Genetic improvement of sorghum for grain mould resistance: I. Performance of sorghum recombinant inbred lines for grain mould reactions across environments

Grain mould on sorghum is an important disease worldwide, which causes considerable qualitative and quantitative damage. Success in breeding for grain mould resistance has been limited because of many mechanisms governing resistance, complex genetics and environmental influence. Objectives of this study were to characterize 200 recombinant inbred lines (RILs) from a cross between ‘296 B’ (susceptible elite parent) and ‘B 58586’ (resistant parent) for grain mould reaction (GMR) at physiological maturity (PM) and at harvest maturity (HM), and to identify sources of resistance. The RILs were characterized in six environments (3 years × 2 locations) for GMR. Five RILs were identified with GMR on par with the resistant parent across various environments. The results of stability analysis for GMR at PM and HM stages showed difference. At PM, there was a significant genotype (G) × environment (E) (linear) interaction plus significant environmental effects for GMR. However, at HM, there was not a significant G × E (linear) interaction but environment effects were significant for GMR. These indicated that part of variation was predictable at PM while the variation was not predictable at HM as it was entirely influenced by environment. It is concluded that grain mould occurring before PM is influenced by genetics and to some extent by environment while that occurring after PM is influenced by environment. Therefore, host plant resistance would be better assessed at PM than at HM, and identification of quantitative trait loci (QTL) which show consistency in expression across environments, even in diverse environments, would be desirable for marker-assisted selection programs.     

Evaluation of the Ugandan sorghum accessions for grain mold and anthracnose resistance

Sorghum accessions from Uganda were evaluated for grain mold and anthracnose resistance during the 2005 and 2006 growing seasons at the Texas A&M University Research Farm, near College Station, TX. Accession PI534117 and SC719-11E exhibited the lowest grain mold severities of 2.4, whereas, accessions PI534117, PI534144, PI576337, PI297199, PI533833, and PI297210, with SC748-5 were highly resistant to anthracnose in both years. Accessions PI534117, PI297134, PI297156 exhibited low grain mold severities in 2006. Significant negative correlation was recorded between grain mold and percent germination and high temperature in both years. In 2006, daily precipitation recorded significant positive correlation with grain mold. The seed mycoflora was analyzed across sorghum lines and treatments. In 2005, Curvularia lunata and Fusarium thapsinum were the most frequently recovered fungal species with 31 and 21% incidence, respectively, followed by Alternaria spp. (19%) and F. semitectum (13%). In 2006, predominant colonizers were F. thapsinum (58%), followed by Alternaria and F. semitectum with 15 and 10, percent respectively, while C. lunata had a 6% incidence. In this study, PI534117 holds promise for multiple disease resistance, as it had the lowest disease severity of grain mold and was highly resistant to anthracnose in both years. It also has a high germination rate, a high seed weight, and its short stature is more advantageous for the new A-line conversion program.     

Decrease in sorghum grain yield due to the dw3 dwarfing gene is caused by reduction in shoot biomass

Positive correlations between plant height and grain yield have been reported for sorghum. The introduction of stay-green in sorghum, and the associated reduction in lodging, has opened the possibility to exploit this positive association. The aim of this study was to analyse the direct effects of the dwarfing gene dw3 (and therefore plant height) on shoot biomass, grain yield, and yield components in pairs of 3-dwarf genotypes and their isogenic 2-dwarf tall mutants. Isogenic pairs with different genetic backgrounds were grown in three field experiments under nutrient and water non-limiting conditions. Tall mutants were significantly taller and produced more shoot and stem biomass than their shorter counterparts. Generally, tall types yielded more grain than short types, but significant interactions between experiment, genetic background and stature affected the consistency of the results. dw3 only affected grain size and not grain number. Increased grain mass of tall types was associated with significantly greater stem mass per grain at anthesis and greater shoot biomass per grain accumulated between anthesis and maturity. The increased biomass of tall plants was therefore important for increased grain yield under optimum conditions. Potential implications of increased biomass production for drought adaptation are discussed.     

