Tomato microsatellite markers used in DNA fingerprinting among five tomato accessions.
Tomato is an important component of every Ghanaian meal, and its cultivation contributes significantly to livelihood improvement. The demand for tomato in Ghana outstrips supply, and therefore local production is augmented by imports from neighbouring countries. Despite the importance of tomato in Ghana, past tomato-breeding programmes have been unsystematic and had not led to the development of new varieties that meet the needs of consumers as well as environmental stresses. This review outlined tomato production trends, constraints and past tomato improvement programmes in Ghana, which mainly focused on germplasm collection, morphological and agronomic characterization, molecular evaluation, diversity study, as well as screening germplasm against biotic and abiotic stresses. The established variability and the outcomes of the evaluations against the various biotic and abiotic stresses have not been utilized in the development of new varieties. This work will serve as a reference for developing future tomato-breeding programmes.
- breeding programmes
Tomato continues to be the most important vegetable in the world due to increasing commercial and dietary value, widespread production as well as model plant for research . Tomato is utilized as a fresh crop or processed into various forms such as paste, puree and juices. Tomato is a rich source of vitamins (A and C), minerals (iron, phosphorus), lycopene, Beta-carotene, high amount of water and low calories . The five leading producers of tomato in the world are China, India, United States of America, Turkey and Egypt . The world’s tomato production in 2014 was 171 million tonnes with an average yield of 37 tonnes per hectare .
According to Norman , tomato (
Despite the importance of tomato in Ghana, tomato-breeding programmes over the years have not been systematic and therefore had not led to the development of new varieties that meet the needs of consumers as well as biotic and abiotic stresses . The major goals of tomato breeding worldwide are increasing yield, tolerance to biotic and abiotic stresses and improvement in sensory and nutritional value of the crop . Consequently, past Ghanaian plant breeders have focused on germplasm collection, evaluation of imported and local accession for morphological and agronomic traits as well as screening accessions for their reactions to biotic and abiotic stresses. Nonetheless, there have been little published breeding programmes in the past that focussed on improving fruit-quality traits or introgression genes that will make cultivars resilient to both biotic and abiotic stresses. In 2014, the Ghana National Tomato Federation stated that the union has been pushing government to support research in the development of high yielding and quality tomato variety suitable for local and export market . This chapter therefore highlights tomato production trends in Ghana, tomato production constraints, past tomato-breeding programmes in the country and future tomato-breeding objectives, which will serve as a locus for developing future tomato-breeding programmes.
2. Tomato production trends and constraints in Ghana
Tomato is mostly produced in seven out of the 10 regions in Ghana. These production regions include Upper East region, Northern region, Brong Ahafo region, Ashanti region, Eastern region, Greater Accra region and Volta region. The demand for both fresh tomato and tomato products is year round although tomato production in Ghana is seasonal due to the differences in the rainfall patterns as well as water availability. In the exception of the Upper East Region where tomato is produced during the dry season under furrow irrigation system and some parts of the Greater Accra region, tomato production is generally rain fed. During the rainy season, harvest is abundant, leading to glut and wastage even though there is scarcity during the dry season. The abundance of tomato during the rainy season results in low prices and low return on investment. Tomato produced during the rainy season is supplied to the market from May to October but the varieties produced during this period are poor in colour, watery, acidic and have a shorter shelf life, making them unsuitable for processing. Due to the unavailability of processing tomato varieties, all the three state-owned tomato-processing factories had to shut down. Tomato varieties that are currently grown by Ghanaian farmers are mostly imported varieties and farmers selected varieties. A very important open-pollinated variety (OPV) grown in Ghana particularly in the Brong Ahafo region is the Power Rano (a cross between Power and Laurano varieties) which was identified by the National Research Institute (NRI) researchers in the 1990s based on its good production and local processing qualities .
