Michael Bairu | University of KwaZulu-Natal (original) (raw)

Papers by Michael Bairu

Heliyon, 2021

The objective of this study was to evaluate mineral element content as a proxy for nutritional va... more The objective of this study was to evaluate mineral element content as a proxy for nutritional value of different taro genotypes. The study evaluated 14 taro accessions at Roodeplaat and Umbumbulu in South Africa based on their calcium (Ca), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), sodium (Na), phosphorous (P) and zinc (Zn) content. The accessions were planted in a randomized complete block design, replicated three times under field conditions. The mineral element content varied significantly (p < 0.05) among the genotypes. Genotypes Amad7-2, Umbu8 and Amad101 exhibited high Ca (!432 mg kg À1), Fe (!32 mg kg À1) and Mg (!229 mg kg À1) across the locations. The first principal component (PC) accounted for 33.7% of the variation and was strongly associated with Zn (r ¼ 0.94, p < 0.001) and P (r ¼ 0.89, p < 0.001). The second PC explained 29.7% of the variation and was associated with Na (r ¼ 0.83, p < 0.001), Mg (r ¼ 0.76, p < 0.001) and K (r ¼ 0.55, p < 0.05). Fe and Mn contributed below the 12.5% threshold to the PCs and were considered as less discriminatory among the accessions. The negative correlations among some of the mineral elements would be a challenge for selection and breeding of nutritious taro accessions. This information is essential to select superior local accessions based on their mineral element content for developing breeding populations and lines for improving nutrition quality among poor households in sub-Saharan Africa.

Plants, Jun 10, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Plants

Cassava (Manihot esculenta Crantz) is the sixth most important food crop and consumed by 800 mill... more Cassava (Manihot esculenta Crantz) is the sixth most important food crop and consumed by 800 million people worldwide. In Africa, cassava is the second most important food crop after maize and Africa is the worlds’ largest producer. Though cassava is not one of the main commodity crops in South Africa, it is becoming a popular crop among farming communities in frost-free areas, due to its climate-resilient nature. This necessitated the establishment of a multi-disciplinary research program at the Agricultural Research Council of South Africa. The objective of this review is to highlight progress made in cassava breeding and genetic analysis. This review highlights the progress of cassava research worldwide and discusses research findings on yield, quality, and adaptability traits in cassava. It also discusses the limitations and the prospects of the cassava R&D program towards development of the cassava industry in South Africa.

Acta Universitatis Cibiniensis. Series E: Food Technology

Cassava root flours from five different cultivars (C-MSAF2, C-P4/10, C-P98/0505, C-P98/0002, and ... more Cassava root flours from five different cultivars (C-MSAF2, C-P4/10, C-P98/0505, C-P98/0002, and C-UKF8) were studied for their potential application in the food industry. Proximate composition, functional, thermal, and pasting properties were investigated. Cassava flours were high in carbohydrates (85-86%) and their amino acid profiles varied. Cultivars C-MSAF2, C-P98/0002, and C-UKF8 showed high protein content (5.06%), mineral content (2.36%), and the largest particle size (72.33 µm), respectively. Solubility of cassava flours decreased as temperatures increased, however, swelling power and water absorption capacity increased. C-MSAF2 showed the highest peak viscosity, breakdown viscosity, and shortest peak time. C-P98/0505 showed the highest final viscosity, the highest pasting temperature, and the longest peak time. Cassava flours studied are promising candidates for utilization in the baking industry, however, their incorporation into baked product formulations needs further i...

South African Journal of Botany, 2013

Plant Science, 2014

Endogenous cytokinin (CK) levels of in vitro-cultured and greenhouse-acclimatized 'Williams' bana... more 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 aromatictype CKs were predominant in all other regenerants. Following acclimatization of the control and 10 M CK regenerants, there was a rapid decline in both isoprenoid and aromatic CK in the greenhousegrown 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 CKtype 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.