QTL identification of kernel composition traits with popcorn using both F2:3 and BC2F2 populations developed from the same cross

Quantitative trait loci (QTL) influencing three main kernel composition traits, starch, protein and oil concentrations, in unselected F_2:3 and selected BC₂F₂ maize populations derived from the same cross of a dent corn inbred Dan232 × an elite popcorn inbred N04 under the same conditions were detected. Four and two QTL for starch, four and three QTL for protein, and four and one QTL for oil were detected in the two populations, respectively, with three QTL jointly detected. The proportion of phenotypic variation explained by a single QTL was 5.2–10.6%, 5.0–14.3%, and 6.2–8.5% for the three traits. Ten QTL had favorable alleles contributed by Dan232. Several QTL detected in this study had identical or similar chromosome regions to those previously identified with other maize germplasms. No QTL with opposite effects for kernel composition traits and popping characteristics were detected in the same or near marker intervals. This reflected that some QTL detected in this study seemed to contribute to trait variation in a diverse array of maize populations and environments, and the opportunity existed for improving popcorn's nutritional quality while maintaining acceptable popping characteristics. Inconsistent broad sense heritability and trait correlation estimates were also observed in the two populations.     

Simultaneous determination of vitamin B1 and B2 in complex cereal foods,by reverse phase isocratic HPLC-UV

The evaluation of nutritional or functional components in grain products is an important feature for the industry, especially when recent regulations require a correct nutrition labelling, valid during all the shelf life of the product. For that reason, industry usually makes many efforts to develop simple and reliable analytical methods that can be easily applied in any quality control laboratories for routine analysis. Spectrofluorimetric analysis of thiamine and riboflavin are sensitive, but need specific equipment. A few HPLC-UV methods have been described but they are less sensitive, and present difficulties due to interfering compounds, particularly in complex food matrixes, as grains and derivatives.     

Isolation and characterization of EMS-induced Dy10 and Ax1 high molecular weight glutenin subunit deficient mutant lines of elite hexaploid wheat (Triticum aestivum L.) cv. Summit

The mixing properties of the dough are critical in the production of bread and other food products derived from wheat. The high molecular weight glutenin subunits (HMW-GS) are major determinants of wheat dough processing qualities. The different alleles of the HMW-GS genes in hexaploid wheat vary in their effect on dough quality. To determine the contribution of the individual HMW-GS alleles, lines deficient in HMW-GS proteins were generated by chemical mutagenesis in the elite bread wheat Triticum aestivum cv. Summit. In this report we describe the identification and characterization of Dy10 and Ax1 deficient lines. Examination of the effect of Dy10 and Ax1 deficiency on dough rheological properties by mixography showed shorter mixing time to reach peak resistance, and weaker and less extensible doughs relative to the wild type control. This is the first time that the role of Dy10 in vivo has been examined apart from the Dx5 + Dy10 allelic pair combination.     

The effects of nitrogen rate and the ratio of NO3:NH4 on Bemisia tabaci populations in hydroponic tomato crops

Nitrogen fertilization is one of the factors that influences Bemisia tabaci (Gennadius) population density. The aim of this study was to determine the effects of three N application rates (75, 205 and 335 mg/l) and three ratios of NO₃⁻:NH₄⁺ ions (92:8, 75:25 and 55:45) in standard nutrient solution (205 mg/l N) on the population density of B. tabaci. The experiments were conducted on spring-summer hydroponic crops of tomato. The effect of plant stratum on the whitefly population was also determined. The aggregation of B. tabaci adults as well as their oviposition rate was higher at 205 and 335 mg/l N than on plants grown at 75 mg/l N. By the end of the experiment (60 d after infestation), the number of nymphs on plants at 205 mg/l N was higher than on plants at 75 mg/l N. The number of pupae was lowest on plants supplied with 75 mg/l N. An increase in NH₄⁺ percentage in standard nutrient solution (from 25% to 45% of the total N) reduced adult population density and oviposition rate. The density of nymphs and pupae, at 60 d after infestation, was lower on the tomato plants grown at 75:25 and 55:45 NO₃⁻:NH₄⁺ ratios compared to the 92:8 ratio. The 75:25 and 55:45 NO₃⁻:NH₄⁺ ratios resulted in a higher incidence of blossom-end rot of tomato fruit, with a lower incidence of disorder at 75:25 than at the 55:45 ratio. Plant stratum influenced adult whitefly distribution in two years of the study. Middle stratum leaves were more attractive to adults in both years. The results demonstrate the effects of N fertilization (N rate and the ratio of NO₃⁻:NH₄⁺) and plant stratum on B. tabaci population density.     

