Search

Black wattle (Acacia mearnsii) has great economic value as a commercial source of tannins, timber and a source of firewood for local and international markets. It has been suggested that to maximize the genetic gain of A. mearnsii plantations in South Africa, the gene pool that exist within ICFR needs to be broadened via introduction of new genotypes with diverse traits. In this work, 282 A. mearnsii samples sourced from the ICFR breeding program were genotyped using 11 cross-species SSR markers. Our results showed low to moderate genetic differentiation (FST) among the six breeding subpopulations, with positive inbreeding (FIS) values that could be attributed to an historical inbreeding event. Low levels of relatedness could however indicate some mechanism of inbreeding avoidance. The effects from a recent supplementation of genetic material from two native Australian populations were observed through genetic structuring analyses. Analysis of molecular variance (AMOVA) revealed that significant genetic variation was mainly distributed within populations (75%) and among individuals (23%). The results provide significant information on A. mearnsii population genetic diversity and structure, which can be used for conservation of the current subpopulations and future tree improvement programs. [ABSTRACT FROM AUTHOR]

Highlights: [•] Globally, the importance of bananas for food security is well known and documented. [•] Use of the micropropagation technique helps to meet increasing demand for bananas. [•] High rate of somaclonal variants remain a major bottleneck during micropropagation. [•] The role of BA and topolins on genetic fidelity was compared at same concentration. [•] Some topolins could reduce genetic variability among micropropagated plantlets. [ABSTRACT FROM AUTHOR]

Abstract: The effect of five topolins (meta-Topolin= mT; meta-Topolin riboside= mTR; meta-Methoxy topolin=MemT; meta-Methoxy topolin riboside=MemTR and 6-(meta-methoxy)-9-(tetrahydropyran-2-yl)-topolin=MemTTHP) on the photosynthetic pigments and leaf structures of micropropagated ‘Williams’ bananas was compared with the commonly used benzyladenine (BA). Surface-decontaminated explants were cultured for 70 d on modified Murashige and Skoog (MS) basal medium and supplemented with 10, 20 or 30μM cytokinins (CKs). At 10 d intervals, the photosynthetic pigments were quantified via spectrophotometric methods for 7 cycles. Generally, the maximum pigment content was attained between 40 and 50 d. The control plantlets had the highest pigment content (1150μg/g FW). Among the CKs, 10μM MemTTHP generally had the best pigment stimulatory effect at the same period. After 40 d, scanning electron microscopy (SEM) of the foliar surface showed that the stomata density was highest in 10μM MemTTHP-treated and lowest in 10μM MemTR-treated plantlets. The stomatal structure and pore area also varied with the type and concentration of CK added. Generally, prolonging culture duration as well as increasing CK concentrations reduced the pigment content. However, the drastic breakdown in chlorophyll pigments beyond 50 d was slightly inhibited by the presence of mT, mTR, MemTTHP and BA compared to the control. The CK-treated plantlets at equimolar concentration had comparable chlorophyll a/b and total chlorophyll/carotenoid ratios after 10 d; probably as an adaptive measure. At the end of the current study, 10μM mT and mTR plantlets remained green as reflected by the higher total chlorophyll/carotenoid ratio as well as by the visual observations. A well-developed photosynthetic apparatus enhances the survival of in vitro plantlets during the acclimatization stage. Current findings provide some insight into the role of meta-topolins on photosynthetic parameters in vitro, which inevitably partly contributed to the better acclimatization capability of meta-topolin-regenerants. [Copyright &y& Elsevier]

A study was done to investigate the effects of some physical and chemical factors on growth and development of Aloe ferox ex vitro and in vitro. The effects of light, temperature, and smoke-water on seed germination, ex vitro seedling growth requirements, and effect of germination medium and cytokinins on shoot induction and multiplication in vitro were investigated. The highest germination percentage of A. ferox seeds was recorded between 15 and 30 °C. Seed germination was inhibited at 10 and 35 °C. There was a nonsignificant increase in germination percentage (78%) for seeds that were germinated under constant dark conditions. Smoke-water-treated seeds showed significant improvement in percentage germination (80%) over the control (66%) at 25 °C with a 16-h photoperiod. Seedlings of A. ferox subjected to alternating temperatures (30/15 °C) or being irrigated three times weekly at 25 °C showed better seedling growth. In an in vitro experiment, seedlings germinated in distilled water and one-tenth strength Murashige and Skoog medium had superior shoot induction competence compared with the other germination media. The cytokinins meta-Topolin (mT) and meta-Topolin riboside (mTR) at 5 µM gave significantly higher shoot multiplication rates compared with the control and benzyladenine (BA)-treated plants. A higher abnormality index was recorded for BA-treated plants. The findings of this study will be beneficial for commercial propagation of Aloe ferox. [ABSTRACT FROM AUTHOR]

Abstract: The effect of the type and concentration of plant growth regulators and sub-culturing on somaclonal variation were studied in Cavendish banana cv. ‘Zelig’ obtained from African Biotechnologies Ltd., South Africa. In vitro grown plants at the fourth multiplication cycle were used for the investigation. Auxins (IAA, IBA and NAA) and cytokinins (BA and TDZ) were used to multiply shoots for 10 generations. Bands generated through RAPD-PCR were scored according to whether they were present (1) or absent (0) to determine the extent of somaclonal variation. Results were then analyzed using cluster analysis. The relationship between multiplication rate and somaclonal variation was assessed using correlation analysis. Results indicated that treatments with higher multiplication rates produced more variants; sometimes as high as 72%. Dwarf off-types accounted for 88% of the variation. A dwarf-specific band, about 1500kb in size, was amplified by the primer OPC-15. The band appeared consistently in normal plants but was absent in all dwarf plants. [Copyright &y& Elsevier]

