Posts Tagged ‘Euphytica’

Simultaneous selection for resistance to five bacterial, fungal, and viral diseases in three Andean × Middle American inter-gene pool common bean populations

Posted by Carelia Juarez on , in Journal Articles

Published in Euphytica 189 (2) : 283-292, 2013

Henry Terán, Carlos Jara, George Mahuku, Stephen Beebe  and Shree P. Singh

Numerous bacterial, fungal, and viral diseases cause severe damage on roots, foliage, stem, pods, and seeds, resulting in yield and quality losses in common bean (Phaseolus vulgaris L.) worldwide. Cultivars with resistance to multiple diseases are needed to reduce these losses and dependence on pesticides for disease control. Our objective was to determine the effectiveness of simultaneous selection in the F1 and F2 for resistance to five diseases, namely angular leaf spot (ALS), anthracnose (ANT), bean common mosaic (BCM), common bacterial blight (CBB), and common bean rust (CBR) in three Andean x Middle American inter-gene pool double-cross populations, namely ST = ‘Chocho’/‘Catrachita’//G 5686/VAX 3, CN = ‘DIACOL Calima’/VAX 6//A 193/G 5686, and CB = A 483/‘Talash’//Wilkinson 2/G 5686. One hundred seventy-five F1 plants of ST, 177 of CN, and 195 of CB and their parents were evaluated in the greenhouse using sequential inoculations with pathogens causing BCM, CBR, ALS, CBB, and ANT, in that order. Progenies of surviving F1 plants were again evaluated in the F2, using similar sequential inoculations. The F4-derived F5 breeding lines were developed using single-seed descent method. No selection was practiced for any trait in the F3 and F4. In the F5, five breeding lines from ST, two from CN, and one from CB exhibited intermediate to high levels of resistance to the five diseases when compared with the parents. Thus, selection in the F1 and F2 was effective for simultaneous introgression of resistance to the five diseases in all three Andean × Middle American inter-gene pool common bean populations.

 

Association of parental genetic distance with heterosis and specific combining ability in quality protein maize

Posted by Carelia Juarez on , in Journal Articles

Published in Euphytica, 2012

Dagne Wegary, Bindiganavile Vivek and Maryke Labuschagne

Genetic distance analysis among quality protein maize (QPM) inbred lines and the correlation of genetic distance with heterosis would help to design breeding strategy and predict hybrid performance. This study was carried out to determine the amount of genetic diversity among QPM inbred lines using SSR markers and morphological distances; to classify the inbred lines according to their relationships; and to estimate the correlations of SSR markers and morphological distances with hybrid performance, heterosis and specific combining ability (SCA). One-hundred and five hybrids generated by diallel crossing of 15 QPM inbred lines were evaluated with the 15 parents for 17 morphological traits at Harare, Zimbabwe and Bako, Ethiopia and also examined for DNA polymorphism using 40 SSR markers. SSR markers and morphological methods of genetic distance estimates showed moderately high genetic distance among the inbred lines studied. Cluster analysis based on the two distance measures grouped the 15 parental lines differently. The SSR marker-based genetic distance was positively and highly significantly correlated with grain yield (r = 0.37), and negatively and highly significantly with days to anthesis (r = −0.40) and days to silking (r = −0.42). These relationships suggest that high grain yield and earliness of QPM hybrids can be predicted from SSR marker determined distances of the parents, although the correlation values were not very high. The correlations of SSR marker distance with heterosis were too low to be of predictive value except for the case of plant height. Morphological distances were of less importance in predicting hybrid performance and SCA effects of hybrids.

Association of staygreen trait with canopy temperature depression and yield traits under terminal heat stress in wheat (Triticum aestivum L.)

