Study on Shoot Tip Culture of Illciaceae Ornamental Plants

[Objective] This study aimed to establish a technology system for tissue culture and rapid propagation of Illciaceae ornamental plants. [Method] Effects of medium components and anti-browning agents on the survival and growth of shoot tips were investigated by using apical buds of IItciaceae plant Haierlian as experiment material and MS as basic medium. [Result] The results showed that apical buds at the early germination period in spring were the most suitable explants for tissue culture of IIIciaceae plant Haierlian. Sterilization with 0.1% HgCI2 for 6 min achieved the best effect, while conventional surface-sterilization with ethanol would affect the survival of explants. The optimal medium for primary culture was MS-D （with modifications in major elements and organic components） ＋ anti-browning agents （equa~ volume） ＋ 2.0 mg/L of 6-BA ＋ 0.5 mg/L of NAA. The optimal subculture medi- um was MS-F （with modifications in inorganic and organic components） ＋ anti-brown- ing agents （equal volume） ＋ 2.0 mg/L of 6-BA ＋ 0.1 mg/L of NAA. [Conclusion] This study laid the foundation for establishment of tissue culture and rapid propagation technology system for Haierlian.

Cell Ultrastructure of Kiwifruit (Actinidia chinensis) Shoot Tips During Cryopreservation

The changes in the cell ultrastructure of in vitro cultured shoot tips from dwarf genotype of kiwifruit （Actinidia chinensis Ganmi 5） during cryopreservation were investigated. Shoot tips were preserved in liquid nitrogen using vitrification, and the cell ultrastructure was examined using transmission electron microscopy （TEM）. The regular ultrastructure of the cell wall, cell membrane and nucleus of shoot tips could be damaged during the freezing and thawing associated with preservation using liquid nitrogen. The cell plasmolysis was increased and freezing tolerance was improved after precultufing and dehydrating in a preservation and vitrification solution （PVS2） （30% glycerol （Gly）＋ 15% ethylene glycol （EG）＋ 15% dimethylsulfoxide （DMSO） ＋ 0.4 mol L^-1 sucrose）. The structure of some cells with low degree of injury and reversible damage was similar to that of the control and they could undergo normal cell division and differentiation. Besides, they could recover automatically and regenerate after their reculture.

Response of carbohydrate metabolism-mediated sink strength to auxin in shoot tips of apple plants

Auxin(indole-3-acetic acid, IAA) has a considerable impact on the regulation of plant carbohydrate levels and growth, but the mechanism by which it regulates sugar levels in plants has received little attention. In this study, we found that exogenous IAA altered fructose(Fru), glucose(Glc), and sucrose(Suc) concentrations in shoot tips mainly by regulating MdSUSY1, MdFRK2, MdHxK1 and MdSDH2 transcript levels. Additionally, we used 5-year-old ’Royal Gala’ apple trees to further verify that these genes play primary roles in regulating sink strength. The results showed that MdSUSY1, MdFRK2, MdHxK1/3 and MdSDH2 might be major contributors to sink strength regulation. Taken together, these results provide new insight into the regulation of the carbohydrate metabolism mechanism, which will be helpful for regulating sink strength and yield.

Effect of Heat Treatment Combined with Shoot Tip Culture on the Virus-Free of Arena Strawberry

With Arena strawberry as experimental materials, heat treatments combined with shoot tip culture were used to explore their detoxification effects. The results indicated that if not heated, splitting shoot tips directly could not completely remove viruses. On the other hand, it will be obviously improved after shoot tips are heated. Incubators heat treatment （inconstant temperature） with shoot tip culture, constant temperature water bath incubation process with meristem-tip culture, hot air treatment （constant temperature） with apical meristem culture were three methods tested in searching for virus-free of Arena strawberry in this experiment. And their virus-free rates were 78.9%, 86.0% and 50.0% respectively. Of the three methods, the second, constant temperature water bath process with shoot tip culture, with 78.7% survival, is the best. Thus, it can be inferred that constant temperature water bath treatment combined with shoot tip culture might be the most appropriate method to remove viruses of Arena strawberry.

