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One of Nigerian's preferred crops is cowpea(Vigna unguiculata(L)Walp) because it is recognized as a key food and nutritional security legume in Sub Saharan Africa. Striga gesnerioides(Willd.)Vatke is a primary biotic constraint of cowpea production in West Africa. There are currently limited sources of resistance in cowpea germplasm and there exists the potential for resistance breakdown. Hence, the objective of this paper was to evaluate post-emergence Striga gesnerioides damages and determination of phosphate fertilizer containment concentration at low inoculum level in cowpea (Vigna unguiculata (L)Walp.) using appropriate standard method with a bid to meet sustainable development (SD) Goal 2.0 (food security), Twenty five morphological traits comprising seventeen quantitative and eight qualitative traits were evaluated. In this research, assessments of cowpea varieties were carried out to determine phenotypic traits which make them Striga resistant/susceptible. Striga gesnerioides damage of cowpea was post-emergent and not pre-emergent as commonly reported. Zero Striga gesnerioides emergence point was 50 kg/ha TSP. [ABSTRACT FROM AUTHOR]

Striga gesnerioides is one of the major biotic constraints to cowpea (Vigna unguiculata [L.] Walp) production throughout West Africa. The best way to control and limit the spread of this weed remains genetic control, but recent works have shown that all cowpea varieties commonly grown in Togo are susceptible to S. gesnerioides. This study aims to investigate the resistance response of cowpea germplasm from Togo to S. gesnerioides. A field test was performed under natural infestation followed by a pots test under artificial infestation. Genotyping was carried out with three molecular markers SSR1, 61RM2 and C42‐2B, known for their linkage to S. gesnerioides resistance genes. The results have revealed three cowpea accessions, TG20_66, TG20_82 and TG20_108, phenotypically resistant to S. gesnerioides. All three resistant accessions have shown the RSG3‐301 resistance gene presence. Potential resistance gene sources to S. gesnerioides exist among cowpea accessions from Togo. [ABSTRACT FROM AUTHOR]

One of Nigerian’s preferred crops is cowpea(Vigna unguiculata(L)Walp) because it is recognized as a key food and nutritional security legume in Sub Saharan Africa.Striga gesnerioides(Willd.)Vatke is a primary biotic constraint of cowpea production in West Africa. There are currently limited sources of resistance in cowpea germplasm and there exists the potential for resistance breakdown . Hence,the objective of this paper was to evaluate post-emergence Striga gesnerioides damages and determination of phosphate fertilizer containment concentration at low inoculum level in cowpea (Vigna unguiculata (L)Walp.) using appropriate standard method with a bid to meet sustainable development (SD) Goal 2.0 (food security), Twenty five morphological traits comprising seventeen quantitative and eight qualitative traits were evaluated. In this research,assessments of cowpea varieties were carried out to determine phenotypic traits which make them Striga resistant/susceptible. Striga gesnerioides damage of cowpea was post-emergent and not pre-emergent as commonly reported. Zero Striga gesnerioides emergence point was 50 kg/ha TSP.

Cowpea (Vigna unguiculata L. Walp.) is an important food and nutrition security crop in Benin, though its production is constrained by absence of information necessary for strategic planning. The objective of this study was to evaluate the diversity of preferred traits and production constraints of cowpea in southern Benin. A survey was conducted in three main cowpea-growing districts in southern Benin, namely Ketou, Zakpota and Klouekanmey. Data were collected from 175 respondents through structured survey, as well as using field observations and via focus group discussions. It was clear that the majority of farmers (82%) grew cowpea in association with other crops, though mostly with maize (Zea mays L.). A total of 75.9% of farmers purchased seeds from agro-dealers in local markets. The perception of cowpea production constraints varied among districts, with weeds infestation, unavailability of certified seeds, drought, low yield, and insect pest attacks as the major production constraints across the districts. Factorial analysis showed that for the sociocultural group Adja, selection of cowpea varieties is based on pod hardness and tolerance to Striga gesnerioides; while for the sociocultural group Fon, cooking time, grain colour and seed price were the main selection criteria. On the other hand, for sociocultural groups Nagot and Holli, selection of the cowpea varieties was based on the ease to separate the coat from the cotyledons and seed size (medium to large). These findings could guide cowpea breeders and extension officers in further research and dissemination programmes in Benin. [ABSTRACT FROM AUTHOR]

