Direct somatic embryogenesis and related gene expression networks in leaf explants of Hippeastrum ‘Bangkok Rose’

Hippeastrum, a highly diverse genus in the Amaryllidaceae family, is a valuable ornamental bulbous flowering plant. Somatic embryogenesis(SE) is an efficient method for mass production of Hippeastrum plantlets. Previous studies have been devoted to the in vitro propagation of Hippeastrum, but the SE and its regulatory networks are rarely reported. In this study, we established a direct SE method of Hippeastrum Bangkok Rose' using leaf bases as explants. MS supplemented with 1.00 mg·L^(-1)NAA +1.00 mg·L^(-1)KT + 0.25 mg·L^(-1)TDZ was the optimal medium for SE. Histological observations showed that the bipolar somatic embryo originated from the epidermal cell layer and underwent initiation,globular, scutellar and coleoptile stages. During SE, endogenous hormones of IAA, CTK, ABA, and SA were highly accumulated. Transcriptomic analysis revealed the genes encoding auxin biosynthesis/metabolic enzymes and efflux carriers were induced, while the auxin receptor of TIR1 and ARF transcriptional repressor of Aux/IAA were down-regulated and up-regulated, respectively, leading to suppression of auxin signaling. In contrast, cytokine signaling was promoted at the early stage of SE, as biosynthesis, transport, and signaling components were up-regulated.Various stress-related genes were up-regulated at the early or late stages of SE. Chromatin remodeling could also be dynamically regulated via distinct expression enzymes that control histone methylation and acetylation during SE. Moreover, key SE regulators, including WOXs and SERKs were highly expressed along with SE. Overall, the present study provides insights into the SE regulatory mechanisms of the Hippeastrum.

Genotypic effects on accelerated propagation of oil palm breeding materials selected(Elaeis guineensis jacq.)using somatic embryogenesis

Vegetable oil production from oil palm(Elaeis guineensis Jacq.)is an important industry due to the rising demand every year.The somatic embryogenesis culture can propagate oil palm duplicate as parent plant,which can be selected as breeding material to produce new planting germplasm with high production or disease resistance.This study aims to evaluate the genotypic effect of somatic embryogenesis,while immature leaflets were employed as explants.The culture used embryo induction medium based on Murashige and Skoog(MS)modifications that contained 5 mg/L Naphthalene Acetic acid(NAA)and 0.5 mg/L Benzyl Amino Purine(BAP).The genotypic effect was statistically significant in the percentage of callus induction,producing somatic embryos,and germination embryos.In this study,we successfully cloned thirteen oil palm genotypes(GE-02,GE-03,GE-06,GE-07,GE-09,GE-23,GE-24,GE-27,GE-28,GE-32,GE-33,GE-34,and GE-35),with the highest number of somatic embryos formed on GE-27 with a percentage of 70.1%.The cloning was successful in accelerating the propagation of oil palm for materials breeding programs to create new varieties with high production and disease resistance.It is necessary to observation the performance of these clones in the field in terms of mantle flower appearance.

