Breeding the common bean (Phaseolus vulgaris L.) for resistance to bean common mosaic virus: alternatives to backcrossing

A series of field experiments was undertaken in order to determine whether resistance to bean common mosaic virus (BCMV) could be incorporated into genotypes of the common bean (Phaseolus vulgaris L.) suitable for cultivation in Zimbabwe without recourse to backcrossing. Six inbred genotypes carrying the resistance-conferring alleles at the loci I and Bc-3 were crossed with five locally-adapted inbred genotypes. The first experiment comprised F₃ progeny rows, each derived from a single unselected F₂ plant, the second, F₃ bulks selected for resistance, and the third, a comparison of selected and unselected F₂-derived F₄ lines. The number of days to flowering and to maturity, the incidence of mosaic and necrosis symptoms, seed yield and seed size were recorded. There was evidence that late flowering and maturity were associated with BCMV resistance in some crosses, though not strongly enough to present an obstacle to plant breeding. The incidence of virus symptoms and seed yield were influenced by genetic factors additional to the major resistance genes, and variation in seed yield was present not only between bulk populations of crosses, but also between single-row plots of lines within crosses. This indicates that early-generation selection for yield in the presence of BCMV, even among progeny selected for BCMV-resistace, is likely to be effective. However, the variation in yield among F₄ lines was least in the highest-yielding crosses, which may represent a limit to successful selection for yield. Seed size was partly under additive genetic control, but there was also evidence of non-allelic interactions. There was no association between large seed size, preferred by consumers, and susceptibility to BCMV in the progeny, indicating that the association between these characters in the parent lines is fortuitous and will not present an obstacle to plant breeding. It is noted that a considerable amount of useful genetic information can be obtained without recourse to elaborate crossing schemes, provided that unselected progeny are included in experiments as controls. The evidence presented indicates that resistance to BCMV can be combined with appropriate values of maturity date, yield and seed size without the need for backcrossing.     

Inheritance of resistance to Acanthoscelides obtectus in a wild common bean accession crossed to commercial bean cultivars

Summary The bean weevil Acanthoscelides obtectus, is an important storage pest of common beans in Latin America and Africa. A few wild bean accessions from Mexico have been identified as highly resistant to the weevil. One accession, G 12952, was crossed to two susceptible bean cultivars differing in seed size. Reciprocal F1 and F2 individual seed were evaluated for days to adult emergence (DAE) and emerged adult weight. Maternally inherited seed size affected resistance measurements only in the F1 reciprocal crosses, however, the overall resistance level of the F1 was more similar to that of the susceptible cultivars. The F2 showed a continuous, but skewed distribution from low to high DAE. Very few F2 individuals had the resistance level of G 12952. When the frequency distributions were divided into discrete categories based on parental response, resistance was found to be inherited as two recessive complementary genes. The F3 generation showed an overall lowering of resistance levels compared to their original F2 evaluations. However, none of the lines classified as resistant (50 DAE) in the F2, fell into the susceptible category in the F3, indicating that the resistant genotypes were relatively stable as expected with recessively inherited traits. Modifying genes from the commercial parents may be responsible for general lowering of resistance. Seed size was negatively correlated with adult weight but not with DAE. The unique resistance of the wild bean accessions is discussed in relation to its inheritance. The results and obstacles encountered in the A. obtectus breeding program at CIAT are described.     

