A segregating population from the cross between drought sensitive (Variant-2) and drought tolerant (Cham-6) genotypes was made to identify molecular markers linked to wheat (Triticum aestivum L.) flag leaf senescence under water-stress. From 38 random amplified polymorphic DNA (RAPD) primers, 25 inter-simple sequence repeat (ISSR) primers and 46 simple sequence repeat (SRR) primers were tested for polymorphism among parental genotypes and F 2 population. Quantitative trait locus (QTL) for flag leaf senescence was associated with 1 RAPD marker (Pr9), 4 ISSR markers (Pr8, AD5, AD2, and AD3), and 1 SSR marker (Xgwm382) and explained 44, 50, 35, 31, 22, and 73 % phenotypic variation, respectively. The genetic distance between flag leaf senescence gene and Pr9 was 10.0 cM (LOD score 22.9).
Estimates of gene actions were obtained for five in vitro traits of immature wheat (Triticum aestivum L.) embryo cultures from a cross of two wheat cultivars and the resulting reciprocal, Fl, F2 and backcross populations. The contribution of additive gene effects to in vitro traits was not as important as the dominance gene effects. Epistatic gene effects were relatively more important than either additive or dominance gene effects. Of the individual types of digenic epistatic effects, the dominance x dominance estimates were relatively larger in magnitude for all in vitro culture traits measured. The maternal effect played a minor role in the inheritance of the in vitro studied traits since the difference among the reciprocal values was not significant. It is shown from the generation mean method that epistasis played a major role in the inheritance of most of the traits under study, The negative values of additive and dominance genetic variance were estimates of zero. Heritability estimates, in broad sense, were relatively high for the in vitro studied traits. In some cases, heritability estimates in broad and narrow senses are almost equal since the estimation of dominance genetic variance led to negative values. According to the results of the gene effects, dominance and epistasis were important for the shoot formation trait. Selection would be effective among the isolated genotypes on individual basis.
Protoplasts of several wildLinum species were isolated enzymatically from roots, hypocotyls and cotyledons of seedlings, and also from theirin vitro grown shoots and cell suspension cultures. When cultured all these protoplasts divided to produce callus but only good plant regeneration capability was evident in the case ofLinum lewissii and to a much lesser extent forL. strictum. Only rhizogenesis was observed withL. alpinum, L. narbonense, L. grandiflorum andL. altaicum. The high plant regeneration capacity ofL. lewissii from protoplast -derived tissues ofin vitro shoots and cell suspension cultures makes this species an attractive experimental system for somatic genetic manipulation.
In order to identify target region amplification polymorphism (TRAP) markers linked to three physiological traits in wheat (Triticum aestivum L.), the segregating F 4 population from the cross between drought-sensitive (Yecora Rojo) and drought-tolerant (Pavon 76) genotypes was made. The parents and 150 F 4 families were evaluated phenotypically for drought tolerance using two irrigation treatments [2.5 and 7.5 m 3 (H 2 O) m -2 (soil)]. Using 40 different TRAP primer combinations tested for polymorphism in parental and F 4 family genotypes, the results revealed that quantitative trait locus (QTL) for chlorophyll content was associated with TRAP 5,
Callus induction derived from root, hypocotyl and cotyledon explants were investigated for four cultivars of Trifolium alexandrinum L . The Murashige & Skoog (1962) medium containing 2 .0 mg/L NAA and 0 .5 mg/L BAP was able to induce callus from different explants . A wide range of culture media were tested to determine the morphogenetic potential of different callus types derived from different explant types . Shoot morphogenetic development was observed with the cultivars Sakha 4 and Giza 10 . Cell suspension cultures were established from hypocotyl derived callus . Methods for isolation and culture of protoplasts from cotyledons are described .
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