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19 random amplified polymorphic DNA (RAPD) and five Inter-simple sequence repeat (ISSR) primers were used to characterize 35 potato accessions originating from Mexico, Europe and U.S.A, with the aim of generating information on the genetic diversity and relationship among the genotypes for better exploitation in breeding programs. A total of 222 and 82 loci were generated by the RAPD and ISSR primers, respectively. Both RAPD and ISSR primers revealed 81.45 and 82.98% polymorphism, respectively. Mantel test showed no correlation between RAPD and ISSR (0.27), RAPD and RAPD + ISSR (0.47) similarity matrices. However, a high level of correlation (0.74) was observed between ISSR and RAPD + ISSR similarity matrices. The ISSR marker was found to be more efficient compared to RAPD marker, thereby influencing more the consensus data. The use of consensus data generated more information related to genetic diversity in potato. RAPD and ISSR markers successfully differentiated between the potato accessions and subgrouped the genotypes based on origin. Information on genetic diversity and relationships will be useful in the selection of parents and mapping studies.

Identification of effective indigenous rhizobia strain nodulating soybean (Glycine max) was conducted in Kakamega County, Western Kenya. This study was carried out to establish the abundance and symbiotic efficiency of native rhizobia strains in soil samples collected from 12 sites in four agroecological zones within the region. The MPN enumeration technique was used to estimate the indigenous rhizobia numbers and showed that 54% of the sampled sites had high abundance. Rhizobia number in the soil collected from the six regions varied from 2.5 × 102 to 3.12 × 103 cells·g− soil. Thirty isolates from the soil collected in the four regions were tested for efficiency using soybean as the trap plant in Leonard jars containing sterilized vermiculite irrigated with nitrogen-free media. Determination of the relationship between rhizobial abundance and symbiotic efficiency with respect to the soil chemical conditions was performed using ANOVA, and the means were compared using Tukey’s honest significant difference test. Inoculation with bacterial isolates significantly ( P < 0.05 ) increased the nodule number and shoot dry weight, while weight of the seeds showed variations across the groups. The soil pH across the 4 regions ranged between 5.41 and 6.52.

La información sobre identificación, diversidad genética y relaciones entre genotipos de papa (Solanum tuberosum L.) es de importancia para su conservación eficiente, mejoramiento genético y utilización de los recursos genéticos de esta especie. Por tanto, con el objetivo de evaluar la eficiencia de los caracteres morfológicos y marcadores tipo RAPD e ISSR para discriminar genotipos de papa, se caracterizaron 15 variedades de papa cultivadas en México. Se evaluaron 12 caracteres cuantitativos y tres cualitativos transformados a una escala nominal. Ambos marcadores detectaron diversidad genética entre variedades y las diferenciaron, pero la prueba de Mantel mostró baja correlación entre la matriz de similitud morfológica y la molecular. Los marcadores moleculares discriminaron completamente a los 15 cultivares analizados, mientras que los marcadores morfológicos fueron incapaces de discriminar algunos de ellos. Para que los programas de mejoramiento sean eficientes es importante seleccionar líneas con base en su diversidad genética y parámetros agro-morfológicos, asistidos con marcadores moleculares.

Prior to Agrobacterium-mediated genetic transformation in vitro regeneration protocol was established for three potato cultivars (Alfa, Cambray Rosa Morelos and Atlantic) grown in Mexico using leaf, node and internodal explants. Regeneration protocol was developed with or without the intervention of callus. Two potato cultivars, namely, Cambray Rosa Morelos and Alpha were transformed using Agrobacterium tumefaciens strain LBA4404 harboring binary plasmid pBI121 containing the GUS and nptII genes. GUS histochemical assay and PCR analysis were conducted on rooted shoots grown in media without hormones but supplemented with antibiotics. Transformed shoots tested positive through GUS histochemical assay and integration of nptII gene was confirmed by PCR analysis DOI: http://dx.doi.org/10.3329/ptcb.v22i2.14193 Plant Tissue Cult. & Biotech. 22(2): 93-105, 2012 (December)

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Diversidad genética entre variedades de papa (Solanum tuberosum L.) cultivadas en México usando marcadores RAPD e ISSR* Genetic diversity among potato varieties (Solanum tuberosum L.) grown in Mexico, using RAPD and ISSR markers