Growth habit and gene pool effects on inheritance of yield in common bean

Summary To satisfy farmer and consumer preferences, breeding efforts to increase yield potential in common bean must take into account the interrelated effects of growth habit, seed size, maturity, and gene pool on yield expression in segregating populations. To examine the relationships among these traits, a genetic study was conducted to determine the effect of growth habit on yield and seed size in crosses among five bean lines from diverse gene pools. Two parental bean lines had determinate, type I growth habits and large seed size typical of the Neuva Granada-Andean gene pool. Two other lines were tropical Mesoamerican types with type II growth habits and small seed size; and the fifth line, G13625, a landrace of the Jalisco gene pool from the Mexican highlands, had a type IV climbing growth habit and medium seed size. Individual F₂ plants from each cross and parental lines were evaluated for growth habit and yield component traits under high input field conditions. The following season, the evaluations were repeated on random F₃ plants. Of the five parental lines, only G13625 showed significant GCA effects for yield in both the F₂ and F₃ generations. Improved yielding ability of G13625 progeny was associated with an increased expression of climbing bean growth habit traits: guide length, climbing ability, node number on main stem, and plant height. Crosses between Andean x Mesoamerican and Andean x Jalisco genotypes, as well between growth habit type I (Andean x Andean) and between type II (Mesoamerican x Mesoamerican) had very low parent-offspring heritability values for yield. Yield heritability was only significant for crosses between Mesomerican x Jalisco gene pools. An apparent simple genetic control of growth habit modification towards semi-climbing and climbing types is proposed as the major reason for increased yields in these crosses. No genetic linkage between genes controlling growth habit and seed size was detected which might restrict the development of high yielding large-seeded type II lines.     

Comparison of recurrent and congruity backcrossing for interracial hybridization in common bean

Summary Two common bean (Phaseolus vulgaris L.) cultivars were used for recurrent backcrossing (i.e., repeated backcrossing to one of the parents) to both parents independently and for congruity backcrossing (i.e., backcrossing alternately to both parents). One cultivar, ICA Pijao of race Mesoamerica, was late maturing, with erect type II growth habit and small seeds. The other was Pinto UI 114 of race Durango, an early maturing cultivar with prostrate type III growth habit and medium seeds. One to three recurrent backcrosses (RBC) to both parents, and two rounds of congruity backcrosses (CBC), were made. Thirty-two random lines from each method along with two parents were compared in a reps-in-set design at two locations (Popayán and Quilichao) in Colombia in 1992–1993.Differences between lines derived through different methods were found for seed yield, 100-seed weight, days to maturity, growth habit, and seed color pattern. The RBC to ICA Pijao produced lines with relatively higher seed yield, smaller seed size, and delayed maturity. Similarly, the RBC to Pinto UI 114 produced lines with reduced yield, medium seed size, and earlier maturity. All lines from one, two, and three RBC to Pinto UI 114 had type III growth habit. While most lines from the RBC to ICA Pijao had erect type II Growth habit, a few type III lines were also found in all the RBC. The lines derived from the CBC mostly possessed yield, maturity, and seed characteristics between those of the two parents and lines derived from RBC to both parents independently. They also had more variation for growth habit. To maximize recombination between and retention of desirable traits from distantly related parents used in interracial crosses, use of the CBC is suggested.     

Inter-and intraracial hybridization and selection for seed yield in early generations of common bean,Phaseolus vulgaris L.

Summary Five parents from each of four race groups of common bean (Phaseolus vulgaris L.) were hybridized to produce five crosses within each group. Also, five crosses were made for each of the six possible combinations among four groups. Parents, F₁ and F₂, and parents, F₂ and F₃ were evaluated for seed yield in 1990 and 1991, respecitively, at two locations in Colombia.Yield of parents belonging to Middle American races and crosses among them was higher than that of races of Andean origin. Positive correlations were found among the mid-parent value, F₁, F₂ and F₃. Also, the mid-parent value predicted the mean seed yield of all possible lines that could be derived from the F-generation in 42 out of 47 crosses. Four crosses, all between common bean races of Andean and Middle American origin, indicated a possible loss of favorable epistatic parental alleles. On average, mean yield of interracial F₁ hybrids was higher than that of intraracial ones.Positive heteroris (26.4%–123.8%) over the mid-parent in 31 crosses, and F₁s yielding higher (23.7%–91.8%) than the high parent in 20 crosses and yielding higher (22.1%–53.2%) than the highest control among all parents (MAM 13) in 12 crosses, were found. Heritability, estimated by the parent-offspring regression, ranged from 0.42± 0.07 to 0.49±0.04. Expected and realized gains from selection (at 20% selection pressure) ranged from 10.3% to 21.0% over the mean of F₁ hybrids and F₂ and F₃ population bulks.     

Linkage of dominant hypersensitive resistance to bean common mosaic virus to seed color in Phaseolus vulgaris L.