Effect of Cytokinins on the Micropropagation of Carob(Ceratonia siliqua L.)through Shoot Tip Culture

In order to determine the most suitable cytokinin for the micropropagation of carob (Ceratonia siliqua L.), the effect of four cytokinins: BAP, zeatin, kinetin and 2-iP, was tested on explants derived from young seedlings of seven days. Organogenesis is better in the presence of BAP (0.5 mg/l), while buds growth is favored by zeatin (0.5 mg/l). The combination of the most suitable cytokinin (BAP at 0.5 mg/l) with IBA improves the caulogenesis when the concentration of this latter is low (0.1 mg/l);high concentrations of IBA have an inhibitory effect on elongation and neoformation of shoots and leaves. The multiplication and growth of shoots are more favorable on WPM medium in the presence of BAP (0.5 and 1 mg/l) alone or combined with 0.5 mg/l with GA3, while rooting is mainly favored by IBA, especially at 2 mg/l.

Influence of Ethylene Inhibitor Silver Nitrate on Direct Shoot Regeneration from in Vitro Raised Shoot Tip Explants of Sphaeranthus indicus Linn.—An Important Antijaundice Medicinal Plant

In the present investigation, an attempt has been made to study the influence of ethylene inhibitor silver nitrate on direct shoot regeneration in Sphaeranthus indicus, an important antijaundice medicinal plant, by using in vitro raised shoot tip explants. The effect of various concentrations of kinetin, BAP (0.5 - 3.0 mg/l), and NAA (0.1 - 0.5 mg/l) along with AgNO3 (0.1 - 1.0 mg/l) was studied. Among the combinations tested MS medium augmented with kinetin (1.0 mg/l), NAA (0.1 mg/l) and AgNO3 (0.4 mg/l) was found to be optimum for production of multiple shoots (34.3 ± 0.36). Addition of AgNO3 to the media not only increases shoot number in all the concentrations tested but also shoot length. AgNO3 at the concentration of 0.4 mg/l produced 35% more number of multiple shoots when compared to multiple shoots (10.8 ± 0.12) produced in control. In the present study by the addition of ethylene inhibitor silver nitrate and growth regulators, more number of multiple shoots (three folds) and shoot length was observed compared to control. These in vitro raised shoots were transferred to the rooting medium containing different concentrations of auxins such as NAA and IAA along with AgNO3 (0.1 - 0.6 mg/l). Better rooting response (21.6) was observed on NAA (2.0 mg/l) and AgNO3 (0.4 mg/l) containing media. The healthy rooted plantlets were transferred to polybags containing soil and vermiculate in 1:1 ratio for hardening. Finally the hardened plants were transferred to field environment for utmost survivability.

Effect of 24-Epibrassinolide on Growth of <i>in Vitro</i>Shoot Tips of Different Yam (<i>Dioscorea</i>Spp.) Species

In this work we compared the effect of the growth regulator content of the culture medium on the growth of in vitro shoot tips of five yam accessions belonging to four yam species (one Dioscorea alata, one D. rotundata, one D. cayenensis and two D. trifida). Medium S contained 0.6 μM benzyl adenine, 1.07 μM naphthalene acetic acid and 0.23 μM gibberellic acid while medium EBR contained 0.23 μM gibberellic acid and 0.1 μM 24-epibrassinolide. After 2 months of culture, oxidation level was significantly reduced on medium EBR compared to medium S for four of the five accessions tested. By contrast, medium EBR did not have any positive effect on shoot length since length of shoots produced after 2 months of culture on medium S and EBR were similar, except with accession 3-45T, for which shoot length was shorter on medium S compared to medium EBR. These results underline the potential of 24-epibrassinolide to reduce oxidation phenomena during in vitro culture and call for its utilization for regeneration of cryopreserved yam shoot tips, which is often impeded by oxidation phenomena.

“粉玉1号”草莓茎尖组织培养体系及其脱毒效果研究

“粉玉1号”是通过杂交育种方式选育的早熟抗病粉果草莓新品种。从大棚栽培的“粉玉1号”草莓植株上取匍匐茎芽为试料,通过外植体消毒、茎尖剥取、不定芽诱导和生根培养建立了“粉玉1号”茎尖组织培养脱毒技术体系,对茎尖培养苗和大棚栽培植株进行了草莓皱缩病毒(SCV)、草莓斑驳病毒(SMoV)、草莓轻型黄边病毒(SMYEV)和草莓镶脉病毒(SVBV)PCR检测。结果表明,“粉玉1号”草莓外植体灭菌方法为75%乙醇处理30 s,再用0.1%升汞溶液处理10 min;匍匐茎芽一般需剥去1片嫩叶和7片幼叶才能剥出茎尖;茎尖初代培养基宜采用MS+0.5 mg/L 6-BA,继代培养基宜采用MS+0.1 mg/L 6-BA,生根培养基宜采用不加植物生长调节剂的1/2 MS。大棚栽培植株样品存在SVBV感染,通过茎尖组培脱除了该病毒,SCV、SMoV和SMYEV在所有样品中均未检出。建立的茎尖脱毒技术体系可为“粉玉1号”草莓工厂化育苗提供参考。

