Copper localization in Cannabis sativa L. grown in a copper-rich solution

Summary With the aim to examine its potential as a renewable resource to decontaminate polluted soils, electron microscopy combined with X-ray microanalysis was used to investigate the localization of copper in Cannabis sativa grown in hydroponic copper-rich culture. Cu was found to accumulate preferentially in the upper leaf epidermal cells; it was also detected in spiculae and in abaxial trichomes too. Primary bast fibres seem to be not involved in copper accumulation.     

Life Cycle Analysis of field production of fibre hemp, the effect of production practices on environmental impacts

Summary Life Cycle Assessment (LCA) was used to assess the environmental impacts of field production of fibre hemp and seven other crops in France. The production of 1 ha of hemp yielded a eutrophication potential of 20.5 kg PO₄-equivalents, a global warming potential of 2330 kg CO₂-equivalents, an acidification potential of 9.8 kg SO₂-equivalents, a terrestrial ecotoxicity potential of 2.3 kg 1,4-dichlorobenzene-equivalents, an energy use of 11.4 GJ, and a land use of 1.02 ha.year. A comparison of hemp (low impacts), wheat (intermediate impacts) and sugar beet (high impacts) revealed that the crops were similar for the relative contributions of emitted substances and resources used to impacts, and for the relative contribution of processes to impacts. A reduction of the impacts of hemp production should focus on eutrophication, and consider the reduction of climate change, acidification and energy use as secondary objectives. Given this objective, the overall environmental effect of the substitution of mineral fertiliser by pig slurry is negative. The introduction of reduced tillage is of interest, as it decreases energy use, acidification and climate change. Measures leading to a reduction in NO₃ leaching are highly interesting, as they strongly decrease eutrophication. Implications for hemp breeding are discussed.     

Optimisation of breeding for agronomic traits in fibre hemp (Cannabis sativa L.) by study of parent-offspring relationships

Summary In the framework of a comprehensive Dutch research project the feasibility of hemp cultivation for paper pulp production is being investigated. This project also includes a hemp breeding programme which was initiated at CPRO-DLO in 1990. Hemp breeding is primarily aimed at improving bast fibre production since bast fibre is qualitatively superior to woody core fibre for paper pulp production. The progress of the ongoing breeding programme is hampered by the lack of knowledge on the inheritance of agronomic traits.The following traits were examined on 252 parental plants in 1991 and subsequently on their progenies in 1992: fibre content, plant height, date of flowering, stem diameter and cannabinoid contents. For each trait heritabilities were estimated and direct and indirect effects of artificial selection were studied.The heritability of bast fibre content was high and mass selection proved to be an efficient method causing no undesirable influence on other characters. Characters not directly related to bast fibre yield such as date of flowering, plant height and stem diameter were shown to have disadvantages as selection criteria for the improvement of bast fibre yield.The cannabinoids THC and CBD were studied, as the acceptance of hemp cultivation requires a low level. The content of THC, the psychoactive component can be successfully reduced by mass selection, but it is not certain that mass selection is the most efficient method.     

Correlated response to recurrent selection for groat-oil content in oats

Summary One hundred random oat (Avena sativa L.) lines from a base (C₀) and each of three populations (C₁, C₂, and C₃) improved for groat (caryopsis) oil content by phenotypic recurrent selection were evaluated for correlated changes in several unselected agronomic traits. In addition, the parents of the base population and four check varieties were evaluated for the same traits. Phenotypic recurrent selection for high groat-oil content resulted in no significant correlated response in mean expression of any trait. Mean grain yield, biomass, groat yield, and harvest index of the improved populations were equal or superior to the mean of the parents and, with the exception of harvest index, equivalent to the mean of the check varieties. Mean test weight and seed weight of all populations were lower than for parents or check varieties. Selection for high groat-oil content caused a decline in genotypic variance for test weight and groat fraction, but reductions in genotypic variance for heading date and plant height may have resulted from culling for good agronomic type. Broad-sense heritability remained moderate to high for all traits except groat fraction. Phenotypic and genotypic correlation coefficients revealed negative, though mostly nonsignificant, relationships between groat-oil content and several traits, which may reflect a purported bioenergetic limitation to increasing groat-oil content in oats. Oil yield, however, was positively correlated with grain and groat yield, groat fraction, biomass, and harvest index. Results suggest that development of high-oil oat cultivars with current levels of production traits via phenotypic recurrent selection is possible.Journal Paper no. J-13038 of the Iowa Agric. and Home Econ. Exp. Stn., Ames, IA 50011. Project 2447.     

