The aim of the performed investigations was to determine which part of the embryo has the optimal properties for callus induction at low concentrations of 2,4-D (2 mgdm-3). The explants were cut along or across the embryo axis into 2, 3, 4 fragments and cultured on the Murashige and Skoog medium for 6 weeks. It was found that callus derived from mature embryos (dry seeds) is characterised by comparable fresh and dry mass and by similar changes in size of the cells with fragments derived from mature embryos (but before the dormant) and from immature embryos. Essential difference was observed in the germination ability of the explants. The percentage of germination of mature embryo fragments was the lowest. It was demonstrated that despite of the embryo type, fragments originating from its central part appeared the most suitable for in vitro culture. In the case of these fragments the highest increase of the fresh mass of callus tissue, optimal morphological features and the appearance of meristematic centres were observed.
The objective of this study was to standardize an induction strategy of chromosome aberrations in maize inbred line L-869. Pollen grains irradiated with 0, 36 and 72 Gy were used for fertilization. Resulting seeds were planted in a greenhouse to assess the number of abnormal meiotic cells. Germination, height, sterility and mortality were verified. Cells with delayed separation of chromosomes, translocation, deficiency, abnormal pairing, later condensation and anaphase bridges were observed. The number of abnormalities increased as the dosage increased but chromosome aberration types were the same regardless of the dosages used. Various chromosome-altered plants were obtained without viability loss.
QTL mapping for plant-height traits has not been hitherto reported in high-oil maize. A high-oil maize inbred 'GY220' was crossed with two dent maize inbreds ('8984' and '8622') to generate two connected F2:3 populations. Four plant-height traits were evaluated in 284 and 265 F2:3 families. Single-trait QTL mapping and multiple-trait joint QTL mapping was used to detect QTLs for the traits and the genetic relationship between plant height (PH) and two other plant-height traits. A total of 28 QTLs and 12 pairs of digenic interactions among detected QTLs for four traits were detected in the two F2:3 families. Only one marker was shared between the two populations. Joint analysis of PH with ear height (EH) and PH with top height (TH) detected 32 additional QTLs. Our results showed that QTL detection for PH was dependent on the genetic background of dent corn inbreds. Multiple-trait joint QTL analysis could increase the number of detected QTLs.
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