JWSS - Journal of Water and Soil Science

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This study was conducted to evaluate the responses of Iranian commercial genotypes of maize (hybrids and their inbred lines) to callus induction and plant regeneration, using mature embryos. Twenty five genotypes comprising of 12 inbred lines, 11 single cross hybrids, 1 double cross hybrid and 1 composite cultivar were used. Mature embryos of the genotypes were plated on MS and N6 media. Callus induction rates were evaluated using relative growth rate of callus (RGR), callus fresh weight (CFW), callus dry weight (CDW) and callus growth rate (CGR).

The results indicated that genotypes highly varied in both callus induction and plant regeneration. IL8 inbred line, SC7 (IL4×IL8) and SC9 (IL6×IL10) hybrids had the highest callus production capacity (based on CFW and CDW), whereas the highest RGR and CGR were obtained for ILl inbred line and SC9 hybrid. The estimated heterosis based on superior parent showed the highest heterosis for CFW, CDW, RGR and CGR in SC9 hybrid. Genotype × medium interactions for CWD, RGR and CGR were significant. For instance, SC9 hybrid on MS medium and IL8 on N6 medium produced the highest CGR. There was a significant difference between the observation periods [8, 12, 16 and 20 days after planting (DAP)], so that CGR was the least at 8 DAP and increased gradually till 16 DAP, but declined afterward. CGR had a range of 0.51 in IL8 inbred line to 0.74 in SC9 hybrid. Comparisons of the genotype for plant regeneration percent indicated that ILl and IL10 inbred lines as well as SC2 and SC4 single cross hybrids had the highest regeneration rates. Considering plant regeneration as a critical and genotypic dependent factor, it can be concluded that ILl and IL10 inbred as well as SC4 (IL4×IL5, ‘single cross 301’), SC2 (IL2×IL3, ‘single cross 704’) and SC7 hybrids are recommended for use in tissue culture-based breeding programs in maize.

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This study was conducted to evaluate the response of 18 rice (Oryza sativa L.) genotypes to callus induction and plant regeneration from immature embryo culture, using three media (MS, LS and N6). To evaluate callus induction rate, the following criteria were used: callus diameter, callus fresh weight and callus dry weight. Percentage of callus water content was also measured. After transferring the produced calli from the induction media to a regeneration medium (MSR), percentage of plant regeneration was evaluated.

A highly significant difference was observed among genotypes for both callus induction and plant regeneration (P<0.01). In callus induction phase, “Nemat” and “Cheram-2” cultivars were superior for callus diameter, having 4.83 and 4.6 mm callus diameter, respectively. “Nemat”, “Cheram-2”, “Sepidrood” and “Taroum” cultivars as well as “33IRCTN91” and “IRFAON-30” lines were significantly superior to other cultivars for callus fresh weight. Among the genotypes “Nemat”, “Zayandehrood”, “33IRCTN91” had the highest percentage of callus water contents. Based on plant regeneration, “33IRCTN91” line and “Anbarbo”, “Nemat”, “Cheram-2” and “Taroum” cultivars showed highest rate of plant regeneration from callus. Significant differences were observed among media. While MS and N6 media did not showed any significant differences for callus diameter, callus fresh weight and rate of plant regeneration, they were superior to LS medium (P<0.01). According to percentage of callus water content, MS and LS media ranked the best and the most inferior medium, respectively. In the present study, MS and N6 media were considered as suitable in vitro culture media of rice immature embryos. Among genotypes, “Nemat” and “Cheram-2” cultivars were ranked the best for both callus induction and plant regeneration. Also, the used Japonica rice cultivars were superior for percentage of plant regeneration. The calculated correlation coefficients between traits showed a non-significant correlation between callus induction and plant regeneration, which, in turn, indicated that these traits were independent.

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In order to investigate the androgenic response of chickpea cultivars, two Iranian Chickpea cultivars, Pirooz and Karaj 12-60-31, were used in this study. After 7 to 10 days of cold pretreatment of flower buds, anther containing uninucleate stage of microspores were placed aseptically on MS medium supplemented with various combinations of growth regulators of 2,4-D (1,2 and 3 mg/l) and kinetin (0.1, 0.2 and 0.5 mg/l). Callus regeneration achieved using MS and modified Blayd’s media with various hormones and different sucrose concentrations. The results indicated that the callus initiation was significantly affected by 2,4-D and kinetin concentrations, and that increasing these hormones reduced callus induction. The best response obtained on media with the lowest concentration levels of 2,4-D and kinetin (1 and 0.2 mg/l, respectively). A highly significant genotypic effect and a genotype  2,4-D interaction were detected, which proved that Pirooz response was the best. Callus differentiation and organogensis occurred in MS medium supplmented with NAA, BA and 3% sucrose. Mature embryos also obtained in modified Blayd’s plus 0.5 mg/l kinetin and 10% sucrose. Cytological studies revealed the presence of haploid cells with chromosome variation in the anther derived callus. Therefore, optimizing the hormone levels of different basal media with a particular sucrose cocentration may improve haploid regeneration in chickpea. It seems a further study should be carried out to characterize calli from induction to regeneration and to determine the effect of cold pretreatment, the results of which could be used to improve anther culture response of chickpea.