Seed protein variation for identification of common buckwheat (Fagopyrum esculentum Moench) cultivars

Summary Total seed proteins of 24 common buckwheat cultivars and cultivated populations within a molecular weight range of 30 to 54 kDa were analysed by SDS-PAGE. Single seed analysis of six cultivars identified a total of 18 alternative protein bands with different mobilities. Differences of individual protein band frequencies extracted from single seeds among six buckwheat cultivars varied distinctively, indicating high intravarietal polymorphism. The relation between frequencies of protein bands revealed by single seed analysis and their appearance on the bulk seed analyses was demonstrated. Regarding to band mobility rate and relative band intensity among 24 bulk samples analysed, 14 had distinctive electrophoregrams while the other 10 were ranged into four distinct groups. Analysis of endosperm and cotyledon proteins showed that proteins stored in these main seed parts are tissue specific. The observed electrophoretic polymorphism related to proteins stored in the cotyledons while there was no apparent variability with endosperm proteins.     

Inter-varietal variations of rutin content in common buckwheat flour (Fagopyrum esculentum Moench.)

Summary To improve the quality of buckwheat flour, we investigated the effect of the cropping season on the rutin content in various cultivars of common buckwheat (Fagopyrum esculentum Moench.). Thirty cultivars of buckwheat were grown under both long day conditions (the summer cropping) and short day conditions (the late summer cropping). The inter-varietal variations and the effect of the cropping season on the rutin content were examined. The rutin content was determined by high performance liquid chromatography (HPLC). Results show that the average rutin content in the late summer cropping was about half that of the summer cropping. There were wide inter-varietal variations of rutin content in the summer cropping. The differences in rutin content in the late summer cropping were less pronounced. Rutin content was closely correlated with the flowering period in summer (r=0.735^***). The later flowering cultivars produced a higher content of rutin than the earlier flowering cultivars in the summer cropping. The differences in the cumulative solar radiation received in the two seasons seems to be a reasonable explanation for this increase in the rutin content of the buckwheat flour. The rutin content of early flowering cultivars, which are suitable for long day conditions, is positively correlated with yield in the summer cropping. However, the rutin content in the intermediate and late summer ecotype cultivars, which are suitable for short day conditions, shows no correlation with yield in the late-summer cropping. In conclusion, there are wide inter-varietal variations of rutin content in buckwheat flour and the rutin content increases under long day conditions.     

Rapid genotyping with DNA micro-arrays for high-density linkage mapping and QTL mapping in common buckwheat (Fagopyrum esculentum Moench)

For genetic studies and genomics-assisted breeding, particularly of minor crops, a genotyping system that does not require a priori genomic information is preferable. Here, we demonstrated the potential of a novel array-based genotyping system for the rapid construction of high-density linkage map and quantitative trait loci (QTL) mapping. By using the system, we successfully constructed an accurate, high-density linkage map for common buckwheat (Fagopyrum esculentum Moench); the map was composed of 756 loci and included 8,884 markers. The number of linkage groups converged to eight, which is the basic number of chromosomes in common buckwheat. The sizes of the linkage groups of the P1 and P2 maps were 773.8 and 800.4 cM, respectively. The average interval between adjacent loci was 2.13 cM. The linkage map constructed here will be useful for the analysis of other common buckwheat populations. We also performed QTL mapping for main stem length and detected four QTL. It took 37 days to process 178 samples from DNA extraction to genotyping, indicating the system enables genotyping of genome-wide markers for a few hundred buckwheat plants before the plants mature. The novel system will be useful for genomics-assisted breeding in minor crops without a priori genomic information.     

Effects of uniconazole or gibberellic acid application on the lignin metabolism in relation to lodging resistance of culm in common buckwheat (Fagopyrum esculentum M.)