Posted by Carelia Juarez on , in Journal Articles

Published in Euphytica, 2012

Maya Kumari, R. N. Pudake, V. P. Singh and Arun K. Joshi

The presence or absence of the staygreen trait was screened for 3 consecutive years in 963 wheat lines from various sources, including Indian and CIMMYT germplasm. Staygreen was assessed at the late dough stage by visual scoring (0–9 scale) and the leaf area under greenness (LAUG) measurement. Around 5.5 % of the lines were staygreen, 10.5 % were moderately staygreen, and the remaining lines showed little or no expression of the trait. One hundred lines showing diversity for the staygreen trait were sown under three different sowing dates (timely, late and very late) for 3 consecutive years in three replications to determine the association of staygreen with heat tolerance. There was a decline in yield, biomass, grain filling duration (GFD) and 1,000 grain weight (TGW) under late and very late sowing conditions owing to terminal stress at anthesis and later stages. However, the decline was relatively less in staygreen genotypes compared to the non-staygreen (NSG) ones. The correlation study showed that LAUG and canopy temperature depression (CTD) were strongly correlated. LAUG and CTD were also significantly associated with grain yield, GFD and biomass. To further confirm the association of the staygreen trait with terminal heat stress, individual F2-derived F7 progenies from the cross of the ‘staygreen’ lines with NSG were evaluated for yield and yield traits at the three sowing dates. In each cross, the staygreen progenies showed a significantly smaller decline in yield and TGW under heat stress than the NSG progenies. These results appear to suggest an association between the staygreen trait and terminal heat stress and, thereby, that the staygreen trait could be used as a morphological marker in wheat to screen for heat tolerance.

Identification of QTL associated with durable adult plant resistance to stem rust race Ug99 in wheat cultivar ‘Pavon 76’

Posted by Carelia Juarez on , in Journal Articles

Published in Euphytica, 2012

P. N. Njau, S. Bhavani, J. Huerta-Espino, B. Keller and R. P. Singh

Stem rust of wheat, caused by Puccinia graminis f. sp. tritici, was under control worldwide for over 30 years by utilizing genetic resistance. The emergence of stem rust in 1998 in eastern Africa in form of race Ug99 and its evolving variants with virulence to many resistance genes were recognized as potential threats to wheat production. In this study we identified genomic regions contributing to putatively durable, adult plant resistance (APR) to wheat stem rust. A recombinant inbred line (RIL) population of 298 lines was previously developed at CIMMYT from a cross between ‘Avocet S’ and ‘Pavon 76’. Pavon 76 has been described to carry APR to stem rust. Avocet S carries the race-specific resistance gene Sr26. A subset of RILs without Sr26 segregated for APR to stem rust race Ug99 when evaluated in Kenya for three years. Single year and joint year analysis by inclusive composite interval mapping using 450 DArT markers identified five quantitative trait loci (QTL) that contributed to the resistance of wheat to stem rust race Ug99. Three of these, including QSr.cim-3B, which probably represents the Sr2 gene, were contributed by Pavon 76 whereas the remaining two QTL were contributed by Avocet S. QSr.cim-3B, or putatively Sr2, on chromosome arm 3BS explained 32 % of the phenotypic variation while the additional QTL in Pavon contributed 24 and 20 %, respectively. Two QTL from Avocet S explained 8 and 6 % of phenotypic variance, respectively. A combination of APR QTL from the two parents resulted in transgressive segregants expressing higher levels of resistance than Pavon 76. Our results indicate that it is possible to accumulate several minor resistance genes each with a small to intermediate effect resulting in a variety that exhibits negligible disease levels even under high stem rust pressure.

 

Characterization of genetic diversity of puroindoline genes in Mexican wheat landraces

Posted by Carelia Juarez on , in Journal Articles

Published in Euphytica, 2012

Marcela Ayala, Carlos Guzmán, Juan B. Alvarez and Roberto J. Peña

Grain hardness is a major factor determining milling performance of common wheat. It determines the amount of damaged starch generated during milling, and therefore the end use of a given variety. One hundred and two lines from 15 Mexican wheat landraces were analyzed for grain hardness and for its genetic control. Sixteen lines were hard and 86 were soft-textured. All hard lines could be explained by a mutation in either the PinaD1 or PinbD1 genes. In six hard lines there was no amplification of PinaD1, suggesting that this gene was deleted (PinaD1b allele). The remaining ten hard lines showed the presence of both PinaD1 and PinbD1. Sequencing the PinbD1 genes of the hard lines revealed the presence of two different alleles (PinbD1b and PinbD1e). The results substantiate the importance of very old Mexican landraces as potential sources of genetic diversity for key quality traits in the development of modern wheat cultivars with different grain textures.

