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5: Cassava Mosaic

Tennant, P.; Fermin, G. CABI PDF

5

Cassava Mosaic

Olufemi J. Alabi,1* Rabson M. Mulenga2 and James P. Legg3

Department of Plant Pathology & Microbiology, Texas A&M

AgriLife Research and Extension Center, Weslaco,

Texas, USA; 2Zambia Agriculture Research Institute,

Mount Makulu Central Research Station, Lusaka, Zambia;

3

International Institute of Tropical Agriculture,

Dar es Salaam, Tanzania

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5.1  General Introduction

The global cassava development strategy launched by the Food and Agriculture

Organization of the United Nations in Rome in 2000 concluded that:

. . . cassava could become the raw material base for an array of processed products that will effectively increase demand for the crop and contribute to agricultural transformation and economic growth in developing countries (http://www.fao.org/ ag/agp/agpc/gcds/).

Although cassava is currently consumed by over 800 million people in Africa and is the third most important source of calories in the tropics, the vision of the Food and Agriculture

Organization would nevertheless represent a major increase in the global significance of a crop that is still largely cultivated by resource-poor farmers utilizing traditional farming tools and practices. A native to South

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11: Papaya Ringspot

Tennant, P.; Fermin, G. CABI PDF

11

Papaya Ringspot

Gustavo Fermin,1* Melaine Randle2 and Paula Tennant2,3

Instituto Jardín Botánico de Mérida, Faculty of Sciences,

Universidad de Los Andes, Mérida, Venezuela; 2Biotechnology

Centre, The University of the West Indies, Mona Campus,

Jamaica; 3Department of Life Sciences, The University of the

West Indies, Mona Campus, Jamaica

1

11.1  Introduction: Disease and

Symptoms

Papaya ringspot disease caused by Papaya ringspot virus (PRSV) is perhaps the most serious disease of papaya (Tennant et al.,

2007; Tripathi et al., 2008), a crop that is well adapted to intensive commercial orchards and backyard stands in tropical and subtropical regions (Purcifull et al., 1984). High prevalence of the disease has been noted in the

Caribbean islands, the USA (Florida, Texas and Hawaii), South America, the Philippines,

Taiwan, Thailand and the southern region of China (Gonsalves, 1998) as far back as the

1930s (Fermin et al., 2010). The aetiological agent exists as two serologically indistinguishable biotypes (Purcifull et al., 1984;

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9: Yam Mosaic

Tennant, P.; Fermin, G. CABI PDF

9

Yam Mosaic

Angela O. Eni*

Department of Biological Sciences, Covenant University, Ota, Nigeria

9.1 Introduction

Yam mosaic virus (YMV), genus Potyvirus, infects and causes mild to severe leaf symptoms both in domesticated edible yam species and their wild relatives (Thouvenel and Fauquet, 1979; Goudou-Urbino et al., 1996a) in all locations where yams are grown (Africa, the

Caribbean, Latin America and the South Pacific)

(Goudou-Urbino et al., 1996b; Hughes et al.,

1997; Eni et al., 2008, 2010; Odedara et al.,

2011). Several other potyviruses described in various yam-growing countries in the 1970s and

1980s including Dioscorea green-banding mosaic virus reported in Togo (Reckhaus and

Nienhaus, 1981), yam virus in Nigeria (Terry,

1976), and Dioscorea trifida virus reported in the Caribbean and in South America (Migliori and Cadilhac, 1976), are synonymous with YMV and were all found to be related to YMV both serologically and in host range (Porth et al.,

1987; Goudou-Urbino et al., 1996a). Japanese yam mosaic virus (JYMV), another Potyvirus isolated from D. japonica in Japan in 1974 was reported as a strain of YMV (Okuyama and Saka,

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12: Tomato Spotted Wilt

Tennant, P.; Fermin, G. CABI PDF

12

Tomato Spotted Wilt

Tsung-Chi Chen1,2 and Fuh-Jyh Jan3,4*

Department of Biotechnology, Asia University, Wufeng,

Taichung, Taiwan; 2Department of Medical Research, China

Medical University Hospital, China Medical University,

Taichung, Taiwan; 3Department of Plant Pathology, National

Chung Hsing University, Taichung, Taiwan; 4Agricultural

Extension Center, National Chung Hsing University,

Taichung, Taiwan

1

12.1  Introduction

Tomato spotted wilt disease was first reported in Australia in 1915 and later identified as a virus-infecting disease caused by Tomato spotted wilt virus (TSWV) (Brittlebank, 1919;

Samuel et al., 1930). Initially, geographically distinct TSWV isolates were classified in a particular ‘group’ on the basis of particle morphology, host range and transmission by thrips (Matthews, 1982). Until Impatiens necrotic spot virus (INSV) was discovered (Law and Moyer, 1990), this group was proposed as the genus Tospovirus and assigned to the family Bunyaviridae by the International

Committee on Taxonomy of Viruses in 1991 based on virion morphology and genome organization (Francki et al., 1991). Currently, tospoviruses have become a worldwide problem. Some tospoviruses, such as TSWV, Iris yellow spot virus (IYSV), Groundnut bud necrosis virus (GBNV) and Watermelon silver mottle virus (WSMoV), are of global importance. TSWV is the most important tospovirus with a worldwide distribution that includes

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10: Sugarcane Mosaic

Tennant, P.; Fermin, G. CABI PDF

10

Sugarcane Mosaic

Laura Silva-Rosales,1* Ricardo I. Alcalá-Briseño2 and Fulgencio Espejel1

Plant-Virus Interaction Laboratory, Department of Genetic

Engineering at Cinvestav-Unidad Irapuato, Guanajuato,

Mexico; 2Department of Plant Pathology, University of Florida,

Gainesville, Florida, USA

1

Monocot species, in particular grasses, are cultivated over large areas worldwide for human and animal consumption and lately for biomass energy production. However, viruses like

Sugarcane mosaic virus (SCMV), alone or in conjunction with other viruses or microorganisms, have emerged in some regions as devastating problems for their cultivation. Here we present the taxonomy, distribution, diversity and economic importance of this virus that infects maize and sugarcane as well as provide some insights into its evolution. Efforts to obtain resistance through classical breeding and transgenic approaches are also described.

10.1  Structure, Taxonomy and Diversity

SCMV, a member of the genus Potyvirus in the

Potyviridae family of plant viruses, belongs to the replication group IV. As such, its genome consists of a single-stranded (+) RNA molecule. Its length of 9.6 kb is encapsidated by approximately 2,000 monomers of the coat protein (CP) forming flexuous filaments of about 750 nm in length (Riechmann et al.,

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