Iranian Journal of Genetics and Plant Breeding
Volume:3 Issue: 1, Apr 2014

Potato virus Y (PVY) as one of the serious diseases on tobacco (Nicotiana tabacum L.), reduces leaf yield and its quality. Use of resistant genotypes is being considered as the most effective, economical and a safe way to reduce damages of the virus. In the present study, the response of 90 oriental and semioriental tobacco genotypes was evaluated against PVY using randomized complete block design with three replications under controlled conditions. Each replicate consisted of 6 seedlings. The leaves of each genotype were inoculated mechanically via rubbing method at 4-6 leaf stage with PVY. Four weeks following inoculation, the studied genotypes showed different severity symptoms associated with PVY. ELISA assay were applied on the inoculated plants by the indirect method using the polyc lonal antibody specific to PVY. Optical density value of each infected sample was read at 405 nm using an ELISA reader. Analysis of variance on ELISA data showed significant differences among genotypes for concentration of PVY. Results revealed that 'Erzeogovina' genotype with OD=0.68881 contained the highest virus concentration whereas the 'KB101' genotype with OD=0.0005 contained the lowest virus concentration. The differed reactions of genotypes to PVY virus encourage the use of resistance genetic resource for the reduction of disease damages.

Apple is one of the most important temperate-zone fruit trees in the world. Micropropagation of apple scion and rootstocks is an important method of rapid production of healthy and disease-free plants. In this research, in vitro propagation of three apple roottocks including Azayesh-Esfahan, Morabbaee- Mashhad and M9 was investigated. Shoot proliferation carried out in two basal media (MS and WPM) containing three concentrations of BA (0.5, 1 and 1.5 mgL-1) and also, rooting of microshoots were investigated in two basal media (MS and ½ MS) with three concentrations of IBA (0.5, 1 and 1.5 mgL-1). The results showed that all studied factors including cultivars, media, BAP, IBA concentrations and interaction among them had significant effects on both shoot proliferation and rooting of rootstocks. Regardless of rootstocks and media, the maximum and minimum shoot proliferation rates were obtained in the media containing 1.5 mgL-1 and 0.5 mgL-1 BA, respectively. The MS medium was more effective on shoot proliferation than WPM medium. The Azayesh- Esfahan and Morabbaee-Mashhad showed the maximum and minimum (4.46 and 3.66 shoots/explants) shoot proliferation values, respectively. However, all roottocks had the maximum rooting in the ½MS media containing 1.5 mgL-1 IBA. In overall, Azayesh- Esfahan showed the maximum shoot proliferation (5.11 shoots/explants) and rooting (48.33 %) among roottocks.

Powdery mildew caused by Erysiphe cichoracearum is an important fungal disease which threatens tobacco (Nicotiana tabacum L.) production. The objective of this study was to determine DNA markers linked to genomic regions associated with resistance to powdery mildew in tobacco through the association mapping approach. Seventy tobacco genotypes were fingerprinted using 26 simple sequence repeat (SSR) primer pairs which were distributed in several chromosomes of tobacco.A total number of 66 alleles were detected by 26 SSR primers with an average of 2.53 alleles per locus. Based on population structure analysis, the studied genotypes were classified into three groups including Chopogh, PD and Tikolak genotypes. Ou of 325 marker pairs, 6.15% showed a significant level of linkage disequilibrium (LD) (P<0.01). The mean of D´ for all marker pairs was 0.268. Using susceptibility data of the 70 genotypes against fungal agent, three loci (pt30034, pt30008 and pt30159) from linkage groups 22, 11 and 14b of tobacco reference linkage map were identified to be associated with the gene(s) controlling resistance to powdery mildew. The identified markers could be good candidates for marker assisted selection in powdery mildew disease resistance breeding programs. However, like any other quantitative trait, there is a requirement to assess the quality of the obtained quantitative trait loci (QTLs) before marker assisted selection (MAS) become a viable proposition.

The study was conducted to investigate the genetic basis of kenaf fiber yield and quality In two sets of generations derived from 1X51 x Ghana07 and Gregg x Ghana07 crosses. Analysis of generation meansusing weighted least squares procedure was performed on stalk dry weight, bast percentage, days to flowering, plant height, and basal stalk diameter. Analysis of generation means revealed that bast percentage was mainly controlled by dominance effects whereas stalk dry weight was mainly controlled by additive effects. Estimates of heterosis based on midparental values were generally high and ranged from 10 to 55% for stalk dry weight and bast percentage. Estimates of inbreeding depression, calculated from F1 and F2 generation means, were 55% for stalk dry weight in Population 1 and 43% in Population 2. Estimates of inbreeding depression for bast percentage were 5% in Population 1 and 15% in Population 2. The results of this study indicated that the portion of phenotypicvariations, which is controlled by additive gene effects, was generally high for stalk dry weight. Thus, selectingthe segregating generations would lead to significant improvement of fiber yield.

Plants encounter various stresses such as drought and salinity which adversely affect growth, development and crop productivity. The expression of the genes Delta -1- pyrroline – 5 - carboxylate synthetase (P5CS) and Betaine aldehyde dehydrogenase (BADH) extends throughout various protective mechanisms in plants and allows them to adapt to unfavorable environmental conditions. P5CS and BADH genes expression patterns in the wheat cultivars Mahuti and Alamut were studied under salt and ABA treatments using a qRT-PCR technique. Results showed that gene expression patterns were significantly different in these two cultivars. Mahuti had significantly higher expressions of P5CS at 3h compared to other time courses, while Alamut had significantly higher expressions of P5CS at 72h. In addition, these result showed that the P5CS gene expression increased after treatment of ABA and NaCl in both Mahuti and Alamut cultivars. Similarly, Mahuti had significantly higher expressions of BADH at 72h compared to other time courses, while Alamut had significantly higher expressions of BADH at 24h. It is likely that the difference in gene expression patterns between Mahuti as a salt tolerant cultivar and Alamut as a salt sensitive cultivar is due to different signaling pathways that activate P5CS and BADH expressions. Lack of significant difference between these genes expression profile under salt and ABA treatment suggest that P5CS and BADH are not induced by the stresses used in this study. It is also possible that different concentrations of NaCl and ABA are required to cause a change in the expression of P5CS and BADH genes.

Hairy roots culture is a potential system for secondary metabolite production in medicinal plants. In this research, hairy root induction in Echinacea angustifolia was established using Agrobacterium rhizogenes. The effects of different A. rhizogenes strains (AR15834, A4, K599 and MSU440) in two solid growth regulator- free culture media, half strength MS salts with B5 vitamins and WPM, were evaluated on hairy root induction in 60-day-old explants. The highest percentage of root induction was obtained by AR15834 strain in the WPM medium (46.6%). Also, the effects of age (20, 40 and 60 day-old) and type (leaf, leaf lamina and petiole) of explant on hairyroot induction were investigated by AR15834 strain in the WPM medium. The high frequency of hairy root induction was obtained in leaf explants (52.4%) and 40 day-old leaf explants (62.3%).Transgenic hairy roots were confirmed by PCR analysis with specific primers of rolB gene.