BES1-Mediated Brassinosteroid Signaling Negatively Regulates Biosynthesis and Signaling of Abscisic Acid to Increase Seed Size in Arabidopsis

Jeehee Roh,Chan‑Ho Park,Seung‑Hyun Son,Seong‑Ki Kim 한국식물학회 2023 Journal of Plant Biology Vol.66 No.3

Expression of ABA-deficient 2 (ABA2) gene involved in ABA biosynthesis was downregulated in bes1-D, but upregulated in bes1-KO. Hence, the expression of ABA2 is negatively controlled by the BES1 transcription factor of brassinosteroid signaling in Arabidopsis thaliana. BES1 is directly bound to the E-box sequences in the promoter of ABA2, which reduced the endogenous levels of ABA in the plant. The seeds of aba2-1 and bes1-KO were larger and smaller, respectively, than those of the wild type. In bes1-KO × aba2-1, the reduced seed size in bes1-KO was partly restored to the seed size in aba2-1. Hence, BES1-mediated regulation of seed size is an upstream process for the homeostasis of endogenous ABA to control the seed size. BES1 suppressed the expression of ABA Insensitive 5 (ABI5), a major transcription factor gene in ABA signaling that determines the seed size. It is directly bound to the promoter of ABI5 by BES1-induced downregulation of ABI5. The expression of SHORT HYPOCOTYL UNDER BLUE1, MINISEED3, and HAIKU2 as positively regulatory genes determining the seed size was activated, increasing the seed size in bes1-D. Conclusively, brassinosteroid signaling through BES1 downregulated both the biosynthesis and signaling of ABA, which increased the seed size in Arabidopsis.

Brassinosteroids modulate ABA-induced stomatal closure in Arabidopsis

Ha, Yunmi,Shang, Yun,Nam, Kyoung Hee Oxford University Press 2016 Journal of experimental botany Vol.67 No.22

<▼1><P><B>Highlight</B></P><P>Brassinosteroids alone promote stomatal closure, and in combination with ABA, they positively and negatively modulate ABA-induced stomatal closure in Arabidopsis.</P></▼1><▼2><P>Stomatal movement in response to water availability is an important physiological process in the survival of land plants. The plant hormone abscisic acid (ABA) and brassinosteroids (BRs) regulate stomatal closure. The physiological functions of ABA and BRs, including germination, cell elongation and stomatal movement, are generally known to be antagonistic. Here, we investigated how BRs affect stomatal movement alone and in combination with ABA. We demonstrate that brassinoslide (BL), the most active BR, promotes stomatal closure in an ABA-independent manner. Interestingly, BL also inhibited ABA-induced stomatal closure when a high concentration of BL was added to ABA. Furthermore, we found that the induction of some genes for reactive oxygen species (ROS) generation by ABA (<I>AtrbohD</I>, <I>NIA1</I> and <I>NIA2</I>) and subsequent ROS production were repressed by BL treatment. The BR signaling mutant <I>bri1-301</I> failed to inhibit ABA-induced stomatal closure upon BL treatment. However, <I>BRI1</I>-overexpressing transgenic plants were hypersensitive to ABA during stomatal closure, and BL reversed ABA-induced stomatal closure more completely than in wild type plants. Taken together, these results suggest that BRs can positively and negatively modulate ABA-induced stomatal closure. Therefore, interactions between ABA and BR signaling are important for the regulation of stomatal closure.</P></▼2>

보리 유묘(幼苗)에 있어서 Abscisic Acid (ABA) 유도체(誘導體)가 생장(生長) 및 Peroxidase 활성(活性)에 미치는 영향(影響)

배경숙,이상갑,강상재,박창동,박우철,Bae, Kyung Sook,Lee, Sang Kap,Kang, Sang Jai,Park, Chang Dong,Park, Woo Churl 경북대학교 농업과학기술연구소 1992 慶北大農學誌 Vol.10 No.-