Dry season production in Ghana on the other hand is challenging, and demand is in excess of supply. This period partially coincides with the Christmas season when demand for tomato is at its peak. In order to meet the dry season demand, there is heavy importation of fresh tomato from neighbouring countries, particularly Burkina Faso to augment local supply. Some parts of the Greater Accra region such as Ashiaman, Tema and Weija grow tomato under irrigation system and mostly supply tomato unto the market from September to December, and the Upper East region then continues tomato supply from January to April
3. Past tomato-breeding programmes in Ghana
Tomato-breeding programmes in Ghana can be traced to the 1950–1978 when cultivars like OK, MH and Wosowoso were developed. A major tomato-breeding programme led by the National Research Institute (NRI) in UK also carried out a study from 1994 to 2000. Post 2000, tomato improvement programmes focussed mainly on screening tomato germplasm for both biotic (particularly the TVLCD) and abiotic stresses as well as mutation breeding; however, none has led to the release of varieties. Robinson and Kolavalli in 2010 stated that since the NRI tomato-breeding work ended in 2000, there have been no breeding programmes and no systematic seed multiplication in the country . Again, a 2013 publication indicated that the varieties developed during the 1950 to 1978 together with farmers’ selection in tomato-growing areas have led to the development of large tomato ecotypes in Ghana .
3.1. Germplasm collection and genetic diversity studies
Germplasm is required for the commencement of any breeding programme. Consequently, the Council for Scientific and Industrial Research-Plant Genetic Resources Research Institute (CSIR-PGRRI) and the National Agriculture Research Programme periodically collected a number of tomato accessions from all the 10 regions in Ghana. The 2012 tomato germplasm collection by the Council for Scientific and Industrial Research-Crops Research Institute of Ghana (CSIR-CRI) included accessions from two districts in Burkina Faso (Kougoussi and Yako), Asian Vegetable Research Development Centre (AVRDC), Rural Development Administration (RDA), National Institute of Horticulture and Herbal Science (NIHHS) and Republic of Korea. This was funded by the Korea Africa Food and Agricultural Cooperation Initiative (KAFACI) project . Recently, 13 accessions were also collected from Afari, Akumdan and Akuawu in the Ashanti region. The recent germplasm collected included accessions such as ‘Atoa’, ‘Daagyine’, ‘Local 1’, ‘Power’, Pectofake 1, Petomech, ‘Akoma’, Pectofake 2, Powerano, ‘Bolga’, ‘Dwidwi’ (cherry), ‘Local 2’ and Rano . Most of the locally collected germplasm and introduced accessions have been evaluated for various agronomic and morphological traits as well as the establishment of genetic variation that exists within this germplasm. The Savanna Agricultural Research Institute evaluated three tomato varieties (ICRISIND, Petomech and Tropimech) for various agronomic traits. Variations were observed in plant height, days to flowering, number of fruits, fruit size and fruit weight . Again in 2013, SARI evaluated the following accessions: S 22, Naywli, Bebi yereye, LBR 7, Keneya, LBR 17, Abhijay and Petomech for variability in various agronomic traits .
In 2014, five introduced fresh market tomato varieties from the USA and Crops Research Institute of Ghana (CRI) were evaluated for genetic variability, adaptability in Ghana as well as plant and fruit attributes. The varieties included Heinz, Shasta, Op-B149, Op-B155 and CRI-P00. With the advent of molecular markers, this study used 15 Simple Sequence Repeat (SSR) primers (Table 1) to determine the genetic diversity existing among the five introduced fresh market tomato varieties . In order to establish the genetic diversity that exists in the germplasm collected in 2015, all the accessions (in exception of Rano) were evaluated in field as well as molecularly characterized using 12 SSR primers. The SSR primers include Tom 8–9-F, Tom 11–28-F, Tom 55–56-F, Tom 59–60-F, Tom 67–68-F together with seven primers listed in Table 1. In the same year, 20 tomato genotypes were evaluated in the greenhouse as well as the field at the University of Ghana Forest and Horticultural Crops Research Centre (FOHCREC), Okumaning-Kade in the Eastern Region of Ghana to determine the genetic variability in agronomic and fruit-quality traits. There was variability in almost all the traits studied .
|Marker no.||Primer sequence (5′-3′)||Number of bases|
The various findings of the germplasm evaluation for morphological and agronomic traits together with the variability that exists in the germplasm can be explored in the development of new varieties.
