Genetic and non-genetic factors affecting germination and vitality in spring barley seed

Germination of eight spring barley varieties, grown in two years at eight different locations in State varietal trials in the Czech republic, was analysed. All the combinations were tested under optimal conditions for germination as recommended by ISTA and also at low temperatures (5 and 10°C), and underwater stress (- 2 and - 4 bar). Germination under low temperature and water stress was considered as a character of seed vitality. Varieties in nearly all experiments were a significant source of variation and their relative contribution to the total variation was higher for vitality (5.7–38.7%) than for germination (2.0–4.3%). However, the percentage of germination were not related to the percentage of vitality. The location in nearly all the experiments caused the greatest variation and the impact was greater for germination than for vitality. Provenance effects were different for germination and for vitality; grains harvested in the lowland had the highest germination values, but not the highest vitality values. The results should encourage breeding for seed vitality and some reconsideration of provenance effects on seed vitality.     

Marker-assisted selection for complex trait in common bean (Phaseolus vulgaris L.) using QTL-based index

A procedure was developed for marker-assisted selection of complex traits for common bean (Phaseolus vulgarisL.) using an index based on QTL-linked markers and ultrametric genetic distances between lines and a target parent. A comparison of the mean seed yields of the top five lines selected by different schemes demonstrated that the highest yielding group was selected on the basis of a combination of phenotypic performance and a high QTL-based index,followed by groups identified by a high QTL-based-index, conventional selection,and a low QTL-based-index. This study demonstrated a simple way to use information obtained from QTL studies to make selection decisions. The study also showed that the use of the QTL-based-index in conjunction with the ultrametric genetic distance to the target parent would enablea plant breeder to select lines that retain important QTL in a desirable genetic background. Therefore, this type of MAS would be expected to be superior to the phenotypic selection. This revised version was published online in August 2006 with corrections to the Cover Date.     

Development of Gossypium hirsutum lines with cytoplasmic bollworm tolerance from Gossypium arboreum and Gossypium tomentosum

American cotton [Gossypium hirsutum (L.)] grown in India belongs to the race Latifolium. It is prone to bollworms [Helicoverpa armigera (Hubner), Erias vitella (Fabricius), Pectinophora gossypiella (Saunders)] infestation which causes considerable crop loss. Two breeding lines ‘Bikaneri (BN)‐arboreum (ARB)‐16’ and ‘BN‐tomentosum (TOM)‐277’ are cytoplasmic diverse genetic stocks. They were developed by crossing experimental lines ‘Delta Branch Experiment Station (DES)‐ARB16’ and ‘DES‐TOM277’ (non‐recurrent parents) with G. hirsutum‘BN’ (recurrent parent). Compared with BN these stocks possessed higher amount of gossypol, flavonol and phenol contents in leaves, stem and square. Plants were tolerant to bollworms and inherited comparable agronomic properties (yield, boll weight, plant height, number of monopods and sympods and fibre quality). Cotton breeders can use these lines for breeding cotton resistant to bollworm.     

The development of Raparadish (x Brassicoraphanus, 2n=38), a new crop in agriculture

Summary Raparadish, x Brassicoraphanus, the amphidiploid hybrid between Brassica rapa (syn. B.campestris) and Raphanus sativus (fodder radish) was made by Dolstra (1982). Primary hybrid plants grew vigorously, suggesting that the amphidiploid AARR might be useful as a fodder crop. Three populations of this new material were studied, with special attention to improvement of fertility and resistance to beet cyst nematode (Heterodera schachtii), whilst preserving genetic variability. For lack of progress one of the populations was abandoned after the fourth generation. The other two populations were observed through nine or ten generations. Apart from the last two generations mass selection for seed set was carried out on the basis of single plants. This led to a considerable increase in average seed production, without losing a wide variation for this trait. Thus more progress is being expected. Five cycles of mass selection for resistance to beet cyst nematodes led to a considerable increase of the level of resistance of both populations. The prospects of this new agricultural crop are discussed.     

Inheritance of resistance to potato virus Y in garden pepper (Capsicum annuum L.)

Summary Bell pepper suffers considerable losses from a strain of potato virus Y (PVY^o-sbp). Crosses were attempted between two resistant lines Perennial and S41-1 and two highly susceptible bell pepper commercial cultivars California Wonder and Yolo Wonder. Studies of F₁'s, F₂'s, back crosses and F₃'s indicated that Perennial and S41-1 carry a recessive gene imparting resistance to potato virus Y.     