Significant efforts have been made to develop cowpea (Vigna unguiculata (L.) Walp.) varieties resistant to Striga gesnerioides in Burkina Faso. Despite these efforts, the resistant genotypes developed still express differential responses to Striga gesnerioides in different zones of the country. This suggests existence of intraspecific variability within the parasite. The objective of this study was to assess the intraspecific variability of cowpea genotypes to Striga gesnerioides infection in Burkina Faso. Ten cowpea varieties were screened over two consecutive years, under artificial infestation with 30 ecotypes of Striga seeds at Kamboinsé research station, in a screenhouse in Burkina Faso. Cowpea varieties used included Moussa local, Komsaré and KVx404-8-1, which are susceptible to all Striga ecotypes; and varieties B301, IT93K-693-2 and IT82D-849, which are free from all Striga ecotypes infestation. Cowpea varieties Tiligré, 524B, local Gorom and Niizwè had specific reactions depending on the ecotypes. The study highlights the existence of varietal specificities according to the geographical origin of Striga gesnerioides seeds. The structuring of the intraspecific diversity showed five biotypes, of which three were clearly identified as SG1, SG5 and SG Kp races; and two biotypes could not be identified. Although this study did not allow for a clear determination of the racial affiliation of the two new biotypes, it offers the possibility of developing new strategies to control Striga by focusing on the selection of resistant varieties based on regional specificities of Striga races in each agricultural zone. [ABSTRACT FROM AUTHOR]

The parasitic plant, Striga gesnerioides (Willd.) Vatke, is one of the most important constraints of cowpea production and food security in West Africa. Currently, few Striga resistant cowpea varieties have been developed that are well‐adapted to the dry savannah regions of Ghana. While genes conferring resistance to Striga races SG1, SG3 and SG5 have been mapped, the genetic locus of resistance to the race of Striga found in Ghana (SG‐GH) has not been characterized. Here, we report identification of genetic markers linked to SG‐GH resistance and define the relationship of this locus to SG3 resistance in recombinant inbred line populations generated from crosses between Striga resistant IT97K‐499‐35 and the Striga susceptible varieties Apagbaala and SARC‐LO2. The populations were genotyped with five genetic markers associated with SG3 and SG5 Striga resistance genes and a genetic map was developed. Genes conferring resistance to SG‐GH and SG3 mapped 4.2 cM from each other on chromosome Vu11. The identification of genetic markers linked to SG‐GH resistance will facilitate the marker‐assisted development of high‐quality Striga resistant cowpea varieties in Ghana. [ABSTRACT FROM AUTHOR]

Historically, conventional breeding has been the primary strategy used to develop a number of Striga-resistant varieties currently grown in the Sahel of Western Africa. In this study, we have successfully developed and applied a marker-assisted selection strategy that employs a single backcross programme to introgress Striga resistance into farmer preferred varieties of cowpea for the Nigeria savannas. In this strategy, we have introduced the Striga resistance gene from the donor parent IT97K-499-35 into an elite farmer preferred cowpea cultivar 'Borno Brown'. The selected 47 BC1F2 populations confirmed the recombinants with desirable progeny having Striga resistance gene(s). The 28 lines selected in the BC1F2:4 generation with large seed size, brown seed coat colour and carrying marker alleles were evaluated in the field for resistance to Striga resistance. This led to the selection of a number of desirable improved lines that were immune to Striga having local genetic background with higher yield than those of their parents and standard varieties. [ABSTRACT FROM AUTHOR]

Experiment was carried out at International Institute for Tropical Agriculture (IITA), Kano, Nigeria. The aim of the study was to evaluate the effect of different levels of Striga infestation on the growth and yield of some varieties of cowpea. Four cowpea genotypes were selected for the study. The experiment was laid out in randomized complete block design with two treatment regimes of Striga infestation. The levels of Striga infestation include 0.05g, 0.1g and 0.0g (control). The results showed that IT97K-499-35 recorded higher plant height at 0.5g and 0.1g of Striga infestation, but DANILA showed lower plant height at 0.1g of Striga infestation. The result for chlorophyll content (SPAD) indicates that at 30 days after Striga infestation, IT99K-241-2 recorded higher chlorophyll SPAD value of 39.2. But IT97K-499-35 had lower chlorophyll SPAD value of 16.3. Higher number of days to 50% flowering was recorded in IT99K-241-2 across the treatment. IT98K-205-8 recorded early days to 50% flowering across the treatment. IT99K-241-2 and DANILA recorded Striga emergence and attachment to their roots. But IT97K-499-35 and IT98K-205-8 had no Striga attachment and emerged. Higher grain yield was recorded in IT97K-499-35, but IT99K-241-2 and DANILA recorded lower grain yield. Higher Fodder yield was recorded in DANILA. The result indicates that fodder yield was reduced in 0.5g and 0.1g of Striga infestation in all the varieties. The present study conclude that varieties IT99K-241- 2 and DAN'ILA were susceptible to Striga at 0.1g of infestation, while IT97K-499-35 was tolerant to Striga at 0.5 and 0.1g of Striga infestation. [ABSTRACT FROM AUTHOR]

