써 종자의 발아가 정상적으로 이루어지게 하는 것으로 생각된다. 또한 CRK29과 CRK28 유전자는 생물적/비생물적 스트레스에 의해 급격하게 발현이 유도되므로 병저항성과의 관련성을 조사하였다. Type III secretion system(T3SS)로 특이적으로 비병원성 인자인 AvrRpm1과 AvrRpt2를 기주식물체로 운반하는 비병원성 균주인 Pst DC300( avrRpm1)과 Pst DC300(avrRpt2)로 박테리아 생장과 Hypersensitive Response(HR)테스트에는 CRK28/29유전자 결함이 된 돌연변이체들은 야생형에 비교해서 저항성에 차이가 크게 없는 것으로 확인되었다. 그러나 병원성 균주인 Pst DC3000 감염에 대한 면역반응에서는 CRK28/29 돌연변이체들에서 Pst DC3000의 생장이 약 10 배 정도 억제되는 저항성의 증가가 확인되었다. 이러한 결과는 ABA는 병저항성에 관련하는 salicylic acid,(SA)호르몬 작용의 음성적인 조절자(negative regulator)로 기능을 한다는 기존의 연구결과와 상반된다. CRK28/29 돌연변이체들에서의 병저항성 증가는 ABA에 의한 SA 매개로하는 한 병저항성 기작과는 다른 경로로 병저항성에 관여할 것으로 생각된다. 앞으로도 이들 유전자를 연구함으로써 식물체가 생물적인/비생물적인 환경스트레스에 적응하는데 필수적인 기능을 하는 ABA 식물호르몬의 신호전달 과정을 이해하는데 많은 도움이 될 것으로 생각된다. 주요어 : CRK28/29유전자, ABA, SA, 애기장대, 음성적인 조절자(negative regulator)

(The) Rice functional ABA receptor OsABAR10 is a positive regulator of the ABA signal transduction pathway in seed germination and early Seedling growth

김현미 성균관대학교 대학원 2011 국내석사

ABA is a phytohormone that positively regulates seed dormancy and stress tolerance, and negatively regulates vegetative growth. PYR/RCAR was identified as an intracellular ABA receptor regulating ABA dependent gene expression in Arabidopsis. However, its function in monocot specieshas not been characterized yet. We showed here that PYR/RCAR orthologues in a monocot rice act a positive regulator of ABA signal transduction pathway. Transgenic rice plants expressing OsABAR10, a PYR/RCAR orthologue of rice were hypersensitive to ABA during seed germination and early seedling growth. I further identified a rice ABA signaling unit comprised of OsABAR10, OsPP2CA8, SAPK2 and OsABI5/OREB1 for ABA-dependent gene regulation by using interaction assays and a transient gene expression assay. Thus, I have demonstrated that PYR/RCAR based ABA signaling is evolutionarily conserved in both monocot and dicot plants. This study may presents valuable ideas to improve its commodity value through rewiring ABA-dependent stress adaptationF in monocot crops. ABA는 종자 휴면이나 스트레스 내성에 대한 양성 조절자이며 영양 생장에 대한 음성 조절자로서 역할을 하는 식물 호르몬이다. PYR/RCAR은 애기장대에서 ABA 의존적인 유전자 발현을 조절하는 세포내의 ABA 수용체로서 밝혀졌다. 그러나 외떡잎식물에서는 이들 유전자의 기능에 대하여 밝혀진 바가 없다. 본 논문에서 외떡잎식물의 모델인 벼로부터 ABA 신호전달 과정에서 양성 조절자로서 역할을 하는 PYR/RCAR의 orthologue들을 분리하고 이들의 기능을 규명하기 위하여OsABAR10 유전자를 과발현하는 형질전환 벼를 제작 하였다. 이들 과발현 형질전환벼들은 종자발아나 초기 유식물의 생장기에 ABA에 대하여 과민감성 표현형을 나타내는 것을 확인 할 수 있었다. 또한, Yeast two hybrid 와 BiFC를 이용한 상호반응 분석과 일시적인 유전자 발현 분석을 이용하여 ABA신호전달 경로 중 하나로서 OsABAR10, OsPP2CA8, SAPK2, OsABI5/ OREB1로 구성된 신호전달 체계를 밝혔다. 결과적으로 PYR/RCAR를 기반으로 하는 상위단계의 ABA 신호전달은 쌍떡잎식물과 외떡잎식물에서 진화적으로 보존되어 있지만 하위단계의 ABA 신호전달은 쌍떡잎식물의 주 신호전달 경로에 참여 한다고 알려진 유전자들 외의 PP2CA 그룹과 SnRK2 subclass Ⅱ그룹이 ABA 신호전달에서 참여함을 밝혔다. 또한 이러한 유전자들이 상호작용하는 세포내 위치가 핵으로 나타는 것을 확인 함으로서 OsABAR10, OsPP2CA8, SAPK2, OsABI5/ OREB1로 구성된 신호전달 체계가 전사적 조절을 통한 경로임을 밝혔다. 이 연구는 외떡잎식물 작물에서의 ABA의존적 스트레스 적응을 재해석함으로서 이들 작물의 생산성을 향상시키는데 귀중한 정보를 제시할 것이다.

