Genetic relationship in Vigna mungo (L.) Hepper and V. radiata (L.) R. Wilczek based on morphological traits and SDS-PAGE

Thirty seven diverse genotypes of Vigna mungo and three of V. radiataresembling to V. mungo for seed characters were studied to determine the extent of genetic variation based on morphological characters. In addition, 4black seeded genotypes in each species and8 green seeded V. radiata genotypes were included for SDS-PAGE analysis. Seed proteins were analyzed through slab type SDS-PAGE. High variance was observed for plant height, days to flowering, days to maturity, number of branches/plant, number of pods/plant, pod length, seeds per pod,biomass yield/plant, grain yield/plant and harvest index (%) during 2 consecutive years. First four components of PCA with eigenvalues >1 contributed 78.7 and79.1% of the total variance amongst 40genotypes during 1998 and 1999. The populations with high PC₁ values were expected to be high yielding characterised by earlyness, high seed weight and harvest index, all traits strictly related to reproductive phase. Four clusters of genotypes were observed during both the years and genetic diversity was in association for both the years. Based on SDS-PAGE, specific bands were suggested to be used for identifying Vigna radiatafrom mixed germplasm with Vigna mungo. The SDS-PAGE proved to be a powerful tool for differentiating Vigna radiata and Vigna mungo, whereas a low level inter-specific genetic diversity was observed and no clear differentiation was observed both for agronomic characteristics and for geographical origin. This revised version was published online in July 2006 with corrections to the Cover Date.     

Variation for reproductive and agronomic traits among T. repens × T. nigrescens third generation backcross hybrids in the field

Interspecific hybridisation with Trifolium nigrescens Viv. is a possible strategy to improve the reproductive potential of white clover (Trifolium repens L.). Following the development of a fertile F1 hybrid, three generations of backcrossing have been carried out usingT. repens as the recurrent parent. Vegetative characteristics, stolon growth and seed yield components of the backcross (BC) 2 and 3 generations, as well as the parental species were measured on spaced plants grown in the field. Leaf size and plant spread of the BC2 and BC3 generations were less than T. repens but there was no difference in plant fresh weight. Numbers of inflorescences per plant and florets per inflorescence of the backcrosses were greater than T. repens however this was not reflected indifferences in seed yield per plant asT. repens had more seeds per floret and per plant than the backcrosses. Differences in stolon length, the proportion of flowering nodes and the pattern of axillary bud development were observed between T. repens and the backcrosses. Significant variation among the BC 3 generation for vegetative and reproductive traits was observed. Individual plants among the BC 3 generation were identified that combine high forage yield, substantial inflorescence production and good fertility, and these will form the basis of further selection. This revised version was published online in August 2006 with corrections to the Cover Date.     

Morphological variation of Medicago sativa subsp. falcata genotypes and their hybrid progeny

Semi-hybrid alfalfa cultivars offer the possibility of capturing non-additive genetic variation. Medicago sativa subsp. falcata and subsp.sativa have been shown to form a heterotic pattern for biomass yield. Objectives of this study were to examine morphological variation in a broad range of falcate germplasm and to determine how falcate morphological variation per se is related to the performance of falcate germplasm in hybrid crosses with subsp. sativa. Falcata genotypes from 40 populations spanning the subspecies native range were selected and biomass yield, plant width, plant height, growth angle, biomass density, plant maturity, and regrowth after cutting were measured on the genotypes and their hybrid progeny three times throughout the growing season. In addition weekly plant heights were measured and growth rates were determined with a Gompertz function. Falcata parental genotypes exhibited a full range of phenotypes for plant width, plant height, growth angle, density, and maturity. Heterosis was not only observed for biomass yield but also for plant width, plant height, and more erect growth habit. The top yielding sativa-falcata hybrids had increased plant width, plant height, and plant density. European germplasm was taller and had faster regrowth than Asian material. Sativa-falcata hybrids produced biomass yield superior to the mid-subspecies mean only after two to three weeks of growth prior to first and third harvests. Prior to second harvest, biomass production was inferior to the mid-subspecies mean for 30 days. Hybrids using falcata as one parent are not currently adapted to intensive harvest management due to their slower regrowth. This revised version was published online in August 2006 with corrections to the Cover Date.     

Analysis of Competitive Ability among Clones of the Palisade Grass, Brachiaria brizantha (Hochst. Ex. A. Rich.) Stapf.

