Kazim Abak

Determination of screening techniques to salinity tolerance in tomatoes and investigation of genotype responses

Abstract In order to determine the predictive screening parameters that can be applied at early development stages of tomato plants, 55 tomato genotypes were grown in nutrient solution with 200 mM NaCI. The relationships among the salinity scale classes based on the visual appearance and shoot Na + accumulation, K + /Na + and Ca 2+ /Na + ratios and shoot-root dry weights were investigated. Tomato genotypes differed greatly for shoot Na + concentration and salinity scale classes were significantly correlated with Na + concentrations. Higher shoot Na + concentrations indicated higher shoot damage. Shoot K + /Na + and Ca 2+ /Na + ratios were significantly correlated with the salinity scale classes. The higher shoot K + /Na + and Ca 2+ /Na + ratios indicated lower shoot damage. Tomato genotypes grown under 200 mM NaCI stress showed significant variations in shoot and root dry weights. However, no significant correlations were found between the shoot-root dry weight and the scale classes and Na + concentration and the ion ratios investigated. These may indicate that plant shoot and root dry weights were independent of salt tolerance at the growth stage reached in this study.

Diversity and relationships among Turkish okra germplasm by SRAP and phenotypic marker polymorphism

Germplasm characterization is essential and molecular markers provide valuable information for breeding programs. Sequence-related amplified polymorphism (SRAP) and phenotypic markers were studied to determine diversity and relationships among 23 okra (Abelmoschus esculentus (L) Moench) genotypes. The 39 combinations of forward and reverse SRAP primers were used to evaluate the 21 Turkish and two randomly selected USA genotypes as outgroups, and produced 97 scorable markers, of which 50% was polymorphic for all 23 genotypes. Seventeen out of the 23 genotypes (74%) were distinguished from each other with mean similarity of 0.93. As to phenotypic markers, 33 heritable traits were evaluated in field with ten replications, 28 of them (85%) were found to be polymorphic. The UPGMA (unweighted-pair group method arithmetic average) dendrogram based on the 33 phenotypic markers distinguished all genotypes, but failed to detect any geographic association of okra genotypes, being consistent with previous study. It can be concluded that SRAP markers are useful for studying diversity and relationships among okra germplasm, and have potential in marker-aided selection, linkage mapping, and evolutionary studies.

Controlled release of aldicarb from carboxymethyl cellulose microspheres: in vitro and field applications

Aldicarb is a carbamate pesticide that is widely used throughout the world in the protection of crops (eg cotton, nuts, potatoes, onion, tobacco, sugar beet and sugar cane). In Turkey, especially in the Cukurova region, it is used for the control of the cotton white fly (Bemisia tabaci) which attacks cotton plants cultivated in this region. Aldicarb contamination in surface and ground water is a serious problem in several countries, partly due to its high water solubility. It is also highly toxic to mammals. In order to overcome these problems, microspheres of aldicarb were prepared using carboxymethyl cellulose (CMC) as the biodegradable support material cross-linked with aluminium chloride. A strong hysteresis behaviour was observed upon drying and reswelling. Encapsulation efficiency was in the range 12-23% and aldicarb contents of 5.7-10.3 mg per 100 mg of microspheres was achieved. In vitro release was distinctly Fickian, and Higuchi constants were very close to 0.5. Release in pots revealed that only one sample had a release capability for more than four weeks. In the cotton plot much longer durations of release (more than seven weeks) were observed while a commercial granular formulation released its content immediately. It was thus possible to construct a controlled pesticide release system that prolonged the bioavailability to about eight weeks. # 1999 Society of Chemical Industry The control of pests often requires periodic applica- tion of pesticide to the crop using conventional formulations, eg powders, granules, or concentrated emulsions. These lead to significant levels of environ- mental pollution due to the application of extensive quantities of pesticide required to prolong effective- ness. Losses can occur due to wash-out, evaporation, surface run-off and dispersion to unintended regions, 1-3 which also has undesirable economical consequences. Such disadvantages can be overcome by providing low levels of the pesticide over the desired period using a bioactive material release system based on the diffusion of the bioactive compound through a matrix or membrane. 4-6

Activities of iron-containing enzymes in leaves of two tomato genotypes differing in their resistance to Fe chlorosis