Plant Growth Regulation, 2011

A common problem often experienced by both small and large scale banana farmers is the reduction ... more A common problem often experienced by both small and large scale banana farmers is the reduction in quality and yield of bananas due to soil moisture deficits and declining soil fertility. To overcome this, mechanisms of improving yield without compromising environmental integrity or public health are being embraced. Globally, researchers have continued to evaluate the competence of environmental-friendly organic fertilizers and smoke solutions to improve the growth, yield and quality of various crops. In the present study, the effect of smoke-water (1:1,000; 1:500 and 1:250 dilutions) and vermicompost leachate (1:20; 1:10 and 1:5 dilutions) treatments on the growth of greenhouse grown bananas was evaluated. Soil drenching (smoke-water and vermicompost leachate) and foliar application (smoke-water) were tested on 1-monthold tissue-cultured banana seedlings under greenhouse conditions. After 3 months, growth parameters such as number and length of roots and shoots; number of leaves and leaf area as well as their fresh and dry weights were analyzed. Soil drenching with smoke-water significantly increased the root

Plant Cell, Tissue and Organ Culture (PCTOC), 2012

The effects of five topolins (meta-Topolin = mT; meta-Topolin riboside = mTR; meta-Methoxy topoli... more The effects of five topolins (meta-Topolin = mT; meta-Topolin riboside = mTR; meta-Methoxy topolin = MemT; meta-Methoxy topolin riboside = MemTR and meta-Methoxy topolin 9-tetrahydropyran-2-yl = MemTTHP) on shoot and root regeneration of micropropagated 'Williams' bananas were compared to benzyladenine (BA). Sterile shoottip explants were cultured on modified Murashige and Skoog (MS) media containing 10, 20 or 30 lM of the above cytokinins (CKs) for 42 days. Using shoot regenerated from optimum CK concentration, rooting experiments involving the use of indole-3-acetic acid, indole-3-butyric acid, naphthalene acetic acid, smoke-water (SW) and karrikinolide (KAR 1) were conducted. Apart from 10 lM BA and 30 lM MemTTHP treatments, the number of shoots produced in all the CK treatments were significantly higher than the control. In addition, 30 lM mT resulted in the highest number of shoots (7.3 ± 1.0). Unlike other CK treatments requiring higher concentrations, optimum mean shoot number per explant rate was attained at the lowest concentration in MemT and MemTTHP (10 lM) treatments. The use of 10 lM MemTTHP had the least root inhibitory effect during the shoot proliferation phase. In terms of abnormality index, mTRregenerated plantlets were of the best quality across all the CKs tested. In mT-and BA-derived shoots, SW and KAR 1 significantly increased the number and length of roots compared to the control. Overall, when compared to BA, the use of topolin demonstrated higher mean shoot number per explant (MemT and MemTTHP) at lowest CK concentrations and the ease of rooting during the shoot proliferation phase (MemTTHP). During the rooting phase, topolin treatments produced more offshoots than BA-treated ones. The current finding is a further demonstration of the increasing importance of topolins in micropropagation.

Journal of Plant Physiology, 2012

The effect of five topolins (meta-Topolin = mT; meta-Topolin riboside = mTR; meta-Methoxy topolin... more 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 30 M 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 (1150 g/g FW). Among the CKs, 10 M 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 10 M MemTTHP-treated and lowest in 10 M 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, 10 M 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.

Experimental Agriculture, 2012

SUMMARYThe positive role of plant-derived smoke on seed germination and post-germination processe... more SUMMARYThe positive role of plant-derived smoke on seed germination and post-germination processes is well documented. The present study examined if plant-derived smoke with various methods of application influence the agronomic performance of a traditional cereal crop, tef [Eragrostis tef (Zucc.) Trotter]. Comparisons were made in potted tef plants, which germinated from seeds treated with smoke-water (1:500 dilution), Karrikinolide1 (KAR1, 10−8 M) solutions and seeds pretreated with cool aerosol-smoke for 10 min (rinsed and unrinsed afterwards). The smoke-related treatments modified a number of physiological, morphological and agronomic features of Eragrostis tef. Compared with the control, KAR1 and aerosol-smoke treatment of the seeds significantly improved plant height. All the smoke-related treatments significantly promoted stem-thickness whereas number of tillers and grain and dry biomass responded positively to aerosol-smoke and smoke-water treatments. These findings indicate...