橡胶树热垦525胚性悬浮细胞系的建立及其胚性能力的维持

易碎胚性愈伤组织和胚性悬浮细胞系都是基因工程和细胞工程的理想受体材料。然而橡胶树(Hevea brasil-iensis)易碎胚性愈伤组织诱导频率低、耗时长,且其胚性能力通常随继代次数的增加而下降甚至完全丧失,限制了相关研究的持续开展。因此,快速获得易碎胚性愈伤组织,建立具有高效体胚发生能力的胚性悬浮细胞系,并尽可能较长时间维持其胚性能力是当前橡胶树基因工程和细胞工程研究的重要内容。本研究以橡胶树热垦525未成熟花药为外植体进行愈伤组织的诱导和胚性悬浮细胞系的建立,分析比较固液2种长期继代方式对维持其胚性能力的影响。结果表明:花药外植体在愈伤诱导培养基中获得的黄色致密初代愈伤组织体胚发生能力低,分散性差,不适合进行悬浮培养。将初代愈伤组织转移至胚性愈伤组织诱导培养基中培养70~80 d后,可观察到有胚性结构的形成和早期体细胞胚发生,同时周围长出鲜黄色小颗粒状易碎胚性愈伤组织。通过常规方法建立的Ⅰ型胚性悬浮细胞系具备胚性细胞的典型特征,体胚发生能力显著高于胚性愈伤组织,但在体胚发生过程中容易重新愈伤化;而通过筛选特定形态的胚性愈伤组织低密度启动悬浮培养建立的Ⅱ型胚性悬浮细胞系,在显微镜下可观察到细胞处在有序的胚性结构中,其体胚发生频率可达100%。在含2 mg/L2,4-D的液体培养中持续继代2 a后细胞明显老化且增殖缓慢,体胚发生能力几近丧失;而在去除2,4-D并添加低浓度脱落酸(0.1 mg/L)和水解酪蛋白(0.5 g/L)的固体培养基上持续继代2 a后,体胚发生能力仍能维持在较高水平。所建立的Ⅱ型胚性悬浮细胞系可为橡胶树遗传转化及原生质体培养等相关研究长期提供优质充足且状态相对稳定的材料来源。

植物遗传转化中体细胞再生的分子机制及应用研究进展

植物遗传转化是转基因技术及以此为基础的基因组编辑、功能基因组学研究和分子育种的关键。其中,物种和基因型差异往往是限制遗传转化效率和基因编辑技术广泛应用的主要瓶颈。随着再生芽发生和体胚发生的分子机制被逐渐探明,在愈伤组织形成、增殖和再生过程中涉及生长素和细胞分裂素合成、响应和信号转导的生长及发育调节基因被用于提高遗传转化效率。本研究首先综述了植物遗传转化过程中体细胞再生的不同途径和方式,以及转化细胞以间接的器官发生方式和体胚发生方式再生的分子机制。然后重点讨论了与生长素和细胞分裂素有关的再生促进基因在提高再生效率,缩短转化时间,以及实现执拗型物种和基因型的遗传转化等方面的应用。最后总结了再生促进基因在转基因和基因编辑中的应用潜力和研究方向。

陆地棉重组自交系再生能力和遗传转化效率筛选

转基因工程育种是棉花种质创新的有效手段,为了拓展陆地棉可再生基因型,丰富棉花转基因受体,本研究以湖北省高产阔叶棉品种‘鄂棉22’(E22)为母本、高再生能力的鸡脚叶品种‘豫早1号’(YZ1)为父本,通过单籽传法构建了F9重组自交系群体(YE);利用棉花中比较成熟的IBA+KT(IK)和2,4-D+KT(DK)2种不同激素组合的培养体系,分别对重组自交系群体的164个家系的愈伤组织诱导率(CIF)、愈伤组织继代繁殖力(CSC)、愈伤组织的出胚率(CRE)以及愈伤组织出胚时间(CET)进行比较,共获得12个可再生的阔叶棉家系;利用目前成熟的棉花遗传转化体系对可再生阔叶棉家系进行遗传转化效率分析,同时对其进行田间农艺性状考察,最终获得了一个遗传转化效率为82.9%并且农艺性状更优良的家系YE3。本研究为棉花的遗传转化及基因功能研究拓展了陆地棉基因型种质资源。

Paired box proteins as diagnostic biomarkers for endocervical adenocarcinoma

In this editorial,we commented on the article by Akers et al published in the recent issue of the World Journal of Clinical Cases.We focused specifically on the role of the transcription factor paired box protein 8(PAX8)belonging to the family PAX in the carcinogenesis of a gynecologic tumor,endocervical adenocarcinoma,arising from the tissue of mesonephric origin,and the potential diagnostic value for the same type of neoplasms.The global vaccination program of human papillomavirus(HPV)has dramatically reduced the incidence of cervical cancer,including cases of adenocarcinoma.The type of adenoid epithelial origin has a lower frequency of HPV detection but tends to be more aggressive and fatal.Cases of endocervical adenocarcinoma occurring in females of menopause age have been described in the 2023 volume of the World Journal of Clinical Cases and in our study recently published in Oncol Lett.The histopathological findings and immunohistochemical assays showed that the lesions had glandular morphology,and the specimens in these two reports were immunohistochemically positive for the transcription factor PAX8,albeit that they had opposing expression profiles of tumor suppressor p16 and estrogen receptor and the presence of the HPV genome.The presence of a mucin protein,MUC 5AC,as revealed in both studies suggested target molecules for the diagnosis of mucinous adenoid type of uterine tumor and other histological origins.The clinical outcome was unfavorable due to metastasis and recurrence.This prompted the improvement of the antitumor modality,with the introduction of precise targeting therapy.Mucin has now been reported to be the therapeutic target for adenocarcinomas.

