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Background. The article presents the results of the studies carried out within the framework of a complex program for the long-term conservation of genotyped accessions of advanced potato cultivars in the cryobank of the N.I. Vavilov All-Russian Institute of Plant Genetic Resources (VIR). These accessions are genetically identical to the nomenclature standards of the corresponding cultivars.Materials and methods. The research material included 24 accessions from the in vitro collection of VIR, corresponding to the nomenclature standards of Russian potato cultivars developed in different breeding centers of the Russian Federation. Cryopreservation was carried out using the droplet vitrification method, several stages of which were modified in the Department of Biotechnology of VIR.Results and discussion. The frequency of post-cryogenic regeneration for the analyzed 24 cultivars in control variants with short-term immersion of explants in liquid nitrogen varied from 20 to 47.3%, and in 9 accessions it exceeded 39% – the current level of reliable long-term preservation of samples in cryobanks. The data of the statistical analysis failed to reveal a significant effect of the genotype or the calendar dates of different experiment replications on the regeneration ability. These 24 accessions were added to the potato cryocollection stored in the VIR cryobank. An analysis of the composition and structure of VIR’s potato cryocollection, which currently includes 140 accessions, is presented.

Cryopreservation of shoot-tips (apexes) excised from in vitro plants is used for long-term preservation of potato cultivars. The most widely used method for creating potato cryo-collections is droplet-vitrification of shoot-tips which, together with its numerous modifications, is widely used in genebanks. A modified protocol of droplet vitrification method is used at VIR for cryopreservation of shoot tips from in vitro potato plants. This paper presents the results of cryopreservation of modern cultivars which were released by seven Russian breeding centers. In vitro clones used in the cryopreservation experiments were genetically identical to the cultivars’ nomenclatural standards and herbarium vouchers.The frequency of post-thaw regeneration in control experiments after short-term cryopreservation varied from 23.3 to 53.3%, depending on the genotype. Five out of 16 accessions (‘Varâg’, ‘Gusar’, ‘Evpatij’, ‘Solnečnyj’, ‘Tango’)* had low post-cryogenic regenerative capacity from 20 to 30%; the regeneration rate exceeded 30% in 11 accessions, and 8 cultivars (‘Grand’, ‘Zlatka’, ‘Lina’, ‘Safo’, ‘Siverskij’, ‘Signal’, ‘Utro’, ‘Ûna’) and ‘Аlyj Parus’ breeding clone had regeneration rate above 40%. The regeneration rate in the studied subset was genotype independent according to the ANOVA results (p=0.711). Viability and regeneration rate were significantly correlated (r=0.86). As a result of the experiments, explants of 14 modern cultivars and two breeding clones with the known post-thaw regeneration rate were successfully cryopreserved in the VIR cryobank. Four cultivars (‘Grand’, ‘Gusar’, ‘Signal’, ‘Utro’) were monitored for their regeneration capacity after the long-term (seven months) preservation in the VIR cryobank. On an average, these four cultivars demonstrated a post-thaw regeneration capacity of 41.8%. It can be concluded that the use of the modified method of droplet vitrification is relevant for increasing the VIR potato cryo-collection.

Molecular tools were largely used to characterise native almond (Prunus dulcis Mill.) cultivars, to elucidate their diversification and to establish their membership to Mediterranean germplasm pools. Hereby, the efficiency of the application of PCR techniques to study the genetic diversity of S alleles in almond was tested to identify self-incompatible cultivar combinations and groups. Hence, an analysis with consensus AS1II and AmyC5R and with allele-specific primers was performed for 25 almond accessions including 17 local Tunisian cultivars, 7 advanced selections, and 1 extra group from Italy in order to identify their S-genotype. Interestingly, all genotypes were assigned to their specific self-incompatible groups and a new group (LI) has been established. The two cultivars 'Dillou' and 'Porto' both considered as self-compatible have been demonstrated to be self-incompatible. Results reveal also a discrepancy for the S-genotype assigned to 'Zahaaf' preserved in the International almond collection. Thus, S genes genotyping of commercially used or newly released cultivars is very useful as we demonstrated that it may show that common knowledge may be partly inaccurate. For important varieties, this immediately has a consequence for cultivation practices, also for smallholder orchards as changing an incorrect practice may in time increase yield and also guarantee yield stability. [ABSTRACT FROM AUTHOR]