Genetic enhancement of Sorghum (Sorghum bicolor (L) Moench) for grain mould resistance: II. Breeding for grain mould resistance

Grain mould causes qualitative and quantitative loss to grain in sorghum. Grain mould resistance is a complex problem as grain mould is caused by complex of fungi and the resistance is governed by many traits. Breeding efforts during the last 3 decades to develop grain mould resistance in high yielding genotypes have not paid many dividends. We developed a strategy to breed for grain mould resistance in high yielding back ground. Twenty five crosses between elite lines and grain mould resistant genetic stocks (susceptible × resistant/moderately resistant and moderately resistant × resistant crosses) were evaluated in F₁, and derivatives performing superiorly for grain mould resistance in F₂-F₄ at physiological maturity were advanced. The early generation material F₂s (10) and F₃s (125) in 6 locations (representing rainy-season-sorghum growing 6 states of India where grain mould is one of the major biotic stresses), and later generations F₄s and F₅s in 3 locations (one location, Parbhani is a hot spot for grain moulds and 2 locations, Hyderabad and Coimbatore in epiphytotic conditions) were evaluated. Only 25 selections out of 384 derivatives in F₄ were superior over locations for grain mould resistance at physiological maturity and harvest maturity (Our simultaneous studies in RILs for grain mould resistance across years and locations have shown that the variation obtained for grain mould resistance at physiological maturity is genetically governed and the grain mould score further gets compounded at harvest maturity depending on rainfall received after physiological maturity). These superior lines were advanced and further evaluated in F₅ and F₆ for grain mould resistance and grain yield. During 2007, out of 25 F₅ derivatives, 12 were on par (scored 3.1-4.4) with resistant check, B 58586 (3.2 score) where as susceptible check, 296 B registered a score of 7.5. GMN nos. 41, 52, 59, and 63 performed on par with resistant check, B 58586 for grain mould resistance over 9 environments. Since we selected for grain mould resistance in early generations at physiological maturity in multi-locations, we could identify superior lines for grain mould resistance. Most of these lines are high yielding and on par with elite check, C43 for grain yield. These lines are distinct for DUS testing traits from grain mould resistant check, B 58586.     

The gluten protein and interactions between components determine mixograph properties in an F6 recombinant inbred linepopulation in bread wheat

One hundred and sixty-eight F₆ recombinant inbred lines (RILs) derived from Chinese wheat cultivars, PH82-2 and Neixiang188, were used to determine the cumulative effects of HMW-GS and LMW-GS composition and quantity of gluten protein fractions on dough mixograph properties. A wide range of variation for all parameters in the RILs was detected. Major gene loci of HMW-GS were associated with variation in mixograph characters, but accounted for no more than 25.3% of the phenotypic variations. Glu-D1, together with Glu-B3, played the most important role in determining the properties. Additive effects of HMW-GS and LMW-GS showed major contributions to most of the variation of mixograph parameters, and epistatic effects were also important and could be counter to additive effects of individual loci. The quantity of gluten protein fractions, especially the quantity of glutenin, LMW-GS, and Glu-B3, showed highly significant correlations with most of the quality parameters, but the correlation coefficients were influenced by grain hardness, protein content, or both. Protein quality could be greatly improved through increasing the quantity of glutenin, while holding desirable composition of HMW-GS and LMW-GS alleles, with an appropriate ratio of quantity of glutenin to gliadin.     