Genetic, agronomic and quality comparisons of two 1AL.1RS. wheat-rye chromosomal translocations

The 1AL.1RS wheat-rye chromosomal translocation originally found in ‘Amigo’ wheat possesses resistance genes for stem rust, powdery mildew and greenbug biotypes B and C, but also has a negative effect on wheat processing quality. Recently, a second 1AL.1RS translocation carrying Gb6, a gene conferring resistance to greenbug biotypes B, C, E, G and I, was identified in the wheat germplasm line ‘GRS1201′. Protein analytical methods, and the DNA polymerase chain reaction were used to identify markers capable of differentiating the 1RS chromosome arms derived from ‘Amigo’ and ‘GRS1201′. The secalin proteins encoded by genes on 1RS chromosome arms differed in ‘Amigo’ and ‘GRS1201′. A 70 kDa secalin was found in the ‘Amigo’1AL.1RS, but did not occur in the ‘GRS1201’1AL.1RS. Polymorphisms detected by PCR primers derived from a family of moderately repetitive rye DNA sequences also differentiated the two translocations. When ‘GRS1201’was mated with a non-1RS wheat, no recombinants between 1RS markers were observed. In crosses between 1RS and non-1RS parents, both DNA markers and secalins would be useful as selectable markers for 1RS-derived greenbug resistance. Recombination between 1RS markers did occur when 1RS from ‘Amigo’ and 1RS from ‘GRS1201’were combined, but in such intermatings, the molecular markers described herein could still be used to develop a population enriched in lines carrying Gb6. No differences in grain yield or grain and flour quality characteristics were observed when lines carrying 1RS from ‘Amigo’ were compared with lines with 1RS from ‘GRS1201′. Hence, differences in secalin composition did not result in differential quality effects. When compared with sister lines with 1AL.1AS derived from the wheat cultivar ‘Redland’, lines with ‘GRS1201’had equal grain yield, but produced flours with significantly shorter mix times, weaker doughs, and lower sodium dodecyl sulphate sedimentation volumes.     

A contribution to the systematics of a piedmontese plum ecotype

Prunus domestica L., P. insititia L., P. salicina Lindl. and P. cerasifera Ehrh. are the most important species included in the plum group. Many ‘cultivars’ have an undefined origin and share very similar morpho‐phenological characteristics that make their identification difficult. This is the case of ‘Ramasin’, a group of Piedmontese genotypes whose fruits are small, ellipsoidal and very tasty. They are commonly considered as P. domestica varieties, even though on the basis of some morphological characteristics they are similar to other species such as P. insititia. In order to study the origin of this group, the DNA of 25 genotypes of ‘Ramasin’, and that of some ‘cultivars’ of P. domestica, P. insititia, P. cerasifera, P. salicina and two selections of P. spinosa L. was examined. The PCR‐RAPDs method (Random Amplified Polymorphic DNA amplified by Polymerase Chain Reaction) was used and all 69 primers that were tested generated more or less polymorphic bands. From the results of these analyses it can be supposed that the ‘Ramasin’ plums are a single genetically heterogeneous group. Moreover it can probably be assumed that ‘Ramasin’ arose from crosses between P. domestica and P. insititia.     

Contribution of Different Organs to Grain Filling in Durum Wheat under Mediterranean Conditions I. Contribution of Post‐Anthesis Photosynthesis and Remobilization

Under Mediterranean conditions, drought affects cereals production principally through a limitation of grain filling. In this study, the respective role of post‐anthesis photosynthesis and carbon remobilization and the contribution of flag leaf, stem, chaff and awns to grain filling were evaluated under Mediterranean conditions in durum wheat (Triticum turgidum var. durum) cultivars. For the purpose, we examined the effects of shading and excision of different parts of the plant and compared carbon isotope discrimination (Δ) in dry matter of flag leaf, stem, chaff, awns and grain at maturity and in sap of stem, flag leaf, chaff and awns, this last measurement providing information on photosynthesis during a short period preceding sampling. Source–sink manipulations and isotopic imprints of different organs on final isotope composition of the grain confirmed the high contribution of both carbons assimilated by ears and remobilized from stems to grain filling, and the relatively low contribution of leaves to grain filling. Grain Δ was highly and significantly associated with grain yield across treatments, suggesting the utilization of this trait as an indicator of source–sink manipulations effects on grain yield. Chaff and awns Δ were better correlated with grain Δ than stem and leaf Δ, indicating that chaff were more involved in grain filling than other organs. Moreover, in chaff, sap Δ was highly significantly correlated with dry matter Δ. These results suggest the use of Δ for a rapid and non‐destructive estimation of the variation in the contribution of different organs to grain filling.