Four clones of palisade grass, Brachiaria brizantha (Hochst. Ex. A. Rich.) Stapf., were studied in a diallel competition trial to investigate their competitive relationship in clonal mixtures. Clone X associate interactions were observed for plant height, number of tillers per plant and dry matter yield per plant. Both general and specific competitive abilities were observed for tiller number and dry matter yield. Clone X associate interaction for plant height was mainly due to the specific competitive ability of individual combinations. The most competitive clone observed was CIAT 6387. Competitive abilities of local clones were low compared to the imported clones. Local clones (RU 127 and RU 139) yielded more than imported clones (CIAT 6387 and PI 292185) under low competitive stresses. General and specific competitive abilities should be taken into consideration when mixing clones of palisade grass.     

Genetic differences in growth within and between Lycopersicon species

Summary Growth analyses were carried out on 88 accessions of five Lycopersicon species. Experiments were conducted in a climate room at 19/14° C day/night temperature which was irradiated at 20 W/m² for eight hours per day. Large differences in plant weights between wild species and the cultivated tomato were observed from 44 to 84 days after sowing. The increase in plant dry weight could be described by a second order polynomial function. When compared at a standardized plant weight of one gram, the relative growth rates (RGR) of the wild and cultivated accessions ranged from 5.3 to 11.8% and 8.5 to 12.2% per day respectively, limiting the use of wild species as sources for strong growth. When expressed at plant weights of one and three g large differences in decrease of the RGR were observed within L. esculentum. The modern hybrid tomato cultivars were among the fastest growing genotypes, with a relatively slow decrease in RGR.     

Morphological changes and self-incompatibility breakdown associated with autopolyploidization in <Emphasis Type="Italic">Hylocereus</Emphasis> species (Cactaceae)

Chromosome duplication—autopolyploidization—may affect plant morphology and breeding systems, ultimately enabling the production of improved genotypes. In this study, the autotetraploid lines obtained from the self-incompatible diploid Hylocereus monacanthus and the autooctapolyploid lines obtained from the self-compatible tetraploid H. megalanthus were studied and compared with the donor accessions. The resulting H. monacanthus autotetraploids exhibit lower fruit weight, seed number, and pollen viability than the donor plant, but it has larger pollen grains. Although the resulting H. megalanthus autooctaploids had larger pollen grains and lower pollen viability compared with the donor plant, only aborted fruits were obtained from these lines. The most valuable change observed was the breakdown of the self-incompatibility system in the H. monacanthus autotetraploid lines. This research provides important information on the horticultural value of vine cacti autopolyploid lines.     

Inheritance of a plant type mutant and its utilization in chickpea

Summary A macro-mutant, E 100Y(M) in chickpea (Cicer arietinum L.) was found to affect several plant and seed characters. For plant type monogenic inheritance was observed. A single pair of recessive genes pt/pt was ascribed to this mutant. The mutant locus seemed to be exerting pleiotropic action. The utilization of this mutant for chickpea improvement has been discussed.     

Pleiotropic effects of the ea7 photoperiod response gene on the morphology and agronomic traits in barley

The photoperiod‐insensitive barley mutant ‘Atsel’, carrying the recessive gene ea₇, was studied together with the donor variety ‘Atlas’ (wild‐type, Ea₇) under different daylengths with the aim of analysing pleiotropic effects. Grown under long and short photoperiods ‘Atsel’ flowered about 10 days and 34 days, respectively, earlier than ‘Atlas’. The significantly shorter life‐cycle of the photoperiod‐insensitive mutant resulted in several changes of plant morphology. Tillering, plant height, number of leaves and number of internodes were reduced. A lower number of florets per main spike was observed for ‘Atsel’, but only in the long photoperiod experiment. Finally, photoperiod insensitivity combined with a lower grain yield per plant was most pronounced under long‐day treatment. The data are comparable with results obtained from single chromosome recombinant lines of wheat that have differences in their photoperiod response caused by the genes Ppd1 or Ppd2.     

Mutation of DEP1 facilitates the improvement of plant architecture in Xian rice (Oryza sativa)

Plant architecture is a complex trait and has a profound impact on crop performance and productivity. We applied the CRISPR/Cas9 system to mutate the DEP1 gene, which has been reported to function as regulator of plant architecture, in elite Xian cultivar ‘Huhan1509’. Sequencing analysis of T₀ transformed plants showed that the CRISPR/Cas9 system was highly efficient in mutagenesis of targeted DEP1 gene, with 30% of the homozygous mutations and 70% of the heterozygous mutations. T₂ homozygous mutants without T-DNA were further examined for the agronomic traits. The DEP1 mutants exhibited an altered plant architecture along with a shorter plant height and grain size and increased spikelets and grain density. Furthermore, phenotypes of raising primary branches and stem diameters were observed in the DEP1 mutants. Our results demonstrate that favourable alleles of the DEP1 gene, developed by CRISPR/Cas9 system, could be used to improve plant architecture in Xian rice.     

