Key message

The addition of cytokinin drastically increases shoot proliferation in Melaleuca. Individual in vitro shoots previously treated with BA showed better rooting development than BA-free culture medium. Reduction of the osmotic potential in the culture medium decreased dehydration of micropropagated plantlets.

Abstract

Melaleuca alternifolia, known as tea tree, is an Australian medicinal plant widely used in the cosmetic and pharmaceutical industries due to its antibacterial and antifungal properties. Propagation of Melaleuca is limited due to low rates of seed germination and multiplication and the poor rooting of stem cuttings. Thus, micropropagation can be an alternative to the propagation of this woody medicinal species. In this study, different concentrations of 6-benzyladenine (BA) (0, 0.55, 1.11 and 2.22 µM) were tested during the in vitro multiplication phase. It was observed that even the lowest concentration of BA (0.55 µM) could drastically increase the multiplication rate in Melaleuca, compared to the BA-free treatment, due to multiple shoot proliferation. At the rooting stage, in the culture medium without phyto-regulators, individual shoots previously treated with BA had a higher rooting percentage (91–97%) and considerable height growth compared to those of the control treatment (without BA) (66%). However, none of the in vitro plantlets survived to acclimatization stage due to excessive and rapid dehydration of the plantlets under ex vitro conditions, making it the most challenging phase for the micropropagation of Melaleuca. Therefore, a second experimental setup was designed, which included treatments with sucrose, sucrose + sorbitol and sucrose + mannitol in the culture medium at − 0.2170, − 0.3255 and − 0.4340 MPa, respectively, to determine the effects of these osmotic agents on the development of Melaleuca in rooting and acclimatization stages. Sorbitol with sucrose at Ψπ = − 0.4340 decreased stomatal density in leaves and reduced dehydration of plantlets under ex vitro conditions, but was not enough to provide successful plantlets acclimatization.

中文翻译：

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通过顶端部分的芽增殖微生白千层

关键信息

细胞分裂素的加入大大增加了白千层的芽增殖。与不含BA的培养基相比，先前用BA处理的单个体外芽显示出更好的生根发育。培养基中渗透势的降低减少了微繁苗的脱水。

抽象的

Melaleuca alternifolia，被称为茶树，由于其抗菌和抗真菌特性，是一种广泛用于化妆品和制药行业的澳大利亚药用植物。由于种子发芽和繁殖率低以及茎插条生根差，千层树的繁殖受到限制。因此，微繁殖可以替代这种木质药用物种的繁殖。在这项研究中，在体外增殖阶段测试了不同浓度的6-苄基腺嘌呤（BA）（0、0.55、1.11和2.22 µM）。据观察，即使最低浓度的BA（0.55 µM）也会大大增加千层网的繁殖率。，与无BA处理相比，由于多次芽繁殖。在生根阶段，在没有植物调节剂的培养基中，与对照处理（不使用BA）相比，先前用BA处理的单个芽具有较高的生根率（91–97％），并且高度增长显着。 。但是，由于离体条件下植物过度快速脱水，所有离体苗都无法存活到适应阶段，这使其成为千层金微繁殖中最具挑战性的阶段。。因此，设计了第二个实验装置，包括在培养基中分别在-0.2170，-0.3255和-0.4340 MPa的条件下用蔗糖，蔗糖+山梨糖醇和蔗糖+甘露糖醇处理，以确定这些渗透剂对发育的影响。在生根和适应阶段的千层树。山梨糖醇在π= − 0.4340的条件下降低了叶片的气孔密度，并减少了离体条件下幼苗的脱水，但不足以使植物成功地适应环境。