The 2030 Agenda for Sustainable Development Goals of the United Nations puts forward a transformational vision to cope with food security, nutrition, and health challenges, in which sweet potato can play an important role. Globally, sweet potato production is valued at $53.83 billion. The Agricultural Research Council of South Africa (ARC) sweet potato research and development (R&D) program over the past seven decades delivered 31 genetically improved cultivars via demand‐led breeding, managed the collection and maintenance of 375 accessions, contributed toward the optimization of cultivation practices, developed crop protection and diagnostic services, and provided streamlined seed systems and technology transfer in processing and enterprise development. The ARC's work is part of a large number of interdependent global programs committed to improving livelihoods and nutrition through sweet potato. This review shares and analyses major achievements, highlights unique research contributions achieved through partnerships, and discusses bottlenecks on funding and uptake of technologies. New research imperatives will involve root phenotyping, employing marker‐based technologies, and genome‐wide association studies through new funding received recently. Exploration of the commercialization potential of processed products made from orange‐fleshed sweet potato will be a major focus of the R&D program. Expansion of partnerships, marketing, and financing will be important for future contribution of sweet potato to the economy. Core Ideas: Sweet potato has great potential to address several Sustainable Development Goals of the United Nations.A comprehensive sweet potato research and development program described herein provided technology across the full value chain.Screening methods for wilt disease, nematodes, protein content, virus, and crop development are highlighted.Expansion of partnerships and financing is essential to retain research momentum.Modern technologies must be key in new research imperatives.This article provides important lessons for public breeding efforts. [ABSTRACT FROM AUTHOR]

Highlights: [•] A total of 47 endogenous cytokinin-forms grouped into 9 classes were quantified. [•] Tissue-cultured plants had more endogenous cytokinin levels than acclimatized plants. [•] 9-Glucosides were the major metabolites in tissue-cultured and acclimatized plants. [Copyright &y& Elsevier]

Summary: Traditional crops have historically provided accessible and affordable nutrition to millions of rural dwellers but have been neglected, with most modern agricultural systems over‐reliant on a small number of internationally traded crops. Traditional crops are typically well‐adapted to local agro‐ecological conditions and many are nutrient‐dense. They can play a vital role in local food systems through enhanced nutrition (particularly where diets are dominated by starch crops), food security and livelihoods for smallholder farmers, and a climate‐resilient and biodiverse agriculture. Using short‐read, long‐read and phased sequencing technologies, we generated a high‐quality chromosome‐level genome assembly for Amaranthuscruentus, an under‐researched crop with micronutrient‐ and protein‐rich leaves and gluten‐free seed, but lacking improved varieties, with respect to productivity and quality traits. The 370.9 Mb genome demonstrates a shared whole genome duplication with a related species, Amaranthushypochondriacus. Comparative genome analysis indicates chromosomal loss and fusion events following genome duplication that are common to both species, as well as fission of chromosome 2 in A. cruentus alone, giving rise to a haploid chromosome number of 17 (versus 16 in A. hypochondriacus). Genomic features potentially underlying the nutritional value of this crop include two A. cruentus‐specific genes with a likely role in phytic acid synthesis (an anti‐nutrient), expansion of ion transporter gene families, and identification of biosynthetic gene clusters conserved within the amaranth lineage. The A. cruentus genome assembly will underpin much‐needed research and global breeding efforts to develop improved varieties for economically viable cultivation and realization of the benefits to global nutrition security and agrobiodiversity. [ABSTRACT FROM AUTHOR]

Abstract: Merwilla plumbea (Lindl.) Speta is an important medicinal plant widely used in traditional medicine. We evaluated the effect of five cytokinins [benzyladenine (BA), 2-isopentenyladenine (2iP), meta-topolin (mT), meta-topolin riboside (mTR), and meta-methoxy-9-tetrahydropyran-2-yl-topolin (MemTTHP)] on the level of phenolic acids and antioxidant activity of M. plumbea during the tissue culture and acclimatization stages. Two cytokinins (mT and mTR) significantly improved the antioxidant activity of tissue culture plantlets while the control plantlets were better after acclimatization. Using UPLC–MS/MS, the levels of hydroxybenzoic and hydroxycinnamic acid derivatives (phenolic acids) varied significantly during tissue culture and acclimatization, depending on the cytokinin and plant part analyzed. Vanillic acid (24.9μgg−1) detected in underground parts of tissue culture plants supplemented with BA was the most abundant phenolic acid detected. The current findings indicate that the phytochemicals together with the bioactivity during in vitro propagation of M. plumbea is influenced by the cytokinin type used and the stage of plant material collection. [Copyright &y& Elsevier]

Africa has the largest diversity of the genus Hypoxis, accounting for 61% of the current globally accepted taxa within the genus, including some endemic species. Using Hypoxis hemerocallidea as a case study, this review addresses the conservation concerns arising from the unsustainable, wild harvesting of a number of Hypoxis species. Hypoxis hemerocallidea is one of the wild-harvested, economically important, indigenous medicinal plants of southern Africa, with potential in natural product and drug development. There are several products made from the species, including capsules, tinctures, tonics and creams that are available in the market. The use of H. hemerocallidea as a "cure-all" medicine puts an important harvesting pressure on the species. Unsustainable harvesting causes a continuing decline of its populations and it is therefore of high priority for conservation, including a strong case to cultivate the species. Reviewing the current knowledge and gaps on cultivation of H. hemerocallidea, we suggest the creation of a platform for linking all the stakeholders in the industry. [ABSTRACT FROM AUTHOR]