Early embryo achievement through isolated microspore culture in Citrus clementina Hort. ex Tan., cvs. 'Monreal Rosso' and 'Nules'

Microspore embryogenesis is a method of achieving complete homozygosity from plants. It is particularly useful for woody species, like Citrus, characterized by long juvenility, a high degree of heterozygosity and often self-incompatibility. Anther culture is currently the method of choice for microspore embryogenesis in many crops. However, isolated microspore culture is a better way to investigate the processes at the cellular, physiological, biochemical, and molecular levels as it avoids the influence of somatic anther tissue. To exploit the potential of this technique, it is important to separate the key factors affecting the process and, among them, culture medium composition and particularly the plant growth regulators and their concentration, as they can greatly enhance regeneration efficiency. To our knowledge, the ability of meta-Topolin, a naturally occurring aromatic cytokinin, to induce gametic embryogenesis in isolated microspores of Citrus has never been investigated. In this study, the effect of two concentrations of meta-Topolin instead of benzyladenine or zeatin in the culture medium was investigated in isolated microspore culture of two genotypes of Citrus. After 11 months of isolated microspore culture, for both genotypes and for all the four tested media, the microspore reprogramming and their sporophytic development was observed by the presence of multinucleated calli and microspore-derived embryos at different stages. Microsatellite analysis of parental and embryo samples was performed to determine the embryo alleles constitution of early embryos produced in all tested media, confirming their origin from microspores. To our knowledge, this is the first successful report of Citrus microspore embryogenesis with isolated microspore culture in Citrus, and in particular in Citrus clementina Hort. ex Tan, cvs. 'Monreal Rosso' and 'Nules.'

Endogenous cytokinin profiles of tissue-cultured and acclimatized 'Williams' bananas subjected to different aromatic cytokinin treatments

Endogenous cytokinin (CK) levels of in vitro-cultured and greenhouse-acclimatized 'Williams' bananas treated with six aromatic CKs were quantified using UPLC-MS/MS. The underground parts had higher endogenous CK levels than the aerial parts. Control plantlets had more isoprenoid CKs while the aromatic-type CKs were predominant in all other regenerants. Following acclimatization of the control and 10 μM CK regenerants, there was a rapid decline in both isoprenoid and aromatic CK in the greenhouse-grown plants. Apart from the control and 6-(3-Methoxybenzylamino)-9-tetrahydropyran-2-ylpurine (MemTTHP) treatment with higher level of isoprenoid CK, aromatic CK remain the predominant CK-type across all CK treatments. The most abundant CK forms were meta-topolin (mT) and benzyladenine (BA) in the micropropagated and acclimatized plants, respectively. Micropropagated plantlets had cis-Zeatin (cZ) as the major isoprenoid CK-type which was in turn replaced by isopentenyladenine (iP) upon acclimatization. On a structural and functional basis, 9-glucoside, a deactivation/detoxicification product was the most abundant and mainly located in the underground parts (micropropagation and acclimatization). The results establish the wide variation in metabolic products of the tested aromatic CKs during micropropagation and acclimatization. The findings are discussed with the possible physiological roles of the various CK constituents on the growth and development of banana plants.

Pharmacological potential and conservation prospect of the genus Eucomis (Hyacinthaceae) endemic to southern Africa

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Eucomis (Hyacinthaceae) consists of 10 species that are extensively used in African traditional medicine. This review is an appraisal of current information on the distribution and morphology, traditional uses, pharmacology, toxicology and approaches devised to enhance the conservation of the genus.

METHODS

A systematic and comprehensive literature search using electronic searches such as Scopus, Google Scholar, Web of Science and ethnobotanical books was conducted.

RESULTS

Evidence from traditional medicine usage shows wide utilization of this genus for ailments such as respiratory, venereal diseases, rheumatism as well as kidney and bladder infections. Pharmacological screening reported antimicrobial, antiplasmodial, antitumor, cytotoxic, phytotoxic and anti-inflammatory properties.

CONCLUSIONS

The potential of the genus Eucomis especially in terms of pharmacology cannot be overemphasized. Apart from the anti-inflammatory properties, the antifungal activity of Eucomis remains a valuable reservoir with potential application in the agriculture sector as a source of an affordable biocontrol agent. Based on the speculated toxic constituents in the genus Eucomis, it will be valuable to conduct detailed toxicological studies. Extensive utilization of members of the genus Eucomis is causing severe strain on wild populations. Although conventional propagation has been relatively effective in the alleviation of the declining status, micropropagation of members may be vital to guarantee the conservation of wild populations.