Novel male-specific molecular markers (MADC5, MADC6) in hemp

Decamer RAPD primers were tested on dioecious and monoecious hemp cultivars to identify sex-specific molecular markers. Two primers (OPD05 and UBC354) generated specific bands in male plants. These two DNA fragments were isolated, cloned and sequenced. Both markers proved to be unique, since no sequence with significant homology to OPD05₉₆₁ and UBC354₁₅₁ markers were found in databases. These markers were named MADC3 (OPD05₉₆₁) and MADC4 (UBC354₁₅₁) (Male-Associated DNA from Cannabis sativa). The markers were converted into sequence-characterized amplified region (SCAR) markers. The SCAR markers correlated with the sex of the segregating F₂ population and proved the tight linkage to the male phenotype. Results of F₂ plant population analysis suggest these markers are to be linked to the Y chromosome. This revised version was published online in August 2006 with corrections to the Cover Date.     

Changes in fatty acid composition associated with recurrent selection for groat-oil content in oat

Summary Groat oil of oat (Avena sativa L.) is a well-balanced oil with respect to saturated, monounsaturated, and polyunsaturated fatty acids. In this study, we measured the effect of six cycles of recurrent selection for high groat-oil content on the fatty acid composition of the groat oil. From each cycle of selection, 50 oat lines were grown in a replicated field experiment at two sites and were evaluated for groat-oil content and fatty acid composition.Concentrations of palmitate and linolenate decreased moderately over cycles of selection, whereas stearate content increased. A major increase occurred in the content of oleate and a major decrease in linoleate. Most of the modification of fatty acid composition took place within the saturated and unsaturated classes. The ratio of unsaturated to saturated fatty acids increased over cycles of selection. Significant genetic variation was present for each fatty acid, indicating that selection for different desired fatty acid compositions in groat oil of oat should be possible in this population.Abbreviations GO groat-oil content - 16:1 palmitate - 18:0 stearate - 18:1 oleate - 18:2 linoleate - 18:3 linolenate     

Photoperiod sensitivity gene controlling heading date in rice cultivars in the northernmost region of Japan

Rice is grown in diverse environments at latitudes ranging from 53^°N to 40^°S. In Japan, Hokkaido is the northernmost rice cultivation region(42–45^°N latitude). Only extremely early maturing (heading) varieties that have extremely low photoperiod sensitivity are adapted to this area. Heading date is the most important trait in adaptation to this particular environment. Also, the efficient manipulation of heading date is a crucial component of rice improvement. To determine the genetic basis for heading date among cultivars grown in Hokkaido, the heading behaviour was analyzed. Clear segregations were observed. To estimate the photoperiod sensitivity of the genes involved, the cultivars and F₁ plants from crosses between the cultivars were grown under different daylength conditions. The results indicated that the genes controlling heading date are photoperiod sensitive, suggesting they play important roles in the northernmost rice cultivation regions in Japan, to which only cultivars with extremely low photoperiod sensitivity are adapted. This revised version was published online in August 2006 with corrections to the Cover Date.     

QTL-based analysis of genotype-by-environment interaction for grain yield of rice in stress and non-stress environments

Use of DNA-based markers can accelerate cultivar development in variable cultivation environments since, in contrast to phenotype, DNA markers are environment-independent. In an effort to elucidate the genetic basis of genotype-by-environment interaction (G × E) for yield of rice (Oryza sativa L.), the associations between 139 AFLP markers and grain yield were determined for rice grown in fresh water (EC of 0.65 dS m⁻¹) and saline conditions (EC of 4–8 dS m⁻¹) with 0 kg ha⁻¹ or 100 kg ha⁻¹ nitrogen fertilizer in the years 2000 and 2001. A population of recombinant inbred lines of rice, developed from an IR29 × Pokkali cross, was used in the study. Both genotype × salinity and genotype × nitrogen level interactions were significant, with the genotype × salinity interaction being stronger. Through multiple regression analysis using a stepwise procedure for selecting markers, 36 markers were detected for grain yield in the four test conditions and of these 28 were detected in only one test condition implying strong environmental specificity for yield QTL expression. However, the fact that eight QTLs were detected in more than one test condition points to the existence of wide-adaptability genes in this cross. Markers with significant associations with yield explained between 37% and 48% of the yield variation in each test condition. Superior genotypes of rice were identified in all four test conditions based on their marker signatures. Furthermore, across N fertilizer regimes, yield predicted from summed additive effects of QTLs were significantly correlated with observed yield in the same year and across years. Thus marker-assisted selection can help breeders overcome the problem of low selection efficiency encountered during phenotypic selection for yield in stress environments.     

