Frontiers of Agriculture and Food Technology

Frontiers of Agriculture and Food Technology ISSN 7295-2849 Vol. 9 (8), pp. 001-006, August, 2019. © International Scholars Journals

Review

In vitro culture of arbuscular mycorrhizal fungi: advances and future prospects

Tahir Abdoulaye DIOP

Université Cheikh Anta DIOP, Faculté des Sciences et Techniques, Département de Biologie végétale, B.P. 5005, Dakar Sénégal/Laboratoire de Microbiologie des Sols, Centre de Recherches ISRA/IRD/UCAD, B.P 1386, Dakar, Sénégal. E.mail: [email protected].

Accepted 25 April, 2019

Abstract

Arbuscular mycorrhizal (AM) fungi are ecologically important for most vascular plants for their growth and survival. AM fungi are obligate symbionts. In recent years, there have been many attempts to cultivate in vitro. Some relevant results indicate efforts are not far from successful growth of AM fungi independent of a plant host. This paper describes the methods to cultivate root organs, and to select and purify AM fungal inocula (intraradical and extraradical forms). Axenic and monoxenic cultures of AM fungi are summarized and we propose a methodology to recover and achieve continuous culture of AM fungi without lost of infectivity. The in vitro systems have proved to be a valuable tool to study fundamental and practical aspects of AM symbiosis, complementing the in vivo experimental approaches. Finally, we give some proposals of in vitro AM researches to exploit more the potentialities of AM symbiosis.

Key words: Arbuscular mycorrhizal fungi, continuous culture, root organ cultures, intraradical and extraradical forms, in vitro.

Frontiers of Agriculture and Food Technology ISSN 7295-2849 Vol. 9 (7), pp. 001-010, July, 2019. © International Scholars Journals

Review

Diagnostic research to enable adoption of transgenic crop varieties by smallholder farmers in Sub-Saharan Africa

Melinda Smale^1,2* and Hugo De Groote³

¹International Food Policy Research Institute (IFPRI), Washington DC, USA.

²International Plant Genetic Resources Institute (IPGRI), Rome, Italy.

³International Maize and Wheat Improvement Centre (CIMMYT), Nairobi, Kenya.

Accepted 24 April 2019

Abstract

Diagnostic research is important in helping to create an enabling environment for promising biotechnology products in smallholder agriculture, before rather than after release. The biotechnology products that now hold promise for poor people in Sub-Saharan Africa are those that tackle economically important, biotic or abiotic problems not easily addressed through conventional plant breeding or pest control, in crops that serve for food as well as cash, while posing little risk of endangering trade. Two biotechnology products we have selected for social science research in East Africa, Bt maize in Kenya and pest and disease resistance in the East African highland banana, meet these criteria. Preliminary research suggests that the expression of the trait is much more visible to farmers in maize than in bananas; for either crop, for different reasons, bottlenecks will be encountered in planting materials systems; and despite differing crop reproduction systems, transgenic varieties of either share the same environmental hazard of heightened genetic uniformity in the inserted trait relative to conventionally bred varieties. Aside from the performance of the technology, many factors that have incidence at national, regional, and farm levels will affect the likelihood that farmers will adopt transgenic varieties. Social science research can help pinpoint necessary complementary investments.

Key words: Bananas, maize, adoption, smallholder farmers, transgenic crop varieties.

Frontiers of Agriculture and Food Technology ISSN 7295-2849 Vol. 9 (7), pp. 001-004, July, 2019. © International Scholars Journals

Review

Molecular techniques: An overview of methods for the detection of bacteria

Olubukola O. Babalola

Department of Botany and Microbiology, University of Ibadan, Ibadan, Nigeria. E-mail: [email protected]. Tel.: +2348037035965.

Accepted 15 April, 2019

Abstract

Several DNA molecular markers are now available for use in surveillance and investigation of food-borne outbreaks that were previously difficult to detect. The results from several sources of literature indicate substantially different degrees of sensitivities between conventional detection methods and molecular-based methods. The new technology is noted for increased sensitivity over the traditional culture methods which they complement.

Key words: molecular techniques, fingerprinting, microorganism.

Frontiers of Agriculture and Food Technology ISSN 7295-2849 Vol. 9 (7), pp. 001-006, July, 2019. © International Scholars Journals

Review

Yam diseases and its management in Nigeria

Amusa, N. A.¹*, Adegbite¹, A. A, Muhammed S.² and Baiyewu R. A.³

¹Institute of Agricultural Research and Training Obafemi Awolowo University, PMB 5029 Moor Plantation, Ibadan, Nigeria.

²Department of Biological Sciences Usmanu Danfodiyo University, Sokoto. ³Forestry Research Institute of Nigeria, P. M B 5054, Ibadan Nigeria.

Accepted 17 November 2018

Abstract

This review presents different diseases associated with yam and the management strategies employed in combating its menace in Nigeria. The field and storage diseases are presented, anthracnose is regarded as the most widely spread of all the field diseases, while yam mosaic virus disease is considered to cause the most severe losses in yams. Dry rot is considered as the most devastating of all the storage diseases of yam. Dry rot of yams alone causes a marked reduction in the quantity, marketable value and edible portions of tubers and those reductions are more severe in stored yams. The management strategies adopted and advocated for combating the field diseases includes the use of crop rotation, fallowing, planting of healthy material, the destruction of infected crop cultivars and the use of resistant cultivars. With regards to the storage diseases, the use of Tecto (Thiabendazole), locally made dry gins or wood ash before storage has been found to protect yam tubers against fungal infection in storage. Finally, processing of yam tubers into chips or cubes increases its shelf live for a period of between 6 months and one year.