CsAHL25通过影响CsHB1、LEC1/B3基因表达调控柑橘体细胞胚发生

【目的】基于柑橘体细胞胚发生相关基因CsHB1的启动子筛选其上游转录因子,以期为柑橘体细胞胚发生分子机制研究提供可靠的候选基因。【方法】利用CsHB1启动子(-1018~-558 bp)进行酵母单杂筛库实验,筛选出CsHB1上游转录因子CsAHL25;利用亚细胞定位实验,确定CsAHL25在细胞中的位置;通过酵母单杂点对点、双荧光素酶实验验证CsAHL25对CsHB1表达的影响;利用qRT-PCR探究CsAHL25基因在柑橘体细胞胚诱导过程中的表达模式;在柑橘愈伤组织中瞬时表达该基因,并检测体细胞胚发生相关基因的表达变化。【结果】CsAHL25在柑橘体细胞胚诱导过程中呈现先上升后下降的表达模式,该蛋白定位在细胞核中,能与CsHB1启动子结合并下调CsHB1的表达。瞬时表达CsAHL25会导致CsHB1表达量下调,及CsABI3、CsFUS3、CsLEC1、CsL1L等促进体细胞发生的LEC1/B3基因表达量上调。【结论】CsAHL25能直接下调CsHB1的表达,并使LEC1/B3基因表达量上升。CsAHL25可能通过调整CsHB1、LEC1/B3基因的表达促进体细胞胚发生。

芍药雌配子发育和2n雌配子诱导

为探究芍药2n雌配子人工诱导体系以获得四倍体后代,以芍药二倍体品种‘朱砂判’(Paeonia lactiflora‘Zhushapan’)为研究材料,通过石蜡切片法探索芍药大孢子及胚囊发生过程,建立芍药花蕾形态与大孢子及胚囊发生过程的关系。在此基础上,通过控制变量法探究秋水仙素质量浓度和注射次数对芍药2n雌配子诱导效率的影响。结果表明:芍药雌配子发育类型为蓼型,倒生胚珠,双珠被。芍药花蕾直径在26 mm≤d<29 mm范围,胚珠发育至二核胚囊主导期,质量浓度为3 g/L的秋水仙素注射花蕾3次,获得2个四倍体后代,2n雌配子诱导率最高,为3.33%。

芥菜小孢子培养及染色体加倍技术体系的优化

为探究不同芥菜基因型和培养条件对小孢子培养效果的影响,建立适合芥菜小孢子培养及染色体加倍的最佳方案,对芥菜8个不同变种的34份自交系进行小孢子培养,比较不同热激时间、活性炭浓度、小孢子密度对出胚率的影响。结果显示,基因型对芥菜小孢子培养成功与否影响较大,34份材料中11份材料成功培养出胚状体;不同材料间出胚效果差异明显,其中,大头菜出胚率最高,可达23.85胚/蕾;芥菜小孢子出胚最佳条件为32℃热激1~2 d,培养基含活性炭3~5 g/L,小孢子密度为1.5×10^(5)~2.0×10^(5)个/mL。染色体加倍试验结果显示,1 g/L秋水仙素溶液浸泡茎尖1 h的处理加倍效率高、嵌合体少,可应用于芥菜染色体的加倍。