3.2. Breeding for fruit quality
Cultivars such as OK, MH series  and Wosowoso  were developed in the 1950s. Agble  also began breeding for processing quality traits, shelf life and heat tolerance lines by making crosses between local accessions with heat-tolerant and nonripening gene (norA) from exotic accessions. Nonetheless, due to lack of continuity, no variety was released despite the positive outlook .
The NRI focused on pure line selection of local landraces in the Brong Ahafo region of Ghana with the aim of releasing pure lines of good open-pollinated varieties. Six varieties consisting of three local and three introduced varieties were used in that study. These varieties were selected based on farmers and traders (fruit quality, good taste and longer shelf life) preferred traits. As part of this project, a tomato breeder seed production trial was then established at Wa in the Upper West region with the five selected varieties. The research was, however, not very successful because there was no long-term impact due to lack of sustainable seed distribution systems to ensure that the resource-poor farmers have access to the developed varieties .
From 2011 to 2013, pure line selection was used to advance a locally identified cultivar commonly called petofake. From the segregating population collected from farmers, 12 progenies (P002, P005, P011, P020, P026, P035, P057, P068, P074, P077, P082 and P085) were selected based on their fruit shape, size, color, surface and yield . Trials are ongoing to release these lines.
Dried seeds of SP 300/184.108.40.206, a variant line selected from second generation (M2) following the irradiation of
3.3. Breeding for biotic stress
Post 2000 has seen some breeding efforts made in screening tomato accessions against biotic stresses. However, most of these programmes focussed on the most devastating tomato disease (TYLCD).
3.4. Screening germplasm for tomato yellow leaf curl disease resistance
TYLCD is a major tomato disease in Ghana and Africa as a whole and can lead to a massive yield loss and consequent impact on livelihood if the vector of the disease (whitefly) is not controlled and infection starts at an early stage of the plant growth . The Tomato Yellow Leaf Curl Virus (TYLCV) causes the TYLCD. It was reported that the USAID West African Regional Programme identified research on Virus resistance (VR) as a priority, and Ghana was included in seven members’ regional investigation of tomato virus complex . The Agricultural Biotechnology Support Project II (ABSPII) aimed to improve agriculture production in the developing countries through Biotechnology, and that is why this project was initiated in 2005 to address tomato production in West Africa. This project was a partnership among researchers from AVRDC, Cornell University and University of California-Davis (UC Davis). The ABSII established the Regional Vegetable Germplasm Trailing Network that evaluated 100 putatively TYLCD-resistant tomato varieties that were adaptable to the growing conditions of West Africa which Ghana was a part from 2005 through 2008. In the 2005–2006 growing season, only 40 varieties were evaluated (Table 2). The resistant varieties used for the entire trial were mainly F1 hybrids since they were sourced from commercial seed companies and some breeding lines from breeding institutions. Based on the TYLCD scoring scale, at the end of the 2007–2008 multilocational trail, varieties such as Lety F1 scored below 1, Yosra scored 1, and Atak, Bybal and Gempride scored between 1.0 and 2.0 in Ghana (Navrongo and Technimanitia). The lower score was an indication of tolerance under the disease pressure. It was noted that the varieties suffered under farmers’ field compared to research stations under comparable disease pressure. At the various trial locations, farmers preferred Lety F1, Yosra, Atak and Bybal. Due to the competitive nature of the tomato-breeding industry in developed world, some of the selected varieties were no longer in use in the countries where they were originally bred .