Summary Evaluation of Phaseolus vulgaris germplasm bank materials and progenies from a large number of crosses using red- or yellow-colored, BCMV-susceptible bean lines, crossed to purple- or grey/brown-colored, hypersensitive-resistant lines, suggested strong trait association between seed color and BCMV resistance. The cross of red-mottled I⁺I⁺ (susceptible) BAT 1255R to isogenic purple-mottled II (resistant) BAT 1255M was made to study the segregation of the two characters and to recover red-mottled resistant progenies. No recombinant genotypes were observed among 353 F₃ families inoculated with BCMV-NL3, suggesting that linkage of purple-mottled seed color and dominant BCMV resistance is very close.Contribution of the Centro Internacional de Agricultural Tropical.     

The inheritance of resistance to Empoasca kraemeri Ross & Moore in the common bean,Phaseolus vulgaris L.

Summary Genotypes of Phaseolus vulgaris differ in their level of resistance to Empoasca kraemeri, but the speed with which these differences can be accumulated into a resistant variety will depend on whether they can be detected in single F₂ plants, and on whether the genetic control of resistance is additive. Thirty-eight homozygous genotypes were therefore grown in small plots with and without insecticidal protection, and also in simulated F₂ populations containing one plant of each genotype. In addition, the F₂ and F₃ generations of crosses were studied. Both generations of a 13 parent diallel were grown with and without insecticidal protection. Six crosses, involving some of the parents in the diallel and two additional genotypes, were studied in more detail. Protected and unprotected F₂ plants from these crosses were harvested individually, and the resulting F₃ families were grown with and without protection. In all the expriments, the level of damage to the unprotected plants and the vigour of the protected plants was assessed visually by means of a numerical score, and the seed yield was measured.The performance of a single homozygous plant was a reasonable predictor of the performance of the same genotype in a small plot, but in the six crosses studies in detail, the correlations between F₂ and F₃ performance were low. In the analysis of the diallel cross, the significant differences among crosses were due to specific combining ability and not general combining ability. These results indicate that the genetic control of resistance is largely non-additive, and that F₂ selection will probably be ineffective. However, F₃ selection should be effective, and transgressive segregants for resistance should be obtainable.In some of the six crosses, the F₃ families differed both in general vigour and in narrow-sense resistance to E. kraemeri, as defined by Galwey & Evans (1982). The visual assessment of damage symptoms in each plot was related to the subsequent seed yield of the plot, but was more heritable than yield. The relationship between these two variables was investigated by the genetic correlation coefficient and by an alternative method, and was found to be partly genetically determined, but partly due to the influence of environmental factors on both variables. This indicates that screening for E. kraemeri resistance should be done by means of a visual damage score in a carefully chosen, uniform environment.     

Evaluation of resistance sources and inheritance of resistance in kidney bean to Indian virulences of Colletotrichum lindemuthianum

Summary Forty nine common bean lines comprising of exotic accessions and locally grown cultivars evaluated against Colletotrichum lindemuthianum exhibited differential resistance to its races in Himachal Pradesh, a north-western Himalayan state of India. Some exotic accessions like G 2333, Cornell 49242, PI 207262, Mexique 222, TO, Perry Marrow, Kaboon and Widusa were resistant to more than five Indian races, whereas two Indian accessions KRC-5 and Hans showed resistance to six and four races, respectively. However, nine accessions KRC-8, KR-40, KR-43, KR-81, KR-62-2, KR-90, KR-142, KR-148, and KR-216 were resistant to three races. Race specific resistance has been observed in different bean cultivars. Studies on inheritance of resistance in exotic accession G 2333 and Indian accession, KRC-5 showed that two independent dominant genes conferred resistance in G 2333 to race 3 and 515 and a single dominant gene controlled resistance in KRC-5 to race 775, indicating resistance from these sources is easily transferable to the locally adapted susceptible cultivars.     

Inheritance of temperature sensitivity of the photoperiod response in common bean (Phaseolus vulgaris L.)

