Authors:W. Abera, H. Shimelis, J. Derera, M. Worku, and M. Laing
Productivity of maize (Zea mays L.) is curtailed by a number of stress factors, predominantly by diseases and insect pests. The Northern leaf blight disease of maize caused by Exserohilum turcicum (Pass.) Leonard and Suggs inflict significant yield losses in the humid tropical regions. The objectives of this study were to determine the leaf blight response of 50 elite maize inbred lines developed for the mid-altitude, sub-humid tropics and to select promising parents for resistance breeding. Inbred lines were evaluated in the field using a 5 × 10 alpha lattice design with three replications. Plants were artificially inoculated at the 4–6 leaf stages during 2011 and 2012. Data on disease severity and incidence, AUDPC and yields were recorded. Inbred lines had significant differences for E. turcicum reactions, and were classified into resistant, intermediate or susceptible categories. The mean disease severity ranged from 2.04% for the inbred line 136-a to 3.25% (Kuleni-C1-101-1-1-1). The upper leaf area infection of inbred lines 143-5-I and 136-a was 3.3%, while the line Kuleni-C1-101-1-1-1 displayed 100% infection. Further, 136-a developed the lowest AUDPC score at 238, whereas Kuleni-C1-101-1-1-1 had the maximum at 700. Overall, inbred lines CML202, 144-7-b, 139-5-j, 136-a, 30H83-7-1-1-1-2-1, ILoo’E-1-9-1-1-1-1-1 and 142-1-e, were identified as promising sources of resistance against E. turcicum. The selected elite inbred lines would be recommended for use in general varietal development, disease management and to enhance maize productivity, in the mid-altitude sub-humid tropics.
Biofortifying food crops with essential minerals would help to alleviate mineral deficiencies in humans. Detection of quantitative trait loci (QTLs) for mineral nutrient contents in rice was conducted using backcross inbred lines derived from an interspecific cross of Oryza sativa × O. rufipogon. The population was grown in Hangzhou and Lingshui, with the contents of Mg, Zn, Fe, Mn, Cu and Se in brown rice measured in both trials and that in milled rice tested in Hangzhou only. A total of 24 QTLs for mineral element contents were identified, including two for both the brown and milled rice, 17 for brown rice only, and five for milled rice only. All the seven QTLs detected for the mineral contents in milled rice and 13 of the 19 QTLs for the contents in brown rice had the enhancing alleles derived from O. rufipogon. Fifteen QTLs were clustered in seven chromosomal regions, indicating that common genetic-physiological mechanisms were involved for different mineral nutrients and the beneficial alleles could be utilized to improve grain nutritional quality by markerassisted selection.
The emergence time and emergence percentage of four inbred lines with different degrees of chilling tolerance (Mo 17, HMv 5316, HMv 5301, HMv 5478) and the dry mass of young shoots were examined in a seed dressing experiment carried out in pots and sown early under field conditions, on soil infected with pathogens or free of infection (control). The advantage of seed dressing was manifested for all the traits examined, with the exception of emergence time, and the dressing agents were found to exhibit a certain degree of variety specificity. The time to emergence was determined chiefly by the genotype of the inbred lines. Differences were observed when the inbred lines were ranked on the basis of the emergence time and the emergence percentage. This was in agreement with the fact that no correlation was observed between the emergence percentage and the emergence time. Genotype HMv 5316 proved to be best on the basis of emergence time and HMv 5301 for emergence percentage. The poorest results for all the traits examined were recorded for Mo 17, which is in agreement with the poor chilling tolerance of this inbred line. In summary, the following conclusions can be drawn: if the chilling tolerance and growth vigour of the genotypes are to be satisfactorily described, traits characteristic of initial plant development (dry mass of the shoots, size of the leaf area, etc.) should also be considered in addition to the emergence time and emergence percentage.
Authors:J. Pintér, E. Kósa, G. Hadi, Z. Hegyi, T. Spitkó, Z. Tóth, Z. Szigeti, E. Páldi, and L. Marton
The level of UV-B radiation reaching the surface of the earth is increasing due to the thinning of the ozone layer in the stratosphere over recent decades. This has numerous negative effects on living organisms.Some of the Hungarian inbred maize lines examined under the climatic conditions in Chile exhibited an unusually high proportion of pollen mortality, flowering asynchrony and barrenness. The evidence suggests that this can be attributed to the approx. 30% greater UV-B radiation in Chile.The investigation of this problem within the framework of abiotic stress breeding programmes is extremely important in the light of the global rise in UV-B radiation, which may make it necessary to elaborate a selection programme to develop inbred lines with better tolerance of this type of radiation.In the course of the experiment the same ten inbred lines, having different maturity dates and genetic backgrounds, were tested for five years in Chile and Hungary. The tests focussed on anthocyanin, a flavonoid derivative involved in the absorption of damaging UV-B radiation.Averaged over years and varieties, the total anthocyanin content in the leaf samples was significantly higher in Chile than in Hungary. This was presumably a response at the metabolic level to the negative stress represented by higher UV-B radiation.In the five early-maturing flint lines the anthocyanin contents were more than 45% greater than those recorded in Hungary. This suggests that these genotypes, originating from northern regions, were not sufficiently adapted to the higher radiation level. In these samples higher UV-B caused a sharp rise in the quantity of anthocyanin, which absorbs the dangerous radiation. In late-maturing genotypes the initial content of the protective compound anthocyanin was higher at both locations, so in these types the high radiation level was not a problem and did not cause any substantial change.Similar conclusions were drawn from the results of fluorescence imaging. The F440/F690 ratio indicative of the stress level was higher in late lines with a high anthocyanin content, good tolerance and good adaptability.