Diversity of sequences encoded by the Gsp-1 genes in wheat and other grass species

The Gsp-1 genes of wheat encode two components, the “grain softness protein” (whose role in determining texture has not been substantiated) and a 15 residue arabinogalactan peptide (AGP) sequence which is O-glycosylated and is also of unknown function. We have determined genomic Gsp-1 sequences from 29 species within the Triticeae tribe and an additional 12 species from the major subfamilies of the Poaceae (Anomochlooideae, Bambusoideae, Ehrhartoideae, Chloridoideae and Panicoideae). Twelve new AGP sequence types were identified with forms present in Agropyron mongolicum, Secale cereale, Oryza sativa subsp. japonica and Sorghum bicolor containing an extra ten amino acids within the AGP sequence. Phylogenetic analysis showed distinct groupings of AGP/GSP sequence types which had no apparent relationship to the species or even the genus. However, individual forms of AGP forms were associated with specific groups of GSP sequences, providing no evidence that the AGP and GSP-1 parts of the protein have diverged at different rates or in different ways.     

Evidence of genetic transmission of antibiosis and antixenosis resistance of sorghum to the spotted stemborer, Chilo partellus (Lepidoptera: Pyralidae)

Spotted stemborer, Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae), is the most important pest of sorghum in Asia and south and eastern Africa. Host plant resistance is an important control tactic for controlling this pest. Two breeding lines 27B × PB 15881-3 and 463B × PB 15881-3 with their parents, resistant and susceptible genotypes were evaluated in the field, glasshouse and laboratory for different resistance parameters. Breeding lines and genotypes varied significantly in foliar damage ratings, percentage of stem length tunneled, percentage of plants with deadhearts, larval survival, larval and pupal weights, larval and pupal duration, and percentage pupation and adult emergence in diets amended with leaf powder of different sorghum genotypes. The breeding lines 27B × PB 15881-3 and 463B × PB 15881-3 showed antixenosis and antibiosis to C. partellus in terms of reduced eggs per plant, larval survival and development. The levels of antixenosis and antibiosis of both breeding lines were similar to their resistant parents. Results indicate that transmission of characteristics responsible for resistance to the progeny from the resistant parent occurred.     

Characterization of free amino acid QTLs in maize opaque2 recombinant inbred lines

The opaque2 (o2) mutation in maize (Zea mays L.) increases the content of free amino acids (FAA) in the endosperm. We investigated the basis of this trait by using recombinant inbred lines from a cross of Oh545o2 (high FAA) and Oh51Ao2 (low FAA) to identify quantitative trait loci (QTL) for FAA content and to determine their effect on FAA composition and protein accumulation. Mapping identified six QTLs that accounted for 71% of the phenotypic variation. Two QTLs in bins 4.01 and 7.02 are close to α-zein genes; high FAA individuals with these QTLs had reduced accumulation of α-zein 19 kDa isoforms and increased FAA abundant in α-zeins. A QTL in bin 3.03 is close to a gene encoding triose phosphate isomerase (tpi4) and a higher expression of this enzyme was found in high FAA individuals. Other differentially expressed proteins included vicilin-like globulins and the enzymes glyceraldehyde-3-phosphate dehydrogenase, enolase-2, sorbitol dehydrogenase and granule-bound starch synthase. The results suggest that the increased levels of FAA in o2 endosperm are mainly due to the reduction of storage proteins and the failure to incorporate their amino acids into other proteins, as well as the alteration of carbohydrate metabolism that may favor amino acid biosynthesis.     