Functional characterization of AP2 domain protein ADAP

이선지 전남대학교 대학원 2008 국내석사

ADAP is a protein that interacts with ARIA, which, in turn, interacts with ABF2. ABF2 is a bZIP class transcription factor, which regulates various aspects of ABA response by controlling expression of a large number of ABA-responsive genes. In order to investigate the in vivo function of ADAP in ABA response, I first examined the expression pattern of ADAP. RT-PCR analysis showed that ADAP is expressed in roots, flowers and siliques. Histochemical GUS staining of the transgenic plants harboring a ADAP promoter-GUS reporter construct revealed that ADAP promoter is very active in the shoot meristem region and in the lateral roots. The ADAP promoter activity was inhibited by ABA and high salt. Subsequently, I generated ADAP overexpression lines and acquired ADAP knockout mutant lines to investigate their phenotypes. The ADAP overexpression lines germinated more slowly than wild type plants and exhibited minor growth retardation. adap mutant plants displayed opposite phenotypes, i,e,, they germinated more efficiently than wild type plants and grew faster. The results indicated that ADAP is a negative regulator of germination and seedling growth under normal condition. Further analysis demonstrated that ADAP overexpression lines were hypersensitive to ABA and salt at the seed germination stage, but partially insensitive to ABA and salt during postgermination growth stage. adap mutant plants, on the other hand, were insensitive to ABA and salt at both germination and postgermination growth stages. Additionally, ADAP overexpression and mutant lines both were sensitive to drought stress. Taken together, these results indicated that ADAP is a positive regulator of ABA and salt responses during germination. The results also showed that ADAP is involved in ABA, salt, and drought responses during postgermination seedling growth. ADAP는 ARIA와 상호작용하는 단백질이며 ARIA는 ABF2와 상호작용한다. ABF2는 bZIP class 전사인자로 수많은 앱식산-반응성 유전자들의 발현을 조절하여 다양한 ABA 반응 양상을 조절한다. ABA 반응에서 ADAP의 in vivo에서의 기능을 조사하기위해 첫 번째로 ADAP의 발현패턴을 조사하였다. RT-PCR 결과에서는 ADAP가 뿌리, 꽃, 열매에서 발현됨을 알 수 있었고, ADAP promoter-GUS reporter construct을 지닌 형질전환 식물의 GUS staining을 통해 ADAP promoter가 경단 분열조직 부위와 측근이 시작되는 부위에서 높은 활성을 가진다는 것을 알 수 있었다. ADAP promoter의 활성은 ABA와 고농도의 염분에서 저해되었다. ADAP가 과다 발현되는 형질전환 식물과 ADAP가 전혀 발현되지 않는 돌연변이체 식물을 가지고 표현형을 조사하였다. 야생형 식물에 비교하여 35S-ADAP 형질전환 식물에서는 종자발아가 더 느렸고, 성장이 저해되는 모습을 보였고, 돌연변이체 식물(adap)에서는 반대되는 표현형을 나타내어 야생형 식물보다 더 빠른 발아와 성장이 촉진되는 모습을 나타냈다. 이 결과를 토대로 정상상태의 성장조건하에서 ADAP가 발아와 유아성장의 음성조절자로 작용함을 알 수 있었다. 35S-ADAP 형질전환 식물체는 발아단계에서 앱식산과 고염에 과민반응을 나타내었으나, 발아단계 이후의 성장단계에서는 반응도가 감소하였다. 한편, adap 돌연변이식물체는 발아단계와 그 이후의 성장단계에서 모두 ABA와 고염조건에 감소된 반응을 나타냈다. 추가적으로 가뭄 스트레스 조건하에서는 35S-ADAP 형질전환 식물과 adap 돌연변이체 식물 모두 과민함을 나타냈다. 종합해보면, ADAP가 발아단계에서 앱식산과 고염 반응의 양성조절자로 작용함을 알 수 있었고, 발아 이후의 성장단계에서도 앱식산, 고염, 가뭄 반응에 관여함을 알 수 있었다.

