Some yield components and ideotype traits in meadowfoam,a new industrial oil crop

Summary Three populations of Limnanthes alba and five of L. douglasii were investigated for relative growth rates, leaf area index, flowering time, seed and oil yield, seed size and shattering. Within each species the early flowering populations had the highest seed yield. Most accessions developed adequate leaf canopy by the time of onset of flowering.An ideotype for breeding goals could be defined in terms of the characters of L. douglasii var. nivea such as early flowering and high seed yield, provided taller plant stature and reduced seed shattering are incorporated.Domestication and breeding might involve a combination of induced mutation, interspecific hybridization and conventional breeding procedures.     

Genetics of New Crop Genus Limnanthes I. Five Morphological Marker Loci in L. alba × L. gracilis Progenies

New crop development often depends on a few essential traits such as nonshattering of seed at maturity and pollination control. In order to domesticate Limnanthes alba (meadowfoam), as a source of industrial oil, we performed genetic analysis of crosses between L. alba and its closest relative Limnanthes gracilis var. gracilis which shows higher selfing ability and nutlet abscission. Differences in pubescence, nutlet abscission, and seedling pigmentation were each found to be governed primarily by a single locus; two interacting loci appeared to control capsule dehiscence. Segregation distortion was detected for pigmentation in F₂ and F₃ populations, and for pubescence in several F₃ families. Loci controlling pubescence, nutlet abscission, and capsule dehiscence resided in a single linkage block which assorted independently of the locus controlling pigmentation.     

Adaptability and variation in <Emphasis Type="Italic">Isatis tinctoria</Emphasis> L.: a new crop for Europe

Isatis tinctoria L. was cultivated until the 19th century to produce indigo, a natural blue pigment used principally for dyestuffs. The current search for alternative crops and interest in natural products has led to reconsidering I. tinctoria as a crop to be grown in marginal areas to produce natural indigo. To reintroduce I. tinctoria into cultivation, its behaviour under different climatic conditions as well as its morpho-physiological and genetic diversity must be assessed in order to evaluate the possibilities of future breeding work. To do this, a Eurasian collection of 15 accessions was studied in a 2-year experiment. The study was carried out in four locations in order to assess plant performance at altitudes ranging from 380 to 1,700 m a.s.l. A second experiment evaluated the morpho-physiological diversity of several traits (some related to agronomic performances) of the collection. In a third experiment the genetic traits of the collection were characterised by using eight AFLP and eight SAMPL markers. The species showed a wide adaptability to different mountainous conditions and the populations showed high morphologic and genetic variability and differed according to their origins. Both morpho-physiological and molecular characterisation allowed the accessions to be distinguished into groups of European and Asian origin. Future breeding work is recommended because some accessions have good agronomic potential.

Cytogenetics of a new trispecies hybrid in cotton: [(Gossypium hirsutum L. × G. thurberi Tod.)2 × G. longicalyx Hutch. & Lee]

A three‐species hybrid named HTL including Gossypium hirsutum L. [2n = 4 x = 52, (AD)₁ genome] was created using the pseudophyletic introgression method with G. longicalyx Hutch. & Lee (2n = 2x = 26, F₁ genome) as donor parent and G. thurberi Tod. (2n = 2x = 26, D₁ genome) as bridge species. The new hybrid was totally self‐sterile and its interspecific status was confirmed using simple sequence repeat markers and cytogenetic analysis. Cytogenetic studies showed that its chromosome configuration was 2n = 52 = 14.13 I + 15.10 II + 1.03 III + 0.9 IV + 0.03 V + 0.13 VI (where I, II, III, IV, V and VI are univalents, bivalents, trivalents, tetravalents, pentavalents and hexavalents, respectively). Prospects for successfully exploiting the HTL hybrid in breeding programmes are discussed.     