천연형(天然形) ABA가 갖는 생물(生物) 활성(活性)을 향상(向上)시키기 위하여 합성(合成)된 ABA 유도체(誘導體)들의 생물활성(生物活性)과 아울러 초기생장(初期生長)과 밀접(密接)한 관계(關係)가 있는 peroxidase 활성도(活性度) 변화(變化)를 조사(調査)한 결과(結果)는 다음과 같다. $26{\pm}1^{\circ}C$, 암실(暗室)에서 7일간(日間) 생장(生長)시킨 보리 유묘(幼苗)의 지상부(地上部) 신장(伸張)은 3.2ppm의 (${\pm}$)-ABA, 1.2ppm의 (S)-(+)-ABA, 0.6ppm의 ABA-methyl cinnamate ester 화합물(化合物)(AC) 및 0.08ppm의 ABA-umbelliferone ester 화합물(化合物)(AU)에서 대조구(對照區)에 비(比)해 80% 이상의 저해(沮害)를 보여 (S)-(+)-ABA가 racemic ABA보다 약(約) 3배(倍), AC와 AU는 (S)-(+)-ABA보다 각각(各各) 약(約) 2.5배(倍), 16배(倍) 더 강(强)한 활성(活性)을 나타내었다. 발아(發芽) 후(後) 생장(生長)이 진행(進行)됨에 따른 보리 유묘(幼苗)의 지상부(地上部)의 peroxidase 활성도(活性度)는 대조구(對照區)에서는 큰 변화(變化)는 없었으나, ABA와 그 유도체(誘導體)를 처리(處理)한 보리 유묘(幼苗)의 지상부(地上部)에서는 계속 증가(增加)하였다. 생장(生長) 저해(沮害) 활성(活性)이 강(强)하게 나타난 고농도(高濃度) [3.2ppm의 (${\pm}$)-ABA, 1.2ppm의 (S)-(+)-ABA, 0.6ppm의 AC 및 0.08ppm의 AU]의 처리(處理)가 저농도(低濃度) [3.0ppm의 (${\pm}$)-ABA, 1.0ppm의 (S)-(+)-ABA, 0.4ppm의 AC 및 0.06ppm의 AU]의 처리(處理)보다 더 높은 peroxidase 활성도(活性度)를 나타내었으며, ABA 유도체들은 ABA보다 저농도(低濃度)에서 더 높은 peroxidase 활성도(活性度)를 나타내었다. This experiment was conducted to investigate biological activity of ABA and its analogues on barley shoot growth and peroxidase activity in barley seedlings. The treatments of 3.2 ppm (+)-ABA, 1.2 ppm (S)-(+)-ABA, 0.6 ppm ABA-methyl cinnamate ester compound (AC), and 0.08 ppm ABA-umbelliferone ester compound (AU) inhibited the growth of barley seedlings by more than 80% as compared with untreated control. The increase in barley shoot-inhibit activity of (S)-(+)-ABA became 3-fold than the activity of racemic ABA, and those of AC and AU higher than that of (S)-(+)-ABA by about 2.5 and 16 times, respectively. Peroxidase activities of barley shoots during the early growth stage were kept at a constant levels without ABA treatment, but in the treatment of racemic ABA, (S)-(+)-ABA, AC and AU increased the activities. Furthermore, the peroxidase activities increased as the higher concentration of ABA and its analogues were applied.

Molecular cloning and characterization of the ABA-specific glucosyltransferase gene from bean (Phaseolus vulgaris L.)

Palaniyandi, S.A.,Chung, G.,Kim, S.H.,Yang, S.H. G. Fischer 2015 Journal of plant physiology Vol.178 No.-

Levels of the plant hormone abscisic acid (ABA) are maintained in homeostasis by a balance of its biosynthesis, catabolism and conjugation. The detailed molecular and signaling events leading to strict homeostasis are not completely understood in crop plants. In this study, we obtained cDNA of an ABA-inducible, ABA-specific UDP-glucosyltransferase (ABAGT) from the bean plant (Phaseolus vulgaris L.) involved in conjugation of a glucose residue to ABA to form inactive ABA-glucose ester (ABA-GE) to examine its role during development and abiotic stress in bean. The bacterially expressed PvABAGTase enzyme showed ABA-specific glucosylation activity in vitro. A higher level of the PvABAGT transcript was observed in mature leaves, mature flowers, roots, seed coats and embryos as well as upon rehydration following a period of dehydration. Overexpression of 35S::PvABAGT in Arabidopsis showed reduced sensitivity to ABA compared with WT. The transgenic plants showed a high level of ABA-GE without significant decrease in the level of ABA compared with the wild type (WT) during dehydration stress. Upon rehydration, the levels of ABA and phaseic acid (PA) decreased in the WT and the PvABAGT-overexpressing lines with high levels of ABA-GE only in the transgenic plants. Our findings suggest that the PvABAGT gene could play a role in ABA homeostasis during development and stress responses in bean and its overexpression in Arabidopsis did not alter ABA homeostasis during dehydration stress.

