Ahmed Manal El-Salato Ala El-Naby
Department of Plant Genetic Resources, Desert Research Center, Cairo, 11753, Egypt.
J Genet Eng Biotechnol. 2022 Sep 7;20(1):130. doi: 10.1186/s43141-022-00406-4.
Dimocarpus longan is a tropical tree that produces edible fruit. It is a neglected plant species that is listed as near threatened. In spite of its economic value, the propagation of longan cultivar using conventional methods is extremely difficult. The goal of this research is to produce and conserve this plant through in vitro propagation.
In order to form new shoots, sterilized shoot tip explants were cultured on Murashige and Skoog (MS) medium supplemented with benzyl adenine (BA) or 2-isobentenyl-adenine (2ip). For direct organogenesis, young leaves of new shoots were cultured on MS medium fortified with various concentrations of Thidiazuron (TDZ) or 6-(4-Hydroxy-3-methylbut-2-enylamino purine) (Zeatin). Gibbrellic acid (GA) at different levels alone or in combination was used for shoot elongation. Also, indole-3-butyric acid (IBA) and naphthalene acetic acid (NAA) were used for root formation. MS medium supplemented with 1.00 mg/l 2ip was suitable for inducing axillary shoots from shoot tips (4.0 axillary shoots/explant). The highest significant 76% and numbers of adventitious buds from leaf base were achieved on MS medium containing 1.0 mg/l TDZ. These buds developed into the longest plantlets on GA at 3.0 mg/l and rooted well in ½MS containing 1.50 mg/l IBA plus 0.50 mg/l (NAA). About 70% in vitro plants were successfully acclimatized. The AFLP profile illustrated the genetic stability of gene expression action. The amplified fragment length polymorphisms (AFLPs) profile illustrated the progenies were extremely similar to the mother plants. According to our findings, MS medium containing 25 ppm salicylic acid (SA) and 5 ppm methyl jasmonate (MeJA) produced the highest percentage of apigenin in longan calli (77.09 and 2.637%, w/w).
A successful and efficient micropropagation protocol has been developed and described here for the first time, and it will be very useful for the clonal propagation and conservation of the near-threatened Dimocarpus longan plant. Micropropagated plants are genetically identical to the donor plant using the AFLP technique. The usefulness of salicylic acid and methyl jasmonate as elicitors for increasing in vitro production of secondary metabolites in plants is demonstrated in this work.
龙眼是一种能结出可食用果实的热带树木。它是一种被忽视的植物物种，被列为近危物种。尽管具有经济价值，但利用传统方法繁殖龙眼品种极其困难。本研究的目的是通过离体繁殖来培育和保存这种植物。
为了形成新梢，将消毒后的茎尖外植体接种在添加了苄基腺嘌呤（BA）或2-异戊烯基腺嘌呤（2ip）的Murashige和Skoog（MS）培养基上进行培养。对于直接器官发生，将新梢的幼叶接种在添加了不同浓度噻二唑素（TDZ）或6-(4-羟基-3-甲基丁-2-烯基氨基嘌呤)（玉米素）的MS培养基上。单独或组合使用不同水平的赤霉素（GA）促进新梢伸长。此外，吲哚-3-丁酸（IBA）和萘乙酸（NAA）用于诱导生根。添加1.00 mg/l 2ip的MS培养基适合从茎尖诱导腋芽（每个外植体4.0个腋芽）。在含有1.0 mg/l TDZ的MS培养基上，从叶基部诱导出的不定芽数量最多，达到76%，且效果显著。这些芽在3.0 mg/l的GA上发育成最长植株，并在含有1.50 mg/l IBA加0.50 mg/l（NAA）的1/2MS培养基上顺利生根。约70%的离体植株成功驯化。AFLP图谱显示了基因表达作用的遗传稳定性。扩增片段长度多态性（AFLP）图谱表明后代与母本极为相似。根据我们的研究结果，含有25 ppm水杨酸（SA）和5 ppm茉莉酸甲酯（MeJA）的MS培养基在龙眼愈伤组织中产生的芹菜素百分比最高（分别为77.09%和2.637%，w/w）。
本文首次开发并描述了一种成功且高效的微繁殖方案，这对于近危物种龙眼的克隆繁殖和保存将非常有用。利用AFLP技术可知，微繁殖植株与供体植株基因相同。本研究证明了水杨酸和茉莉酸甲酯作为诱导剂在提高植物次生代谢产物离体产量方面的有效性。