Alectrol was first isolated from root exudates of cowpea ( Vigna unguiculata), a genuine host of a root parasitic weed Striga gesnerioides, as a germination stimulant for seeds of the parasite. The proposed structure, an isomer of strigol, was disproven by chemical synthesis. Recently, another structure, namely orobanchyl acetate, was proposed. Surprisingly, however, the synthetic compound having this proposed structure for alectrol was not active in inducing germination of S. gesnerioides seeds although it was active toward seeds of other root parasitic weeds such as S. hermonthica and Orobanche minor. Detailed studies on H NMR, mass and CD spectra of naturally occurring alectrol, re-isolated from cowpea root exudates, revealed that the genuine structure of the germination stimulant is not orobanchyl acetate but its stereoisomer ent-2′- epi-orobanchyl acetate. Accordingly, the structure of natural orobanchol was revised to ent-2′- epi-orobanchol 12 years after a tentative structure of orobanchol was proposed. Strict stereochemical requirements of strigolactones for germination induction of S. gesnerioides seeds, authentic samples of synthetic strigolactones and advanced analytical instruments made the structural assignment possible, thus ending a 20 years controversy concerning the true structure of alectrol. [ABSTRACT FROM AUTHOR]

Field trials were conducted in 2012 and 2013 at the Teaching and Research Farm of the Department of Agricultural Technology, Plateau State College of Agriculture, Garkawa (08°52'N, 69°24'E) to evaluate the effect of different Parkia pulp levels in the control of Striga gesnerioides in the Southern Guinea Savannah of Nigeria. The treatments consisted of different Parkia rates, applied per hole before planting, thus: 1.0, 2.0, 3.0, 4.0 g/ hill, seed coated with Parkia pulp before planting and control (no Parkia pulp). These treatments were laid out in a Randomized Complete Block Design and replicated three times. The result indicated general delay in the emergence of Striga when Parkia pulp was applied. Similarly, application of 2, 3 and 4 g/ hill of Parkia pulp before planting significantly reduced the number of crop plants infested with Striga and Striga shoot count while crop vigour was increased. Generally, application of Parkia products significantly delayed flowering of Striga and reduced number of capsules per Striga plant. Crop maturity was earliest in the no Parkia treatment. Number of pods per net plot, pod weight and grain yield were not significantly affected by the Parkia treatments though the general trend showed increase with increase in the Parkia pulp up to 3.0 g/hill: however the use of 4.0 g/hill and the seed coated treatments did not show increase in grain yield. The application of Parkia pulp reduced significantly the number of capsules per plant of Striga. The implication of this is that there will be depletion of seed bank build up for future infestation, thereby ensuring control of Striga over time. [ABSTRACT FROM AUTHOR]

Key message: Structure-activity relationship studies of strigolactones and Striga gesnerioides seed germination revealed strict structural requirements for germination induction and a new function of the plant hormones as germination inhibitors. Abstract: Stereoisomers of the naturally occurring strigolactones, strigol, sorgolactone, orobanchol, sorgomol and 5-deoxystrigol, 36 in total, were prepared and screened for the ability to induce and/or inhibit the germination of Striga hermonthica and Striga gesnerioides seeds collected from mature plants that parasitized on sorghum and cowpea, respectively. All of the compounds induced S. hermonthica seed germination, albeit displayed differential activities. On the other hand, only a limited number of the compounds induced significant germination in S. gesnerioides, thus indicating strict structural requirements. Strigolactones inducing high germination in S. gesnerioides induced low germination in S. hermonthica. Strigolactones with the same configuration at C3a, C8b and C2′ as that in 5-deoxystrigol ( 9a) induced high germination of S. hermonthica seeds, but most of them inhibited the germination of S. gesnerioides. The differential response of S. gesnerioides to strigolactones may play an important role in the survival of the species. However, the compounds could be used as means of control if mixed cropping of cowpea and sorghum is adopted. [ABSTRACT FROM AUTHOR]