Acta Physiologiae Plantarum, 2012

The effects of five topolins (meta-Topolin, mT; meta-Topolin riboside, mTR; meta-Methoxy topolin,... more The effects of five topolins (meta-Topolin, mT; meta-Topolin riboside, mTR; meta-Methoxy topolin, MemT; meta-Methoxy topolin riboside, MemTR and meta-Methoxy topolin 9-tetrahydropyran-2-yl, MemTTHP) on the phenolic content and subsequent acclimatization potential of micropropagated 'Williams' bananas were compared to benzyladenine (BA). Sterile shoot-tip explants were cultured on modified Murashige and Skoog (MS) media containing 10, 20 or 30 lM of the above aromatic cytokinins (CKs) for 42 days. Phenolic contents were quantified spectrophotometrically. Growth parameters and photosynthetic pigments of the greenhouse-acclimatized plants were determined after 5 months. Total phenolic levels were highest in 10 lM mTtreated plantlets within the aerial parts and 30 lM MemTTHP for the underground parts. In the underground parts, 10 lM mT resulted in the production of the highest amount of proanthocyanidins which was approximately five-fold higher than in the control plants. Furthermore, 10 lM MemTTHPtreated plantlets had significantly higher total flavonoids (30.1 ± 0.24 mg CE/g DW) within the aerial parts. Plantlets regenerated using MemT, MemTR and MemTTHP had significantly longer roots and better shoot/root ratios compared to the control and BA-treated plants. In terms of root fresh weight, it was significantly higher in MemT-treated plantlets than in the control and BA treatments. Chlorophyll a/b ratio was significantly improved with the use of MemT, mTR and mT compared to control. Current findings indicate the potential of topolins in stimulating the accumulation of phenolic compounds in micropropagated plantlets. In view of the importance of plant secondary metabolites, their substantial accumulation probably enhanced the acclimatization and subsequent ex vitro survival of the micropropagated plantlets. Topolins, particularly, the new derivative MemTTHP could be an alternative CK for the micropropagation of plant species based on their stimulatory effect on ex vitro rooting that inevitably enhances acclimatization competence. Furthermore, topolins are demonstrated as potential elicitors in micropropagation. Keywords Cytokinins Á Chlorophyll Á Phenolics Á Micropropagation Á Musa spp Abbreviations BA N 6-Benzyladenine CCE Cyanidin chloride equivalents CE Catechin equivalents CK Cytokinin DMRT Duncan's multiple range test DW Dry weight Folin-C Folin-Ciocalteu FW Fresh weight GAE Gallic acid equivalents MemT meta-Methoxy topolin MemTR meta-Methoxy topolin riboside Communicated by J. V. Jorrin-Novo.

Scientia Horticulturae, 2013

ABSTRACT The effects of five topolins on genetic fidelity of micropropagated 'Williams&am... more ABSTRACT The effects of five topolins on genetic fidelity of micropropagated 'Williams' bananas were compared to that of 6-benzyladenine (BA). Sterile shoot-tip explants were cultured on modified Murashige and Skoog (MS) media supplemented with 30 mu M cytokinins (CKs) for 42 days. After the seventh subculture cycle, the degree of variability in regenerants was assessed using 10 inter simple sequence repeat (ISSR) markers. When compared to BA, the use of mTR and MemTTHP proved superior as they had a lower deleterious effect on the regenerants. However, the other topolins either produced a similar effect (MemTR) as BA or were even worse (mT). Inasmuch as the CK contribute to the degree of variation, the effect of subculture cycle remain prominent. Perhaps, the establishment of new culture lines after a few subculture cycles may mitigate the rate of variability. The current findings highlight the beneficial effect as well as the increasing importance of some of the topolins in alleviation of commonly observed physiological disorders during micropropagation.

Journal of Plant Physiology, 2013

Merwilla plumbea (Lindl.) Speta is an important medicinal plant widely used in traditional medici... more 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 (24.9 g g −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.

Journal of plant research, 2021

Black wattle (Acacia mearnsii) has great economic value as a commercial source of tannins, timber... more 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 tha...

Biostimulants for Crops from Seed Germination to Plant Development, 2021

In modern agriculture, obtaining sustainable techniques to promote plant growth and enhance crop ... more In modern agriculture, obtaining sustainable techniques to promote plant growth and enhance crop productivity is crucial. In low-input agriculture, as explicitly practiced in the less developed regions of the world, environmental-friendlier practices are limited, and the depletion of natural resources are generally on the increase. The application of biostimulants can contribute to plant yield and nutrient uptake, while reducing chemical fertilizer dependency. Comprehensive studies have documented improved nutrient acquisition and distribution within plants in response to biostimulant application. In this chapter, environmental-friendly techniques for low-input agricultural systems are reviewed, emphasizing the implementation of different biostimulants derived from agricultural by-products for improved crop growth and enhancing nutrition efficiency. The increase in the global market for biostimulants coupled with the global nutrient imbalance necessitates biostimulant development fo...

South African Journal of Botany, 2007

Diversity, Mar 25, 2020

Africa has the largest diversity of the genus Hypoxis, accounting for 61% of the current globally... more 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.