Genomic characterization of drought tolerance-related traits in spring wheat

Posted by Carelia Juarez on , in Journal Articles

Published in Euphytica 186 (1): 265-276, 2012

Sundeep Kumar, Sunish Kumar Sehgal, Uttam Kumar, P. V. Vara Prasad, Arun Kumar Joshi and Bikram Singh Gill

Drought tolerance was investigated in ‘C306’, one of the most drought tolerant wheat cultivars bred in India in the 1960’s. An intervarietal mapping population of recombinant inbred lines of the cross ‘C306’ × ‘HUW206’ was evaluated for drought tolerance components, namely potential quantum efficiency of photosystem (PS) II (Fv/Fm), chlorophyll content (Chl), flag leaf temperature (Lt), and grain yield per plant (Gyp) under stress. Three independent experiments were conducted under well-watered and water-stressed conditions in greenhouses and growth chambers at Kansas State University (USA). Five hundred and sixty microsatellite markers covering the entire genome were screened for polymorphism between the parents. A QTL (QLt.ksu-1D) for Lt (low flag leaf temperature under stress) on the short arm of chromosome 1D between markers Xbarc271 and Xgwm337 at LOD 3.5 explained 37% of the phenotypic variation. A QTL for Fv/Fm (QF v /F m .ksu-3B) and Chl (QChl.ksu-3B) controlling quantum efficiency of PS II and chlorophyll content under stress were co-localized on chromosome 3B in the marker interval Xbarc68-Xbarc101 and explained 35-40% of the phenotypic variation for each trait. A QTL (QGyp.ksu-4A) for Gyp on chromosome 4A at a LOD value of 3.2 explained 16.3% of the phenotypic variation. Inconsistent QTLs were observed for Fv/Fm on chromosomes 3A, 6A, 2B, 4B, and 4D; for Chl on 3A, 6A, 2B and 4B; and for Lt on 1A, 3A 6A, 3B and 5B. The identified QTLs give a first glimpse of the genetics of drought tolerance in C306 and need to be validated in field experiments using the marker-phenotype linkages reported here.

Improved winter wheat genotypes for Central and West Asia

Posted by Carelia Juarez on , in Journal Articles

Published in Euphytica, 2012

R. C. Sharma, S. Rajaram, S. Alikulov , Z. Ziyaev, S. Hazratkulova , M. Khodarahami , S. M. Nazeri, S. Belen, Z. Khalikulov, M. Mosaad, Y. Kaya, M. Keser, Z. Eshonova,  A. Kokhmetova, M. G. Ahmedov, M. R. Jalal Kamali  and A. I. Morgounov

High grain yield and resistance to stripe (yellow) rust are the most important traits for successful adoption of winter wheat varieties in Central and West Asia. This study was conducted to determine the stripe rust response and agronomic performance of a set of breeding lines recently developed by the International Winter Wheat Improvement Program (IWWIP). Replicated field studies were conducted in 2010 and 2011 using 38 experimental lines, one regional check (Konya) and one local check. Stripe rust scores were recorded at Karshi, Uzbekistan, and Karaj and Mashhad, Iran, in 2010. Grain yield was recorded at two sites each in Uzbekistan (Karshi and Kibray) and Iran (Karaj and Mashhad) and one site in Turkey (Eskisehir). The test lines showed variation for stripe rust severity, grain yield, 1,000-kernel weight, days to heading and plant height. Several stripe rust resistant genotypes were either higher yielding or equal to the local checks at different sites. Based on stripe rust resistance and yield performance in 2010, a set of 16 genotypes was selected and evaluated in 2011. All 16 were resistant at Almaty, Kazakhstan, and Dushanbe, Tajikistan, in 2011, whereas 9 of the 16 were resistant at Terter, Azerbaijan. The genotypes ‘TCI-02-138, ‘Solh’, ‘CMSS97M00541S’, ‘TCI -2-88(A)’ and ‘TCI-02-88(C)’ were consistently resistant to stripe across all sites in both years. Several lines showed high grain yields and superior agronomic performance across four sites in Uzbekistan and one site in Tajikistan. One genotype has been released in Uzbekistan and another in Tajikistan.

 

Development of in vivo haploid inducers for tropical maize breeding programs

Posted by Carelia Juarez on , in Journal Articles

Published in Euphytica 185(3): 481-490, 2012

Vanessa Prigge, Wolfgang Schipprack, George Mahuku, Gary N. Atlin and Albrecht E. Melchinger