Sorghum (Sorghum bicolor L. Moench) contains a XIP-type xylanase inhibitor but none of the TAXI- and TLXI-types

A xylanase inhibitor of the xylanase-inhibiting protein (XIP) type was detected in sorghum (Sorghum bicolor L. Moench) whole meal using Western blot and immunoprobing with polyclonal anti-XIP antibodies. No detectable levels of Triticum aestivum xylanase inhibitor (TAXI) and thaumatin-like xylanase inhibitor (TLXI) type xylanase inhibitors were present. Trichoderma longibrachiatum xylanase affinity chromatography (AC) was used for the purification of sorghum XIP. Biochemical characteristics and protein sequence data show that sorghum XIP strongly corresponds to wheat (T. aestivum L.) XIP-I. Like wheat XIP-I, it inhibits both glycoside hydrolase family (GH) 10 and 11 xylanases, indicating that the XIP-I active site residues are well conserved in sorghum XIP. However, in contrast to wheat XIP-I, the inhibitor is unable to affect Aspergillus niger GH 11 xylanase activity. Its specific inhibition activities towards the other xylanases tested are comparable to those of wheat XIP-I. Based on the available sorghum expressed sequence tag (EST) database, XIP is expressed in sorghum in different tissues and developmental stages. Also expression in the presence of several plant hormones and under biotic as well as abiotic stress conditions is suggested.     

A comparison of monitoring systems used for Ceratitis species (Diptera: Tephritidae) in South Africa

For 16 years a bucket-type trap known as the Sensus fruit fly trap has been used to monitor three fruit fly pest species Ceratitis capitata, Ceratitis rosa and Ceratitis cosyra in South African fruit industries. The relative efficiencies of lures sold for monitoring fruit flies with the Sensus trap in South Africa were determined in field experiments where laboratory-reared C. capitata, C. rosa and C. cosyra were released in a mango orchard within a few metres of Sensus traps containing either Capilure (trimedlure or tert-butyl 4 (or 5) -chloro-2-methylcyclohexane carboxylate), Ceratitislure (protein hydrolysate plus β-caryophyllene) or Questlure (protein hydrolysate plus plant extracts). When using 12-day-old flies, Capilure caught 3 times more C. capitata males than C. rosa males and this difference was more extreme when 3-day-old flies were released. Ceratitislure caught significantly more 12-day-old C. cosyra males than 12-day-old C. capitata males, but the difference was reversed when 3-day-old flies were compared. Questlure showed the least differences between species and age but recovered the lowest proportion of released species. Further comparisons were conducted in an orchard with wild flies using other known attractants in larger yellow Probodelt bucket traps. Capilure caught more male C. capitata than BioLure Fruit Fly 3-component, but BioLure 2-component (trimethylamine and ammonium acetate) was more effective than Questlure for C. capitata females. The 3-component lure was also more effective than both Capilure and Questlure for male and female C. rosa, respectively. Ceratitislure was the most effective lure for male C. cosyra flies and BioLure 3-component was more effective than Ceratitislure and Questlure for female C. cosyra flies. The intervention threshold of 4 flies/trap/week previously used in citrus with Capilure for C. rosa was lowered to 2 C. rosa/trap/week when using the Sensus trap due to the lower sensitivity of this trap-lure combination found for C. rosa in this study. The 3-component lure, or the 2-component combination of trimethylamine and ammonium acetate in a ratio of 1:8 in the Sensus trap capsule, would be more effective for both sexes of all three Ceratitis species than the Questlure that is currently being used.     

High level of resistance to Sclerotinia sclerotiorum in introgression lines derived from hybridization between wild crucifers and the crop Brassica species B. napus and B. juncea