앱시스산 신호전달성분의 분리 및 기능분석

이선지 전남대학교 대학원 2012 국내박사

To identify novel ABA signaling components, I analyzed the functions of a number of genes that encode putative ABA signaling components. In the first part of my study, I investigated the functions of three AP2 domain protein genes, AtERF13, RAP2.4 and RAP2.4L. The genes encode proteins that bind to one of the ABA response elements, CE1, and are referred to as CEBFs (CE1 Binding Factors). AtERF13 was expressed mainly in the meristemic region of the shoot, whereas RAP2.4 and RAP2.4L were expressed in most of the vegetative tissues. Subcellular localization study revealed that the CEBFs were localized in the nucleus. The physiological functions of the CEBFs were determined by analyzing their overexpression and knockout/RNAi lines. Overexpression of AtERF13 enhanced ABA sensitivity during postgermination growth, suggesting that it is a positive regulator of ABA response. RAP2.4 and RAP2.4L overexpression, on the other hand, did not affect ABA sensitivity, suggesting that they are not involved in ABA response. However, their overexpression lines were hypersensitive to glucose and high salt. The reduced expression of the CEBFs resulted in faster plant growth. It appears that they affect seedling growth rate. In the target gene expression analysis, changes in the expression levels of several ABA-responsive genes were observed, suggesting that the CEBFs play a regulatory role in vivo. In the second part of my study, I investigated the functions of two C3H1 zinc-finger proteins, AtC3H49/AtTZF3 and AtC3H20/AtTZF2, by examining their expression patterns and their overexpression and knockout/RNAi phenotypes. Both AtC3H49/AtTZF3 and AtC3H20/AtTZF2 genes were expressed in various vegetative tissues and in flowers, and their encoded proteins were localized in the cytoplasm. Overexpression of AtC3H49/AtTZF3 or AtC3H20/AtTZF2 resulted in ABA hypersensitivity, reduced transpiration and enhanced drought tolerance. Their overexpression also altered plant growth pattern. The transgenic plants grew slowly during the early stage of growth. But, their growth rates were accelerated as the plants grew older, and mature plants were larger than the wild type plants. Moreover, the transgenic plants displayed delayed senescence and enhanced longevity. Subsequent experiments showed that JA-induced senescence was also delayed. Quantitative RT-PCR analyses indicated that the expression of a number of genes involved JA, ABA and biotic/abiotic stresses were altered in the transgenic lines. The knockout/RNAi lines of AtC3H49/AtTZF3 and AtC3H20/AtTZF2 exhibited weak phenotypes, presumably because of their functional redundancy. In the third part of my study, I characterized the ABA-insensitive mutant, ais143, which was isolated previously by activation tagging screen. TAIL-PCR and plasmid rescue showed that T-DNA was inserted in the middle of the Arabidopsis MAPKKK gene, Raf10. To confirm its involvement in ABA response, I examined its expression patterns and analyzed its overexpression and knockout phenotypes. Raf10 is highly homologous to another MAPKKK, Raf11. Therefore, I also analyzed Raf11 function. Quantitative RT-PCR analysis revealed that genes encoding the MAPKKKs are slightly induced by ABA and abiotic stresses. Their promoter activity, on the other hand, was detected in most of the seedling tissues and in floral organs. Subcellular localization study employing YFP fusion proteins demonstrated that the two kinases are localized in the cytoplasm. To determine their in planta functions, I prepared and analyzed their overexpression and knockout lines. Under normal growth condition, seed germination of both Raf10 and Raf11 overexpression lines were delayed significantly. By contrast, their knockout lines exhibited reduced seed dormancy, indicating that Raf10 and Raf11 controls seed dormancy. The Raf10 and Raf11 overexpression lines were hypersensitive to ABA during germination and seedling growth. In addition, the transgenic plants were hypersensitive to glucose, high salt and mannitol. The Raf10 and Raf11 single knockout mutants were insensitivity to ABA, glucose, salt and mannitol. Double knockout mutant, on the other hand, exhibited stronger phenotypes than the single knockout mutants, suggesting that functional redundancy exist between Raf10 and Raf11. Expression analysis of ABA-responsive genes in the Raf10 and Raf11 overexpression lines showed that expression levels of a number of ABA-responsive genes, especially those involved in seed maturation and seed dormancy, were enhanced significantly. In an effort to identify Raf10 and Raf11 substrates, I carried out yeast two-hybrid screens and was able to isolate a number of positive clones. Subsequent analysis of the clones showed that some of them are known ABA signaling components. In summary, my study revealed that the AP2 domain protein AtERF13 is involved in seedling growth control and ABA response. The zinc-finger proteins, AtC3H49/AtTZF3 and AtC3H20/AtTZF2, appear to be involved not only in ABA response but also in jasmonic acid response. Raf10 and Raf11 were also found to be regulators of ABA response during germination and postgermination growth. In particular, my results indicated that the MAPKKKs are important regulators of seed dormancy.