There have been reports of breakdown of striga resistance in previously resistant cowpea cultivars in Burkina Faso. This could be attributed to new striga races emerging or to an increase in the aggressiveness of current striga races. Therefore, cowpea genotypes were evaluated in fields infested with S. gesnerioides at three striga hot spots in Burkina Faso and in pots under artificial infestation with striga races SR 1, SR 5 and SR Kp to identify new, adapted and striga -resistant sources. Cowpea genotypes showed differential reactions for striga resistance over sites and for striga races in pot experiments, indicating differences in the races involved, and SR Kp was reported as a new race. Resistant sources conferring site-specific or multiple striga-race resistance were identified. Genotypes 58-57, Sanga 2, IT84S-2049, IT98K-205-8, IT93K-693-2, KVx771-10, KVx775-33-2, KVx61-1, Gorom local, Mouride and Melakh conferred resistance to all three striga races. These genotypes are potential donor parents for breeding new, adapted and striga-resistant genotypes. Cowpea landraces including Moussa local and Niaogo local with farmers' preferred traits were susceptible and need improvement for striga resistance. [ABSTRACT FROM AUTHOR]

Background: Cowpea (Vigna unguiculata L.) is an important grain and forage legume grown throughout sub- Saharan Africa primarily by subsistence farmers on poor, drought prone soils. Genetic improvement of the crop is being actively pursued and numerous functional genomics studies are underway aimed at characterizing gene controlling key agronomic characteristics for disease and pest resistances. Unfortunately, similar to other legumes, efficient plant transformation technology is a rate-limiting step in analysis of gene function in cowpea. Results: Here we describe an optimized protocol for the rapid generation of transformed hairy roots on ex vitro composite plants of cowpea using Agrobacterium rhizogenes. We further demonstrate the applicability of cowpea composite plants to study gene expression involved in the resistance response of the plant roots to attack by the root parasitic weed, Striga gesnerioides. The utility of the new system and critical parameters of the method are described and discussed herein. Conclusions: Cowpea composite plants offer a rapid alternative to methods requiring stable transformation and whole plant regeneration for studying gene expression in resistance or susceptibility responses to parasitic weeds. Their use can likely be readily adapted to look at the effects of both ectopic gene overexpression as well as gene knockdown of root associated defense responses and to the study of a broader range of root associated physiological and aphysiological processes including root growth and differentiation as well as interactions with other root pests, parasites, and symbionts. [ABSTRACT FROM AUTHOR]

Background: Cowpea, Vigna unguiculata L. Walp., is one of the most important food and forage legumes in the semi-arid tropics. While most domesticated forms of cowpea are susceptible to the root parasitic weed Striga gesnerioides, several cultivars have been identified that show race-specific resistance. Cowpea cultivar B301 contains the RSG3-301 gene for resistance to S. gesnerioides race SG3, but is susceptible to race SG4z. When challenged by SG3, roots of cultivar B301 develop a strong resistance response characterized by a hypersensitive reaction and cell death at the site of parasite attachment. In contrast, no visible response occurs in B301 roots parasitized by SG4z.Results: Gene expression in the roots of the cowpea cultivar B301 during compatible (susceptible) and incompatible (resistant) interactions with S. gesnerioides races SG4z and SG3, respectively, were investigated at the early (6 days post-inoculation (dpi)) and late (13 dpi) stages of the resistance response using a Nimblegen custom design cowpea microarray. A total of 111 genes were differentially expressed in B301 roots at 6 dpi; this number increased to 2102 genes at 13 dpi. At 13 dpi, a total of 1944 genes were differentially expressed during compatible (susceptible) interactions of B301 with SG4z. Genes and pathways involved in signal transduction, programmed cell death and apoptosis, and defense response to biotic and abiotic stress were differentially expressed in the early resistance response; at the later time point, enrichment was primarily for defense-related gene expression, and genes encoding components of lignifications and secondary wall formation. In compatible interactions (B301 – SG4z), multiple defense pathways were repressed, including those involved in lignin biosynthesis and secondary cell wall modifications, while cellular transport processes for nitrogen and sulfur were increased. Conclusion: Distinct changes in global gene expression profiles occur in host roots following successful and unsuccessful attempted parasitism by Striga. Induction of specific defense related genes and pathways defines components of a unique resistance mechanism. Some genes and pathways up-regulated in the host resistance response to SG3 are repressed in the susceptible interactions, suggesting that the parasite is targeting specific components of the host’s defense. These results add to our understanding of plant-parasite interactions and the evolution of resistance to parasitic weeds. [ABSTRACT FROM AUTHOR]

