A segregating F₄ population from the cross between drought sensitive (Yecora Rojo) and drought tolerant (Pavon 76) genotypes was made to identify molecular markers linked to a wheat (Triticum aestivum L.) abscisic acid (ABA) content at two water regimes. The parents and 150 F₄ lines were evaluated phenotypically for drought tolerance using two irrigation treatments [0.25 and 0.75 m³(H₂O) m^-2(soil)]. Forty different target region amplification polymorphism (TRAP) primer combinations, 98 different sequence-related amplified polymorphism (SRAP) primer combinations, and 400 simple sequence repeat (SSR) primers were tested for polymorphism among the parental genotypes and the F₄ lines. Seven loci in the F₄ lines treated with the drought stress were identified. Single quantitative trait loci (QTLs) were located on chromosomes 1B, 2A, 3A, 5D, and 7B and each of them explained from 15 to 31 % of phenotypic variance with a LOD value of 7.2 to 15.7. Five QTLs were located on chromosome 4A and six QTLs on chromosome 5A. In control (well-watered) F4 lines, two QTLs were mapped on chromosome 3B and one QTL on each chromosome 5B and 5D. Statistically the most significant groups of QTLs for the ABA content were identified in the regions of chromosomes 3B, 4A, and 5A mostly near to Barc164, Wmc96, and Trap9 markers. Therefore, these markers linked to QTLs for the drought-induced ABA content can be further used in breeding for drought tolerance in wheat.

Nine cultivars of Chrysanthemum morifolium were screened using the ray floret explants to determine the capability for plant regeneration on four media protocols and subsequently to find out the best genotype source linked with the optimum medium conditions for the high potentiality of shoot formation. The results indicated that all in vitro culture traits were highly significantly influenced by the differences in genotypes, medium protocols and their interaction. The percentage of explants which developed calli ranged from 73.83% “Ping Pong” to 25.67% “Palisade White” among the cultivars across the four medium protocols with an average of 48.28%. The highest percentage of embryogenic callus, shoot formation and mean value of shoot length was produced by cultivar "Delistar White" when calli were differentiated on medium protocol B. The medium protocol B showed the greatest potential for shoot length across the cultivars and it was significantly superior to all other medium protocols except the medium protocol A. The present study indicated that the medium protocol “B” and then "A" appear to be the best protocols for plant regeneration. The cultivar "Delistar White" with the medium protocols B and then A, could be successfully utilized for further in vitro mutagenesis investigations. Key words: Chrysanthemum morifolium, in vitro culture, plant regeneration.

Segregating F4 families from the cross between drought sensitive (Yecora Rojo) and drought tolerant (Pavon 76) genotypes were made to identify SSR markers linked to leaf chlorophyll content, flag leaf senescence and cell membrane stability traits in wheat (Triticum aestivum L.) under water-stressed condition and to map quantitative trait locus (QTL) for the three physiological traits. The parents and 150 F4 families were evaluated phenotypically for drought tolerance using two irrigation treatments (2500 and 7500 m3/ha). Using 400 SSR primers tested for polymorphism in testing parental and F4 families genotypes, the results revealed that QTL for leaf chlorophyll content, flag leaf senescence and cell membrane stability traits were associated with 12, 5 and 12 SSR markers, respectively and explained phenotypic variation ranged from 6 to 42%. The SSR markers for physiological traits had genetic distances ranged from 12.5 to 25.5 cM. These SSR markers can be further used in breeding programs for drought tolerance in wheat.

In vitro shoot multiplications were obtained successfully from shoot tips of Ziziphus spina-christi by placing explants into solidified medium (MS medium) supplemented with 0.01 mg/l NAA and 0.1 mg/l BA or 0.1 mg/l IAA and 1.0 mg/l kinetin. It was concluded that lower concentrations of all cytokinin studied were better for lateral bud proliferation and that BA and 2IP were better than kinetin in the production of lateral branches. No growth regulators were required for shoot growth and elongation. The shoots rooted best on MS medium supplemented with 1.0 mg/l IBA. Plantlet survival after transfer to soil was more than 90%. The shoot proliferation method described could be used for the mass clonal propagation of selected genotype cv Noaf variety. The variety is in a great demand due to its attractive fruit characteristics such as flavour, sweetness and fruit yield. Key words: Clonal propagation, cidir, shoot tip culture, Ziziphus spina-christi (L.) Desf.