Factorial regression analysis of genotype by environment interaction in ryegrass populations, using both isozyme and climatic data as covariates

A sample of 58 natural ryegrass populations (Lolium perenne L.) from the French and Spanish oceanic coast was evaluated for three seasonal growth traits (i.e. spring, autumn and winter vigour traits) in 5 evaluation sites (three in France and two in Spain). This sample showed a high level of genotype (population) × environment (evaluation sites) interactions for the three agronomic traits. A factor regression analysis, using both isozyme frequencies of populations and climatic factors of evaluation sites as covariates, was carried out on a sub-sample of 30 populations in order to explain these interactions. This method succeeded in explaining most population × location interactions by the product of two covariates. For instance, for spring vigour trait, 72.8% of the interaction term could be explained by the use of two covariates: the PGI2-20 allelic frequency of populations and the minimum temperature of the coldest month of evaluation sites. This study shows the advantage of such a method for plant breeders who need to identify promising ryegrass populations for their breeding objectives. A number of genetic and evolutionary hypotheses are also discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Genetic diversity in the parental lines and heterosis of the tropical rice hybrids

Genetic diversity within and between the maintainer (B) and restorer (R) lines used in hybrid breeding programs of the Philippine was investigated with information from analysis of pedigree record, quantitative traits and SSR assays. Mean coefficients of coancestry were calculated as 0.11 within R lines, 0.27 within B lines, and 0.04 between R and B lines, indicating greater diversity among R lines than among B lines, and the significant divergence between B and R lines. These results are consistent with those obtained from quantitative trait analysis and SSR marker assays. Relative gene diversity for 37 random SSR markers averaged 0.20 within B lines,0.28 within R lines, and 0.52 between two groups of lines. There were no consistent associations among various genetic diversity measures. Random sets of SSR marker and pedigree based diversity measures had no significant correlation with mid-parent heterosis for grain yield and biomass, indicating that prediction of heterosis for complex traits based on these two genetic diversity estimates is difficult. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effect of source germplasm and season on the in vivo haploid induction rate in tropical maize

For in vivo production of doubled haploid (DH) lines in maize, the rate of haploid induction is of crucial importance. Maternal haploid induction depends primarily on the inducer used as a pollinator. However, the source germplasm used as a maternal parent and the environmental conditions for induction may also influence haploid induction and these aspects have not been examined in tropical maize so far. The objectives of our study were to (i) monitor the variation for haploid induction rate (HIR) among diverse source germplasm in tropical maize, (ii) determine the relative importance of general (GCA) and specific (SCA) combining abilities for HIR, and (iii) investigate the influence of summer and winter seasons and genotype × season interactions on this trait. Ten inbreds were mated in a half diallel design. The resulting 45 F₁ single crosses were pollinated with the haploid inducer hybrid RWS × UH400 during the summer 2008 and winter 2009 seasons in a lowland tropical environment in Mexico. HIR of the single crosses averaged over seasons ranged from 2.90 to 9.66% with an overall mean of 6.74%. Mean HIR was significantly (P < 0.01) higher during the winter (7.37%) than summer season (6.11%). Significant (P < 0.01) variation was observed due to GCA effects of parental inbreds of single crosses but not for SCA, GCA × season and SCA × season interactions. Our study underpins that a higher HIR in tropical maize can be obtained by selecting appropriate source germplasm and undertaking pollination under favorable environmental conditions.     

Evaluation of androgenic competence through anther culture in common eggplant and related species