百合斑驳病毒在卷丹顶端分生组织中的分布

【目的】百合斑驳病毒(lily mottle virus,LMoV)是危害重要食药用百合卷丹的主要病毒之一,每年给百合种植业造成数十亿的损失。通过原位杂交技术明确LMoV在卷丹顶端分生组织中的分布,为百合脱毒培养提供支撑。【方法】采用种植于贵州省清镇市的栽培卷丹作为试验材料,利用RT-PCR并于NCBI网站下载不同地方LMoV分离物构建进化树鉴定卷丹所携带的病毒种类,据检测结果选取LMoV为对象,基于LMoV基因组序列设计并制备RNA荧光探针,开展卷丹茎尖和根尖石蜡切片组织的RNA原位杂交,观察卷丹茎尖和根尖中LMoV的分布。【结果】RT-PCR检测表明卷丹材料侵染了LMoV,构建进化树发现本实验分离物与吉林和辽宁的LMoV分离物关系最近,原位杂交进而表明卷丹茎尖中LMoV杂交信号主要分布在顶端分生组织下方0.15-0.2 mm的组织中,靠近紧挨分生组织叶原基的初生叶基部有较弱的病毒杂交信号,靠近初生叶的成熟叶顶端中病毒荧光信号强烈,感染LMoV的卷丹分生组织中心纵切面无毒区大小为(0.4-0.6)mm×(0.15-0.2)mm;在根尖0.25 mm×0.2 mm分生组织中无杂交信号分布,在皮层细胞中信号最强烈,在根冠和根伸长区信号较弱。【结论】卷丹顶端分生组织及最接近顶端的一个叶原基[大小约(0.4-0.6)mm×0.2 mm]未发现病毒信号,可作为茎尖脱毒的起始材料。根顶端分生组织外侧根冠有较强病毒信号,不适合作为卷丹脱毒培养的外植体。

牛尾山药茎尖培养及快繁技术研究

为建立牛尾山药脱毒培养和快繁体系,采用培养技术,筛选茎尖培培养、茎段扩繁和生根培养适宜的培养基,并研究适宜的炼苗条件。结果表明:在MS+0.5 mg·L^(-1)6-BA+1.5 mg·L^(-1)NAA培养基中,茎尖的膨大率和成活率较高;对茎尖的褐变现象抑制效果最佳的聚乙烯吡咯烷酮(PVP)浓度为0.01%,其褐变率仅为11.67%;培养基MS+1 mg·L^(-1)6-BA+0.3 mg·L^(-1)NAA诱导节茎段萌芽的效果较好;在生根培养中,MS+0.5 mg·L^(-1)6BA+1 mg·L^(-1)NAA培养基最合适;混合基质(珍珠岩∶秸秆腐殖物=1∶1)、温度20℃、遮光率75%、相对湿度80%是山药组培苗最适宜的炼苗条件。综上,本研究为牛尾山药脱毒培养和快繁奠定基础,对山药产业可持续发展有重要意义。

