مجله پژوهش های ژنتیک گیاهی
سال چهارم شماره 1 (بهار و تابستان 1396)

To conduct any breeding program, understanding of the genetic structure of traits and effect of environment and genetic by environment interaction as well as effects of random or fixed in the analysis of results is essential. Subsequently, analysis of variances and variance components are important in plant and animal breeding. The ANOVA is one of the best estimators for variance components. But this estimator is not preferred to maximum likelihood (ML) and Restricted Maximum Likelihood (REML) methods when variance components are negatively estimated and unbalanced datasets arise. Therefore, the objective of this research is a review of comparison of estimates of variance components using ANOVA, ML and REML method in linear mixed models using experimental data.

Drought is a worldwide risk seriously influencing production of agricultural plants such as coriander. In order to evaluate heritability and gene action for important quantitative traits in coriander in three irrigation regimes, including well water (WW), mild water stress (MWS) and severe water stress (SWS), a cross between two genotypes of TN-59-158 (Sensitive parent) and TN-59-230 (Tolerant parent) was done. Parents and progenies of triple test cross were evaluated in filed condition through a randomized complete block design with three replications. Days to 50% flowering (DTF), days to harvest (DTH), fruit yield (FY), thousand fruit weight (TFW), harvest index (HI), relative water content (RWC), essential oil yield (EOY) were measured. Results showed that total epistasis effect was observed for all traits except RWC in WW. Also, total epistasis effect was observed for all traits except DTF in MWS and SWS. Partitioning of total epistasis revealed that [i] type of epistasis was contributed to determining DTF and TFW in WW and MWS treatments, DTH, FY and RWC in MWS and SWS treatments, and HI and EOY in WW, MWS and SWS treatments.

Under drought stress conditions, as one of the most important limiting factors of grain yield in wheat at arid and semi-arid regions, the remobilization of assimilates gain would be more valuable to grain filling. There are a few reports on the importance of remobilization of the root during the grain filling period under drought stress conditions. An advanced mutant line of bread wheat (T-65-7-1) along with its wild type (cv. Tabasi), were planted at two moisture conditions (normal and 30-40% of field capacity) as a factorial experiment based on a completely randomized design with three replications. Sampling for gene expression analysis was conducted from the root in two stages (7 and 21 days after anthesis). In these genotypes, fructan remobilization, efficiency of fructan remobilization, and relative expression of genes involved in the synthesis and hydrolysis of fructan during the grain filling period, in root, were studied under terminal drought stress. The results showed that the stored fructan in the root participated in the assimilate remobilization. Higher fructan remobilization through root to grain in mutant line under drought stress conditions was due to over-expression of genes involved in the synthesis of fructan (1-SST and 6-SFT) at 7-days after anthesis and in hydrolysis of fructan (6-FEH) at 21-days after anthesis, compared to wild type. Drought stress did not cause a significant change in gene expression of 1-FFT and 1-FEH genes in the root of both genotypes, which confirms the only β (2,6) linkages as predominant form of fructan has affected under drought stress conditions. In wheat breeding programs, 1-SST, 6-SFT and 6-FEH can be used as molecular markers for selecting genotypes with high fructan content and more remobilization.

Figs as an important product in recent decades due to biotic and abiotic stresses have been faced to genetically erosion. The aim of this study was to determine the genetic diversity of taxa belonged to Ficus genus using Inter-simple sequence Repeat markers (ISSR). For this purpose, 23 accessions belonging to the fig genus collected from across the Iran country and genomic DNA was extracted from leaves. Out of 18 ISSR primers pairs, six primers pairs selected and PCR process were achieved for them. A total of 83 bands were produced, of which 78 were polymorphic. Using PAUP software, through Neighbor Joining methods, 23 populations of fig were divided in four groups. Among the primers, (AG) 8 C, (TG) 8 A and (GT) 8 C were identified as the most appropriate primers for using in future studies. Based on the results obtained from the analysis of data from ISSR, 23 populations of Ficus were classified into four groups. The results of the analysis of molecular variance (AMOVA) showed that there is no difference between the taxa and the highest genetic distance between populations within species. The results of this study showed that taxa belonging to the Ficus genus in Iran are very closely related phylogentically, and the relationship between reproductive and genetic flow is high.

Ispaghula (Plantago ovata) is used to reduce gastrointestinal and urinary tract infections, as well as control blood glucose and cholesterol levels in the human body. The phylogeny and genetic diversity of 22 different ecotypes of Ispaghula were evaluated using 12 ISSR markers and nine morphological and phenological traits. Analysis of variance showed that there were significant differences among cultivars for all traits. Cluster analysis grouped 22 different ecotypes of Ispaghula in two groups using UPGMA method based on field data. The assessment of genetic diversity among ecotypes based molecular markers showed that the 12 primers amplified 91 polymorphic bands. The maximum number of bands (11) was produced by UBC813 and primers UBC811 with 10 bands were in the next steps, respectively. The minimum band number (4) was produced by UBC824. Polymorphism information content (PIC) value was varied from 0.26 to 0.45 and Marker index (MI) was varied from 0.90 to 4.13. Cluster analysis using UPGMA based on molecular markers, placed 22 ecotypes in the study in five groups, include 1, 1, 2, 3 and 15 ecotypes, respectively. Grouping of ecotypes with molecular markers was different with classification of the ecotypes based morphological traits. According to the results, ecotypes that are far apart can be used in the breeding program of Ispaghula.

Water stress is one of the most common environmental stresses that limited tobacco production in IRAN. Identification of genetic diversity in tobacco germplasm and genetic relationships between traits help to improve tolerant varieties. In this study, the genetic diversity of 100 flue–cured tobacco (Nicotiana tabacum L.) cultivars was analyzed using 15 morpho-physiological traits and 25 ISSR primers. The cultivars were cultured in a simple lattice design (10×10) with two replications (with and without water stress) in Tirtash Tobacco Institute, Iran. Results showed relative water content (RWC) and cell membrane stability (CMS) in normal condition were significantly higher than stress condition. The estimated broadsense heritability was low for RWC and CMS that represents large environmental effects on these two traits. The results of genotypes clustering by UPGMA method with ISSR markers and by WARD method with morph-physiological traits did not match. Primer UBC814: (CT) 8A with 16 polymorphic bands of the 17 bands, had higher resolution than other primers and seems appropriate for molecular diversity studies in tobacco. The K394 genotype was identified as well as drought tolerant varieties. We can use results of this study for selecting genotypes with great genetic differences and chose the desirable traits and use in breeding programs for producing high heterosis hybrid with tolerance to drought stress in tobacco.