Brassinosteroid reduces ABA accumulation leading to the inhibition of ABA-induced stomatal closure

Ha, Yun Mi,Shang, Yun,Yang, Dami,Nam, Kyoung Hee Elsevier 2018 Biochemical and biophysical research communication Vol.504 No.1

<P><B>Abstract</B></P> <P>Proper regulation of stomatal movement in response to various environmental stresses or developmental status is critical for the adaptation of many plant species to land. In plants, abscisic acid (ABA)-induced stomatal closure is a well-adapted method of regulating water status. In addition to ABA, we previously showed that plant-specific steroidal hormone, brassinosteroid (BR), also induces stomatal closure; however, BR modulates ABA-induced stomatal closure negatively at high concentrations. In this study, we further investigated the cross-talk between ABA and BR in relation to stomatal movement. In contrast to previous reports that ABA-induced stomatal closure was inhibited by brassinolide (BL), the most active BR, we showed that BL-induced stomatal closure was enhanced by ABA, indicating that the sequence of ABA or BL treatments led to different results. We found that this phenomenon occurred because the guard cells still had the capacity to be closed further by ABA, as the degree of stomatal closure by BL was always less than that by ABA. We also found that BL-induced stomatal closure required Open Stomata 1 (OST1) activity and the induced expression of <I>OST1</I> was indifferent to the sequence of ABA and/or BL treatments. In addition, we examined the underlying mechanism by which inhibition of ABA-induced stomatal closure by BL occurred. We revealed that the downregulation of ABA-biosynthetic genes by BL resulted in a lower accumulation of ABA. These results suggested that the regulation of stomatal movement is finely controlled by the combined effects of plant hormones, ABA and BR.</P> <P><B>Highlights</B></P> <P> <UL> <LI> ABA strengthened BL-induced stomatal closure. </LI> <LI> Expression of <I>OST1</I> was induced by BL, and BL-induced stomatal closure required OST1. </LI> <LI> Inhibition of ABA-induced stomatal closure by BR was due to reduced ABA accumulation. </LI> </UL> </P>

Hydrogen peroxide is involved in abscisic acid-induced adventitious rooting in cucumber (Cucumis sativus L.) under drought stress

Xue-Ping Li,Qing-Qing Xu,Wei-Biao Liao,Zhan-Jun Ma,Xiao-Ting Xu,Meng Wang,Peng-Ju Ren,Li-Juan Niu,Xin Jin,Yong-Chao Zhu 한국식물학회 2016 Journal of Plant Biology Vol.59 No.5

Abscisic acid (ABA) and hydrogen peroxide (H2O2) are important regulatory factors involved in plant development under adversity stress. Here, the involvement of H2O2 in ABA-induced adventitious root formation in cucumber (Cucumis sativus L.) under drought stress was determined. The results indicated that exogenous ABA or H2O2 promoted adventitious rooting under drought stress, with a maximal biological response at 0.5 μM ABA or 800 μM H2O2. The promotive effects of ABA-induced adventitious rooting under drought stress were suppressed by CAT or DPI, suggesting that endogenous H2O2 might be involved in ABA-induced adventitious rooting. ABA increased relative water content (RWC), leaf chlorophyll content, chlorophyll fluorescence parameters (Fv/Fm, ΦPS II and qP), water soluble carbohydrate (WSC) and soluble protein content, and peroxidase (POD), polyphenol oxidase (PPO) and indoleacetate oxidase (IAAO) activities, while decreasing transpiration rate. However, the effects of ABA were inhibited by H2O2 scavenger CAT. Therefore, H2O2 may be involved in ABA-induced adventitious root development under drought stress by stimulating water and chlorophyll content, chlorophyll fluorescence, carbohydrate and nitrogen content, as well as some enzyme activities.

Heat Shock Proteins atHSP93-III and atHSP93-V Affect ABA Response and Leaf Senescence

Soo Young Kim,Min Young Park 한국식물학회 2018 Journal of Plant Biology Vol.61 No.6

We carried out activation tagging screen toisolate ABA signaling components and isolated an ABAhypersensitivemutant, ahs716 (ABA-hypersensitive 716). TDNAwas inserted in the 5’ flanking region of the atHSP93-III gene in the mutant, and the atHSP93-III transcript levelwas barely detectable, indicating that it is a knockdownmutant. The mutant exhibited poor viability, and, therefore,we prepared and analyzed its overexpression (OX) lines tostudy its function. Plants overexpressing atHSP93-III werehypersensitive to ABA, and several ABA-regulated geneswere up-regulated in the transgenic plants. We also investigatedthe role of atHSP93-V in ABA response. atHSP93-V is aparalog of atHSP93-III and encodes an isoform of HSP93. Although it is highly homologous to atHSP93-III, atHSP93-V OX did not affect ABA sensitivity. However, the atHSP93-VOX lines displayed early senescence phenotype, and changesin the expression levels of several senescence-related geneswere observed in the transgenic lines. Collectively, our datasuggest that, whereas atHSP93-V is involved in leaf senescence,atHSP93-III is involved in ABA response. Considering thatHSP93 is a molecular chaperone essential for chloroplastbiogenesis and function, the resuls provide evidence thatchloroplast function is important for normal ABA response.