The resistance of
maize inbred lines and their hybrids to Western Corn Rootworm was investigated
in a 4 × 4 full diallel system. The most tolerant line against WCR
larvae was the inbred line P26. Four maize inbred lines and their 12 normal and
reciprocal crosses were investigated for resistance to Fusarium ssp. and
European Corn Borer under natural conditions in four replications in 1998-2000.
The highest GCA values were found for the inbred lines P26 and P50. Studies
were also made to determine the optimum concentration of imidazolinone in the
selective medium for the detection of resistant cell lines originating from
homozygous genotypes produced by irradiation.
Authors:B. Barnabás, T. Spitkó, K. Jäger, J. Pintér, and L. C. Marton
In the present study the applicability of a self-constructed doubled haploid line (DH 105) in the in vitro breeding of maize was evaluated. This line, which contained only 50% exotic (Chinese) germplasm, could be used to transmit in vitro androgenic ability into non-responsive breeding materials. F1 hybrids resulting from single crosses between the moderately responsive line DH 105 and recalcitrant genotypes with high breeding value showed a considerable heterosis effect in their androgenic responses. Most of the hybrids had favourable morphological and agronomic characters on the basis of “per se” evaluation. The data of the experiments showed that these F1 hybrid plants could be successfully used as anther donors, since numerous fertile DH plants were developed from their anther cultures. By the use of this in vitro breeding strategy the genetic variability can be widened and the effectiveness of inbred line production might be improved.
Authors:Ksenija Taski-Ajdukovic, Nevena Nagl, Dragana Miladinovic, and A. Mikic
The plant regeneration from sunflower protoplast was achieved by protocols that considerably differ with respect to basal medium and concentration of growth regulators added. In most cases regeneration was restricted to a small proportion of genotypes. In this experiment, sunflower inbred line Ha-74A, with a high regeneration ability was used for protoplast isolation from etiolated hypocotyls. Isolated protoplasts were embedded in agarose droplets and cultured according to different regeneration protocols. The best results were obtained when protoplasts were cultured on L4 medium followed by transfer of regenerated microcalluses to solid regeneration media. Shoot regeneration was achieved by culture of calluses on SE regeneration medium after the treatment with 2.2 μM thidiazuron.
Authors:B. Kobiljski, S. Dencic, A. Kondic-Spika, U. Lohwasser, and A. Börner
The International Triticeae Mapping Initiative (ITMI) recombinant inbred line (RIL) population was used to detect quantitative trait loci (QTL) underlying some key agronomic characters in bread wheat (
L.). Trait measurements were taken from five independent field experiments performed in Serbia. Stable across environment QTL involved in the determination of heading/flowering time and ear morphology/grain yield were detected on, respectively, chromosome arms 2DS and 4AL. These map locations are consistent with those obtained where the same population has been grown in contrasting geographical sites. However, as a result of QTL × environment interactions, not all these QTL are expressed in all environments. Nevertheless the (pleiotropic) effect on ear morphology appears to be expressed in almost all environments, and so represents a high value target for wheat improvement.
Authors:F. Cui, J. Li, A. Ding, C. Zhao, X. Li, D. Feng, X. Wang, L. Wang, and H. Wang
To comprehensively understand the genetic basis of plant height (PH), quantitative trait locus (QTL) analysis for internode lengths, internode component indices and plant height component index (PHCI) were firstly conducted in the present study. Two related F8:9 recombinant inbred line (RIL) populations comprising 485 and 229 lines were used. Two hundred and nine putative additive QTL for the eight traits were identified, 35 of which showed significance in at least three trials. Of these, at least 11 pairwise QTL were common to the two populations. PH components at the QTL level had different effects on PH, confirming our previous multivariate conditional analysis (Cui et al. 2011). Eleven major QTL that showed consistency in expression across environments should be of great value in the genetic improvement of PH in wheat. The results above will enhance the understanding of the genetic basis of PH in wheat.