|Seed source||Variety name||Resistance source|
|AVRDC||CLN 2123A Ty-2|
CLN 2460E Ty-2
CLN 2468A Ty-2
CLN 2498E Ty-2
CLN 2545A Ty-2
CLN 2545B Ty-2
PT 4722A Ty-2
TLCV 15 Ty-2
|Cirad Guadeloupe||O4 108|
|De Ruiter Seeds||Bybal|
Industry DR 10403
Industry DR 10403
|Harris Moran||FTC 6231|
|Hebrew University||Favi 9||Ih902|
|Seminis—India||Sasya 0202 F1|
Nirouz TH 99806
Yassamen TH 99802
|Tropicasem||F1 3019 Galina|
|F1 3019 Galina|
In 2008, three distinct isolates of the TYLCD virus were identified in Ghana from infected tomato plant samples collected from the Ashanti region in Ghana. The three strains of virus identified are the Tomato Yellow Leaf Curl Ghana Virus, Tomato Yellow Leaf Curl Kumasi Virus and the Tomato Yellow Leaf Curl Mali Virus .
Fifteen tomato accessions (collected from AVRDC-Taiwan and CSIR-Crops Research Institute, Ghana) that have been reported to be resistant to TYLCD as well as susceptible checks were screened against the TYLCD in a greenhouse at the Kwame Nkrumah University of Science and Technology (KNUST) in Kumasi (Table 3). These 15 accessions were later on evaluated in the field at Afari (hot spot) in the Ashanti region. The whiteflies used for the greenhouse inoculation were collected from infested tomato plants at Akumadan, Agogo and Afari. The incidence and severity of TYLCV were scored 30, 45 and 60 days after transplanting using the severity scale 0–4 developed by Lapidot and Friedmann in 2002. At 60 days after transplanting in the greenhouse, accessions A2 (FLA456-4), G14 (WSP2F7 (3) PT.3) and G15 (WSP27F7 (3) PT.3) expressed moderate symptoms in terms of incidence of the TYLCD while accessions A8 (99S-C-39-20), A9 (H24), G13 (WS273.3LARGE) and G12 (WSP2F1PT.3) also showed mild symptom of the disease. A1 (TY52), A3 (FLA478-6-3-0), A6 (TLB111) and A7 (LA 1969) expressed slight severity to the TYLCD. Accessions G11 (PIMPILIFOLIUM) and A1 (FLA505) had the lowest incidence rate compared to accessions A10 (CLN2026D), G13 (WS273.3LARGE) and A4 (FLA653-3-1-0) that had the highest incidence of TYLCV infection in the field. At 60 days after transplanting only accession, A1 (FLA505) showed no TYLCD symptoms .
|TY52 (A7)||LA 1969||D. Zamir, Hebrew University|
|‘FLA456–4 (A2)||Tyking, LA2779 (||J. Scott, University of Florida|
|FLA505 (A1)||LA1969, Tyking, Fiona||J. Scott, University of Florida|
|FLA496–11–6-1-0 (A5)||LA1932||J. Scott, University of Florida|
|FLA478–6–3-0 (A3)||LA1938 (||J. Scott, University of Florida|
|FLA653–3–1-0 (A4)||LA2779 (||J. Scott, University of Florida|
|99S-C-39-20 (A8)||Unknown||Namdhari Seeds, India|
|H24 (A9)||G. Kalloo, India|
|CLN2026D (A10)||Susceptible check||AVRDC|
|WSP2F7 (3) PT.3 (G14)||Unknown||CSIR-CRI|
|WSP27F7 (3) PT.3 (G15)||Susceptible Check||CSIR-CRI|
Again, 30 accessions (including the 15 accessions that were screened in the greenhouse and the field in 2010) were screened against the local strains of virus in Afari in the Ashanti region (Table 4). Some of these accessions were reported to be resistant in other countries. Only two accessions (Local Rano and Petomech-Ghana/France) out of the 30 accessions expressed mild symptoms whilst accessions WSP2F1pt.3 and Tomato Red Cloud expressed moderate symptoms after 60 days of transplanting. In order to confirm the resistance or susceptibility observed in the field, six viral detection primers were used to screen all the 30 tomato accessions (Table 5). From the results obtained in that study, none of the primers amplified viral DNA in Tomato Red Cloud. For WSP2F1pt.3, only one of the six primers (PAL/PAR) amplified the viral DNA. Only MF/MR primer amplified the viral DNA in Local Roma. For Petomech (Ghana/France), two primers (GHF/GHR and KR/KF) amplified the viral DNA. None of the 30 accessions was considered resistant since none of them showed no symptom in the field as well as no TYLCV DNA amplification .