Inbreeding depression and heterosis in autotetraploids with application to Medicago sativa L.

Inbreeding depression observed in Medicago sativa L. is greater in the early generations of self-fertilization than is expected for an autotetraploid based upon the coefficient of inbreeding (F). Forage yield often is reduced by 30 percent or more after one generation of selfing, while F is only one-sixth, =0. A high frequency of loci containing 3 or 4 different alleles is postulated as a basis for this rapid loss of vigor. A formula is developed that permits computation of the proportions of loci with 1, 2, 3 and 4 different alleles, along with estimates of additive and non-additive values of genes.Forage yield data for backcross and sib-mated populations indicate that quantitative characters are inherited tetrasomically.Journal Paper No. J-5190 of the Iowa Agricultural and Home Economics Experiment Station. Project 1048.Graduate Assistant and Professor of Agronomy, Department of Agronomy, Iowa State University, Ames, Iowa.     

Research on the inheritance of fasciation in lettuce (Lactuca sativa L.)

Summary Inheritance of fasciation was investigated in reciprocal crosses between two lettuce varieties: Suzan (non-fasciated) and Noran (fasciated). In glasshouses parental plants, F₁, F₂, and F₃ populations were assessed for fasciation according to a scale from 0 (non-fasciated)-9 (extremely fasciated).The observed environmental variation for fasciation of the homozygous parents was very low or absent, but the environmental variation for the F₁ populations was large. On the basis of this large variation of the heterozygous F₁ plants we supposed that such a variation also occurred in F₂ and F₃ populations.Considerable mortality was observed in all generations, which supposedly occurred at random in parents and F₁ but was non-random in the segregating F₂ and F₃ populations. So, means and variances of F₂ populations will be biased and therefore they were not used for genetical analyses of fasciation.From F₁ and F₃ populations and from some F₂ populations it appeared that no differences occurred between reciprocals. The differences for fasciation between reciprocal F₂ populations in the 1977 A experiment may result from non-random plant survival. A regression of F₃-means on the values for fasciation of parental F₂ plants, adjusted for their inbreeding, resulted in a realized h²-narrow of 0.4. This indicates that in the surviving plants of the F₂ populations still additive genetic variation was present to select successfully for non-fasciated plants.     

Predicting the chemical composition of fibre and core fraction of hemp (Cannabis sativa L.)

Summary Fibre formation in hemp (Cannabis sativa L.) is a dynamic process. In order to follow this process, the chemical composition of the hemp stem was studied during plant development using the acid and neutral detergent fibre and lignin methods. Additionally, near infra-red spectroscopy was carried out. To predict the chemical composition of the stem samples partial least square (PLS) analysis was carried out. The developed PLS models can predict the level of %ADF and %NDF in the hemp bast and core samples. For %ADL, the models are only suited for either core or bast tissues and can not be used for both tissues simultaneously.     

A new gene for resistance in rice to Asian rice gall midge (Orseolia oryzae Wood Mason) biotype 1 population at Raipur, India

The Asian rice gall midge, Orseolia oryzae Wood Mason (Diptera: Cecidomyiidae), is a major pest of rice in several South and South East Asian countries. The maggots feed internally on the growing tips of the tillers and transform them into tubular galls, onion leaf-like structures called ‘silver shoots’ resulting into severe yield loss to the rice crop. We studied the mode of inheritance and allelic relationships of the resistance genes involved in resistant donor Line 9, a sib of a susceptible cultivar ‘Madhuri’. The segregation behaviour of F₁, F₂ and F₃ populations of the cross between Line 9 and susceptible cultivar MW10 confirmed the presence of a single dominant gene for resistance. Tests of allelism with all the known genes giving resistance to this population indicated that Line 9 possessed a new gene which was designated Gm 9 This revised version was published online in July 2006 with corrections to the Cover Date.     

Histochemical and supramolecular studies in determining quality of hemp fibres for textile applications

Summary The composition and supramolecular structure of hemp primary bast fibres have been assessed using microscopy, compositional analysis, wide-angle X-ray diffractometry and CP-MAS ¹³C-NMR, in order to unambiguously define some quality parameters. The main components of the fibre wall were detected by histochemical reactions and modifications occurring during the plant growth have been pointed out. Some differences in fibre lignification degree were recorded among cultivars and confirmed by means of compositional and structural analysis. As for flax and kenaf, X-ray patterns revealed semicrystalline structure of hemp cellulose. NMR spectra and their probabilistic elaboration by MaxEnt method gave further insight on the presence of paracrystalline and amorphous phases and provided an accurate evaluation of polymeric components.     