Lignin plays an important role in increasing the mechanical intensity of culm and improving lodging resistance of culm. In this study, three common buckwheat, Youqiao2 (lodging‐tolerant cultivar; YQ2), Ningqiao1 (middle lodging‐tolerant cultivar; NQ1) and Ukraine daliqiao (lodging‐susceptible cultivar; UD), were used to investigate the effects of spraying exogenous hormones uniconazole (S‐3307) or gibberellic acid (GA3) on lignin metabolism and its relation to lodging resistance in the three common buckwheat cultivars. Results showed that application of S‐3307 significantly increased lignin content and its related enzymes activities of phenylalanine ammonia‐lyase (PAL), 4‐hydroxy cinnamoyl CoA ligase (4CL), cinnamyl alcohol dehydrogenase (CAD) and peroxidase (POD). The major genes involved in lignin synthesis, PAL, CCR (cinnamyl CoA reductase), C4H (cinnamate4‐hydroxylase), 4CL and CCoAOMT (caffeoyl CoA O‐methyltransferase), were all upregulated expression, and COMT (catechol‐O‐methyltransferase) was downregulated. What is more, application of S‐3307 significantly improved the resistance of common buckwheat stem to lodging and increased yield. Whereas, spraying with GA3 caused opposite effect on those characteristics. These results suggested that application of exogenous S‐3307 or GA3 significantly changed the risk of lodging occurred by regulating the lignin metabolism in culms of common buckwheat.     

In vitro germination and viability of buckwheat (Fagopyrum esculentum Moench) pollen

An in vitro method for the germination of common buckwheat pollen was developed. Pollen grains were successfully germinated in an artificial medium consisting of 0.2 g each of MnSO₄, Ca(NO₃)2.4H₂O and KNO₃, 0.04 g H₃BO₃, 15 g sucrose and 30 g polyethylene glycol (molecular weight approximately 20,000) dissolved in 100 ml of double distilled water. The viability of pollen was assessed by in vivo and in vitro germination tests at 20 °C and 25 °C over a 38 h time period. Pollen grains were collected and germinated at 4 h intervals from freshly harvested flowers grown under 16 h day length and a constant temperature. Maximum pollen viability was found 2 h and 6 h after first light when plants were maintained at 25 °C and 20 °C, respectively. Viability, as measured by germination percentage, was similar at both temperature regimes. Some pollen remained viable for approximately 34 to 38 h in intact flowers, but all pollen lost viability in less than an hour when stored at room temperature without humidity control. This revised version was published online in July 2006 with corrections to the Cover Date.     

Genetic analyses of agronomic traits in Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.)

The consumption of products made from Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.) has increased in recent years in Japan. Increased consumer demand has led to recognition of the need for early varieties of this crop with high and stable yields. In order to accomplish this, more information is needed on the genetic mechanisms affecting earliness and yield. We conducted genetic analysis of 3 agronomic traits (days to flowering, plant height and total seed weight per plant) to segregate F₂ and F₃ populations derived from a cross between Tartary buckwheat cultivars ‘Hokuriku No. 4’ and ‘Ishisoba’. Broad-sense heritability estimates for days to flowering, plant height and total seed weight were 0.70, 0.62 and 0.75, respectively, in F₃ population. Narrow-sense heritability for total seed weight (0.51) was highest, followed by heritability for days to flowering (0.37), with heritability for plant height (0.26) lowest. Later flowering was associated with increased plant height and higher yields. From the F₄ generation, we identified twelve candidate plants with earlier maturity and reduced plant height compared to ‘Hokuriku No. 4’, but almost the same total seed weight. These results suggest that hybridization breeding using the single seed descent (SSD) method is an effective approach for improving agronomic characteristics of Tartary buckwheat.     

苦荞SSR分子遗传图谱的构建及分析

构建苦荞遗传连锁图谱,为今后有关苦荞基因组结构、重要农艺性状QTL定位、分子标记辅助育种和基因克隆等研究工作奠定基础。以栽培苦荞‘滇宁一号’和苦荞野生近缘种杂交产生的119份F4代分离材料为作图群体,利用SSR分子标记来构建苦荞的分子遗传连锁图谱。本研究构建的连锁图谱包含15个连锁群,由89个标记组成,其中偏分离的标记有22个,占24.7%,每条连锁群上的标记在2~16之间。连锁群长度在6.9~165.8 cM的范围,覆盖基因组860.2 cM,总平均长度9.7 cM。本研究构建了首张苦荞SSR遗传连锁图谱,为苦荞QTL定位、基因克隆、遗传选育等研究奠定了基础。     