|FLA 505||A1||LA 1969 (||J. Scott, Univ. Florida|
|FLA 456–4||A2||Tyking, LA2779 (||J. Scott, Univ. Florida|
|FLA 478–6–3-0||A3||LA1938, Tyking, Fiona||J. Scott, Univ. Florida|
|FLA 653–3–1-0||A4||LA2779 (||J. Scott, Univ. Florida|
|FLA 496–11–6-1-0||A5||LA1932 (||J. Scott, Univ. Florida|
|TY52||A7||LA 1969 (||D. Zamir, Hebrew Univ.|
|99S-C-39-20-11-24-17-0||A8||Unknown||Namdhari Seeds, India|
|H24||A9||G. Kallo, India|
|WSP2F7 (3) pt.3||G14||Unknown||CSIR-CRI|
|Tomato Money Maker||B17||Unknown||USA|
|Tomato Roma-Jam Vf||B18||Unknown||Burkina Faso|
|Tomato Red Cloud||B24||Unknown||Holland|
|Tomato Rio Grande||B25||Unknown||Holland|
|Tomato Roma VF||B27||Unknown||USA|
|Petomech (Ghana/Burkina)||B28||Unknown||Burkina Faso|
|Tomato Ventura F||B30||Unknown||USA|
|Marker name||Primer sequence||Source|
|Rojas et al. (1993)|
|Wyatt and Brown (1996)|
|Zhou et al. (2008)|
|GHF/GHR||F: GCCCGAAAGCTTCGTTGTT TTCCCGCT|
R: ACGGATGGCCGCTTTGGGT ATTCG
|Osei et al. |
|KF/KR||F: GGACCCGGCGCACTATTTAT GTTGGC|
|Osei et al. |
|Osei et al. |
Again, between 2010 and 2011, seven tomato varieties (Table 6) were grown in the fields against the TYLCD in the University of Ghana and the Volta region of Ghana. The symptom expression of the varieties against the TYLCV was confirmed in the laboratory using the set of primers in Table 5 in addition to Beta 01/02. The study also identified Ty-3 gene in tomato that confer resistance to TYLCV using the primers in Table 7. From the field screening, it was found that Burkina (obtained from farmers in the Volta region) had the highest TYLCD incidence, followed by Petomech and the susceptible check. However, Petomech expressed higher severity than Burkina. Both severity and incidence were lower in the hybrids in exception of F1 Thorgal that showed no symptom. AC1048/AV494 detected the most viral DNA in the samples collected. The primer set T0302-F/T0302-R did not amplify the Ty-2 gene in any of the varieties evaluated. However, Primer P6-25-F/P6-25-R amplified a band size of approximately 400 bp in F1 Jaquar, F1 Nadira and
|F1 Jaguar||TYLCV||Technisem (AgriSeed Company Ltd.)|
|F1 Nadira||TYLCV||Technisem (AgriSeed Company Ltd.)|
|F1 Thorgal||TYLCV||Technisem (AgriSeed Company Ltd.)|
|Petomech||Unknown||University of Ghana|
|Reported resistance to TYLCV||Farmers|
|Ji and Scott (2006)|
|P6–25-F/P6–25-R||F: GGT AGT GGA AAT GAT GCTGCTC|
R: GCT CTG CCT ATT GTC CCA TAT ATA ACC
|Ji et al. (2007)|
Between 2011 and 2012, a group of researchers also evaluated the susceptibility of 10 accessions to TYLCD under field conditions. The accessions include
The observed symptoms on the hybrids together with the backcrosses were slight yellowing of margins of apical leaflets and moderate yellowing and slight curling of leaflet tips. The results from the phenotypic screening were verified with a molecular marker detection of the viral DNA among the accessions. This work also deployed both triple antibody sandwich enzyme-linked immunosorbent assay (TAS-ELISA) and PCR method (using the primers in Table 5) for the TYLCV detection in order to recommend a better way of detecting TYLCV in infected samples. A TAS-ELISA kit with a known TYLCV-infected