Creating favourable morphological and yield variations for rapeseed by interspecific crosses between Brassica rapa and Brassica oleracea

Brassica napus is a most important oilseed grown worldwide with a limited genetic background, due to the short history of speciation, domestication and cultivation. To create novel germplasm for rapeseed breeding, we made interspecific crosses followed with chromosome doubling between B. rapa and B. oleracea to generate novel B. napus with favourable agronomic traits. The resynthesized (S0) hybrids were confirmed by SSR and cytogenetic analysis, and the fertility was increased from 32.7% in S0 generation to ~97.31% in S1 generation. The plant shapes of the progeny were dramatically improved compared to the diploid parents and B. napus cv. ‘Yangyou 6’, especially for the branch initiation height, branch number and pod number. The single‐plant yield was significantly improved in S1 progeny for the variations in branching sites and number. Significant improvement in plant shape and yield was observed on S2 generation compared to the local elite commercial open‐pollinated cultivar, which would be further fixed by intensive selection and pyramiding breeding. Such variation is of great value for breeding rapeseed with improved plant architecture and harvest index.     

Intergeneric hybrids and an amphiploid between Elymus canadensis and Psathyrostachys juncea

Summary Fifty four hybrid plants between Elymus canadensis and Psathyrostachys juncea were obtained by handpollination and embryo culture. The average cross compatibility between both species was 31.2 percent. One amphiploid plant was induced by colchicine treatment. The hybrid and amphiploid plants resembled P. juncea in appearance but showed a higher plant height and dry matter yield than the parents. The hybrids showed extremely low pollen stainability and were completely sterile. With the exception of one plant (2n=3x+1=22), all hybrid plants were allotriploids (SHN, 2n=3x=21). The amphiploid plant (SSHHNN, 2n=6x=42) showed 58.9% pollen stainability and 11.6% seed fertility.Mean chromosome associations of the hybrids and amphiploid at metaphase I were 0.02IV+0.06III+2.03II+16.91I and 0.07III+18.00II+5.85I, respectively. Lagging chromosomes, chromosome bridges, abnormal cytokinesis, and micronuclei were occasionally observed at the anaphase, telophase, or tetrad stage.     

The response to saprol (systemic fungicide) in lettuce species and cultivars and its inheritance

Summary The response of Lactuca sativa, L. serriola and L. saligna to saprol was studied. Spraying the whole plant or part of a leaf caused wilting of susceptible plants. A similar effect was observed when leaves were soaked in a solution containing saprol.Inheritance studies with L. sativa and L. serriola showed that resistance to the wilting reaction caused by saprol is controlled by a single recessive gene.Contribution no. 198-E, 1978 series.     

A method for testing drought tolerance in <Emphasis Type="Italic">Fragaria</Emphasis> based on fast screening for water deficit response and use of associated AFLP and EST candidate gene markers

Drought stress is one of the most important environmental factors that limit plant growth and development, thus reducing yield. The objective of the present research was to correlate the genetic structure of different Fragaria genotypes, as assessed by Expressed Sequence Tag (EST) and Amplified Fragment Length Polymorphism (AFLP) markers, and plant responses to drought stress. Firstly, physiological parameters related to the plant response to drought stress such as leaf relative water content (RWC) and water losing rate (WLR) were measured. WLR and RWC were compared for 20 cultivars of the octaploid Fragaria × ananassa, two ecotypes of the diploid species F. vesca and one octaploid species F. chiloensis. These parameters could discriminate genotypes showing a contrasting response to water stress. Secondly, AFLP and ESTs were compared in terms of their information content and efficiency in the study of genetic diversity and relationships among these 23 Fragaria genotypes. To evaluate the genetic basis for the observed variation in the measured physiological parameter, the effect of specific AFLP/EST loci on WLR and RWC for the different Fragaria genotypes was quantified by Kruskal–Wallis analysis. By Mantel testing, the hierarchical clustering of the Fragaria genotypes based on associated EST or AFLP markers was compared to the observed eco-physiological relevant grouping. A better discriminating capacity for associated markers was noted, enabling a functional marker selection approach to screen the strawberry gene pool for drought tolerance. Correlation of EST markers to leaf RWC and WLR enforces them as potential candidate genes in control of plant responses to drought stress in Fragaria sp.     

