Dissecting the genetic basis of popping ability in nuña bean,an ancient cultivar of common bean

Nuña beans (Phaseolus vulgaris L.), an ancient and pre-ceramic landrace native to Andean region, possess the property of popping and a high content of proteins and carbohydrates, which makes it an alternative nutritious snack. Knowledge on the genetic bases of popping ability is relevant for common bean improvement. Progenies derived from two nuña bean crosses were used in a generation mean based mating design to determine the inheritance and gene action for five popping related traits: length of popped seeds (PSL), popping dimension index (PDI), percentage of un-popped seeds (PUS), popping percentage average (PPA) and expansion coefficient (EC). Significant additive gene effects were found for all traits, and was the only source of the observed variation for PSL, while dominance and higher-order interactions among loci contributed to the genetic divergence for the other traits. The dominance of the cultivated over nuña alleles for PDI, PPA, EC and PUS, was confirmed by high mid-parent heterosis values and generation mean comparisons. The [d] and [dd] gene effects were in opposite direction for PPA and EC, indicating duplicate epistasis. Therefore, epistasis is likely to be an important explanation for the heterosis in both traits. For PDI and PUS, the opposite signs for [aa] and [dd] gene effects indicated that the genes for increasing popping are dispersed between the parents. Generation means and variances of BC₁P₂ indicated advantages of the backcross breeding procedure to improve the adaptation of the exotic germplasm and at the same time, transfer part of the desired donor genes to cultivated common bean. The backcross to the nuña parent could be an alternative to maintain/recover the favorable epistatic gene combinations found for PDI, PPA, EC and PUS traits.     

Epistasis in an Andean × Mesoamerican cross of common bean

The objective of this investigation was to check if epistasis is present in Andean × Mesoamerican beans crosses using triple test cross (TTC) method. The parents of the segregating population were Carioca–MG (Mesoamerican) and BRS Radiante (Andean). In July 2005, F₂ progenies (backcrossed with the parents and F₁ generation) were evaluated at two locations for three characters: number of pods plant⁻¹, number of grains plant⁻¹ and grain weight plant⁻¹. The presence of epistasis was detected for all yield components. In the partitioning of epistasis in additive x additive (i) and dominant x dominant (j) and dominant × additive (l) it was observed that, for the traits number of pods/plant and number of grains/plant, only epistasis of the type (j) + (l) were significant. For the trait grain mass/plant, all types of epistasis were significant.     

DNA marker-assisted selection to pyramid rust resistance genes in “carioca” seeded common bean lines

This work reports a gene pyramiding approach assisted by DNA markers used to develop “carioca” seeded common bean (Phaseolus vulgaris L.) elite lines harboring three different rust resistance genes. Rust is among the most destructive diseases that attack P. vulgaris and cause serious damage worldwide. The rust resistance genes Ur-5 (from ‘Mexico 309’), Ur-11 (from ‘BelMiDak RR-3’), and Ur-14 (from ‘BRS Pioneiro’, a “carioca” seeded cultivar derived from the resistance source ‘Ouro Negro’) were combined in the “carioca” seeded bean cultivar ‘Rudá’. Firstly, two different backcross programs were conducted separately to produce progenies harboring individually the Ur-5 and Ur-11 genes. Molecular fingerprinting analysis was used to select plants genetically similar to ‘Rudá’ in the backcross cycles to accelerate the recurrent-background recovery. The obtained progenies were initially intercrossed and then crossed with ‘BRSMG Pioneiro’ (Ur-14). The final F₁ plants derived from these crosses were screened with DNA markers linked to the three rust resistance genes: SI19 (Ur-5), SAE19 (Ur-11) and OPX11 (Ur-14). The plants selected as harboring all the alleles of interest were used to obtain the next generations. The selection based on DNA markers was conducted up to the F_4:5 generation. We were able to select F_4:7 progenies showing all the DNA markers associated to the genes of interest and resistant to all specific races of U. appendiculatus used for phenotypically detecting each one of the rust resistance genes. Yield evaluations show that these selected lines are as productive as the recurrent parent ‘Rudá’ and high-performing control cultivars grown in Brazil.     