Recently, there was a phenotypic evaluation of 36 local tomato genotypes (Table 8) for the source of resistance against TYLCD in two locations (University of Cape Coast and Asuansi) in Ghana. The results showed that five accessions (K005-Petomec, K100-Local 3, K213-AVTO 9804, K116-Ashanti 2 and K042-Tomatose) out of the 36 genotypes were selected for mild severity, two genotypes showed severe symptoms (K027-Local, K202-AVTO 0102) and one genotype (LV-Fadzebegye) showed moderate severity. In order to confirm the infection or otherwise of the eight tomato accessions selected for mild and severe symptom expression, two of the viral detection primers (AV494/AC1048 and PTYv787/PTYc1121) were used for the detection of the virus in infected plant samples (Table 5). The primer pair AV494/AC1048 amplified the viral DNA in all the eight genotypes (K100, K027, K116, K005, K202, LV, K213 and K042) in the University of Cape Coast and six out of the eight genotypes in Asuansi (K100, K027, K116, K005, K202 and K042) (Table 8). The primer pair PTYv787/PTYc1121 on the other hand amplified viral DNA in all the samples from both locations .
|K116||Ashanti 2||Ghana (Ashanti region)|
|K045||Tomatose||Ghana (Volta region)|
|K042||Tomatose||Ghana (Volta region)|
|K100||Local 3||Ghana (Upper East)|
|K074||Local 6||Ghana (Northern region)|
|K144||BK-Dotvert Yako||Burkina Faso (Burkina Faso)|
|K124||Local 1||Ghana (Ashanti region)|
|K005||Petomec||Ghana (Eastern region)|
|K138||BK-Koly zy||Burkina Faso|
|K027||Local||Ghana (Volta region)|
|K088||Local1||Ghana (Upper East)|
|K205A||AVTO 1006||Taiwan (AVRDC)|
|K197||REX||Ghana (Eastern region)|
|P077||Local 9||Ghana (Northern region)|
|K213||AVTO 9804||Taiwan (AVRDC|
|K050||Asante tomato||Ghana (Western region)|
|K011||Ntose||Ghana (Eastern region)|
|K106||Local 2||Ghana (Upper East)|
|K200||2001 heat tolerant||Ghana (Eastern region)|
|K006||Power Rano||Ghana (Eastern region)|
|K202||AVTO 0102||Taiwan (AVRDC)|
|P009||Mmoboboye||Ghana (Eastern region)|
|K206||AVTO 1008||Taiwan (AVRDC)|
|L.V||Fadzebegye||Ghana (Central region)|
|FLA 505-BL1172||AVRDC, Taiwan|
|FLA 496–11–6-0||AVRDC, Taiwan|
|Adwoa Deede||Commercial, Ghana|
|Terminator F1||Green seeds, India|
|Roma-JAM VF||Commercial, USA|
|Burkina Petomech||Commercial, France|
|Roma VF||Commercial, B. Faso|
|Ventura F||Commercial, France|
|Ghana Petomech||Petomech Commercial, France|
|FLA 478–6–3-0||AVRDC, Taiwan|
|Money maker||Comm. South Africa|
|Rio grande||Commercial, Holland|
|VFNT (Resist. check) TGRC, V. Williamson||VFNT (Resist. check) TGRC, V. Williamson|
|UC82 (Suscept. check) TGRC, V. Williamson||UC82 (Suscept. check) TGRC, V. Williamson|
3.5. Molecular screening of tomato germplasm for root knot nematodes resistance
This study involved the use of primer Mi23/F//Mi23/R to detect the presence or absence of
3.6. Screening for abiotic stress
Another important tomato-breeding objective is breeding for abiotic stress; nonetheless, there is limited published work on screening of tomato against abiotic stresses in Ghana. It was reported that 19 tomato cultivars (Table 10) were screened for adaptation to high temperature, and it was found that Nkansah, King 5, 181 (CLN 2318 F) and DV 2962 cultivars were better adapted to heat stress .