Construction of a chromosome-assigned,sequence-tagged linkage map for the radish,Raphanus sativus L. and QTL analysis of morphological traits

The radish displays great morphological variation but the genetic factors underlying this variability are mostly unknown. To identify quantitative trait loci (QTLs) controlling radish morphological traits, we cultivated 94 F₄ and F₅ recombinant inbred lines derived from a cross between the rat-tail radish and the Japanese radish cultivar ‘Harufuku’ inbred lines. Eight morphological traits (ovule and seed numbers per silique, plant shape, pubescence and root formation) were measured for investigation. We constructed a map composed of 322 markers with a total length of 673.6 cM. The linkage groups were assigned to the radish chromosomes using disomic rape-radish chromosome-addition lines. On the map, eight and 10 QTLs were identified in 2008 and 2009, respectively. The chromosome-linkage group correspondence, the sequence-specific markers and the QTLs detected here will provide useful information for further genetic studies and for selection during radish breeding programs.     

Identification of a major QTL for adult plant resistance to coffee leaf rust (Hemileia vastatrix) in the natural Timor hybrid (Coffea arabica x C. canephora)

Most of the commercial varieties of coffee (Coffea arabica L.) derived from the Timor hybrid (TH) have been shown to contain major genes for coffee leaf rust (CLR) resistance. To identify markers tightly linked to such genes, an F₂ mapping population derived from a cross between ‘Caturra’ (susceptible variety) and the TH‐derived DI.200 line (highly resistant) was generated. Using expressed sequence information and a bioinformatics approach, both targeted region amplified polymorphism (TRAPs) markers and simple sequence repeat (SSR) markers were identified. Phenotypic evaluations in the field and under controlled conditions confirmed the existence of one quantitative trait locus for CLR resistance. Four candidate SSR markers were associated with high CLR resistance. They spanning a region of 2.5 cM designated Q_{CLR_4} located within chromosome 4 of the international C. canephora map. The presence of this region was confirmed in a set of elite lines and commercial varieties. The Q_{CLR_4} region corresponds to a new and genetically independent S_H locus that could potentially be useful in gene pyramiding with other genes to enhance rust resistance in TH derivatives.     

Maternal inheritance of male sterility in the progeny of a natural hybrid between Cajanus lineatus and C. cajan

Adoption of pigeonpea hybrids in central and southern India is showing high impact with on‐farm yield advantages of >30%. The hybrid pigeonpea technology, the first in any legume crop, is based on a cytoplasmic‐nuclear male‐sterility (CMS) system. For a long‐term sustainability of hybrid programme, it is imperative that both nuclear diversity and cytoplasmic diversity are maintained among hybrid parents. In this context, a continuous search for new CMS‐inducing cytoplasms is necessary. This paper reports detection of maternal inheritance of male sterility in the progeny derived from a natural hybrid between a wild relative [Cajanus lineatus (W. & A.) Maesen comb. nov.] of pigeonpea and an unknown pigeonpea [Cajanus cajan (L.) Millsp.] genotype. In the present study, the male sterility was maintained up to BC₇F₁ generation by an advanced breeding pigeonpea line ICPL 99044. This male sterility inducing cytoplasm of C. lineatus was tagged as A₆. In future, this CMS genetic stock can be used to develop a range of new pigeonpea hybrids with high yield and adaptation.     

Genetic variation and phylogenetic relationships in East and South Asian melons, Cucumis melo L., based on the analysis of five isozymes

Genetic structure and phylogenetic relationships in East and South Asian melons were analyzed, based on the geographical variation of five isozymes. The analysis of Indian melon accessions showed a continuous variation in seed length, ranging from 4 to 13 mm. Most of the East Asian melons, vars. makuwa and conomon, were classified as the small seed type with seed length shorter than 9 mm. The frequency of the small seed type increased from the west to the east in India. Allelic variation was detected at a total of nine loci of five isozymes among 114 melon accessions. Gene diversity calculated for the nine loci indicated that Indian melon was rich in genetic variation, which decreased from India towards the east. Clear geographical variation was detected in two enzymes, APS and6-PGDH. Pgd-1 ¹ and Ap-3 ¹ were frequent in India and Myanmar, while most of the melons in Laos, China, Korea and Japan carried Pgd-1 ³ and Ap-3 ³, except var. inodorusin China. Among the latter two alleles, the frequency of Ap-3 ³ was more than 50% in the small seed type in north and east India, indicating that vars. makuwa and conomon were related to the small seed type in these areas. It was also suggested that the small seed type with wet tolerance originated in central India and was selected under wet condition in the east. This revised version was published online in August 2006 with corrections to the Cover Date.     