Sclerotinia rot caused by the fungus Sclerotinia sclerotiorum is one of the most serious and damaging diseases of oilseed rape and there is keen worldwide interest to identify Brassica genotypes with resistance to this pathogen. Complete resistance against this pathogen has not been reported in the field, with only partial resistance being observed in some Brassica genotypes. Introgression lines were developed following hybridization of three wild crucifers (viz. Erucastrum cardaminoides, Diplotaxis tenuisiliqua and E. abyssinicum) with B. napus or B. juncea. Their resistance responses were characterized by using a stem inoculation test. Seed of 54 lines of B. napus and B. juncea obtained from Australia, India and China through an Australian Centre for International Agricultural Research (ACIAR) collaboration programme were used as susceptible check comparisons. Introgression lines derived from E. cardaminoides, D. tenuisiliqua and E. abyssinicum had much higher levels (P < 0.001) of resistance compared with the ACIAR germplasm. Median values of stem lesion length of introgression lines derived from the wild species were 1.2, 1.7 and 2.0 cm, respectively, as compared with the ACIAR germplasm where the median value for stem lesion length was 8.7 cm. This is the first report of high levels of resistance against S. sclerotiorum in introgression lines derived from E. cardaminoides, D. tenuisiliqua and E. abyssinicum. The novel sources of resistance identified in this study are a highly valuable resource that can be used in oilseed Brassica breeding programmes to enhance resistance in future B. napus and B. juncea cultivars against Sclerotinia stem rot.     

Effects of agrochemical treatments on the occurrence of Fusarium ear rot and fumonisin contamination of maize in Southern Italy

The efficacy of agrochemical treatments, based on three different fungicides combined with an insecticide, was tested in southern Italy for two years on three maize hybrids to control Fusarium ear rot of maize and the accumulation in the maize kernels of the carcinogenic mycotoxins fumonisins. Insect damage incidence and severity, disease incidence and severity, identification of Fusarium species and levels of fumonisin contamination in kernels were determined. Field trials showed in both years that natural colonization of maize kernels by the fumonisin producing species Fusarium proliferatum and F. verticillioides (up to 81.5 and 26.5%, respectively) and total fumonisin contamination (up to 68.2 μg g⁻¹) were highly severe. For all hybrids and in both years, the treatment with the insecticide applied alone reduced the insect damage severity consistently and the content of fumonisins in the kernel only in half of the cases, whereas fungicide treatments applied in combination with the insecticide showed a further significant reduction of fumonisin contamination in the three hybrids and in both years.     

Evaluation of A1, A2, A3, A4(M), A4(G) and A4(VZM) cytoplasms in iso-nuclear backgrounds for grain mold resistance

Breeding for resistance to grain mold, an economically important disease of sorghum, has been only partially successful. Hybrid technology is well developed in sorghum due to availability of the cytoplasm male sterility (CMS) system and at present almost all commercial hybrids are based on the A₁ CMS system. To compare the available alternate CMS systems for grain mold resistance, 72 hybrids were produced by crossing 36 A-lines (six CMS systems; A₁, A₂, A₃, A_4(M), A_4(G), A_4(VZM) each in six nuclear backgrounds) with two common restorers, and were evaluated during the 2006 and 2007 rainy seasons in grain mold nursery at ICRISAT. Data analyses indicated influence of cytoplasm on the responses of hybrids to grain mold infection as measured by panicle grain mold resistance (PGMR) score. The A₁ cytoplasm seemed to contribute to grain mold resistance followed by A_4(VZM) and A₂ cytoplasms. The A_4(M) cytoplasm had superior general combining ability (GCA) effects while the A₁ and A_4(VZM) cytoplasm based hybrids had superior specific combining ability (SCA) effects on the PGMR score. Almost all hybrids had significant mid-parent heterosis. The A₁ cytoplasm is the best suited for the development of sorghum hybrids for the rainy season adaptation with grain mold resistance. However, use of alternate cytoplasms (A₂ and A_4(VZM)) for hybrid development will not increase susceptibility to grain mold in commercial grain production.     