|‘Petomech’||Monarch Seed, Holland|
|‘Rio Grande VF’||Griffaton Producteur Grainier, France|
|Tomato Rockstone VF’||Griffaton Producteur Grainier, France|
|‘Caracoli’||Griffaton Producteur Grainier, France|
|F1 Ninja’||Technisem, France|
|‘Petomech VF II||Improved Petoseed Seminis, Netherlands|
|‘Moneymaker’||Griffaton Producteur Grainier, France|
|‘18I (CLN 2318 F)’||AVDRC|
|14IR Island Red’||Samoa Island|
|‘8S Selected SM1’||Samoa Island|
|‘5C Roma’||Samoa Island|
|‘17I (CLN 2443B)’||AVDRC|
|‘Nkansah’||Forest and Horticulture Crops Research Centre, Kade, University of Ghana|
|‘DV-2962’||Seminis Monsanto, Thailand|
|‘Champion’||Crop Science Department, University of Ghana|
|Wosowoso’||Crop Science Department, University of Ghana|
The outcome of these various screening programmes can be utilized in a hybridization programme by crossing genotypes expressing mild symptoms to the TYLCV and nematodes as well as genotypes that are tolerant to heat with locally adapted accessions that are susceptible to these stresses to develop resilient varieties.
3.7. Potential tomato breeding objectives
Tomato varieties currently grown in Ghana are generally acidic, watery, poor in color, poor shelf life and susceptible to TYLCV as well as intolerant to heat. Future tomato-breeding programmes should focus in the short-term on introgression of Tomato Yellow Leaf Curl Disease Resistant genes into locally adapted varieties and improving the shelf life of these locally adapted tomato varieties. These will address the major constraints facing the tomato industry in Ghana. Long-term tomato-breeding objectives should encompass the improvement of fruit color, increasing brix, improving rainy season varieties with good fruit-quality traits, increasing variability through irradiation, resistance to other biotic and abiotic stresses as well as sensory and nutritional value. Due to the pressing nature of these short-term breeding objectives, students of the West Africa Centre for Crop Improvements (WACCI), University of Ghana, are currently breeding for TYLCD-resistant varieties and prolonged tomato shelf life. Other students of the same institution are also working on breeding for processing quality and Bacteria Wilt-resistant tomato varieties.
Tomato is indispensable in all Ghanaian recipes and contributes significantly to the economy of Ghana. Ghana has the potential to meet the country’s tomato demand; however, low yield, unavailability of quality tomato varieties, pests and diseases have hindered this potential. This review presented tomato production trends in Ghana, past tomato-breeding programmes that have been carried out as well as some potential tomato-breeding objectives. Ghana will achieve self-sufficiency in tomato production if the government, Universities, Research Centres and National Research Institute (NRI) will invest more resources into tomato breeding to achieve both the short- and long-term-breeding objectives. This review will serve as a reference for improving tomato in the country.
I would like to thank Mr. Richard Agyare of the Savannah Agriculture Research Institute (SARI), Mr. Emmanuel K. Quartey and Mrs. Rosemary Adjei-Kusi, of the Biotechnology and Nuclear Agriculture Research Institute (BNARI), for sharing information on tomato-breeding activities in their various institutions.