Effects of donor plant temperature,photoperiod, and age on anther culture response of Capsicum annuum L.

Summary Effects of temperature and photoperiod for donor plant growth on embryo formation in Capsicum annuum anther culture were investigated. Donor plants were grown in glasshouses at minimum temperatures between 16 and 30° C and at photoperiods between 11 and 19 h. Anthers were collected from individual plants over five to nine week periods to test the significance of donor plant age. Embryos were obtained at all temperature regimes with a calculated optimum temperature of 26.4° C. Embryo formation was unaffected by the photoperiods tested. Embryo formation varied among successive samplings. However, a significant decline in anther culture response with increasing donor plant age was observed in all three experiments.Abbreviations AT average air temperature the week before anther incubation - EMB 100 1n (embryos per 100 anthers +1)     

Callus Production and Plant Regeneration from Mature Embryos of Poa pratensis L.

Plant regeneration from callus cultures may provide a source ot somaclonal variation for the improvement ot the apomictic grass Poa pratensis L. It is first necessary to be able to induce callus and regenerate plants in this species at a high frequency. Variation was observed between 50 cutivars of Poa pratensis for callus induction and plant regeneration. Using the cultivars ‘Merion’ and ‘Victa’, three basal media were tested along with various media additives. Murashige and Skoog's basal medium with 0.2 mg 1^?1 2,4-dichlorophenoxyacetic acid, 0.1 mg 1^?1 6-benzylamanopurine, 100 mg 1^?1 casein hydrolysate and 25 g 1^?1 sucrose is considered to be a good medium for callus growth and plant regeneration. Embryo-like structures were observed in the callus of some cultivars but plant regeneration appeared to be predominantly from shoot meristems on the callus surface. The majority of regenerated shoots were green, but chlorophyll deficient shoots were obtained from media containing coconut milk. Green plantlets could be transferred to soil without difficulty.     

Study of genetic diversity in safflower genotypes using agro-morphological traits and RAPD markers

This research was conducted to study the genetic diversity in safflower (Carthamus tinctorius L.) using agro-morphological traits and RAPD markers. Sixteen selected lines derived from landraces growing in various agro-climatic regions of Iran along with four exotic genotypes were evaluated in a randomized complete block design with three replications under field conditions. Days to emergence, days to initial flowering, days to flowering, days to maturity, plant height, branches per plant, capitula per plant, seeds per capitulum, 1,000-seed weight, seed yield per plant, seed yield, and reaction to powdery mildew (Leveillula taurica Arnaud) were evaluated in this study. Genetic diversity of the genotypes was assessed by RAPD markers. The results indicated significant differences among genotypes for the agro-morphological traits and clustering based on these traits classified the genotypes into five groups. Analysis of the RAPD markers revealed 15 polymorphic primers out of 50 used primers. Based on RAPD data, the highest genetic similarity was observed between the cultivars of “AC Sunset,” “AC Sterling” from Canada and the lowest relatedness observed between a local breeding line “E₂₄₂₈” and genotype “GE₆₂₉₂₃” from Germany. Cluster analysis based on RAPD markers and 54% coefficient of similarity divided the genotypes into five distinct groups. Comparing the clusters based on agro-morphological traits with those from molecular markers showed slight similarities. The finding of high genetic variation for agro-morphological traits and polymorphism at DNA level reveal that agronomic traits can be improved by selection programs.     

Somaclonal variation for some morphological traits, herb yield, essential oil content and essential oil composition in an Indian cultivar of rose-scented geranium

Somaclonal variation for plant height, plant spread, leaf shape, leaf size, leaf form, herb yield, essential oil content and 10 important constituents of the essential oil was studied in an Indian cultivar, ‘Bourbon’ of rose‐scented geranium (Pelargonium graveolens). Significantly larger variance was observed among in vitro‐regenerated plants of the SC1 generation (first generation following an in vitro phase) than among parental plants raised from stem cuttings for herb yield, plant height, leaf size, essential oil content, and for the contents of cis‐rose oxide, trans‐rose oxide, isomenthone and 10‐epi‐γ‐eudesmol in the essential oil. Plants of the SC₁ generation showing values beyond the higher or lower limit (depending on the trait) of the range observed among parental plants for different traits were developed into clones by their multiplication through stem cuttings, and evaluated again in the SC₂ generation (second generation following the in vitro phase). Somaclones selected for plant spread, and for the contents of linalool and trans‐rose oxide in their essential oils did not breed true in the SC₂ generation. However, for the remaining traits studied, 13–100% of the selected clones retained their selected traits in the SC₂ generation, suggesting that the changes in these somaclones were due to genetic causes.     