Key words: Yam, field and storage diseases, resistant varieties, yam nematodes, disease management, fungicides, Nigeria.

Frontiers of Agriculture and Food Technology ISSN 7295-2849 Vol. 9 (7), pp. 001-008, July, 2019. © International Scholars Journals

Full Length Research Paper

Effect of decomposition intensity of incorporated chickpea manure on stability and saturated hydraulic conductivity of a clay loam and clay soil

I. I. C. Wakindiki ¹* and R.Yegon²

¹Department of Agronomy, University of Fort Hare, Private Bag X1314 King William’s Town Road 5700 Alice, South Africa.

²Department of Crops, Horticulture and Soils, Egerton University, P.O. Box 536 20107 Njoro, Kenya.

Accepted 18 March, 2019

Abstract

The role of organic matter (OM) in soil aggregation and saturated hydraulic conductivity (Ksat) has long been recognised but their depedence on the intensity of decay is less studied. The objective of this study was to determine the effect of decomposition intensity of incorporated chickpea manure on soil aggregate stability and Ksat. Samples of a clay loam and clay soil were collected from the top 15 cm layer and amended with chickpea green or mature dry manure and incubated at 30°C and ~60% water holding capacity. Decomposition intensity was determined by measuring CO ₂ evolution using NaOH traps, aggregate stability by wet sieving and Ksat by the constant head method. All determinations were made 3, 7 and 30 days after incubation and the data analysed following the general linear model for a 2 x 3 × 3 factorial in randomised complete block design. Evolution of CO₂ in both soils and manure was highest on day 7 compared to day 3 and 30. In both soils >60% of the soil aggregates were macroaggregates >0.5 mm but the relative proportion of microaggregates <0.5 mm increased from ~10 to ~20% in the control and to ~15% in the amended cay loam soil in the day 30 treatments. Decomposition intensity was increased by incorporating chickpea manure which resulted in improved soil aggregate stability and Ksat especially in soil with low clay content. CO₂ which is a simple product of decomposition may be used as a rapid indicator of soil aggregate stability and water movement in agricultural soils.

Key words: Green manure, organic matter, aggregate stability, chickpea, incubation, soil texture.

Frontiers of Agriculture and Food Technology ISSN 7295-2849 Vol. 9 (6), pp. 001-011, June, 2019. © International Scholars Journals

Review

Molecular taxonomic, epidemiological and population genetic approaches to understanding yam anthracnose disease

Mathew M. Abang¹*, Stephan Winter², Hodeba D. Mignouna³, Kim R. Green⁴, Robert Asiedu⁵

¹International Center for Agricultural Research in the Dry Areas (ICARDA), P.O. Box 5466, Aleppo, Syria, and Root and Tuber Program, IRAD, B.P. 2123 Messa, Yaoundé, Cameroon.

²German Collection of Microorganisms and Cell Cultures (DSMZ) c/o BBA, Messeweg 11/12, D-38104 Braunschweig, Germany.

³Virginia State University, Agricultural Research Station, Box 9061 Petersburg, VA 23806, USA

⁴ADAS Arthur Rickwood, Mepal, Ely, Cambs, CB6 2BA, UK.

⁵International Institute of Tropical Agriculture (IITA), Oyo Road, PMB 5320 Ibadan, Nigeria.

*Corresponding author. E-mail: [email protected]. Phone: +963-21-2213433. Fax: +963-21-2213490.

Accepted 18 November 2018

Abstract

Water yam (Dioscorea alata L.) is the most widely cultivated yam species globally. The major limitation to the profitable and sustainable production of D. alata is its susceptibility to anthracnose disease. The availability of resistant varieties could potentially form the cornerstone of an integrated management strategy for yam anthracnose; however, anthracnose resistance breeding is hampered by the dearth of knowledge on pathogen identity and diversity. Four forms of Colletotrichum are now known to be associated with foliar anthracnose of yam: the slow-growing grey (SGG), the fast-growing salmon (FGS), the fast -growing olive (FGO), and the fast-growing grey (FGG) forms. The close phylogenetic relationship of the first three forms to reference isolates of Colletotrichum gloeosporioides, and the fact that only strains of these forms have been observed to induce typical anthracnose symptoms on D. alata , recently confirmed that C. gloeosporioides is the causal agent of yam anthracnose disease. The FGG form possibly represents a distinct, endophytic, species as indicated by morphological, biological and molecular criteria. Previous research emphasized epidemiology and control but limited progress was made in understanding yam anthracnose disease based on this classical approach. Molecular approaches have started to unravel the systematics and ecology of Colletotrichum strains associated with yam anthracnose, as well the population biology of C. gloeosporioides on yam. Sexual recombination is a likely mechanism contributing to the high genetic diversity of C. gloeosporioides in yam-based cropping systems. Studies have been initiated to understand the mechanisms that generate genetic variation in C. gloeosporioides, and to gain some insight into the biochemistry of the interactions between the pathogen and yam. Our thesis in this article is that integrating traditional and molecular approaches to understanding C. gloeosporioides systematics, epidemiology and population genetics will lead to a much better understanding of yam anthracnose disease, and thus to the development of effective and sustainable control measures. Research successes and challenges are discussed, as well as their implications for future studies on pathogen evolutionary potential, anthracnose resistance breeding, and the deployment of resistance genes.

Key words: Anthracnose, Colletotrichum gloeosporioides, Dioscorea spp., molecular markers, molecular systematics, population biology, resistance breeding, yam.