Conformity and genetic relatedness estimation in crop species having a narrow genetic base: the case of cucumber (Cucumis sativus L.)*

A set of 155 SSR (107) and SCAR (48) markers were used to evaluate 53 cucumber (Cucumis sativus L.) accessions of diverse origin to characterize genetic relationships and to define a standard marker array that was most effective in detecting genetic differences in this germplasm array. A multivariate marker‐based analysis of diverse germplasm using this standard marker array (17 SSR and 5 SCAR markers) was compared with results from a set of 70 previously reported RAPD markers, and then used to explore the potential value of these genetic markers for plant variety protection (PVP) and the establishment of essential derivation (ED) threshold values in this species using elite lines and hybrids and backcross progeny. Diversity analysis allowed identification of distinctly different lines that were used for the construction of three sets of backcross families (BC₁‐BC₃). While general genetic relationships among accessions were similar in SSR/SCAR analyses (r_s= 0.65) using two genetic distance (GD) estimators, differences in accession relationships were detected between RAPD and SSR/SCAR marker evaluations regardless of the estimator used. The GDs among elite germplasm with known pedigrees were relatively small (0.06‐0.23 for any pairwise comparison). GD values decreased and degree of fixation (at three to seven loci depending on the mating) increased with increased backcrossing such that recurrent parent allelic fixation occurred in least one family of each of the BC₃ families. In many instances the degree of fixation of loci was not uniformly achieved in the BC₃. Although the level of genetic polymorphisms will likely restrict the use of molecular markers for PVP and the establishment of ED values, the use of single nucleotide differences will likely provide opportunities to define specific functional distances that have potential for PVP in cucumber. Nevertheless, without an expanded, genetically robust standard marker array (e.g. 50 codominant markers), ED threshold values will be difficult to define in this species, and perhaps will require the appraisal of single nucleotide polymorphisms as discriminators of difference in this species.     

Genetic analysis and fine mapping of tms9, a novel thermosensitive genic male‐sterile gene in rice (Oryza sativa L.)

Two‐line hybrid rice as a novel hybrid breeding method has huge potential for yield increasing and utilization of intersubspecific heterosis, and it is of major significance for the food security of rice‐consuming populations. Zhu1S is a thermosensitive genic male‐sterile line of rice with low critical temperature and excellent combining ability, which has been widely exploited as a female parent in Chinese two‐line hybrid rice breeding. Here, genetic mapping in F₂ populations was used to show that its male sterility is inherited as a single recessive gene and that responsible gene (termed tms9) lies on the short arm of chromosome 2. A high‐resolution linkage analysis which was based on the Zhu1S/R173 F₂ population found that the thermosensitive genic male‐sterile gene tms9 of Zhu1S was fine mapped between insertion–deletion (Indel) markers Indel 37 and Indel 57, and the genetic distance from the tms9 to the two markers was 0.12 and 0.31 cM, respectively. The physical distance between the two markers was about 107.2 kb. Sequence annotation databases showed that the two Indel markers (Indel 37 and Indel 57) were located on two BAC clones (B1307A11 and P0027A02). There are sixteen open reading frames (ORF) present in this region. The results of this study are of great significance for further cloning tms9 and molecular marker–assisted selection.     

Cytological observation of anther structure and genetic investigation of a new type of cytoplasmic male sterile 0A193‐CMS in Brassica rapa L.

