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The growth and physiological parameters of fourteen tomato cultivars were measured during both mild and severe drought. The tomato cultivars showed decrease in growth traits, relative water content and pigments content under both drought treatments compared with the control. By contrast, proline accumulation, malondialdehyde and electrolyte leakage increased in the cultivars. The activity of superoxide dismutase was more correlated to drought stress than those of ascorbate peroxidase or catalase. The combined approach of principal component analysis, hierarchical clustering analysis and calculating mean tolerance value showed relative differences in drought tolerance among the cultivars. The studied cultivars were clustered into four groups. Four cultivars were placed in cluster I as the drought-tolerant group. Moderately tolerant cultivars were grouped into Cluster II. The clusters III and IV represented the sensitive and highly sensitive cultivars, respectively. Early orbana, Roma and Cal-j cultivars were indicated as the highly sensitive tomato cultivars. It was concluded that such an approach could be used as a useful tool to screen the other abiotic or even biotic stress tolerance in tomato. [ABSTRACT FROM AUTHOR]

Highlights • Variation analysis of Prunus scoparia by molecular marker. Abstract Evaluation of spatial and non-spatial distribution is of great importance for protection of plant's genetic resources. Prunus scoparia , a wild almond species, is an important economically and ecologically food resource plant in Iran with specific characteristics such as self-compatibility, resistant to drought and fungus, bitterness as well as small nuts. This wild species can provide an enlarged gene pool and may be considered as a valuable germplasm source for breeding the cultivated almond. In this study, the conservation planning and genetic variation of 158 Prunus scoparia accessions was investigated with the aid of 36 SSR markers to reveal genetic distinctness and structure. The molecular markers studied showed quite high level of genetic diversity on the basis of N a = 6.47, H o = 0.603 and H e = 0.737. The result of Neighbor net analysis was not in parallel with STRUCTURE data as classified samples into two and 12 main groups, respectively. On the other hand, the results of GENELAND analysis ensured the population classification and the genetic relatedness between populations from STRUCTURE analysis due to use of geographical data. All samples were grouped based on their geographical location. Moreover, utilization of GIS data accompanied by appropriate number of SSR markers could provide the possibility of prioritizing of distribution regions in natural and unnatural environments. The species distribution modeling would also help gain comprehensive information on conservation strategies of this wild almond species. [ABSTRACT FROM AUTHOR]

Abstract: A set of twelve simple sequence repeat markers was used to evaluate the genetic background of 738 pomegranate (Punica granatum L.) accessions, which belonged to the Iranian National Pomegranate Collection, from 23 provinces of Iran. Genetic diversity among the accessions was analysed using several variability parameters. Forty-three alleles were detected with a mean of 3.59 alleles per locus. The highest levels of polymorphism were found for the locus ABRII-MP26. The mean values of expected heterozygosity and polymorphic information content were 0.521 and 0.458, respectively. Neighbour-Net analysis based on uncorrected P distances and a model-based method separated the accessions into 8 main groups and several subgroups, with a tendency to cluster by geographical origin. From the simple sequence repeat analysis, it can be concluded that the genetic base of the Iranian National Pomegranate Collection is broad enough to ensure future progress in breeding programmes and these markers are effective tools for conducting genetic diversity studies in pomegranate and developing strategies for germplasm management. [Copyright &y& Elsevier]