Functional characterization of rice ABA signaling components by reconstitution of the signaling pathway in yeast and rice protoplasts

Kim, Namhyo Sungkyunkwan University 2015 국내석사

Abscisic acid (ABA) is a phytohormone that regulates stress responses; one aspect of ABA function is the induction of stress-responsive gene expression. Upon ABA binding, the PYR/PYL/RCAR receptors can interact with group A 2C-type protein phosphatases (PP2Cs) and interrupt the interaction between PP2Cs and SnRK2s, thus resulting in activation of the SnRK2s. Activated SnRK2s then phosphorylate and activate AREB/ABFs, which finally induce ABA-responsive gene expression that the pathway has been elucidated in Arabidopsis. Those signaling components are reported to be involved in both ABA-dependent and ABA-independent pathways, so it is difficult to classify the two pathways precisely. In this work, to characterize the function of signaling components and examine the potential crosstalk between ABA-dependent and ABA-independent signaling components, I reconstituted signaling pathways in yeast and rice protoplasts. I screened and selected major components involved in ABA signaling, namely OsbZIP46, SAPK4, OsPP2CA2, OsPP2CA6, OsPYL/RCAR8, by yeast-two hybrid assay. The functions of these components were characterized by transactivation assays in yeast and rice protoplasts. OsbZIP46 could bind ABRE and transactivate a Rab16A-fLuc reporter gene with or without ABA. OsbZIP46 could be activated by SAPK4 in the absence of ABA. In the presence of OsPP2CA2 and OsPP2CA6, SAPK4 was inhibited. The activity of these OsPP2CAs could be inhibited in a concentration-dependent manner by OsPYL/RCAR8, and the inhibition of OsPP2CA6 showed ABA dependence. Taken together, my results suggest that pathways composed of OsbZIP46-SAPK4-OsPP2CA2 and OsPP2CA6-OsPYL/RCAR8 can transduce both ABA-dependent and ABA-independent signaling. This study therefore provides insight into the crosstalk between ABA-dependent and ABA-independent signaling pathways.