Cytoplasmic male sterility (CMS), a maternally transmitted failure in pollen formation, is an effective pollination control system in hybrid rapeseed (Brassica napus) breeding. However, CMS is not widely used in the related oilseed species Brassica rapa. In the past years, several male sterile plants have been isolated from the B. rapa landrace ‘0A193’, collected in Shaanxi, China, in 2011. It is noteworthy that the fertility expression of 0A193‐CMS was affected by temperature. In contrast to pol CMS, fertility tests with 18 B. rapa and 9 B. napus accessions suggest that a different system of maintaining and restoring is responsible for the observed phenotype. Further on, genetic investigation evidenced that fertility of 0A193‐CMS is controlled by both cytoplasmic and one pair of nuclear recessive genes. Interestingly, plants of the 0A193‐CMS type possess a highly specific fragment of the mitochondrial gene orf222, a crucial regulator of male sterility in nap CMS. Our study broadens the CMS resources in B. rapa and provides a highly applicable alternative to pol CMS and ogu CMS for hybrid breeding production.     

The influence of photoperiod on the Vrn-H2 locus (4H) which is a major determinant of plant development and reproductive fitness traits in a facultative × winter barley (Hordeum vulgare L.) mapping population

To determine the effect of Vrn‐H2 locus on plant developmental and agronomic traits, detailed controlled environment tests involving a factorial set of vernalization and photoperiod treatments were carried out using doubled haploid lines developed from a facultative (Vrn‐H2^?) × winter (Vrn‐H2⁺) barley cross. The allele phase at the Vrn‐H2 locus influenced heading date as well as the developmental and agronomic traits. The performance of Vrn‐H2⁺ lines was significantly influenced by vernalization: reproductive fitness traits showed significant decreases without vernalization. However, the effects of alleles at the Vrn‐H2 locus extended beyond simple satisfaction of the vernalization requirement. Vrn‐H2⁺ lines showed increased reproductive fitness compared with Vrn‐H2^? lines when vernalization was followed by a long photoperiod. The responses of the two Vrn‐H2 allele classes to photoperiod duration were quite different in terms of heading date, developmental and agronomic traits. These results suggest that alleles at the Vrn‐H2 locus – and/or tightly linked gene(s) – respond primarily to the exogenous signal of vernalization (temperature), but when the vernalization requirement has been fulfilled, they also respond to photoperiod duration.     

The effects of climatic variation in Europe on the yield response of spring wheat cv. Minaret to elevated CO2 and O3: an analysis of open-top chamber experiments by means of two crop growth simulation models

In the ESPACE-Wheat programme, 25 open-top chamber experiments were carried out in 1994, 1995 and 1996, on nine locations, divided over eight European countries. In most experiments, spring wheat cv. Minaret was subjected to two levels of atmospheric CO₂ and two levels of ozone. Grain yields in the control treatments (ambient levels of CO₂ and O₃) varied strongly between sites. Also, yield response to elevated CO₂ and O₃ showed great variation. The present study was conducted to determine whether climatic differences between sites could account for the observed variation.

Two simulation models were used for the analysis: AFRCWHEAT2-O3 and LINTULCC. AFRCWHEAT2-O3 simulates phenology, canopy development and photosynthesis in greater detail than LINTULCC. Both models account for the effects of radiation and temperature on crop growth. New algorithms were developed to simulate the effects of CO₂ and O₃. Weather data that were measured in the experiments were used as input, and simulated growth responses to CO₂ and O₃ were compared with measurements. No attempt was made to merge the two models. Thus two independent tools for analysis of data related to climate change were developed and applied.

