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Abstract. Konan NO, Akaffou MA, Kouadio L, Akaffou DS, Mergeai G. 2020. Genetic diversity of exotic and local eggplants (Solanum spp.) cultivated in Côte d’Ivoire based on ISSR markers. Biodiversitas 21: 3651-3658. Eggplants are important vegetables in Côte d'Ivoire. Despite an increase in the cultivation of exotic genotypes and their progressive dominance over local cultivars, which could represent a threat of genetic erosion, there are not enough molecular data available on the genetic diversity of the eggplants currently cultivated in this country. This study is a contribution to the knowledge of the genetic diversity of the current eggplant cultivars grown in Côte d’Ivoire. It aimed to assess the genetic variation of nine exotic and local eggplants commonly cultivated in Côte d'Ivoire, using five inter-simple sequence repeat (ISSR) primers. The results revealed for the exotic cultivars 42 ISSR loci of which 31 were polymorphic (73.81 %), and for local cultivars 51 loci of which 49 (96.08%) were polymorphic. The Nei’s genetic diversity and Shannon’s information index of local cultivars (He = 0.3333 and I = 0.4863) were higher than those of exotic cultivars (He = 0.2000 and I = 0.2971). The Gst value and the AMOVA analysis found more than 70% of the total genetic diversity within the groups. The Jaccard’s dissimilarity coefficients between the cultivars, ranged from 0.324 to 0.966 with an average of 0.741. The clustering of genotypes with the neighbor-joining unrooted tree and PCoA analysis differentiated three main clusters with exotic cultivars grouped in cluster I and local cultivars in cluster II and III. In view of these results, the local eggplants had higher genetic diversity and constitute an interesting germplasm which needs to be conserved for potential breeding programs.

To improve cotton fiber fineness, the (Gossypium hirsutum L. × Gossypium longicalyx Hutch. & Lee)² allohexaploid and the [(Gossypium hirsutum L. × Gossypium thurberi Tod.)² × G. longicalyx] allotetraploid were backcrossed to G. hirsutum to produce introgressed genetic stocks. The ribbon width (RW) of 600 swelled fibers produced by the hybrids, their parents, and their backcross progeny were analyzed for each compared genotype using an optical microscope. The RWs varied between 6.41±2.15 µm for G. longicalyx to 17.45±2.98 µm for the G. hirsutum parent cultivar C2. Fibers produced by the trispecific hybrids and their progeny were finer than the bispecific hybrid material. For the introgressed stocks, the lowest RWs were observed for the trispecific hybrid (10.79±2.14 µm) and certain backcross progenies (between 11.98±1.27 µm to 12.71±1.61 µm). The allohexaploid RW was 13.58±1.41 µm. One of its tetraploid progeny produced approximately the same value (13.94±2.48 µm). These results show that G. longicalyx is a potential genetic stock for cotton fiber fineness improvement. The genetic stocks produced are valuable materials for improve the fineness of cotton fiber.

Wild cotton species are an important source of desirable genes for genetic improvement of cultivated cotton Gossypium hirsutum Linnaeus, 1763. For the success of such an improvement, chromosome pairings and recombinations in hybrids are fundamental. The wild African species G. longicalyx Hutchinson & Lee, 1958 could be used as donor of the desirable trait of fiber fineness. Twelve BC1 plants obtained from the backcrossing of [(G. hirsutum × G. thurberi Todaro, 1877)2 × G. longicalyx] (AhDhD1F1, 2n = 4x = 52) trispecies hybrid (HTL) by G. hirsutum (cv. C2) (AhAhDhDh, 2n = 4x = 52) were investigated for meiotic behaviour and plant fertility. Their chromosome associations varied as follows: (2.5 to 11.5) I + (17 to 22) II + (0.31 to 1.93) III + (0.09 to 1.93) IV + (0 to 0.07) V + (0 to 0.14) VI. Their pollen fertility ranged from 4.67 to 32.10 %. Only four BC1 plants produced a few seeds through self-pollination. The remaining BC1 were totally self-sterile and usually presented the highest number of univalents. All BC1 materials produced BC2 seeds (0.44 to 6.50 seeds per backcross) with the number of seeds negatively correlated with the number of univalents (R2 = 0.45, P < 0.05). Most BC1 plants gave significantly finer fiber compared to the cultivated G. hirsutum. SSR markers showed a segregation of wild alleles among the backcross derivatives and Genomic in situ hybridization (GISH) revealed presence of entire chromosomes of G. longicalyx as well as recombinant chromosomes in the backcross derivatives. The significance and details of these results are presented and the prospects of successfully exploiting these plant materials are discussed.

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Bacterial wilt caused by Ralstonia solanacearum is one of the most damaging tomato diseases in the world. The best strategy for controlling this disease is to use genetically resistant tomato plants. In this study, 28 tomato cultivars were evaluated in the field for their resistance to bacterial wilt in Daloa, one of the most important agricultural regions of Côte d'Ivoire. The experiments were carried out during the dry and rainy season and the experimental design was a Randomized Complete Block Design (RCBD) with three replications. The results showed the presence of wilt disease. The streaming test and bacterial culture on growth medium proved the bacterial origin of the wilt symptoms observed. The results of the staining reactions revealed short, straight, rod and Gram negative bacteria similar to R. solanacearum. The severity of the disease was found to be higher in the dry season than in the rainy season. Of 28 cultivars evaluated, 7 cultivars were resistant and did not show any diseased plants during the two study periods. These cultivars constitute interesting sources of resistance for a breeding program aimed at the development of new resistant cultivars adapted to the region of Daloa. Keywords: Bacterial wilt, Ralstonia solanacearum, resistance, tomato, Solanum lycopersicum, breeding program.