RAPD variability in rice (Oryza sativa L.) plants derived from desiccation-tolerant calli

Genetic modification from selfed progenies of 18 rice (Oryza sativa L.) plants regenerated from callus tissues which survived desiccation, were investigated at the DNA level using the random amplified polymorphic DNA (RAPD) method. Twelve 10-mer random primers were used to amplify DNA of progenies from the regenerated plants, and a total of 228 PCR products and 1780 DNA fragments were obtained by primers, generating between four to thirteen major bands. The size of the amplified fragments ranged from 0.2 to 2.55 kb. The results showed that 10 out of 12 primers produced polymorphic bands, two primers (RA31 and RA185) showed no polymorphism among plants tested. A dendrogram of the genetic distance was constructed based on their polymorphism, demonstrating that somaclonal variation exists in rice plants regenerated from callus which survived the desiccation treatment. Part of this variation can be useful in rice breeding. This revised version was published online in August 2006 with corrections to the Cover Date.     

The sexual differentiation of Cannabis sativa L.: A morphological and molecular study

Summary Cannabis sativa L. is a dioecious species with sexual dimorphism occurring in a late stage of plant development. Sex is determined by heteromorphic chromosomes (X and Y): male is the heterogametic sex (XY) and female is the homogametic one (XX). The sexual phenotype of Cannabis often shows some flexibility leading to the differentiation of hermaphrodite flowers or bisexual inflorescences (monoecious phenotype). Sex is considered an important trait for hemp genetic improvement; therefore, the study of the mechanism of sexual differentiation is of paramount interest in hemp research. A morphological and molecular study of Cannabis sativa sexual differentiation has been carried out in the Italian dioecious cultivar Fibranova.Microscopic analysis of male and female apices revealed that their reproductive commitment may occur as soon as the leaves of the fourth node emerge; the genetic expression of male and female apices at this stage has been compared by cDNA-AFLP. A rapid method for the early sex discrimination has been developed, based on the PCR amplification of a male-specific SCAR marker directly from a tissue fragment.Five of the several cDNA-AFLP polymorphic fragments identified have been confirmed to be differentially expressed in male and female apices at the fourth node. Cloning and sequencing revealed that they belong to nine different mRNAs that were all induced in the female apices at this stage. Four out of them showed a high degree of similarity with known sequences: a putative permease, a SMT3-like protein, a putative kinesin and a RAC-GTP binding protein.     

Effect of various plant factors on the expression of creeping-rootedness in lucerne (Medicago sativa L. complex)

Although agronomically interesting, selection of creeping-rootedness inlucerne, that is, the ability to form adventitious shoots on horizontal,spreading roots, remains difficult because of the complex and still unclear geneticcontrol of this character, coupled with the possible occurrence of external factorsthat affect unpredictably its expression. Two experiments were undertaken onprogenies of creeping-rooted plants, to verify previous findings and inferences,and test novel hypotheses, concerning the effect of various plant factors on theexpression of creeping-rootedness. The ultimate aim was to provide information onthe most appropriate germplasm, procedures, or indirect selection criteria, that wouldimprove the efficiency of breeding for this character. The factors here examinedincluded genotype, age, kind of progeny, vigour, spreading ability, and undergroundmorphology. Some genotypes appeared to be good donors of the character, whereasothers did not. The proportion of creeping-rooted plants increased in allcases with the plant age. Selfing consistently depressed the expression ofthe character compared with clonal propagation or crossing. It is suggestedthat the effect of age and selfing on the penetrance of creeping-rootedness ismediated through their effect on plant vigour. Both aerial and root vigour showedindeed an effect per se on the presence of the character. Beside thevigour, possible indirect selection criteria were identified in the frequenciesof swollen zones and latent stem primordia on horizontal roots. Proportion ofcreeping-rooted plants in progenies after one year of growth appeared as a simple anduseful criterion to predict future trends. Consistent with previous conclusions, theresults provided evidence that a combination of family and individualselection may enhance the character expression.     