Linkage fine-mapping and QTLs affecting morpho-agronomic traits of a Mesoamerican × Andean RIL common bean population

This paper proposes the construction of a genetic linkage map with 376 recombinant inbred lines (RILs) derived from a cross between Mesoamerican?×?Andean common bean (Phaseolus vulgaris L) parents based on single nucleotide polymorphism (SNP) markers; and to detect quantitative trait loci (QTLs) associated with seven morpho-agronomic traits: number of days to flowering (DF), number of days to maturity (DM) or crop cycle; plant architecture (ARC); seed yield (YLD); degree of seed flatness (SF); seed shape (SS); and 100-seed weight (SW). A total of 3060 polymorphic SNP markers were used and 2041 segregated at a 1:1 ratio in the RIL population, as expected. These markers were subjected to linkage analysis in each chromosome. The genetic linkage analysis resulted in linkage maps with a total of 1962 markers spanning 1079.21 cM. A total of 29 QTLs associated with seven morpho-agronomic traits were detected on the 11 chromosomes, which explained between 3.83 and 32.92% of the phenotypic variation in DF. A total of 18 candidate genes associated with the detected QTLs were identified and related with biological processes, molecular functions and cellular components.     

Inheritance of the virgata pattern of partly colored seed coats in ‘Early Giant’ common bean

The inheritance of the virgata pattern of partly colored seed coats found in common bean (Phaseolus vulgaris L.) Early Giant (EG) was studied by a series of test crosses with line 5-593 and genetic stocks developed by backcrossing selected genes into the recurrent parent 5-593, a Florida dry bean breeding line with a self-colored, black seed coat with genotype T Z Bip P [C r] J G B V Rk. Analysis of the F₂ from the cross EG × 5-593 led to the hypothesis that the virgata pattern of EG has genotype t z bip^vgt, where vgt stands for virgata. The test cross EG × t z virgarcus BC₃ 5-593 confirmed the hypothesis that EG carries t z from data recorded in F₁, F₂, and 27 F₃ progenies from randomly selected F₂ plants. The F₃ segregation was also consistent with the hypothesis that a single recessive gene converts virgarcus into virgata. The test cross EG × t z bip bipunctata BC₃ 5-593 failed to show genetic complementation in F₁ progeny, and the F₂ segregated 3:1 for the parental phenotypes virgata and bipunctata, respectively. Including previously published data, all possible crosses were made among bipunctata, virgata, and virgarcus parents, supporting a multiple allelic series at Bip. We propose the gene symbol bip^vgt for the new allele at Bip, where the allelic series has the order of gene dominance Bip > bip^vgt > bip. Based on test crosses, the complete seed-coat color and pattern genotype of EG is tz bip^vgt P [C r] J G B v^lae rk^d.     

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

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.     

Genetic control of resistance to Meloidogyne incognita race 1 in the Brazilian common bean (Phaseolus vulgaris L.) cv. Aporé

The use of resistant cultivars is one of the best methods for nematode control and reduction of economic losses caused by these pathogens. Studies of inheritance of nematode resistance in common bean (Phaseolus vulgaris L.) are nonetheless scarce. The present paper reports on the estimation of genetic parameters associated with resistance to the root nematode Meloidogyne incognita race 1 in common beans. Two contrasting bean lines, ‘Aporé’ (P₁ = nematode resistant) e ‘Macarr?o Rasteiro Conquista’ (P₂ = susceptible), and the generations F₁ (P₁ × P₂), F₂ (P₁ × P₂), BC₁(P₁) = (F₁ × P₁) and BC₁(P₂) = (F₁ × P₂), were assessed 45 days after nematode inoculation, through a scale related to the number of eggs per gram of root tissue. Dominant genetic effects were inferior in magnitude to additive effects, indicating incomplete dominance of nematode resistance. Dominance was in the direction of increased nematode resistance (i.e., lower number of eggs per g root). Resistance to Meloidogyne incognita race 1 in common bean is under control of a single gene locus, with incomplete dominance of the resistance allele present in ‘Aporé’, but modifier genes affecting its expression appear to be present in the susceptible parent ‘Macarr?o Rasteiro Conquista’.     