茶树嫩梢形态与力学特性试验研究

为探明茶树嫩梢芽叶形态分布及采摘部位受力形变规律,进行了嫩梢形态特征参数统计与力学特性试验。首先,以龙井43、中茶108、白叶1号等6类茶树品种为试验对象,分析适采期茶树嫩梢芽叶分布形态特征与采摘农艺要求;其次,对嫩梢进行了物理参数统计,包括各叶片生长基部到嫩梢顶端距离、茶梢茎秆径宽尺寸以及嫩梢含水率等;最后,开展了茶树嫩梢剪切与弯曲力学特性试验。结果表明,茶树嫩梢叶顶距与各茎秆段等效直径呈正态分布。六种茶树样本一、二、三叶位叶顶距分布范围依次为16~22、25~35、40~60 mm。茶梢的一、二、三茎秆段等效直径分别集中在1.2~1.4、1.4~1.6、1.6~2.0 mm范围内,含水率逐渐降低,大致保持在78%~86%。随着由上至下叶位的变化,茎秆的抗弯刚度和剪切应力逐渐增大,不同茶树品种之间存在差异,但变化趋势相似;茶梢茎秆在受压弯曲试验过程中存在压力突变区间,并以龙井43为研究对象,定量分析了嫩梢在下压过程中茎秆采摘部位的力学特征,该研究为进一步了解茶树嫩梢的物理特征和优化设计茶叶采摘装置提供了理论依据。

基于变异系数对叶菜型甘薯新品系的选育分析

为了提高叶菜型甘薯新品系选育效率,探讨变异系数对叶菜型甘薯新品系选育的影响,以7个叶菜型甘薯品系为试验材料,研究其不同采摘期各品系间、各品系不同采摘期间及不同品系各重复间的茎尖数量、茎尖产量及其变异系数,并对茎尖性状及变异系数进行相关性分析。结果表明,叶菜型甘薯新品系茎尖性状的变异系数由大到小依次为各品系不同采摘期间、不同采摘期各品系间、不同品系各重复间;高产稳产新品系在各采摘期间的茎尖产量和茎尖数量的变异系数普遍较高,而重复间的变异系数较低;品系2019-1-15、2018-2-76、2018-2-37的茎尖产量比对照品种福薯7-6高,且产量差异达极显著水平(P<0.01);叶菜型甘薯茎尖数量与茎尖产量呈极显著正相关(r=0.5589,P<0.01),茎尖数量变异系数与茎尖产量变异系数呈极显著正相关(r=0.6683,P<0.01)。由此得出,变异系数对叶菜型甘薯新品系选育有重要意义,在高产稳产叶菜型甘薯新品系选育过程中,可以优先选择茎尖数量多的新品系,并综合考虑其茎尖产量和茎尖产量变异系数的影响;2019-1-15、2018-2-76、2018-2-37是相对高产稳产的叶菜型甘薯新品系。

Tissue Culture and Rapid Multiplication Techniques of Apocynum L.

[Objective] This study aimed to investigate rapid multiplication of Apocynum by tissue culture so as to provide plantlet sources for its industrialized cultivation. [Method] The asepsis seedlings were obtained by dealing with Apocynum seeds. Its cotyledons, hypocotyls and shoot tips were cultured on the media containing different concentrations of hormones. Finally, the influence of different hormone combinations on differentiation of cotyledons and hypocotyls, rapid multiplication of shoot tips, rapid multiplication of regenerated shoots, and rooting of test-tube plantlets was com- pared. [Result] MS＋2.0 mg/L BA＋0.03 mg/L NAA and MS＋0.07 mg/L NAA were the optimum medium for inducing regenerated buds from cotyledons and hypocotyls re- spectively; MS＋2.0 mg/L BA＋0.02 mg/L NAA was the best medium for rapid multi- plication of shoot tips; MS＋1.9 mg/L BA＋I.7 mg/L NAA was the best medium for rapid multiplication of regenerated buds： and 1/2MS＋0.6 mg/L NAA was the best medium for inducing roots. [Conclusion] The optimum hormone combination was de- termined for Apocynum rapid multiplication by tissue culture, which provides technical support on Apocynum industrialized cultivation.

蜜薯茎尖脱毒快繁体系优化与脱毒效果的研究

针对蜜薯病毒病严重的问题,对蜜薯进行茎尖脱毒,研究不同消毒剂与消毒时间对蜜薯外植体消毒效果和脱毒率的影响。通过RT-PCR技术检测蜜薯苗所带病毒种类;针对检测出的病毒进行茎尖脱毒处理,研究不同消毒剂与消毒时间对蜜薯外植体消毒效果的影响;通过正交试验研究6-BA、NAA、GA_(3)和IAA激素浓度配比对茎尖诱导及根诱导的影响,以此优化蜜薯快繁体系;最后,用RT-PCR检测茎尖脱毒效果。结果表明:蜜薯病毒初检发现,蜜薯中主要携带SPVG、SPFMV和SPCSV 3种病毒,其中SPVG带毒率最高;茎尖诱导适宜的外植体消毒方式为:70%酒精清洗45 s,再用0.1%升汞溶液浸泡7~8 min;茎尖诱导适宜的培养基选择为:MS+1.0 mg·L^(–1)6-BA+0.1 mg·L^(–1)NAA+1.0 mg·L^(–1)GA_(3),生根诱导最适宜培养基为1/2 MS+0.1 mg·L^(–1)NAA+0.1 mg·L^(–1)IAA。经茎尖脱毒后SPFMV脱除效果最好,脱毒率为100%,SPVG次之,SPCSV脱除效果最差,仅降低了约3.33%。