Inheritance of the resistant reaction of the lettuce cultivar `Grand Rapids' to the southern root-knot nematode Meloidogyne incognita (Kofoid & White) Chitwood

Resistance to the southern root-knot nematode Meloidogyne incognita Chitwood would be an important attribute of lettuce Lactuca sativa L. cultivars adapted to both protected and field cultivation in tropical regions. `Grand Rapids' and a few other cultivars are reported to be resistant to this nematode. In this paper, we studied the inheritance of the resistant reaction of `Grand Rapids' (P₂) in a cross with a standard nematode-susceptible cultivar Regma-71 (P₁). F₁(Regina-71 × Grand Rapids) and F₂ seed were obtained, and inoculated along with the parental cultivars with different races of M. incognita to evaluate nematode resistance. Broad sense heritability estimates for the number of galls and of egg masses per root system, gall size and gall index were generally in the order of 0.5 or higher. Class distributions of these variables over generations P₁, P₂, F₁ and F₂ were in agreement with simulated theoretical distributions based on monogenic inheritance models. F₃ families were obtained from randomly sampled F₂ plants and tested for reaction to the nematode. The frequency ratio of homozygous resistant, segregating and homozygous susceptible F₃ families did not differ from the 1:2:1 ratio expected from monogenic inheritance. M. incognita resistance appears to be under control of a single gene locus. The Grand Rapids allele (for which the symbol Me is proposed) is responsible for the resistant reaction, and shows high (though incomplete) penetrance, variable expressivity and predominantly additive gene action. This revised version was published online in July 2006 with corrections to the Cover Date.     

An improved breeding strategy for autotetraploid alfalfa (Medicago sativa L.)

Alfalfa cultivar development will be enhanced by breeding strategies whichutilize the full potential of autotetraploid population genetic structures. Thisstudy evaluates the effectiveness of an allelic selection scheme, which wasdeveloped to overcome limitations of inbreeding depression and to exploitgeneral and specific combining ability effects in autotetraploid populations.Allelic selection entails the minimization of non-additive genetic effects byselecting among full-sib families (F1) which are at uniform levels ofheterozygosity. Such F1 lines are developed by crossing individuals fromtwo unrelated random mating populations. Selected F1 lines wereintercrossed to form an improved population. Eight random matingpopulations of alfalfa were developed to study the effectiveness of allelicselection. Selection for increased dry matter yield resulted in alfalfapopulations with 38 percent greater yield than the parent populations. Twocycles of intercrossing, among selected F1 lines, did not dissipate the gainfrom selection. This result has important implications for synthetic cultivardevelopment in which a major limitation is the decline in productivity withadvancing generations of seed increase. A positively correlated response toselection for dry matter yield was observed for plant height and stemdiameter. The results of this research indicate that continued testing of theallelic selection scheme is warranted and could have a significant impact onthe breeding of autotetraploid alfalfa, particularly for synthetic cultivardevelopment.     

Oil content, tocopherol composition and fatty acid patterns of the seeds of 51 Cannabis sativa L. genotypes

The oil content, the tocopherol composition, the plastochromanol-8 (P-8) content and the fatty acid composition (19 fatty acids) of the seed of 51 hemp (Cannabis sativa L.) genotypes were studied in the 2000 and 2001 seasons. The oil content of the hemp seed ranged from 26.25% (w/w) to 37.50%. Analysis of variance revealed significant effects of genotype, year and of the interaction (genotype × year) on the oil content. The oil contents of the 51 genotypes in 2000 and 2001 were correlated (r = 0.37**) and averaged 33.19 ± 1.45% in 2000 and 31.21 ± 0.96% in 2001. The -tocopherol, -tocopherol, -tocopherol, P-8- and -tocopherol contents of the 51 genotypes averaged 21.68 ± 3.19, 1.82 ± 0.49, 1.20 ± 0.40, 0.18 ± 0.07 and 0.16 ± 0.04 mg 100g^–1 of seeds, respectively (2000 and 2001 data pooled). Hierarchical clustering of the fatty acid data did not group the hemp genotypes according to their geographic origin. The -linolenic acid yield of hemp (3–30 kg ha^–1) was similar to the -linolenic acid yield of plant species that are currently used as sources of -linolenic acid (borage (19–30 kg ha^–1), evening primrose (7–30 kg ha^–1)). The linoleic acid yield of hemp (129–326 kg ha^–1) was similar to flax (102–250 kg ha^–1), but less than in sunflower (868–1320 kg ha^–1). Significant positive correlations were detected between some fatty acids and some tocopherols. Even though the average content of P-8 in hemp seeds was only 1/120^th of the average -tocopherol content, P-8 content was more closely correlated with the unsaturated fatty acid content than -tocopherol or any other tocopherol fraction. The average broad-sense heritabilities of the oil content, the antioxidants (tocopherols and P-8) and the fatty acids were 0.53, 0.14 and 0.23, respectively. The genotypes Fibrimon 56, P57, Juso 31, GB29, Beniko, P60, FxT, Félina 34, Ramo and GB18 were capable of producing the largest amounts of high quality hemp oil.