Spatial regulation of AtABCG25, an ABA Exporter, Is an Important Component of the Mechanism Controlling Cellular ABA Levels

박영민 포항공과대학교 일반대학원 2017 국내박사

The phytohormone abscisic acid (ABA) has important roles in various physiological processes, such as dormancy, development and response to biotic and abiotic stresses, in plants. Recently, multiple ABA transporters including importers and exporters were identified helping to understand ABA transport system within the cells and long distance transport of ABA. In this study, we examined the internalization and recycling of an ABA exporter, ATP-BINDING CASETTE G25 (ABCG25), by genetic and biochemical approaches. ABA levels in the cells can be regulated by transport system as well as biosynthesis pathways and catalytic pathways. However, it is not known how ABA transporters are controlled under diverse conditions to maintain ABA homeostasis. Here, we report that spatial regulation of ABCG25 is an essential mechanism controlling its activity. ABCG25 localized to the plasma membrane and was subject to post-translational regulation via clathrin- and adaptor protein complex-2 dependent endocytosis followed by trafficking to the vacuole for its degradation. The levels of ABCG25 at the plasma membrane were regulated by abiotic stresses and exogenously treated ABA; the endocytosis of ABCG25 was activated under abiotic stress in an ABA-independent manner while the recycling of ABCG25 was enhanced from early endosomes to plasma membrane upon application of exogenous ABA. Based on these results, we propose that the spatial regulation of ABCG25 is an important component of the mechanism by which plants fine-tune cellular ABA levels according to cellular and environmental conditions.

The Epigenetic Regulation of Chloroplast and Mitochondrial Functions Under Abiotic Stress : HDA9 Epigenetically Regulate Chloroplast, Mitochondria Redox System Under ABA Stress

최종휴 건국대학교 대학원 2022 국내석사

Plants hormonal and environmental changes alter the stomatal aperture by regulating a complex signaling cascade within the guard cells in the stomata. Mitochondria is a key component regulating the production of reactive oxygen species (ROS) in plants. Also known to trigger stomatal movement. However, mitochondria and chloroplast regulator of the ROS pathway is still in debate. Abscisic acid (ABA) induces ROS production in the guard cells leading to stomatal closure in response to drought stress. Transcriptomic evidence in Arabidopsis shows upregulation of the ROS-inducer proteins NADPH oxidases (RbohD and RbohF) accompanied by downregulation of some ROS scavengers like mitochondria complex I and III. However, the regulatory mechanism of ROS inducers and scavengers in ABA and drought stresses is still unclear. Thus, I am proposing an epigenetic regulation of the mitochondria electron transport system by Histone deacetylase 9 (HDA9). Loss of function mutant (hda9-1) shows ABA insensitive phenotype, this represents its negative regulation in ABA stress. Moreover, transcriptomic analysis of hda9-1 shows upregulation in cytochrome C oxidase like protein thioredoxin M-4, and ferrdoxin-1 transcripts and downregulation of NADPH oxidases, opposite to wild type plants. In addition, cytochrome C oxidase like protein, thioredoxin M-4, and ferrdoxin-1 loci were enriched in ChIP-seq analysis. Thus, our data indicate that HDA9 binds to cytochrome C oxidase like protein, thioredoxin M-4, and ferrdoxin-1 loci on the chromatin and repress its transcription in response to ABA stress. 식물의 호르몬 및 주변의 환경 변화는 기공의 공변세포 내에서 복잡한 신호전달의 과정을 조절하여 기공의 크기를 조절한다. 미토콘드리아와 엽록체는 식물에서 활성산소종(ROS)를 조절하는 핵심구성요소로써 기공의 움직임을 유발시킬 수 있는 기관으로 알려져 있다. 그러나, 식물에서 조절자로서 ROS 경로에서의 미토콘드리아와 엽록체의 역할은 아직 잘 알려져 있지 않다. 앱시스산 (ABA)은 공변세포에서 ROS의 생성을 유도하여 가뭄 스트레스에 대한 반응으로 기공폐쇄를 유도한다. 이에 대한 전사적 증거로 미토콘드리아 복합체 I 및 III와 같은 일부 ROS 제거자의 하향조절과 함께 ROS 유도단백질인 NADPH 산화 효소 (RbohD 및 RbohF)의 상향 조절이 있다. 그러나 아직 ABA 및 가뭄 스트레스에서 ROS 유도제 및 제거자의 조절 메커니즘은 여전히 불분명합니다. 따라서 본 논문에서는 히스톤 탈아세틸화효소 9(HDA9)에 의한 미토콘드리아와 엽록체 산화환원 시스템의 후성유전적 조절을 제안하고 있다. HDA9 기능 상실 돌연변이체(hda9-1)는 ABA에 둔감한 표현형을 가지며 이는 ABA 스트레스에서의 음성조절을 나타내고 있으며 또한, hda9-1의 전사체 분석을 통해 야생형 식물과 반대되는 cytochrome C oxidase like protein (Cyto Oxi), thioredoxin M-4 (TRX M4), and ferredoxin-1(FD-1)의 상향조절과 NADPH 산화 효소의 하향조절을 보여주고 있다. 이와 더불어 ChIP-seq 분석에서 Cyto Oxi, TRX M-4, and FD.1 유전자좌가 많아진 것을 확인하였습니다. 이러한 결과들을 통해 본 논문에서는 HDA9이 Cyto Oxi, TRX M-4, and FD1의 유전자좌에 결합하며 ABA 스트레스 시 전사를 억제한다는 것을 나타낸다.