Discovery and genetic analysis of non-bitter Tartary buckwheat (Fagopyrum tataricum Gaertn.) with trace-rutinosidase activity

In a screening of about 500 lines of Tartary buckwheat, we identified lines that contained no detectable rutinosidase isozymes using an in-gel detection assay. We confirmed that seeds of these individuals had only a trace level of in-vitro rutinosidase activity. To investigate the heritability of the trace-rutinosidase characteristic, we analyzed the progeny of crosses between rutinosidase trace-lines, ‘f3g-162’, and the ‘Hokkai T8’. The F₂ progeny clearly divided into two groups: those with rutinosidase activity under 1.5 nkat/g seed (trace-rutinosidase) and those with activity over 400 nkat/g seed (normal rutinosidase). The segregation pattern of this trait in F₂ progeny exhibited 1 : 3 ratio (trace-rutinosidase : normal rutinosidase), suggesting that the trace-rutinosidase trait is conferred by a single recessive gene; rutinosidase-trace A (rutA). In addition, sensory panelists evaluated the bitterness of flour from trace-rutinosidase individuals and did not detect bitterness, whereas flour from normal rutinosidase individuals was found to have strong bitterness. Although at least three bitter compounds have been reported in Tartary buckwheat seeds, our present findings indicate that rutin hydrolysis is the major contributing factor to bitterness. In addition, the trace-rutinosidase line identified here, ‘f3g-162’, is a promising material for generating a non-bitter Tartary buckwheat variety.     

A source of resistance to seed shattering in kleingrass,Panicum coloratum L.

Summary Seed of kleingrass, P. coloratum, ripen nonuniformly and shatter readily at maturity. Consequently, it is difficult to maximize both seed quality and yield. A source of resistance to seed shattering is needed. In this investigation, two kleingrass populations, the cultivar Selection-75, and an introduction from South Africa, PI 410177, were evaluated for seed shattering during three seed production seasons. Individual inflorescences from field-grown plants were enclosed in seed traps and all shattered seed was collected at weekly intervals until 49 days after anthesis. Although there were seasonal differences, PI 410177 always shattered seed at a slower rate than Selection-75 in each of the three seasons. Averaged over all seasons Selection-75 had shattered 74% of its seed by 49 days after anthesis while PI 410177 shattered only 37%. A separate greenhouse-field experiment demonstrated that seasonal differences in seed shattering are primarily the result of varying weather conditions during the period of seed production. PI 410177 is the first reported source of resistance to seed shattering in P. coloratum.     

Effect of sowing time on buckwheat (Fagopyrum esculentum Moench) growth and yield in central Korea

Buckwheat (Fagopyrum esculentum MOENCH) is a traditional Korean crop that gaining global attention as a health food due to its rich nutrition. Climate change effects such as high temperature, cold weather, flooding, and drought induce plant stress, reduced production yield of upland crops. In general, buckwheat is grown during the fall season in Korea. Flooding is a severe environmental stress factor, and flooding during the early growth stage of buckwheat causes large reductions in yield. Therefore, we established optimum growth parameters to maximize buckwheat yield. The optimum temperature for harvesting of buckwheat was approximately 1,083 ~ 1,515°C. The number of growing degree days (G.D.D.) from flowering to harvest was 509 ~ 673°C. Plant hight, stem diameter, and dry matter weight were reduced as planting date was delayed (p < 0.05). We investigated buckwheat sowing time during fall, and established an optimum cropping system according to the local climate conditions in central Korea. The growth period of buckwheat cultivar ‘Yangjueol’ was approximately 56 ~ 60 days during fall, and yield was higher than that of cultivar ‘Daesan’. The results indicated that buckwheat yield in central Korea was maximized by sowing cultivar on 25th August and cultivar ‘Daesan’ on 15th August. The yield of Yangjeol sown in spring was 119 kg 10a^-1, whereas the yield of Daesan sown in summer was 158kg 10a^-1. The results of this study established the effects of sowing time on growth and yield in central Korea. We propose an optimum cropping system for improving quality.     