The average measured grain yield in the control treatment, across all 25 experiments, was 5.9 tons per hectare (t ha⁻¹), with a standard deviation (SD) of 1.9 t  ha⁻¹. The models predicted similar average yields (5.5 and 5.8 t ha⁻¹ for AFRCWHEAT2-O3 and LINTULCC, respectively), but smaller variation (SD for both models: 1.2 t ha⁻¹). Average measured yield increase due to CO₂-doubling was 30% (SD 22%). AFRCWHEAT2-O3 expected a slightly lower value (24%, SD 9%), whereas LINTULCC overestimated the response (42%, SD 11%). The average measured yield decrease due to nearly-doubled O₃ levels was 9% (SD 11%). Both models showed similar results, albeit at lower variation (7% yield decrease at SDs of 6 and 4%). Simulations accounted well for the observation that, at elevated CO₂, the percentage yield loss due to O₃ was lower than at ambient CO₂.

The models predicted lower variation among sites and years than was measured. Yield response to CO₂ and O₃ was predicted to depend on the climate, with a predominant effect of temperature on the response to CO₂. In the measurements, these climatic effects were indeed observed, but a greater part of the variation was not related to light intensity, temperature, CO₂, or O₃. This unexplained variability in the measured dataset was probably caused by factors not accounted for in the models, possibly related to soil characteristics.

We therefore conclude that even perfect information on the climate variables examined in ESPACE-Wheat, i.e. light intensity and temperature, by itself would be insufficient for accurate prediction of the response of spring wheat to future elevated levels of CO₂ and O₃.     

Allelic variation at the <Emphasis Type="Italic">Glu-1</Emphasis> and <Emphasis Type="Italic">Glu-3</Emphasis> loci,presence of the 1B.1R translocation,and their effects on mixographic properties in Chinese bread wheats

Allelic variations at the Glu-1 and Glu-3 loci play an important role in determining dough properties and bread-making quality. Two hundred and fifty-one cultivars and advanced lines from four major Chinese wheat-producing zones in the autumn-sown wheat regions were used to investigate the high-molecular-weight glutenin subunits (HMW GS) and low-molecular-weight glutenin subunit (LMW GS) composition controlled by the Glu-1 and Glu-3 loci, respectively, as well as the presence of the 1B.1R translocation, and to determine the association of storage protein composition with protein content, SDS sedimentation value, and dough-mixing properties measured by mixograph. Three, nine, and four allelic variations were present at Glu-A1, Glu-B1, and Glu-D1, respectively. Subunits 1, N, 7+8, 7+9, and 2+12 are the dominant HMW GS, with frequencies of 51.3, 39.4, 38.2, 45.0, and 59.8%, respectively. Five and eight allelic variations were present at the Glu-A3 and Glu-B3 loci (data of Glu-D3 were not available), Glu-A3a, Glu-A3d, Glu-B3j (presence of the 1B.1R translocation), and Glu-B3d are the dominant LMW GS, with frequencies of 37.1, 31.7, 44.6, and 20.3%, respectively. The frequencies of allelic variation at Glu-1 and Glu-3 differ greatly in different regions. The effects of HMW GS and LMW GS on SDS sedimentation value, mixing time, and mixing tolerance were significant at P = 0.01, with Glu-D1 and Glu-B3 showing the largest contributions to mixing time and mixing tolerance. Averaged data from two locations showed that the quality effects of glutenin loci could be ranked as Glu-B3 > Glu-B1 > Glu-A1 > Glu-D1 > Glu-A3 for SDS sedimentation value, Glu-D1 > Glu-B3 > Glu-A1 = Glu-B1 = Glu-A3 for mixing time, and Glu-D1 > Glu-B3 = Glu-B1 > Glu-A3 > Glu-A1 for mixing tolerance, respectively. The significant and negative effect of the 1B.1R translocation on dough properties was confirmed. It was concluded that the high frequency of undesirable HMW GS and LMW GS and the presence of the 1B.1R translocation are responsible for the weak gluten property of Chinese germplasm; hence, reducing the frequency of the 1B.1R translocation and integration of desirable subunits at Glu-1 and Glu-3 such as 1, 7+8, 14+15, 5+10, Glu-A3d, and Glu-B3d, could lead to the improvement of gluten quality in Chinese wheats.