基于外植体生理复幼的麻栎茎段无菌离体培养

以离体休眠枝条复幼处理后的萌芽茎段为外植体,开展20年生成龄麻栎的离体再生影响因素研究。结果表明:初代培养,以1/2 MS+3.0 mg/L 6-BA+2.0 mg/L KT+0.2 mg/L IBA为优选培养基,不定芽诱导率可达69.70%;继代培养,以1/2 MS+2.0 mg/L 6-BA+2.0 mg/L KT+0.2 mg/L IBA为优选增殖培养基,芽增殖系数约为2.0,但茎尖死亡率高,影响不定芽的连续继代。在影响继代苗茎尖死亡率的各试验因素中,培养基种类、继代转接时间、培养基中氯化钙浓度、硼酸浓度对继代培养中不定芽茎尖死亡率均有显著影响。WPM培养基中,继代培养23 d,硼酸质量浓度为12.4 mg/L,茎尖死亡率最低(13.06%)。在改良WPM+0.3 mg/L IBA+0.2 mg/L NAA的培养基上,成龄麻栎继代苗生根率最高(19.91%)。本试验为麻栎树种改良及无性快繁奠定了基础。

山丹茎尖玻璃化超低温保存技术体系的建立

为建立山丹(Lilium pumilum DC.)茎尖玻璃化超低温保存技术程序,以山丹无菌苗茎尖为试验材料,采用单因素试验方法,对玻璃化超低温保存技术的关键因素预培养基蔗糖浓度、预培养时间、装载处理时间、PVS2溶液处理时间进行依次筛选。最佳条件为:将茎尖接种于含0.5 mol/L蔗糖的预培养基中预培养7 d,装载处理20 min,PVS2溶液处理80 min后,保存于液氮中即可;可获得70.91%的茎尖存活率和51.85%的再生率,为山丹种质资源提供了简单易行、高效的长期保存方法。

Improving Effect of Salicylic Acid on the Multipurpose Tree <i>Ziziphus spina-christi</i>(L.) Willd Tissue Culture

Salicylic acid (SA) is one of numerous phenolic compounds found in plants with numerous important physiological events. Exogenously application of Salicylic acid (SA) is useful for the growth and development of plants. This investigation aimed to study the improving effect of salicylic acid on the tissue culture of Ziziphus spina-christi. To study its improving effect were used shoot-tip explants cultured on Murashige and Skoog (MS) solid medium supplemented with different concentrations and various combinations of auxins, cytokinins and Salicylic acid. Media without growth regulators enhanced the growth and elongation of shoot-tip explants not its proliferation. Lower concentrations of cytokinin were better for shoot-tip proliferation than higher ones. 6-Benzylaminopurine (BAP) was superior to kinetin (KN) in shoot-tip proliferation. The optimum culture conditions for shoot-tip proliferation were achieved on MS medium supplemented with 0.25 mg/l 6-Benzylaminopurine (BAP) and 25 mg/l Salicylic acid (SA). The optimum culture conditions for callus formation were obtained on MS medium supplemented with 3 mg/l 2,4-Dichlorophenoxyacetic acid (2,4-D) and 25 mg/l Salicylic acid (SA), while the optimum culture conditions for somatic callus formation were obtained on MS medium supplemented with 2.0 mg/l 2,4-Dichlorophenoxyacetic acid (2,4-D) and 10 mg/l Salicylic acid (SA). The optimum culture conditions for rooting of shoots were obtained on MS medium supplemented with 0.25 mg/l of Indole-3-butyric acid (IBA) and 10 mg/l Salicylic acid (SA). The highest percentage of survival plants was obtained in the soil mixture supplied with 10 mg/l Salicylic acid (SA). Salicylic acid (SA) showed positive effect and good response on callusing, shooting and rooting of Z. spina-christi. Cultures received small amounts of salicylic acid were better than those lack it.