Summary Photoperiod response of flowering in common bean (Phaseolus vulgaris L.) is thought to be controlled by the genes Ppd and Hr. However, cultivars also vary in the degree that cooler temperatures reduces their sensitivity to photoperiod. To examine the inheritance of this temperature sensitivity, crosses of cvs. Gordo x de Celaya and Flor de Mayo × Rojo 70 were evaluated at two sites differing in mean temperature and using 12.5-h natural photoperiod or 18-h artificially extended photoperiod. Under 18-h photoperiod at the warmer site, Palmira, no plants of the parents or of the F₂ populations flowered, confirming that the parents were sensitive to photoperiod. Under 12.5-h photoperiod at the cooler site, Popayan, the parents for each cross flowered at similar dates and no segregation for days to flower was observed. However, under 18-h photoperiod, de Celaya and Rojo 70 and the F₁ populations did not flower within 100 days after planting, while the F₂ and F₃ populations showed segregation that was consistent with single gene inheritance, late flowering being dominant. Late flowering at Popayan under 18-h photoperiod indicates a lack of temperature sensitivity, so temperature insensitivity of the photoperiod response was dominant to sensitivity. The name Tip, for temperature insensitivity of photoperiod response, is proposed for this gene, with the recessive form of this gene conditioning earlier flowering at cooler temperatures with long daylengths. It is recognized that the observed segregation patterns could represent the effect of multiple alleles at the Ppd or Hr loci, and studies are proposed to test this possibility with molecular markers and recombinant inbred lines.     

Development of common bean (Phaseolus vulgaris L.) lines resistant to the bean pod weevil,Apion godmani Wagner,in Central America

Summary The larva of the bean pod weevil (BPW), Apion godmani Wagner (Coleoptera: Curculionidae), causes serious yield losses in common bean (Phaseolus vulgaris L.) in Mexico and Central America, by consuming the seed as it develops in the immature pod. Resistance to the BPW was identified in bean germplasm of highland Mexican origin, and these sources of resistance were incorporated into a pedigree breeding program to recover locally adapted lines resistant to Bean Common Mosaic Virus and BPW, with commercial grain for Guatemala, Honduras and El Salvador. These lines yielded as well as or better than local cultivars in the absence of the insect, and better than local cultivars when the BPW was present. Resistance appeared to be governed by several genes, and was stable across geographic areas, seasons and planting systems.     

Effect of selection for pollen grain size on various traits in common bean

Summary Selection among microgametophytes usually exploits variation in pollen grain germination. Studies of variation in pollen grain size in common bean (Phaseolus vulgaris L.) suggested that selection for size might lead to changes in sporophytic traits. To determine whether microgametophytic selection based on size would affect pollen grain size in subsequent generations or sporophytic traits that were correlated with pollen grain size, pollen grains from three crosses were separated into two size categories by sieving and then used to pollinate cv. Diacol Calima. Selection resulted in changes in pollen grain diameter for pollen from F₁, F₂ and F₃ plants for all crosses. In vitro germination indicated no differences between vigor of large and small grains, but extraction and sieving reduced germinability. F₁ seed from two of the crosses with size-selected pollen varied in weight according to pollen grain size, but in subsequent generations, the effect disappeared. Both size categories of selected pollen resulted in F₂ progeny with reduced numbers of seeds per pod as compared to controls, suggesting that the size selection process may have resulted in indirect selection for traits reducing seed set. The overall results suggested that genes determining pollen grain size in bean have little or no effect on sporophytic traits such as seed size and seed yield.     

A procedure for combining a quantitative inheritance study with the first cycle of a breeding program

Summary The number of effective factors controlling the inheritance of a quantitative character can be estimated by analysis of F₃ lines where the parental lines are homozygous. The procedure is illustrated with data from a study of pod length inheritance in common bean (Phaseolus vulgaris L.). The mean pod length of Sprite, the parent with longer pods, was compared statistically with the means of F₃ progenies derived from F₂ plants obtained from the appropriate tail of the F₂ frequency distribution for pod length. The data indicate that analysis of F₃ progenies avoids much of the underestimation of the effective factor number which is characteristic of other procedures. The number of effective factors was estimated to be a minimum of 4 and the correlation between random F₂ parents and F₃ progeny means was r=0.82.Florida Agricultural Experiment Station Journal Series No. 406.     