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The rates of grain-setting in apical and basal spikelets in wheat directly affects the kernel number per spike. In this study, 220 wheat lines from 18 Chinese provinces and five foreign countries were used as a natural population. Phenotypic analysis showed differences in grain-setting rates between apical and basal spikelets. The broad-sense heritability of grain-setting rate in apical spikelets (18.7-21.0%) was higher than that for basal spikelets (9.4-16.4%). Significant correlations were found between kernel number per spike and grain numbers in apical (R2=0.40-0.45, P＜0.01) and basal (R2=0.41-0.56, P＜0.01) spikelets. Seventy two of 106 SSR markers were associated with grain setting, 32 for apical spikelets and 34 for basal spikelets. The SSR loci were located in 17 chromosomes, except 3A, 3D, 4A and 7D, and explained 3.7-22.9% of the phenotypic variance. Four markers, Xcfa2153-1A202, Xgwm186-5A118, Xgwm156-3B319 and Xgwm537-7B210, showed the largest effects on grain numbers in the apical and basal spikelets. High grain numbers in the apical and basal spikelets were associated with elite alleles. Ningmai 9, Ning 0569 and Yangmai 18 with high grain-setting rated carried larger numbers of favorable alleles. Comparison of grain numbers in basal and apical spikelets of 35 Yangmai and Ningmai lines indicated that the Ningmai lines had better grain-setting rates (mean 21.4) than the Yangmai lines (16.5).

The rates of grain-setting in apical and basal spikelets in wheat directly affect the kernel number per spike (KNPS). In this study, 220 wheat lines from 18 Chinese provinces and five foreign countries were used as a natural population. Phenotypic analysis showed differences in grain-setting rates between apical and basal spikelets. The broad-sense heritability of grain-setting rate in apical spikelets (18.7-21.0%) was higher than that for basal spikelets (9.4-16.4%). Significant correlations were found between KNPS and grain numbers in apical (R2 = 0.40-0.45, P < 0.01) and basal (R2= 0.41-0.56, P < 0.01) spikelets. Seventy two of 106 SSR markers were associated with grain setting, 32 for apical spikelets, and 34 for basal spikelets. The SSR loci were located on 17 chromosomes, except 3A, 3D, 4A, and 7D, and explained 3.7-22.9% of the phenotypic variance. Four markers, Xcfa2153-1A202, Xgwm186-5A118, Xgwm156-3B319, and Xgwm537-7B210, showed the largest effects on grain numbers in apical and basal spikelets. High grain numbers in apical and basal spikelets were associated with elite alleles. Ningmai 9, Ning 0569, and Yangmai 18 with high grain-setting rates carried larger numbers of favorable alleles. Comparison of grain numbers in basal and apical spikelets of 35 Yangmai and Ningmai lines indicated that the Ningmai lines had better grain-setting rates (mean 21.4) than the Yangmai lines (16.5). [ABSTRACT FROM AUTHOR]

The rates of grain-setting in apical and basal spikelets in wheat directly affect the kernel number per spike (KNPS). In this study, 220 wheat lines from 18 Chinese provinces and five foreign countries were used as a natural population. Phenotypic analysis showed differences in grain-setting rates between apical and basal spikelets. The broad-sense heritability of grain-setting rate in apical spikelets (18.7-21.0%) was higher than that for basal spikelets (9.4-16.4%). Significant correlations were found between KNPS and grain numbers in apical (R (2) = 0.40-0.45, P < 0.01) and basal (R (2) = 0.41-0.56, P < 0.01) spikelets. Seventy two of 106 SSR markers were associated with grain setting, 32 for apical spikelets, and 34 for basal spikelets. The SSR loci were located on 17 chromosomes, except 3A, 3D, 4A, and 7D, and explained 3.7-22.9% of the phenotypic variance. Four markers, Xcfa2153-1A 202 , Xgwm186-5A 118 , Xgwm156-3B 319 , and Xgwm537-7B 210 , showed the largest effects on grain numbers in apical and basal spikelets. High grain numbers in apical and basal spikelets were associated with elite alleles. Ningmai 9, Ning 0569, and Yangmai 18 with high grain-setting rates carried larger numbers of favorable alleles. Comparison of grain numbers in basal and apical spikelets of 35 Yangmai and Ningmai lines indicated that the Ningmai lines had better grain-setting rates (mean 21.4) than the Yangmai lines (16.5).