The article examines the molecular genetics of race-specific resistance of the warm-season legume cowpea to the root hemiparasitic weeds Striga gesnerioides (Willd.). Farmers in West and Central sub-Saharan Africa have been planting cowpea for human consumption and animal forage. Striga gesnerioides is a significant biotic constraints to cowpea production in which about seven races have been determined within the regions of West Africa. However, some race-specific resistance genes of cowpea have been determined and located to any of two linkage groups of the plant's genetic map. The examination of the mechanism of race-specific resistance of cowpea suggests that the pathogenesis-related gene (PR5) expression may serve as a useful marker of infection due to Striga gesnerioides.

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Cowpea is an important food crop in the dry savannas of West and Central Africa because of its high protein content. Yields are, however, considerably reduced by the parasitic angiosperm Striga gesnerioides. Field trials over 2 years in two localities in northeast Nigeria evaluated the performance of diverse cowpea varieties under conditions of natural infestation by Striga. Grain yield was higher in Tilla than in Damboa where the higher Striga infestation may be caused by the lower rainfall and the sandy nature of the soils. Two varieties (IT97K-499-35 and IT90K-82-2) were confirmed to be resistant to Striga. Yield gain from IT97K-499-35 over the local variety ranged from 30% in Tilla in the northern Guinea savanna to 126% in Damboa in the Sudan savanna. The local variety Borno Brown and two improved varieties were found to be as susceptible to Striga as the susceptible control, TVX-3236, and therefore may not be recommended for cultivation in areas where Striga infestation is a problem. One variety, reported previously to be resistant to one or two races of Striga supported moderate levels of emerged Striga, suggesting that it is not totally resistant to the Striga race in the two localities. However, it produced grain yields that were comparable to the resistant varieties in the locality that was most infested, suggesting that it is tolerant to Striga. There are concerns about the adoption potential of the Striga-resistant variety IT97K-499-35 because of its medium-sized white seeds. Farmers in this zone prefer large-seeded brown cowpea. We recommend that efforts be made to develop Striga-resistant varieties that satisfy end-user preferences. [ABSTRACT FROM AUTHOR]

Striga gesnerioides is a root hemiparasite that primarily parasitizes dicotyledonous species, including cowpea (Vigna unguiculata L.) and other legumes. Based on the differential resistance response of various cultivars, landraces, and breeding lines, it has been proposed that several distinct races of cowpea-parasitic S. gesnerioides exist in West Africa. In this study, we used amplified fragment length polymorphism profile analysis to examine the genetic variability within and among populations of cowpea-parasitic S. gesnerioides within the suspected distribution range of a particular race, and statistical clustering methods to define the phenetic relationships of the various races in West Africa. Our data indicate that genetic variability within and among populations of each of the previously recognized races of cowpea-parasitic S. gesnerioides is extremely low. On the basis of genotypic profile and host differential resistance responses, 2 previously unknown races were identified. Of the 7 races now identifiable, races SG1 (from Burkina Faso) and SG5 (from Cameroon) are the most closely related, and SG4 (from Benin) and SG3 (from Niger/Nigeria) are the most divergent. SG6, a new race of the parasite identified in Senegal, was found to be the most genetically similar to SG4 from Benin. We also demonstrate that a hypervirulent isolate of the S. gesnerioides from Zakpota, in the Republic of Benin, is genotypically distinct from other populations of SG4, thereby warranting designation as a separate race, which we called SG4z. To further support our race classification scheme, we identified a group of molecular markers that effectively discriminate each of the various races. Finally, we show that an isolate (designated SG4i) of the wild legume Indigofera hirsuta–parasitic S. gesnerioides is genetically distinct and significantly diverged from the various races of cowpea-parasitic S. gesnerioides. Our data suggest that both geographic isolation and host-driven selection are critical factors defining race formation in S. gesnerioides in West Africa. [ABSTRACT FROM AUTHOR]