低溫·光中斷 및 ABA處理가 마늘의 生育과 內生 ABA 및 GA 類似物質의 消長에 미치는 影響

장전익 忠南大學校 大學院 1985 국내박사

Effects of cold storage of seed bulbs, planting date, abscisic acid(ABA), application and light break on growth and secondary growth of southern Sanghai early and some native garlics were determined to elucidate physiological mechanisms of abnormal development such as secondary growth. Influences of cold storage of seed bulbs and light break on seasonal change of endogenous growth substances were aso determined and relationships among contents of growth substances, growth and secondary growth were evaluated. The results obtained are summarized as follows. 1. When cold stored seed bulbs were planted, there were positive correlations between secondary growth and aboveground plant characteristics such as the number of alive green leaves, leaf sheath length and diameter, and plant height in Sanghai early but negative correlations in Cheju native. However, negative correlations between percentage of secondary growth and underground characteristics such as clove differentiation stage and bulb weight were observed in both cultivars. 2. The earlier the planting, the earlier the appearance of secondary growth of Sanghai early without regard to cold storage while planting time did not affect secondary growth of Cheju native. 3. Percentage of secondary growth increased with increasing cold storage period and with earlier planting, and higher in Sanghai early than in Cheju native. 4. Days to clove differentiation stage and bulb yield tended to be more reduced in Sanghai early than in Cheju native as cold storage period was increased. 5. The number of alive green leaves, leaf sheath length and diameter and plant height tended to be decreased by cold storage and ABA application 3 times at 80 ppm. 6. Light break at 1,000 to 1,500 lux for 2 hours in the middle of dark period effectively prevented secondary growth. 7. Secondary growth tended to be higher in case that contents of ABA like substances were lower and contents of Giberrellin like substances were higher. 8. The above results indicate that early season cultivation of Sanghai early for ○ and high yielding in Cheju area is possible by planting seed bulbs cold stored for 30 to 60 days in early to middle September and treating plants with light break or proper grows regulators after clove differentiation stage.

ABA가 소나무 유묘의 세근 발달에 미치는 효과

서형민 建國大學校 2002 국내석사

This study was carried out to investigate the effect of abscisic acid on lateral root development of Pinus densiflora S. et Z. seedlings. Developmental stage of seedling was divided into three stages; the hypocotyl hook stage, the first needle emergence stage and the post needle emergence stage. At each stage, ABA was treated and the stem and root growth of seedling was measured for 3 months. The results were as follows : 1. ABA 10^-5~10^-4mole/liter(M) treatment had little effect on root and cotyledon growth at hook development stage. Development of lateral root was not observed in all the treatment at this stage. 2. No effect of 500~5000ppm vaseline treatment applied to the cotyledon at the first needle emergence stage was observed in 15 days after hook opening. No effect of the 500ppm ABA, but the promotive effect of the 5000ppm ABA was observed in 30 days after hook opening. At this period root tip cut had promoting effect on lateral root development regardless of ABA treatment. 3. In the post first needle emergence stage, the ABA treatment to cotyledon at the concentration 10^-5M had an effect on development of lateral root. However the lateral root development at 10^-4M treatment was less than of 10^-5M and the same as that of the control.