Studies on the Influence of Photoperiod and Temperature on Floral Traits in Buckwheat (Fagopyrum esculentum Moench) under Controlled Stress Conditions

Floral traits of three Japanese and one European buckwheat varieties were studied in a phytotron under three photoperiods (short-day 10/14 h, long-day 14/10 h, extreme long-day 18/6 h) and two thermoperiods (25/20, and 15 °C constant temperature). The Japanese varieties showed a strong delay in flowering under prolonged day length, whereas one European variety reacted almost day-neutral. Also affected by the photoperiod were the number of flower clusters as well as their sizes. A constant low temperature of 15 °C led to a strong delay in flowering under short- and long-day in all the varieties tested. In particular, the Japanese varieties were sensitive to temperature, developing more flower clusters under high temperature. Furthermore the experiments revealed complex genotype/pliotopenod/thermoperiod interactions. The study, conducted to investigate the causes of low seed-set observed in buckwheat, offered some suggestions for new breeding strategies. Insensitive genotypes, showing less sensitivity to photoperiod as well as to thermoperiod, should be included in further buckwheat improvement.     

Tartary buckwheat breeding (<Emphasis Type="Italic">Fagopyrum tataricum</Emphasis> L. Gaertn.) through hybridization with its Rice-Tartary type

Tartary buckwheat (Fagopyrum tataricum) is a highly nutritious crop that is widely grown in Asia, but the flour contains a large portion of the hull if it is ground with industrial processing since the hull is very hard to remove as it adheres to the testa layer of the groat. Rice-Tartary, a particular type of Tartary buckwheat, has seeds with a loose hull and the presence of splits on the sides of the seeds that make dehulling easily. The present study reports on the first attempt of crop improvement in Tartary buckwheat breeding through hybridization. Hybrids were obtained by hybridization of crosses between Tartary buckwheat and Rice-Tartary. Additional crosses were made among selected progenies of these crosses. Based on progeny analysis of the F₁, F₂, and F₃, the character of Rice-Tartary, as exhibited as the presence of splits on the sides of the seeds, is controlled by one gene which is homozygous recessive. A Tartary buckwheat breeding program has been conducted for 6 years based on these crosses. Advanced lines with easy dehull and yield potential are at the stage of ready for yield trials. Production of easy dehulling Tartary buckwheat in the future could boost Canada’s domestic and international markets.     

Perspectives of breeding for resistance to ‘yellow disease’, Xanthomonas hyacinthi(Wakker)Dowson,in hyacinths (Hyacinthus L.)

Summary Since 1880 yellow disease has been known as a very serious disease in hyacinth. The breeding of resistant varieties can constitute an important contribution to the solution of this problem. Therefore it was first aseertained how the differences in resistance between the varieties can be determined as accurately as possible. To this end bulbs and plants of well known cultivars were inoculated with bacteria, and the degree of infection compared with that of bulbs grown in the field. It was found that the infection of the inoculated bulbs corresponded little, if at all, with infection in practice, but the infection of the inoculated leaves did. So the degree of leaf infection seems a useful selection criterion. Comparison of the infection of juvenile and adult plants also yielded an indication of the possibility of preselection for yellow disease resistance in seedling populations.     

甜荞FaesFUL4基因的克隆与表达分析

本研究采用同源克隆的方法,从甜荞(Fagopyrum esculentum Moench.)品种‘北早生’中分离出调控果实发育的FaesFUL4基因,该基因的cDNA序列全长795 bp,包含一个长为714 bp完整的开放阅读框,共编码237个氨基酸和1个终止密码子。分子系统发生分析和同源蛋白比对结果显示:FaesFUL4蛋白属于A类MADS-box基因家族AP1/SQUA亚家族的euFUL进化系,含有MADS、I、K和C末端四个明显的结构域,且C末端转录激活区含有2个保守的模体(Motif):FUL motif和paleoAP1 motif。基因表达的组织特异性分析表明:FaesFUL4基因主要在甜荞叶片、花序和果实中表达,在根和茎中有微量表达,其在花序中的相对表达量最高。进一步分析基因在果实不同发育时期的表达量发现,其在果实迅速膨大期表达量最高。因此推测该基因不但参与调控花器官的发育过程,且对于维持果实的正常发育具有重要作用。     