4种无患子科植物的SMXL家族全基因组鉴定、进化及DlSMXLs在龙眼体胚发生过程中的表达分析

【目的】为研究无患子科SMXL家族的生物学特性提供理论参考,深入探究该基因家族在无患子科植物非生物胁迫响应中的调控机制。【方法】基于模式植物拟南芥SMXL家族的氨基酸序列,利用TBtools对龙眼、红毛丹、无患子和荔枝的SMXL家族成员进行全基因组鉴定,Expasy、MEGA11等软件用于4种无患子科植物的进化和功能分析,同时利用龙眼转录组数据进行体胚发生早期阶段的表达分析。【结果】4种无患子科植物共鉴定出48个SMXL家族成员,其中龙眼11个、红毛丹11个、无患子9个以及荔枝17个。依据拟南芥SMXL家族成员的分类,将4种无患子科SMXL家族成员分为5个亚族且亚细胞定位于叶绿体、细胞核、细胞质或线粒体。蛋白互作分析表明,无患子科SMXL家族成员可能与多种蛋白存在互作关系,主要分为两类:一种是与受到非生物胁迫时大量表达的热休克蛋白(HSPs)或CLPs互作;另一种是与独角金内酯受体蛋白D14、karrikins受体蛋白KAI2和调控SL信号传导途径的蛋白MAX2进行互作。启动子顺式作用元件分析表明,4种无患子科植物SMXL家族成员存在较多的光响应元件、抗氧化反应元件(ARE)和脱落酸响应元件(ABRE)等,推测该基因家族广泛参与非生物胁迫响应。此外,DlSMXL家族成员在龙眼体胚发生早期存在5种不同的表达模式,其中DlSMXL4基因家族成员在胚性愈伤组织(EC)、不完全胚性紧实结构(ICpEC)和球形胚(GE)阶段相较其他成员呈现较高表达。基于5-氮胞苷、PEG、SL、光、温度和各种激素处理龙眼EC时期转录组数据分析可知,龙眼DlSMXL5在干旱、GR24、黑暗和高温处理下表达量均明显增加,推测该成员能够通过响应植物激素和应激胁迫维持胚性愈伤组织形态。其次DlSMXL8在5-氮胞苷处理时表达上调,推测其可能参与DNA甲基化在龙眼体胚发生过程中发挥作用。【结论】4种无患子科植物SUPPRESSOR OF MAX2-LIKE(SMXL)家族除了在植物生长发育过程种发挥重要的作用,同时还广泛参与植物非生物胁迫调控过程。本研究结果为无患子科植物中SMXL的分类和生物学功能提供了理论依据,并为SMXL在龙眼早期体细胞胚胎发生中的功能验证提供了更好的认识。

抗性湿地松体细胞胚的发育、成熟及萌发

为加快抗松针褐斑病湿地松体细胞胚胎发生技术的产业化应用进程,本文研究了肌醇浓度、脱落酸(ABA)及其添加方式、基本培养基、聚乙二醇(PEG-6000)浓度、琼脂糖种类及浓度、活性炭浓度、液体悬浮培养等因素对抗性湿地松体细胞胚的发育、成熟及萌发的影响。结果表明:添加8 g/L肌醇较适宜,过高浓度的肌醇则不利于湿地松体细胞胚发育;ABA可以采用高压灭菌;基本培养基、ABA、PEG-6000互作对湿地松体细胞胚的成熟影响很大,基本培养基以LP为最佳,ABA的最适浓度为10m g/L,PEG-6000以添加25、50 g/L为宜;在湿地松体细胞胚的成熟培养过程中,PEG-6000的浓度不能高于100 g/L;在湿地松体细胞胚的成熟培养基中,添加60 g/L蔗糖最合适;湿地松体细胞胚的成熟培养基中添加0.5 g/L或1 g/L的活性炭较适宜;培养基状态对体细胞胚的高频率诱导具有一定的影响,悬浮培养以100 mL三角瓶装培养液30 mL、摇床转速130 r/min为宜,液体转固体时吸取培养液1 mL为宜;未建立成熟的体细胞胚发生体系前,以采用固体培养为佳。最佳成熟培养基、激素及部分添加物组合为LP+10 mg/L ABA+50 g/L PEG-6000+60 g/L蔗糖+1.0 g/L活性炭。