Anther culture is a convenient technique to obtain androgenic haploid and doubled haploid (DH) plants. In common eggplant (Solanum melongena), this technique has been used to develop DH pure lines for producing uniform F1 hybrid seed of some commercial varieties. However, a comprehensive study of the variation of this useful trait among different materials of common eggplant and related species is still lacking. In this work, we studied the androgenic response of 12 accessions of common eggplant and related materials from the primary (eggplant complex) and secondary genepools. We cultured anthers of all the accessions under the same experimental conditions, and studied their competence to produce calli, embryos and plants, as well as the quality and origin of the embryos produced. In our conditions, anthers of 11 out of the 12 accessions produced somatic calli, whereas only 5 also produced microspore-derived embryos, with variable results in terms of embryo quality and of frequency of embryo induction and plant germination. Embryos of responding accessions were initially haploid, and reached the DH status, verified with SSR markers, after a defined period of culture. In addition to other aspects common to many androgenesis-responsive species, our results allowed us to extract conclusions particular to common eggplant and relatives, including the difficulty for finding sources of androgenic competence out of S. melongena, the reduced impact of calli in the production of non-DH individuals, and the need to avoid the occurrence of severe anatomical and functional problems in the apex of most embryos, which seriously reduces their germinative success.     

Untangling the genetic control of maize plant architecture plasticity

Euphytica - The hard-shelled character of ordinary cultivated Tartary buckwheat has become a factor influencing its taste and nutritional efficacy. However, the local variety, Rice-Tartary, can...     

The fracture toughness and properties of thermally modified beech and ash at different moisture contents

The fracture toughness of thermally modified beech (Fagus sylvatica L) and ash (Fraxinus excelsior L) wood under Mode I loading was quantified using Compact Tension (CT) specimens, loaded under steady-state crack propagation conditions. The influence of three heat-treatment levels and three moisture contents, as well as two crack propagation systems (RL and TL) was studied. Complete load–displacement records were analysed, and the initial slope, k _init, critical stress intensity factor, K _Ic, and specific fracture energy, G _f, evaluated. In the case of both species, thermal modification was found to be significantly affect the material behaviour; the more severe the thermal treatment, the lower the values of K _Ic and G _f, with less difference being observed between the most severe treatments. Moisture content was also found to influence fracture toughness, but had a much less significant effect than the heat treatment.     

Temperate agroforestry research: considering multifunctional woody polycultures and the design of long-term field trials

The many benefits of agroforestry are well-documented, from ecological functions such as biodiversity conservation and water quality improvement, to cultural functions including aesthetic value. In North American agroforestry, however, little emphasis has been placed on production capacity of the woody plants themselves, taking into account their ability to transform portions of the landscape from annual monoculture systems to diversified perennial systems capable of producing fruits, nuts, and timber products. In this paper, we introduce the concept of multifunctional woody polycultures (MWPs) and consider the design of long-term experimental trials for supporting research on agroforestry emphasizing tree crops. Critical aspects of long-term agroforestry experiments are summarized, and two existing well-documented research sites are presented as case studies. A new long-term agroforestry trial at the University of Illinois, “Agroforestry for Food,” is introduced as an experiment designed to test the performance of increasingly complex woody plant combinations in an alley cropping system with productive tree crops. This trial intends to address important themes of food security, climate change, multifunctionality, and applied solutions. The challenges of establishing, maintaining, and funding long-term agroforestry research trials are discussed.     

A new acylated quercetin glycoside and other secondary metabolites from Helleborus foetidus

A new acylated flavonol glycoside, quercetin 3-O-(2-trans-caffeoyl)-alpha-L-arabinopyranosyl-(1-->2)-beta-D-glucopyranoside (1), together with the known 25R,26-[(beta-D-glucopyranosyl)oxy]-22alpha-hydroxy-5beta-furostan-3-beta-yl O-alpha-l-rhamnopyranosyl-(1-->4)-beta-D-glucopyranoside (2), anemonin (3), beta-D-glucosyl-p-hydroxyphenylethyl alcohol (4), and 1-beta-O-caffeoyl-D-glucose (5) were isolated from Helleborus foetidus leaves and identified on the basis of detailed spectral analysis.     

Genetic diversity of selected pigmented traditional rice (Oryza sativa L.) varieties from Mindanao,Philippines using agromorphological traits and simple sequence repeats markers

Journal of Crop Science and Biotechnology - Philippine pigmented traditional rice varieties (TRVs) offer potential novel genes for genetic improvement. In this study, forty-three pigmented...