Growth analysis in a reduced leaf mutant of common bean (Phaseolus vulgaris L.)

Summary A comparison between the Royal Red bean variety and a reduced leaf mutant on the basis of growth indices is reported. The mutants has lower leaf area index (LAI) and leaf area duration (LAD) (–43.7%), higher specific leaf weight (SLW) (on the mean +33.3%) and accumulates less dry matter (–7.7%) than the normal genotype. When the net assimilation rate (NAR) is considered, the mutant is superior to the normal (+62.3%). It is concluded that the unit area of the mutant leaves accumulates dry matter more efficiently than that of the corresponding normal variety.     

Rooting of bean leaves and use in germplasm evaluation for common bacterial blight resistance

Summary A simple protocol for leaf rooting in beans (Phaseolus vulgaris L.) was developed and used to investigate the reaction of Xanthomonas campestris pv. phaseoli (Xcp), causal pathogen of common bacterial blight disease, in detached versus attached bean leaves. Trifoliate leaves of different sizes (one-third, two-thirds, and fully expanded), either with or without the pulvinus attached to the petioles, were excised from 20 day-old plants of six bean cultivars/lines. Leaf cuttings were cultured in potting medium and then incubated for 5 to 10 days under transparent polyethylene plastic cover in the greenhouse. Roots were readily initiated along the petioles of the leaf cuttings, whether the pulvinus was present or absent. All leaves which were two-thirds expanded and fully expanded developed roots 5 to 7 days after culture. Eighty to 90 percent of the leaves which were one-third expanded formed roots 8 to 10 days after incubation. Laminae of the rooted leaf cuttings were viable and green during the 2 to 3 months period in culture after removing the plastic cover. The common bacterial blight reactions were similar for inoculated attached leaves, detached rooted leaves (inoculated either after or prior to rooting), and moistened detached leaves incubated without rooting. The latter were only usable for evaluation of the Xcp reaction in growth chamber experiments but not under greenhouse conditions. The rooted leaves would be useful for screening bean lines for multiple disease resistance, especially if the pathogens require different environments for disease expression.Abbreviations CBB Common Bacterial Blight - Xcp Xanthomonas campestris pv. phaseoli (Smith) Dye     

Inter simple sequence repeat (ISSR) markers as a tool for the assessment of both genetic diversity and gene pool origin in common bean (Phaseolus vulgaris L.)

In this study, we report the use of ISSR to assess genetic diversity and to determine the relationships among ten cultivars of common bean developed in Argentina and three materials from France. ISSR markers resolved two major groups corresponding to the Andean and Mesoamerican gene pools of common bean. We compared the results of previous analysis, performed with RAPD markers (Galván et al., 2001), with the results generated by means of ISSR. It appears that ISSR are better tools than RAPDs to identify beans by gene pool of origin though they did not revealed as many differences between individuals as RAPDs. This revised version was published online in July 2006 with corrections to the Cover Date.     

Evaluation of a DNA probe for the quantitative detection of common bacterial blight in common bean and its application in a breeding program

Summary Breeding of Phaseolus vulgaris L. for resistance to common bacterial blight (CBB) can be done with visual evaluations of symptoms to distinguish broad resistance classes, but a more quantitative measure was needed for genetic studies of resistance. A novel method of evaluation was developed by quantifying Xanthomonas campestris pv. phaseoli (XCP) in bean leaf tissue infected with CBB using a ³²P-labeled probe and densitometric analysis of hybridization signals. Quantification of bacterial populations using the probe was highly correlated (r=0.98) with the number of colony forming units (CFU) from plate counts of the same leaf samples. The probe was used to follow XCP population dynamics on susceptible (BAT 41) and resistant (OAC 88-1) bean genotypes. OAC 88-1 supported a maximum XCP population which was approximately tenfold less than BAT 41. The probe was also used to study an F₂/F₃ population segregating for resistance. Narrow sense heritability estimates were less for resistance measured on the basis of bacterial populations (0.18–0.26) than on visual scores of symptoms (0.29–0.38). The anticipated response to selection for CBB resistance would be less based on bacterial numbers than based on symptom expression in this population. In breeding for resistance to CBB, selection based on visual symptoms combined with measurements of XCP populations using a DNA probe can be used to develop bean genotypes that are both resistant to symptom development and bacterial multiplication.Abbreviations CBB common bacterial blight - CFU colony forming units - XCP Xanthomonas campestris pv. phaseoli     

Inheritance of pod cross-section in beans (Phaseolus vulgaris L.)