Abstract Two tomato (Lycopersicon esculentum Mill., cvs. Pakmor and Target) genotypes differing in resistance to iron (Fe) deficiency were grown in nutrient solution under controlled environmental conditions over 50 days to study the relationships between severity of leaf chlorosis, total concentration of Fe, and activities of Fe‐containing enzymes in leaves. The activities of Fe‐containing enzymes ascorbate peroxidase, catalase, and guaiacol peroxidase, and additionaly the activity of glutathione reductase, an enzyme that does not contain Fe, were measured. Plants were supplied with 2 × 10−7 M (Fe deficient) and 10−4 M (Fe sufficient) FeEDTA, respectively. Leaf chlorosis appeared more rapidly and severely in Target (Fe deficiency senstive genotype) than Pakmor (Fe deficiency resistant genotype). On day 50, Pakmor had 2‐fold more chlorophyll than Target under Fe deficiency, while at adequate supply of Fe the two genotypes were very similar in chlorophyll concentration. Despite distinct differences in development of leaf chlorosis and chlorophyll concentrations, Pakmor and Target were very similar in concentrations of total Fe under Fe deficiency. In contrast to Fe concentration, activities of Fe‐containing enzymes were closely related to the severity of leaf chlorosis. The Fe‐containing enzymes studied, especially catalase, showed a close relationship with the concentration of chlorophyll and thus differential sensitivity of tomato genotypes to Fe deficiency. Glutathione reductase did not show relationship between Fe deficiency chlorosis and enzyme activity. The results confirm that measurement of Fe‐containing enzymes in leaves is more reliable than the total concentration of Fe for characterization of Fe nutritional status of plants and for assessing genotypical differences in resistance to Fe deficiency. It appears that Fe deficiency‐resistant genotype contains more physiologically available Fe in tissues than the genotype with high sensitivity to Fe deficiency.

Inheritance of tolerance to leaf iron deficiency chlorosis in tomato

By using two tomato genotypes, “227/1” (Fe chlorosis susceptible) and “Roza” (Fe chlorosis tolerant), and their reciprocal F1, F2 and BC1 generations, the inheritance of tolerance to leaf Fe deficiency chlorosis of Roza was studied. Plants were grown in a nutrient solution and subjected to 2.0 × 10−6 M Fe EDDHA and 10 mM NaHCO3 to induce Fe deficiency stress by stabilization of pH to 7.8–8.2. A rating scale of 1–3 for chlorophyll was used and both monogenic and polygenic inheritance hypotheses were tested. Better responses to Fe deficiency, as measured by SPAD meter values, were obtained from the cross “Roza × 227/1” than from the reciprocal cross. Data from F2 and BC1 suggest Fe chlorosis tolerance of Roza is to be controlled by polygenic loci with a relatively high additive effect.

Citrulline is an important biochemical indicator in tolerance to saline and drought stresses in melon.

Salt- and drought-induced alterations in citrulline were assessed in 4 local melon genotypes, 2 sensitive (CU-52, CU-94) and 2 tolerant (CU-196, CU-280), grown in vermiculite in a growth chamber. Salt and drought stresses were started using 30-day-old plants, with 250 mM NaCI and 45 mM PEG (−1.0 MPa) and continued for 12 days. After 12 days under salt and drought conditions, the citrulline contents were increased in the tolerant CU 196 to 25.10 μmol gDW−1 and 24.10 μmol gDW−1 for salt and drought stresses, respectively. However, the citrulline contents of the sensitive CU-52 were 11.68 μmol gDW−1 and 11.76 μmol gDW−1 for salt and drought, respectively. The striking alteration was obtained in the citrulline accumulation. The tolerant melons accumulated 2 times more citrulline than the sensitive melons. For assessing or screening melon genotypes in a large number of accessions or breeding lines for their tolerance to salinity and drought during their young plant stage, the amount of citrulline accumulation in response to the given treatments might be considered as a novel biochemical indicator of interest in early selection studies.

Development of Callus Colonies from the Isolated Microspore Culture of Capsicum Annuum L.

ABSTRACT Androgenesis in Capsicum annuum L. via isolated microspore culture, with a limited scope, was studied. Donor genotype, i.e. U-130, was a doubled haploid. Intact flower buds containing microspores from early to late uninucleate stages were pretreated with a mannitol starvation medium both at 10 and 35°C for 7 days. High temperature treatment tested here, although considered effective in Capsicum anther culture, was detrimental and therefore flower buds from this treatment were not used. Following pretreatment at 10°C microspores were isolated and cultured on NLN medium (20) without growth regulators. Osmoticum and carbon was supplied to the microspores with 100, 130, and 170 g/1 sucrose. Only 170 g/1 culture was maintained and the rest of the cultures were lost to contamination. Callus colonies were obtained on the 30th and 60th days at rate of 40.5 and 67%, respectively. Callus colonies were subcultured to MS media containing 2, 4-D at 1 and 2 mg/1, but further development was not obtained. It was concluded that the approach adopted earlier on the cellular and molecular characterization studies of induced multinucleate Capsicum microspores (12, 14, 15) may lead to high frequency regeneration of haploids via callus colonies, as obtained in the present study, hence, isolated microspore culture using mannitol starvation as pretreatment has potentiality in Capsicum annum L. breeding.