不同IAA和6-BA质量浓度组合对甘薯茎尖培养和表型变异的影响

以甘薯品种烟薯29号的茎尖为外植体,MS培养基为基本培养基,研究不同质量浓度IAA(0.1、0.5 mg/L)和6-BA(0.1、0.5、1.0 mg/L)组合下愈伤组织诱导、芽分化、植株再生和表型变异情况。结果表明,MS培养基中IAA质量浓度为0.5 mg/L时对烟薯29号愈伤组织的诱导效果最佳,且利于茎尖成活,在此质量浓度下,平均愈伤组织诱导率和茎尖成活率分别达到了92.00%和88.00%。芽诱导率和丛生芽率随着培养基中6-BA质量浓度的升高总体上增加,在IAA质量浓度为0.1 mg/L的处理中,平均芽诱导率和丛生芽率分别达到了64.27%和80.56%。MS培养基中IAA质量浓度为0.5 mg/L时有利于植株再生,平均植株再生率达到了39.33%,在此质量浓度下,植株再生率和成苗数均随着6-BA质量浓度的升高而增加,成苗周期随着6-BA质量浓度的升高而缩短。烟薯29号的再生植株中出现了1株无性系变异植株,命名为YM6-11,其叶脉色、花冠形状和杂交亲和性与烟薯29号相比发生了改变。综上,烟薯29号茎尖培养最佳培养基组成为MS+0.5 mg/L IAA+1.0 mg/L 6-BA,将获得的再生植株用于实际生产时,应进行表型和遗传学鉴定,及早发现变异植株,减少不必要的经济损失。

茎尖离体培养小黄姜变异株品质特征及转录组学分析

本研究采用恒温干燥法、水蒸气法和HPLC等方法分析茎尖离体培养小黄姜变异株的干物质含量、精油含量、姜辣素含量等品质特性,并利用高通量测序技术和生物信息学方法进行转录组学分析。结果表明,小黄姜突变株干物质、纤维素含量显著低于正常株,分别为13%和0.6%;木质素、精油及姜辣素含量分别为正常株的1.5倍、1.54倍和1.26倍。转录组学分析共获得43989条Unigene的注释结果,13342个SSR标记。获得DEG 338条,其中,上调表达164条,下调表达174条。有信息注释DEG的239条,分别在GO、COG、KEGG、KOG、Pfam、Swiss-Prot、eggNOG等功能数据库注释到DEG 132条、88条、81条、130条、186条、171条和224条。DEGs主要集中在光合作用碳的固定(GOT1)、植物激素信号传导(AXU/IAA、B-ARR、ERFL1/2、MYC2)、萜烯类和姜辣素等次生代谢物的合成(CHS)、植物生理节律(CRY)等生物途径。由此可知,AXU/IAA、B-ARR、ERFL1/2、MYC2等基因的差异表达导致小黄姜突变株的精油含量、姜辣素含量以及其他农艺性状发生改变,故在栽培前期可以通过对相关基因的表达差异分析确定植株属性,从而区分正常株与突变株。

草莓茎尖组培繁育体系优化及SRAP遗传稳定性检验

以组培苗遗传稳定和植株健壮为标准,优化草莓茎尖组培繁育体系,以期为草莓工厂化育苗提供科研和技术依据。以‘凤冠’和‘天仙醉’草莓为材料,设置植物生长调节剂浓度梯度,调整培养基基础配方,调查茎尖分化情况、增殖苗形态、增殖系数、生根苗叶片及根系等性状,并比对组培前后植株SRAP标记扩增条带的差异。筛选出初代培养基配方MS+6-BA 0.5 mg/L+NAA 0.01 mg/L,增殖培养基配方MS+6-BA 0.3 mg/L+NAA 0.01 mg/L,生根培养基配方1/2MS+硝酸钙0.45 g/L;组培前后植株DNA使用19对SRAP引物特异性扩增,得到的72个基因位点条带未发生变化,以上条带形成的DNA指纹没有差异。研究得到的草莓茎尖组培繁育体系具备植物生长调节剂种类少且浓度低、继代次数少、增殖系数低、组培时间短、组培苗健壮且基因稳定等特征。