葡萄风信子愈伤组织再生体系的构建

以葡萄风信子常见种亚美尼亚的花蕾和叶片作为外植体,开展不同因素对葡萄风信子愈伤组织诱导和植株再生影响的研究。结果表明:亚美尼亚的花蕾和叶片愈伤组织诱导和增殖的最佳培养基配方为:MS+1.0 mg/L 2,4−D+0.1 mg/L 6−BA,其愈伤组织诱导率为100%,且继代35 d后不同培养基上的花源和叶源愈伤组织的鲜质量无显著差异;液体培养和光照培养有利于愈伤组织细胞增殖,1 g亚美尼亚花源和叶源愈伤组织经液体培养4个继代周期后,平均鲜质量最高可达(10.36±1.13)g和(10.55±2.29)g,表明不同培养基配方对亚美尼亚花蕾和叶片愈伤组织细胞增殖无显著影响,且液体培养和光照培养均有利于愈伤组织的增殖;胚性和非胚性2种愈伤组织分别通过体细胞胚发生和器官发生2种途径可再生形成完整植株,再生率均为100%。

The paternal epigenome and embryogenesis： poising mechanisms for development

The scope of paternal contributions during early embryonic development has long been considered limited. Dramatic changes in chromatin structure throughout spermatogenesis have been thought to leave the sperm void of complex layers of epigenetic regulation over the DNA blueprint, thus leaving the balance of that regulation to the oocyte. However, recent work in the fields of epigenetics and male factor infertility has placed this long-held, and now controversial dogma, in a new light. Elegant studies investigating chromatin and epigenetic modifications in the developing sperm cell have provided new insights that may establish a more critical role for the paternal epigenome in the developing embryo. DNA methylation, histone tail modifications, targeted histone retention and protamine incorporation into the chromatin have great influence in the developing sperm cell. Perturbations in the establishment and/or maintenance of any of these epigenetic marks have been demonstrated to affect fertility status, ranging in severity from mild to catastrophic. Sperm require this myriad of chromatin structural changes not only to serve a protective role to DNA throughout spermatogenesis and future delivery to the egg, but also, it appears, to contribute to the developmental program of the future embryo. This review will focus on our current understanding of the epigenetics of sperm. We will discuss sperm-specific chromatin modifications that result in genes essential to development being poised for activation early in embryonic development, the disruption of which may result in reduced fecundity.

The MADS-box transcription factor CmAGL11 modulates somatic embryogenesis in Chinese chestnut(Castanea mollissima Blume)

Somatic embryogenesis(SE)is an effective approach of in vitro regeneration that depends on plant cell totipotency.However,largely unknown of molecular mechanisms of SE in woody plants such as Chinese chestnut(Castanea mollissima Blume),limits the development of the woody plant industry.Here,we report the MADS-box transcription factor Cm AGL11 in Chinese chestnut.Cm AGL11 transcripts specifically accumulated in the globular embryo.Overexpression of Cm AGL11 in chestnut callus enhanced its SE capacity,and the development of somatic embryos occurred significantly faster than in the control.RNA-seq results showed that Cm AGL11 affects the expression of several genes related to the gibberellin,auxin,and ethylene pathways.Moreover,the analysis of DNA methylation status indicated that the promoter methylation plays a role in regulation of Cm AGL11 expression during SE.Our results demonstrated that Cm AGL11 plays an important role in the SE process in Chinese chestnut,possibly by regulating gibberellin,auxin,and ethylene pathways.It will help establish an efficient platform to accelerate genetic improvement and germplasm innovation in Chinese chestnut.

Somatic Embryogenesis and Plant Regeneration from Two Recalcitrant Genotypes of Gossypium hirsutum L.