Abstract: Parasitism of crop plants by Striga species is a major constraint in the savanna zones of West Africa. Farmers ranked Striga as a leading constraint during a livelihood analysis of 30 communities in northeast Nigeria. A field survey was conducted to ascertain the extent of infestation by Striga spp. About 935 crop and fallow fields were surveyed across 30 communities in three agro-ecological zones. Four major Striga species were identified: Striga hermonthica in sorghum or maize; Striga aspera in rice; Striga densiflora in pearl millet and fallow and Striga gesnerioides in cowpea. About 68% of all fields sampled were infested, about 75% of compound fields and 60% of bush fields. The level of infestation was 60% in southern Guinea, 68% in Sudan and 74% in northern Guinea savanna. The level of infestation of cereal fields by S. hermonthica was in the order of Sudan savanna>Northern Guinea>Southern Guinea. Infestation of cowpea with S. gesnerioides was in the order of Northern Guinea savanna>Sudan savanna>Southern Guinea savanna. Across the three ecozones, about 85% of fields planted to maize and sorghum were infested with S. hermonthica and 81% of cowpea fields with S. gesenerioides. S. aspera infested 40–59% of rice fields and S. densiflora infested 27–60% of millet fields and fallow. [Copyright &y& Elsevier]

An in vitro growth system was used to investigate the expression of resistance of cowpea [Vigna unguiculata (L.) WaIp.] varieties B301 and 58-57 to the angiosperm parasite Striga gesnerioides (Wilid.) Vatke. Variety Blackeye was included in experiments as a susceptible control. Seeds of S. gesnerioides germinated on the roots of all varieties. Two different mechanisms of resistance were expressed in B301 and 58-57 after penetration of host roots by parasite radicles. The first mechanism was expressed in both varieties; host tissue around invading Striga radicles became necrotic in association with the early death of the parasite and lack of tubercle formation. On variety 58- 57, the necrosis response was expressed only when the roots were inoculated with Striga from Burkina Faso but Striga from Mali successfully parasitized the roots of variety 58-57. The second mechanism was observed only on variety B301. Striga radicles infected cowpea roots, tubercles were formed but remained at 1-2mm in diameter with very limited stem growth. No further development of the parasite occurred in vitro or when infected cowpea were grown in soil or vermiculite. Similarities between the expression of resistance of cowpea to Striga and of plants to plant pathogenic fungi are discussed. [ABSTRACT FROM AUTHOR]

The association between the parasite Striga gesnerioides and cowpea (Vigna unguiculata) was investigated using measurements of growth and gas exchange together with calculations of the carbon budget of the association. Striga gesnerioides has a very low photosynthetic capacity coupled with high rates of respiration. Even at photosynthetic light saturation shoots exhibit no net carbon gain. Thus S. gesnerioides is highly dependent on its host for carbon as well as for water and inorganic solutes. It is estimated that 70% of the carbon transferred from host to parasite is used in parasite respiration. Infected cowpea had a lower photosynthetic capacity, at times less than half that of uninfected plants. Infection with S. gesnerioides reduced the growth of cowpea by 75%. Calculations indicate that the loss of carbon from the host by export to the parasite is more important than reduced photosynthetic capacity of the host in accounting for the observed growth reductions. [ABSTRACT FROM AUTHOR]

Pot and laboratory experiments were performed in order to elucidate the genetics of resistance of three cowpea (Vigna unguiculata (L.) Walp.) resistant sources to two biotypes of the parasitic weed Striga gesnerioides (Willd.) Vatke (witchweed). B301, Suvita-2 and IT82D-849 were crossed to susceptible cultivars. Roots of each plant of parental, F1, F2, BC1 and BC2 populations were washed free of soil and examined closely for S. gesnerioides attachment. Data on resistant and susceptible cowpea plants were analyzed using the chi-square test to ascertain the goodness of fit to different genetic ratios. Segregation patterns indicate monogenic dominant inheritance of resistance to both S. gesnerioides biotypes in B301. Suvita-2, which is susceptible to the biotype from Maradi, Niger, showed segregation patterns that indicate monogenic dominant inheritance of resistance to S. gesnerioides biotype from Cinzana, Mali. Results also indicate monogenic dominant inheritance of resistance to S. gesnerioides biotype from Cinzana in IT82D-849. However, the inheritance of resistance to the biotype from Maradi would be monogenic and recessive in this line. These results suggest that the resistance of all three sources would be easy to transfer to promising breeding lines. [ABSTRACT FROM AUTHOR]