Characterization of resistance to angular leaf spot of common bean (Phaseolus vulgaris L.) breeding line SPS50HB

The common bean (Phaseolus vulgaris L.) makes an important contribution to the human diet, particularly in Africa and Latin America. Because angular leaf spot (ALS), caused by the fungal pathogen Pseudocercospora griseola, is one of the most severe foliar diseases of the bean plant, an important priority is to identify genes encoding resistance. The present study focused on the resistance shown by the Mesoamerican common bean breeding line SPS50HB. From the pattern of segregation for resistance displayed in an F₂ population bred from a cross between SPS50HB and the ALS-susceptible Ethiopian variety Red Wolaita, it was concluded that the resistance of SPS50HB is controlled by two unlinked dominant genes. An allelism test indicated that one of these genes was either identical with, allelic to, or closely linked to the major gene Phg-2 carried by variety Mexico 54. The sequence-characterized amplified region assays OPEO4 and PF13, which are diagnostic for an ALS resistance gene carried by the germplasm accession G10909, both tracked a possible second gene present in SPS50HB.     

Farmer and formal breeding of sorghum (Sorghum bicolor (L.) Moench) and the implications for integrated plant breeding

Sorghum (Sorghum bicolor (L.) Moench) is the fifth most important cereal crop worldwide and it is the fourth most important crop in Ethiopia. The national average yield amounts 1302 kg/ha. In order to assess the achievement in farmer breeding various types of research were undertaken. These include survey research to quantify the trend in productivity, the level of and reasons for adoption of improved varieties, yield performance and preference evaluation of farmers’ varieties (FVs) and improved varieties (IVs). As per the trend analysis over the last four decades, total production and yield per hectare has increased by 11.63 and 14.2%, respectively. However, area allocated to sorghum has decreased over years by −2.93%. The lack of consistent productivity is attributed to the fluctuation of environmental factors. Sorghum production in Ethiopia is predominantly based on varieties developed by farmers. The share of IVs is very low. FVs and IVs are adopted by 87.3 and 12.7% of the farmers, respectively. Besides, the adoption of IVs is limited to the lowland crop ecology. The comparative yield of FVs is higher than IVs by 132%. On top of yield, farmers do prefer their varieties for other multipurpose values namely feed, fuel wood and construction material. FVs under production are identified in each wereda. Farmer breeding has been successful compared to four decades of formal breeding. On the other hand, both farmer and formal breeding are not without weaknesses; a comparative balance sheet is outlined for both. Ideotypes for the three major crop ecologies are suggested and integrated plant breeding is anticipated to develop the proposed ideotypes thereby increase sorghum productivity in the region.     

New techniques for breeding maize (Zea mays) varieties with fall armyworm resistance and market-preferred traits for sub-Saharan Africa

Deploying maize varieties with fall armyworm (Spodoptera frugiperda [J.E. Smith]; FAW) resistance, desirable product profiles (PPs) and climate resilience is fundamental for food and economic security in sub-Saharan Africa (SSA). This study reviewed and identified challenges and opportunities for effective and accelerated breeding of demand-led maize hybrids with FAW resistance and adaptation to the diverse agro-ecologies of SSA. Lessons were drawn on improving breeding efficiency through adequate genetic variation delivered via prebreeding programmes, speed breeding and a reduced breeding stage plan. Appropriate PPs aligned with demand-led breeding approaches were highlighted as foundations for variety design and commercialization. Challenges to accelerated FAW resistance breeding in maize included inadequate funds and modern tools; poor adaptation of some exotic donor parental lines; lack of information on FAW resistance among local varieties; lack of integration of molecular markers associated with FAW resistance and agronomic traits into selection plans; and limited infrastructure for FAW rearing and germplasm screening. Integration of modern breeding tools and scientific innovations were recommended for accelerated development and release of FAW resistant and market-preferred maize varieties.