An improved protocol has been developed for somatic embryogenesis and plant regeneration of recalcitrant cotton cultivars. High callus frequencies and embryogenic tissue were developed in MSB medium supplemented with gradient concentrations of KT and 2,4-D, their concentration decreasing from 0.1 to 0.01 mg·L^-1. Somatic embryos were successfully incubated in 1/2 macronutrient MSB suspension supplemented with 0.5 g· L^-1 glutamine and 0.5 g·L^-1 asparagine. Decrease in macronutrient concentration of MSB significantly alleviated browning and was beneficial to suspension cells. Transformation of somatic embryos into plants was induced in MSB medium supplemented with 3% sucrose, 0.5 g·L^-1 glutamine, 0.5 g·L^-1 asparagine, and 6.0 g·L^-1 agar. The effect of sucrose as carbohydrate was better than that of glucose for plant germination. Using this protocol, regenerated plantlets from the CCRI521 and Zhongzhi86-6 reached to as much as 19.6 and 18.5% somatic embryos, respectively.

Indirect somatic embryogenesis and regeneration of Fraxinus mandshurica plants via callus tissue

Somatic embryogenesis of Fraxinus mandshurica has the problems of low somatic embryo(SE) yield,unsynchronized SE development,and a high percentage of deformed SEs.We aimed to improve F.mandshurica SE production by synchronizing SE development,improving SE quality,and inducing root formation to obtain complete regenerated plants.Cotyledons of immature zygotic embryos of F.mandshurica were induced to form callus and then SEs.The SE induction percentage from explants differed among 32 mother trees,and the one with the highest SE induction percentage(29.8%) was used for further experiments.The highest callus induction percentage was94.2% on 1/2-strength Murashige and Skoog medium(MS1/2)supplemented with 0.15 mg·L^(-1) naphthalene acetic acid.The highest callus proliferation coefficient(240.5) was obtained on McCown's Woody Plant Medium containing 0.1 mg·L^(-1)6-benzyl adenine and 0.15 mg·L^(-1) 2,4-dichlorophenoxyacetic acid.The highest number of SEs(1020.5 g~(-1) fresh weight) was obtained on MS1/2 medium supplemented with1 mg·L^(-1) 6-benzyladenine.The highest number of cotyledon embryos(397/g fresh weight) was obtained by incubating materials on medium containing 1 mg·L^(-1) abscisic acid and then applying a drying treatment.The cotyledon embryos were milky white,uniformly sized(average length 4.7 mm),and 80% of them were normal.The SE rooting percentage on 1/2 MS medium containing 0.01 mg·L^(-1) NAA was 37.5%.Overall,the germination percentage of SEs was 26.4%,and complete regenerated plants were obtained after transplanting and acclimation.These results provide more possibilities for the preservation and breeding of F.mandshurica.

Selection of culture conditions for callus induction and proliferation by somatic embryogenesis of Pinus koraiensis

The induction and proliferation of embryogenic callus are key steps for large-scale propagation of somatic embryogenesis pathway and long-term preservation of coniferous germplasm.Callus can be induced from immature embryos of Korean pine(Pinus koraiensis Sieb.et Zucc.;Pinaceae)as explants,but there are problems,such as low proliferation efficiency,loss of embryogenicity,poor vigor;thus,best conditions for proliferation and culture of immature embryos of Korean pine are not yet clear.To solve the problems with somatic embryogenesis of Korean pine and determine the best culture conditions for callus induction and proliferation,we varied hormone concentration,subculture cycle of proliferation and other plant growth regulators combinations in media to induce callus formation by megagametophytes of three Korean pine families at different developmental stages,then analyzed the effects on embryogenic callus retention and cell proliferation using a quadratic regression orthogonal rotation design.The results showed that the family origin and collection date of explants significantly affected callus induction(induction rate reached 1.67%).Embryogenic maintenance and callus proliferation were best on DCR medium supplemented with 0.25 mg L^(−1)6-benzyl adenine,1 mg L^(−1)naphthaleneacetic acid,30 g L^(−1)sucrose,500 mg L^(−1),L-glutamine,500 mg L^(−1)casein hydrolysis and 6.5 g L^(−1)agar.In addition,the combination of 2,4-dichlorophenoxyacetic acid+6-benzyl adenine also had a better proliferative effect on callus.The effects of different combinations of growth regulators on callus proliferation efficiency were significantly different.Transfer to new medium every 13–15 days not only maintained robust callus vigor,but also yielded a larger proliferation coefficient.The techniques and conditions for embryogenic callus induction and proliferation of Korean determined here will serve as a foundation for establishing a large-scale system for somatic embryogenesis and propagation of Korean pine.