Genetic progress during 22 years of black bean improvement

The common bean breeding program coordinated by Embrapa Arroz e Feijão released 50 new cultivars from 1984 to 2010. The aim of the present study was to estimate genetic progress in terms of seed yield and other agronomic traits achieved by the black-type common bean breeding program in Brazil over the 22-year period from 1985 to 2006. Two types of field experiments were performed to assess genetic progress. In regard to experiments on lines, the three best breeding lines from each of 11 evaluation cycles constituted 33 treatments. These evaluations were made in 20 environments and served to estimate progress in seed yield and seed size because these were the criteria applied in selecting the elite lines. Cultivar evaluations included nine cultivars recommended by Embrapa during the period under investigation, and the evaluations were established in 21 environments. These evaluations served to estimate improvements in reaction to angular leaf spot, plant architecture and tolerance to lodging because cultivars usually exhibit superior phenotypes for such characteristics. Evaluations were performed from 2008 to 2010. Estimated improvement in seed yield was 25.2 kg ha^?1 or 1.1 % per year. Improvements were also found in tolerance to lodging (1.7 % per year) and 100-seed weight (0.65 % per year). There was no significant progress for the plant architecture and resistance to angular leaf spot traits.     

75 years of breeding pinto bean for resistance to diseases in the United States

Diseases are major production constraints of pinto bean despite 75 years of breeding. The objectives were to (1) assess progress made and (2) discuss future breeding strategies. Bean common mosaic virus (BCMV), anthracnose, rust, white mold, common blight, and halo blight and growth habit, seed weight, and seed coat darkening were evaluated for 52 cultivars released between 1944 and 2001. Sixteen cultivars were resistant to BCMV, 12 to race 53 of rust, five to race 73 of anthracnose, two to halo blight, and none to common blight and white mold. Four were resistant to two and none to three or more diseases. Four had Type I, ten Type II, and others Type III growth habit. Bill Z, Grand Mesa, Montrose, Olathe, Othello, Ouray and Pindak darkened slower in storage. Pintoba had the largest and Cahone smallest seed. An integrated breeding strategy is suggested for simultaneous improvement of resistance to multiple-diseases.     

Response of 21 common beans of diverse origins to two strains of the common bacterial blight pathogen,Xanthomonas campestris pv. phaseoli

Common bacterial blight (CBB) is a severe disease of common bean and the use of resistant cultivars is the most effective control. The objectives were to determine (i) the most appropriate leaf type for CBB evaluation, (ii) the aggressiveness of two bacterial strains, (iii) the presence or absence of SAP6, BC420, and SU91 resistance QTL linked markers, and (iv) the most resistant genotypes. The CBB response in the primary and trifoliolate leaves of 21 genotypes of diverse origins and two checks was evaluated in two greenhouses. Mean trifoliolate leaf score (4.8) was higher than the primary leaf (2.5). The strain Xcp25 (3.2 primary, 5.4 trifoliolate) was more aggressive than ARX8AC (1.7 primary, 4.2 trifoliolate). Andean ‘Montcalm’ with SAP6 QTL was intermediate (6.0) to ARX8AC and susceptible (8.3) to Xcp25 in the trifoliolate leaf. New Andean RCS52-2, RCS53-3, and RCS63-5B with BC420 and SU91, and 08SH840 with SAP6 and SU91 QTL were intermediate (3.5–6.2) to both strains. But, Middle American VAX 3, VAX 4, and VAX 6 with SAP6 and SU91 QTL were resistant (2.3–2.5) to ARX8AC and intermediate to Xcp25 (3.4–6.5) in the trifoliolate leaf. Further efforts are required to pyramid higher levels of resistance from across Phaseolus species and introgressed in Andean common bean.     

Monosomic analysis of fertility restoration in common wheat ‘Prof. Marchal’

Summary In common wheat (Triticum aestivum L.) a monosomic set of Chinese Spring and male-sterile Janus (with cytoplasm of T. timopheevi Zhuk.) were used to determine the chromosomal location of Rf-genes in Professeur Marchal. As revealed by test cross data, a major gene cofeerring fertility restoration was present in Prof. Marchal on chromosome 1B. A significant deviation towards sterility was observed in some fest cross progenies. Chromosome 1B of Chinese Spring appeared to carry a dominant restoring gene, which caused partial restoration of fertility.     