Comparative susceptibility of Ostrinia furnacalis, Ostrinia nubilalis and Diatraea saccharalis (Lepidoptera: Crambidae) to Bacillus thuringiensis Cry1 toxins

Transgenic corn hybrids that express toxins from Bacillus thuringiensis (Bt) are highly effective against the European corn borer, Ostrinia nubilalis (Hübner), and the closely related Asian corn borer, Ostrinia furnacalis (Guenée). Since the registration of Bt corn hybrids in the U.S. in 1996, there has been a great deal of information generated on O. nubilalis. However, relatively little information exists for O. furnacalis. To help determine whether the information generated for O. nubilalis can be leveraged for decisions regarding the use of transgenic Bt corn against O. furnacalis, experiments were designed to determine whether the pattern of sensitivity to various Bt Cry1 toxins is similar between the two species. Test insects included laboratory-reared O. furnacalis originating from Malaysia, a Bt-susceptible laboratory colony of O. nubilalis maintained at the University of Nebraska-Lincoln (UNL) and an out-group consisting of the sugarcane borer, Diatraea saccharalis (F.), from Louisiana which represents a different genus from the same family. O. furnacalis and O. nubilalis exhibited a similar pattern of susceptibility to all the Cry1 toxins and were highly susceptible to the range of Bt toxins tested including Cry1Aa, Cry1Ab, Cry1Ac and Cry1F. Both of the Ostrinia species were more tolerant to Cry1Ba compared with D. saccharalis, although sensitivity of O. furnacalis was intermediate and did not differ significantly from that of O. nubilalis and D. saccharalis. D. saccharalis was also susceptible to the range of toxins tested but unlike the two Ostrinia species, was more tolerant to Cry1F and more susceptible to Cry1Ba. These results indicate that both of the Ostrinia corn borer species are similar in sensitivity to the Cry1Aa, Cry1Ab, Cry1Ac, Cry1Ba and Cry1F toxins, thus suggesting shared toxin receptors and mechanisms of toxicity for the two species.     

Effects of the replacement of Glu-A1 by Glu-D1 locus on agronomic performance and bread-making quality of the hexaploid wheat cv. Courtot

The aim of this study was to evaluate the cumulative and interactive effects on wheat (Triticum aestivum L.) gluten strength and mixing properties of dough associated with the duplication of the Glu-D1 locus. A partially isohomoeoallelic line RR240, in which a segment of the wheat chromosome 1D containing the Glu-D1 locus encoding the Dx2 + Dy12 subunits and translocated to the long arm of the chromosome 1A through homoeologous recombination, was assessed. Agronomic traits and yield components were studied in the translocated line RR240 and compared with the control line cv. Courtot. Both lines were evaluated under field conditions in two experimental years. Technological effects resulting from the duplication of HMW glutenin subunits Dx2 and Dy12 were evaluated using the Alveograph test, the Mixograph test and the baking test. The RR240 line was shown to have a lower agronomic performance for 1000-kernel weight and grain yield. However the duplication of the Glu-D1 allele was associated with a significant effect on dough strength and mixing resistance, and on the Zeleny sedimentation volume. Baking parameters were not significantly modified between both lines although the score values of the CNERNA test were observed to be slightly higher in RR240 than in Courtot.     

Boiling water treatment: A simple,rapid and effective technique for nematode and banana weevil management in banana and plantain (Musa spp.) planting material

We studied the effect of treating banana and plantain (Musa spp.) suckers using boiling water for the generation of healthy planting material. Small, medium and large-sized suckers of two East African highland bananas (cvs. Mbwazirume, Kibuzi, AAA-EA) and one of plantain (cv. Agbagba, AAB) were dipped in boiling water for 10, 20 or 30 s after root removal and corm (sucker) paring. Treatments were compared with a conventional farmer method (control), which was not pared or treated with boiling water, and also with pared only. At three months after treatment, germination, plant height and girth of plants were similar within sucker size and between treatments for each cultivar. Root health was improved by boiling water treatment for all cultivars compared to untreated controls. Boiling water treatment of suckers reduced combined nematode densities of Helicotylenchus multicinctus, Radopholus similis and Meloidogyne spp. to 0.7% of farmer controls. Boiling water-treated suckers had less banana weevil damage than controls. Treatment of pared suckers for at least 20 s and up to 30 s was highly efficient for disinfesting banana and plantain planting material. This modification of the hot water treatment is a practical adaptation, suitable for smallholder growers to improve the quality of banana and plantain planting material in smallholder farms.