Effect of plant growth regulators on direct somatic embryogenesis in camphor tree(Cinnamomum camphora L.)from immature zygotic embryos and embryogenic calli induction

A description of a successful direct somatic embryogenesis induction from immature zygotic embryos of a camphor tree （Cinnamomum camphora L.） is presented. After a subculture of 2-3 years, embryogenic calli could be derived from primary somatic embryos. Immature zygotic embryos were cultured on a Murashige and Skoog （MS） basal medium supplemented with a range of combinations of cytokinins （BA） and auxins （2,4-D or NAA） for somatic embryo induction. Primary somatic embryos could be induced directly in almost all PGR combinations. A positive effect of 2,4-D on somatic embryogenesis from immature zygotic embryos of camphor tree was obtained. BA at appropriate concentrations （〈 5 mg-L-1） had an effect similar to 2,4-D, whereas high concentrations （〉 5 mg·L^-1） of BA had the effect of restraining somatic embryo induction. NAA had a less positive effect on somatic embryogenesis than 2,4-D.

Oxidative Stress Responsive <i>SERK1</i>Gene Directs the Progression of Somatic Embryogenesis in Cotton (<i>Gossypium hirsutum</i>L. cv. Coker 310)

Somatic embryogenesis (SE) is a prominent mode of regeneration in plants. The acquisition of SE is predominantly invoked by the oxidative stress which plays an important role in signal transduction and cellular redox. Since balanced generation of oxidants is important to cellular differentiation, modulation in cell redox could be responsive to genotypic refinement for SE. To study the dynamics of cellular redox during SE, we conducted comparative expression analyses of cotton (Gossypium hirsutum), using two independently purified near-isogenic lines for the trait of SE. We interrogated expression changes in cell-signaling factor Somatic Embryogenesis Receptor Kinase (SERK) and activity of antioxidant Glutathione in different developmental stages including cotyledonary leaf, calli from different stages of regeneration of fully-regenerating (FR) and non-regenerating (NR) lines of Coker310 cultivar. At evolutionary scale, the cotton SERKs showed high sequence similarity in receptor kinase domain with diverse systems. Exclusively, SERK1 responsible for potential signaling processes during SE revealed significant expression up-regulation in the embryogenic calli of FR line. Similarly, activity of antioxidant glutathione was substantially up-regulated in embryogenic calli of FR line in comparison to its counterpart form. In contrast, calli from early-stages of regeneration of both FR and NR lines had no significant influences on the regulation of SERK and glutathione levels prior to the acquisition of embryogenesis. These results highlight that in vitro purification of FR line in cotton for enhanced regeneration potential (through SE) resulted in signaling and metabolic transformations of the manner in which cellular redox levels have become modulated.

Plantlet regeneration through somatic embryogenesis in Nordmann's fir (Abies nordmanniana)

I studied the influence of various combinations of auxin and cytokinin concentrations, and the increased content of zinc and enzymatic casein hydrolizate in SH medium on initiation and proliferation of embryogenic callus of Abies nordmanniana （Steven） Spach. Addition- ally, the effect of ABA, PEG-4000 and different wave- lengths on the maturation of somatic embryos was tested. The use of optimum composition of modified SH medium with BA, KIN and 2.4-D while simultaneously ensuring appropriate external conditions resulted in 15.5 % embryogenesis. Finally, satisfactory results of microprop- agation of A. nordmanniana by somatic embryogenesis were obtained providing seven lines of embryogenic callus with high proliferation capacity. Those lines gave properly developed seedlings in white LED light with a wavelength of 400-700 nm, preceded by eight-week vernalization treatment of the callus. This paper may provide a protocol by which all stages of somatic embryogenesis of A. nord- manniana can be carded out, including the preceding 24-h seed disinfection with NaOCl and PVP, which resulted in 100 % frequency of uninfected zygotic embryos that were capable of starting embryogenesis.