Molecular mapping of quantitative trait loci for plant growth, yield and yield related traits across three diverse locations in a doubled haploid rice population

A doubled haploid (DH) population of 125lines derived from IR64 × Azucena, an indica – japonica cross were grown in three different locations in India during the wet season of 1995. The parents of mapping population had diverse phenotypic values for the eleven traits observed. The DH lines exhibited considerable amount of variation for all the traits. Transgressive segregants were observed. Interval analysis with threshold LOD > 3.00 detected a total of thirty four quantitative trait loci (QTL) for eleven traits across three locations. The maximum number of twenty QTL were detected at Punjab location of North India. A total of seven QTL were identified for panicle length followed by six QTL for plant height. Eight QTL were identified on three chromosomes which were common across locations. A maximum of seven QTL were identified for panicle length with the peak LOD score of 6.01 and variance of 26.80%. The major QTL for plant height was located on Chromosome 1 with peak LOD score of 16.06 flanked by RZ730-RZ801 markers. Plant height had the maximum number of common QTL across environment at the same marker interval. One QTL was identified for grain yield per plant and four QTL for thousand grain weight. Clustering of QTL for different traits at the same marker intervals was observed for plant height, panicle exsertion, panicle number, panicle length and biomass production. This suggests that pleiotropism and or tight linkage of different traits could be the plausible reason for the congruence of several QTL. Common QTL identified across locations and environment provide an excellent opportunity for selecting stable chromosomal regions contributing to yield and yield components to develop QTL introgressed lines that can be deployed in rice breeding program. This revised version was published online in July 2006 with corrections to the Cover Date.     

Changes in Frequency of Plants Resistant to Barley Leaf Rust Caused by Puccinia hordei Otth. in a Barley Composite Cross Population

The response of barley Composite Cross XLI to selection for resistance to leaf rust was evaluated. Representative samples from eight cycles of recurrent selection were inoculated with an isolate of Puccinia bordei Otth. in both the seedling and adult plant stage. Disease symptoms were evaluated 14 days after inoculation. The resistance in CC XLI increased with selection in the seedling stage from 15.1 to 20.5 %, and in the adult plant stage from 20.5 to 37.5 %, respectively. The largest gains in resistance were observed in the earlier cycles of recurrent selection. Significant fluctuations in percent resistant plants occurred between the years.     

Genetic analyses of agronomic and seed quality traits of doubled haploid population in Brassica napus through microspore culture

Summary The results showed that the F1 genotype from the cross (Brassica napus cv. Zheshuang 758 × cv. Z-4115) had good response to embryogenesis, and their embryo yield and rate of plant regeneration reached 69.8 embryo/bud and 46.9%, respectively. Characters from the doubled haploid (DH) populations in B. napus were analyzed and it was showed that the means of each agronomic trait were between their parents, but they were nearer to the paternal in 6 agronomic traits (plant height, branch position, number of pods in the main raceme, length of pod, number of pods/plant and number of seeds/pod). The number of genes controlling each agronomic trait was analyzed based on the DH populations. The results showed that the number of genes controlling number of pods in the main raceme was the highest (15.6), and the least number of genes was involved for stem width (only 7.9). According to estimated coefficients of skewness and kurtosis of the traits tested, gene interaction was found to be absent for stem width, plant height, length of main raceme, number of primary and secondary branches, pod density in the main raceme and seed weight/plant. Complementary interaction was also observed in five agronomic traits (number of pods in the main raceme, length of pod, number of pods/plant, number of seeds/pod and 1000-seed weight). A significantly positive correlation was observed between seed yield/plant and four agronomic traits (length of main raceme, length of pod, number of pods/plant and 1000-seed weight). The experiment also showed that the erucic acid, glucosinolate, oil and protein contents of DH populations were 34.23%, 87.09 μmol/g, 44.09% and 42.67%, respectively. The numbers of genes controlling each quality trait were 7.8, 9.7, 9.4 and 8.7, respectively. Partial correlations between the seed quality traits and the agronomic characters of DH populations were analyzed. In this experiment, the partial correlations among seed quality traits were also analyzed and it was found that the oil content had a negative correlation with the other three seed quality traits.