ATHB17 Is a Positive Regulator of Abscisic Acid Response during Early Seedling Growth

박민영,김수영,김성아,이선지 한국분자세포생물학회 2013 Molecules and cells Vol.35 No.2

We performed activation tagging screen to isolate abscisic acid (ABA) response mutants. One of the mutants, designated ahs10 (ABA-hypersensitive10), exhibited ABA-hyper-sensitive phenotypes. TAIL-PCR analysis of the mutant revealed that T-DNA was inserted in the promoter region of the Arabidopsis gene, At2g01430, which encodes a homeodomain-leucine zipper protein ATHB17. Subsequent expression analysis indicated that ATHB17 was activated in ahs10. To recapitulate the mutant phenotypes, we prepared ATHB17 OX lines and investigated their phenotypes. The results showed that ATHB17 confers ABA-hypersen-sitivity and drought tolerance. On the contrary, ATHB17 knockout lines were ABA-insensitive and drought-sensi-tive, further demonstrating that ATHB17 is involved in ABA and water-stress responses. Interestingly, the ATHB17 effect on seedling growth in the presence of ABA was observed only during the postgermination seedling establishment stage, suggesting that it functions during a narrow developmental window of early seedling growth.

토양수분조건 및 화학물질처리가 오이묘의 저온장해에 미치는 영향

남윤일(Yooun Il Nam),우영회(Young Hoe Woo),이관호(Kwan Ho Lee) (사)한국생물환경조절학회 2006 시설원예‧식물공장 Vol.15 No.4

오이묘가 저온피해를 입기 전, 후 토양수분조건과 몇 가지의 화학물질처리가 오이묘의 냉해 경감에 미치는 영향을 연구한 결과 토양수분 -0.3bar 적습상태에서 07:00시에 2℃로 저온처리를 했을때, 생존율은 28.3%이었으나 -5.5ba에서는 83.3%로 높아져 토양수분이 건조하면 저온피해가 감소되었다. 그러나 18:00시에 저온처리하면 -0.3bar에서도 생존율은 87% 이상이었다. 토양수분이 건조하면 엽신의 ABA함량은 크게 증가되었다. 저온처리 전, 후 ABA의 토양 및 엽면처리는 오이묘의 생존율을 유의하게 증가시켰고 세포의 전해질 누출량도 현저하게 감소시켰으며, 수량의 감소를 경감시켰다. 또한 ABA 처리는 저온처리 후보다는 저온처리 전에, 엽면처리보다는 토양에 처리하는 것이 보다 효과적이었다. ABA(10??M)와 더불어 요소(0.2%)와 KH₂PO₄의 엽면살포는 오이의 생장과 수량에 미치는 저온피해를 경감시키는데 효과적이었다. This study was conducted to investigate the effects of chemical application and amout of soil moisture on low temperature stress of cucumber seedling under the greenhouse conditions. When chilling treatments (2℃) were begun at 07:00AM, survival rates of seedlings of two conditions; -0.3 bar and -5.5 bar were 28.3% and 83.3% respectively. But when chilling treatments were begun at 6:00PM - even the soil moisture condition was -0.3 bar - the survival rate was above the 87%. When reducing the soil moisture from -0.3 bar to -9.0 bar, ABA content in leaf was increased by 6.5fold. Spraying of abscise acid (ABA) before or after the chilling significantly increased the survival rates of seedlings, decreased the amounts of leaking electrolytes and prevented the yield reductions. ABA application on the soil before the chilling appeared to be more effective than the application after the chilling with foliar spray. Spraying of ABA (10?? M), urea (0.2%) or KH₂PO₄ was effective in counteracting the low temperature, which causes growth deterioration and yield reduction in cucumbers.

An ARIA-Interacting AP2 Domain Protein Is a Novel Component of ABA Signaling

Sun-ji Lee,Dong-im Cho,Jung-youn Kang,Soo Young Kim 한국분자세포생물학회 2009 Molecules and cells Vol.27 No.4

ADAP is an AP2-domain protein that interacts with ARIA, which, in turn, interacts with ABF2, a bZIP class transcription factor. ABF2 regulates various aspects of the abscisic acid (ABA) response by controlling the expression of a subset of ABA-responsive genes. Our expression analyses indicate that ADAP is expressed in roots, emerging young leaves, and flowers. We found that adap knockout mutant lines germinate more efficiently than wild-type plants and that the mutant seedlings grow faster. This suggests that ADAP is involved in the regulation of germination and seedling growth. Both germination and postgermination growth of the knockout mutants were partially insensitive to ABA, which indicates that ADAP is required for a full ABA response. The survival rates for mutants from which water was withheld were low compared with those for wild-type plants. The result shows that ADAP is necessary for the response to stress induced by water deprivation. Together, our data indicate that ADAP is a positive regulator of the ABA response and is also involved in regulating seedling growth. The role of ADAP is similar to that of ARIA, which is also a positive regulator of the ABA response. It appears that ADAP acts through the same ABA response pathway as ARIA.