Summary OSU 5062, a green bean line with a tendency for pods to become creasebacked (wider than deep) in cross-section, was crossed to near-round-podded cultivars Oregon 83 and Slenderette, oval-podded Bountiful, and flat-podded Roma, to further clarify the inheritance of pod cross-section. Differences among generations in pod cross-section index (PCS), calculated as pod width/depth, were small in the near-round x creaseback crosses (1.07 and 1.01 for Oregon 83 and Slenderette versus 1.20 for OSU 5062). Bountiful (0.63) and Roma (0.50) differed to a greater extent from 5062. Generation means of individual plant PCS of the F₁ and F₂ were almost identical, were almost exactly intermediate between parents, and strongly supported additive inheritance. Backcross data generally supported additive inheritance, but in some cases indicated degrees of dominance of higher PCS. A generation means analysis indicated additive gene action, but deviations from an additive-dominance model were significant in each cross.     

Allozyme evaluation of upright common bean genotypes

Summary In common bean (Phaseolus vulgaris L.) the diaphorase (DIA) allozyme variant Diap-2 ¹⁰⁵ is frequently present in plants with upright, type II plant architecture. The genetic relationship between upright plant architecture and Diap-2 ¹⁰⁵ was investigated in eight F₂ populations derived from crosses between navy bean and pinto bean parental lines differing for type I, II, and III growth habit and DIA genotype. Segregation at the Diap-2 locus followed the expected 1:2:1 ratio in all eight F₂ populations and when pooled across F₂ populations. F₂ data from 1345 individuals indicated that plant architecture and the Diap-2 locus are not linked (r=0.03, P=0.333). However, the Diap-2 ¹⁰⁵ allozyme was present in 71% of advanced navy, pinto, and great northern genotypes with type II plant architecture. Due to random drift, Diap-2 ¹⁰⁵, initially associated with type II architecture through founder effect, may be maintained in such genotypes without providing greater fitness or without being associated with a locus or linked loci governing upright plant architecture.     

Variation of the storage protein phaseolin in common bean (Phaseolus vulgaris L.) from the Mediterranean area

Summary Variation of phaseolin, the major storage protein in Phaseolus vulgaris L., was analysed in seeds of a germplasm collection from the Mediterranean area. Results showed a number of subvariants differing from the reference patterns for the presence, absence or faintness of single polypeptides. Maximum concentration of variation was found in the Cyprus material. Sources and causes of variation are discussed.     

Genetic control of low temperature tolerance in germination of the common bean (Phaseolus vulgaris L.)

Summary Cultivars tolerant to low temperature during the germination and emergence stages and carriers of the grain quality standards demanded by consumers are needed to increase the success of irrigated common bean in Southern Minas Gerais State. To study the genetic mechanisms controlling these traits and assess the possibility of generating the desirable materials, a diallel cross involving ten cultivars including introductions and pure lines from the breeding program of ESAL was carried out. Speed of germination of the F₂ generation from the crosses was assessed under laboratory conditions at 12°C. The diallel analysis was carried out using Griffing's method IV (1956) and predictions of the cross potential were made by the methodology developed by Jinks & Pooni (1986). The results indicated that the parents differed in germination speed at low temperatures with Small White, A-488 and Rio Vermelho being the most tolerant and Carioca, ESAL 591 the most sensitive. No effect of the reciprocal crosses was observed either for germination percentage or germination speed. The parents A-488, Small White and Rio Vermelho showed the greatest general combining ability. Additive genetic effects predominated for both traits. Our results suggest that cold tolerance can be bred successfully into commercially acceptable cultivars.