Lack of adapted haploid inducers currently impedes adoption of the doubled haploid technology in tropical maize breeding programs.             Our objective was to generate inducers with improved adaptation to tropical conditions. We developed segregating generations             from crosses between temperate inducers having haploid induction rates (HIR) of 8–10 % and tropical CIMMYT maize lines (CML;             HIR = 0 %) and evaluated these for HIR and agronomic performance under tropical lowland field conditions. The applied pedigree             breeding scheme comprising mass selection on individual F2 plants for highly heritable and visually scorable traits, followed by family-based selection for HIR and other agronomic             characteristics in advanced selfing and backcross (BC) generations seems highly suitable for breeding improved haploid inducers             with adaptation to different agroecologies. The most advanced tropical inducer candidates (TIC) combine HIR of up to 10 %             with improved pollen production, disease resistance, and plant vigor compared to temperate inducers under tropical conditions.             Agronomic characteristics were significantly improved in the BC to CML compared to BC to inducers, while mean HIR of both             populations were similar, indicating that backcrossing to the adapted parent was suitable to improve adaptation of new inducers             without sacrificing high HIR. When screening random open-pollinated maize accessions, HIR of up to 3 % were observed, suggesting             that novel genetic variation may be present in maize accessions that could be exploited to improve HIR in maize. In conclusion,             tropical inducer development proceeds well, but evaluation of TIC in multi-environment trials needs to be completed before large-scale dissemination can commence.

Can Mediterranean durum wheat landraces contribute to improved grain quality attributes in modern cultivars?

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Published in Euphytica, 2011

Can Mediterranean durum wheat landraces contribute to improved grain quality attributes in modern cultivars?

Ruyman Nazco, Dolors Villegas, Karim Ammar, Roberto Javier Peña, Marc Moragues and Conxita Royo

The variability for quality attributes existing in a collection of 154 durum landraces from 20 Mediterranean countries and 18 modern cultivars was determined with the ultimate goal of identifying potential quality-enhancing genotypes for use in breeding programs. Field experiments were conducted during 3 years under rainfed conditions in northeastern Spain. Environmental effects were the most important in determining protein content, grain yield and yellow color index of the endosperm (grain flour), and the least important in determining EU quality index (QI), gluten strength and grain filling rate. QI is a weighed composite index determined from protein content, gluten strength, yellow color index and thousand kernel weight. Multivariate analysis detected four groups; three including landraces and one comprising modern cultivars. Landraces from the eastern Mediterranean countries had the highest mean QI and the widest variability for individual quality traits, but were characterized by relatively small grains. Landraces from the western Mediterranean countries had greater grain filling rates and heavier grains. Protein content, gluten strength and yellow color index were similar between eastern and western groups. The low QI and reduced variability characterizing the landrace group from the north Balkan Peninsula support the hypothesis of a different origin for this group. Modern cultivars, as a group, were the most productive and showed high QI, but they had the lowest grain protein content and phenotypic variability. Landraces that could be used as sources of quality-improving attributes and/or those that could be used in breeding programs without substantial quality handicaps were identified from different groups. Landraces can be particularly useful in breeding programs to improve gluten strength, grain weight and accelerate grain filling rate.

Combining ability, heterosis and genetic diversity in tropical maize (Zea mays L.) under stress and non-stress conditions

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Published in Euphytica  180(2): 143-162, 2011

Combining ability, heterosis and genetic diversity in tropical maize (Zea mays L.) under stress and non-stress conditions

 Dan Makumbi, Javier F. Betrán, Marianne Bänziger and Jean-Marcel Ribaut

 Drought and low soil fertility are considered the most important abiotic stresses limiting maize production in sub-Saharan Africa. Knowledge of the combining ability and diversity of inbred lines with tolerance to the two stresses and for those used as testers would be beneficial in setting breeding strategies for stress and nonstress environments. We used 15 tropical maize inbred lines to (i) evaluate the combining ability for grain yield (GY), (ii) assess the genetic diversity of this set of inbred lines using RFLP, SSR, and AFLP markers, (iii) estimate heterosis and assess the relationship between F1 hybrid performance, genetic diversity and heterosis, and (iv) assess genotype × environment interaction of inbred lines and their hybrids. The F1 diallel hybrids and parental inbreds were evaluated under drought stress, low N stress, and well-watered conditions at six locations in three countries. General combining ability (GCA) effects were highly significant (P < 0.01) for GY across stresses and well-watered environments. Inbred lines CML258, CML339, CML341, and CML343 had the best GCA effects for GY across environments. Additive genetic effects were more important for GY under drought stress and well-watered conditions but not under low N stress, suggesting different gene action in control of GY. Clustering based on genetic distance (GD) calculated using combined marker data grouped lines according to pedigree. Positive correlation was found between midparent heterosis (MPH) and specific combining ability (SCA), GD and GY. Hybrid breeding program targeting stress environments would benefit from the accumulation of favorable alleles for drought tolerance in both parental lines.