A dominant gene for garnet brown seed coats at the <Emphasis Type="Italic">Rk</Emphasis> locus in ‘Dorado’ common bean and mapping <Emphasis Type="Italic">Rk</Emphasis> to linkage group 1

The color of the seed coats of ‘Dorado’ (Phaseolus vulgaris L.) is garnet brown (dark red kidney bean color) and differs from most other dry bean varieties in the Honduran red bean market class. A genetic investigation of the color of ‘Dorado’ (same as DOR364) and G19833 (Liborino market class) seed coats was conducted. Crosses with genetic tester stocks demonstrated that the gene for garnet brown (GB) in ‘Dorado’ was not allelic with the R gene for dominant red (oxblood) seed coat. An allelism test between the ‘Dorado’ gene for GB seed coat and the rk ^drv gene for recessive expression of GB demonstrated allelism. We propose the gene symbol for Rk ^r for the ‘Dorado’ GB seed coat color gene. Rk ^r expresses partial dominance over Rk, where Rk ^r/Rk expresses a paler and highly variable intermediate red color. The interactions of Rk ^r, rk ^drv, and c ^u are discussed. Segregation analysis in the mapping population made up of DOR364 (same as ‘Dorado’) × G19833 recombinant inbred lines showed that the Rk ^r gene mapped to linkage group 1. The new allele at Rk was located at a distance of 17 cM from the RFLP marker Bng130 with a LOD > 3.0.     

A wheat–Thinopyrum ponticum–rye trigeneric germplasm line with resistance to powdery mildew and stripe rust

An individual plant, line 0-123-1-1 with the chromosome number 2n?=?42 was obtained in the BC₃F₄ progeny of a cross between a wheat 1BL.1RS translocation line 48112 and wheat?CThinopyrum ponticum partial amphiploid BE-1. Molecular markers specific for 1RS, Glu-B3, and the T. ponticum genome specific marker SCAR₉₈₂ revealed that the line was trigeneric having alien chromatin from both T. ponticum and rye. Resistance tests with mixed races of Blumeria graminis f. sp. tritici and an individual race of Puccinia striiformis at the seedling and adult stages revealed that 0-123-1-1 was immune to powdery mildew and stripe rust for the whole growth period. High levels of disease resistance and good and stably agronomic traits make the 0-123-1-1 line a good germplasm for breeding in wheat.     

Genetic control of a response to the segregation distortion allele,Sd-1d,in the common wheat line ‘Indis’

Summary A translocated chromosome segment, derived from Thinopyrum distichum, carries the leaf rust resistance allele Lr19d and a segregation distorter allele, Sd-1d. In translocation heterozygotes, male and female gametophytes lacking the translocation are aborted, the severity of the effect depending on the genotype of the hybrid. The selective abortion of the gametophytes with a normal chromosome 7D appears to be based on the absence of the translocated chromosome rather than the presence of the normal chromosome. The magnitude of the gametocidal response, elicited by Sd-1d, is under multigenic control. A number of chromosomes, the individual effects of which are generally small, may act to suppress or promote the response. Chromosome arms 2AL, 2BL, 5BL and 5DL of Chinese Spring were found to reduce sensitivity to the presence of the gametocidal chromosome. Chromosome 3B of Inia 66-1 also reduce the gametocidal response while chromosome arm 6DS of Chinese Spring may promote the effect     

Long-term effects of lime and phosphogypsum application on tropical no-till soybean–oat–sorghum rotation and soil chemical properties

Root growth, nutrition and crop yield can be affected by soil chemical modifications caused by superficial limestone and phosphogypsum application in a no-till system. Using this approach, this study was conducted in southeastern Brazil, continuing an experiment that has been on-going since 2002 with the objective of evaluating the residual effects of the surface application of lime and phosphogypsum on the soil chemical characteristics and the root growth, nutrition and yield of soybean, black oat and sorghum in a dry winter region cultivated in 2008/2009 and 2009/2010. The experimental design was a randomized block with 4 replications. The treatments were applied in November 2004 and were as follows: original conditions, limestone application (2000 kg ha⁻¹), phosphogypsum application (2100 kg ha⁻¹), and limestone (2000 kg ha⁻¹) + phosphogypsum (2100 kg ha⁻¹) application. Superficial liming with or without phosphogypsum reduced the surface and subsurface soil acidity 5 years after application in the no-till system. The movement of Ca²⁺ and Mg²⁺ from the surface layer into the subsoil over time was evident. The phosphogypsum application associated with liming increased the Ca²⁺ levels throughout the soil profile. Liming maintained high levels of Mg²⁺ throughout the soil profile with or without phosphogypsum application. The organic matter content increased with liming with or without phosphogypsum, indicating that in the long term, these practices can increase the C accumulation. Phosphogypsum application had a residual effect on the SO₄-S levels, and high sulphate concentrations were observed in the subsoil after 5 years. Superficial liming improved crop nutrition and, when associated with phosphogypsum, increased Ca absorption by soybean and sorghum, as reflected in the increased yields of these crops.     

Decoding Australia's China threat narrative during 2016–2021

Australia–China relations began to sour in 2016, and the China threat narrative began to dominate since then. Unlike previous studies which either use a qualitative approach or cross-sectional dataset for empirical analysis, this study creatively creates high-frequency weekly and monthly time series datasets using the Google Trends search results during January 2016–February 2021. Based on a series of time series modellings, this study examines the roles of various actors, including China's own policies, the Australian Strategic Policy Institute and Clive Hamilton, various factors, including Chinese purchase of Australian housing, Chinese investment in Australia, Chinese students in Australia and China's rise and various media outlets, including the Australian Broadcasting Corporation, Australian Financial Review, Sydney Morning Herald, Daily Telegraph and Herald Sun, in contributing to Australia's China threat narrative. This study makes significant contributions to academia in methods by bringing a new quantitative approach to international relations studies and to policy-makers as well by quantifying the roles of various actors, factors and media outlets in Australia's China policy debate.     

稻–麦轮作下9000kg hm~(–2)产量水平扬麦20的群体质量及花后光合特征

在稻麦两熟制条件下,于2010—2011和2011—2012年度,通过氮肥施用量、施用时期及比例的调控,建立了扬麦20不同产量水平群体,比较≥9000 kg hm–2群体(P1)与9000 kg hm–2群体(P2)的产量构成、群体质量及花后光合特征,为稻茬小麦大面积高产提供理论依据和技术支撑。P1较P2群体产量高约10%,每穗粒数高约5.5%,差异显著,但两群体的穗数和千粒重差异不显著。P1群体的穗数、穗粒数和千粒重分别为482~538万hm–2、47~49粒和34~39 g。籽粒产量与孕穗和开花期叶面积指数(LAI)及花后LAI衰减率和光合势呈抛物线关系,与乳熟期LAI、粒(重)/叶比和群体生长率呈显著线性正相关。两年度试验结果表明P1群体具有以下特征,孕穗期、开花期和乳熟期的LAI分别为6.5~7.0、5.0~6.0和4.0~4.5;粒(数)/叶比为0.37~0.39,粒(重)/叶比为13.5~14.5;花后LAI衰减率、群体生长率、光合势和净同化率分别为0.13~0.15 d–1、19~20 g m–2 d–1、103×104~118×104 m2 d hm–2和9~11 g m–2 d–1。花后21d和28 d,剑叶SPAD值、净光合速率、丙二醛(MDA)含量及3种抗氧化酶(CAT、POD和SOD)活性与产量相关性均达极显著水平。研究表明,稻–麦轮作体系中,扬麦20达到9000 kg hm–2产量水平的栽培技术关键点是获得适宜穗数的基础上,主攻每穗粒数与千粒重的协调增加,使群体在花前具有较高的光合面积和光合速率,花后光合面积衰减速率低,维持较高的光合面积,从而充分积累花后光合物质,在适宜库容基础上保障对库充实的需求。