Genes for resistance to stripe rust in four spring wheat varieties

Summary The stripe rust resistant spring wheat (Triticum aestivum L.) varieties Anza, Glennson 81, Ollanta, and Yecora Rojo gave 1,2,2, and 2-gene segregations, respectively, in hybrids with susceptible Jupateco 73 when inoculated in field conditions at Davis, California USA with Puccinia striiformis West. pathotype CDL-6 and rated at post-heading stage. Intercrosses of these varieties, Anza/Yecora Rojo was not studied, permitted the following conclusions about the genes expressed in adult plants: Anza, one recessive gene; Glennson 81, two dominant genes; Ollanta, two genes, at least one is dominant; and Yecora Rojo; one dominant and one recessive gene, one of which is common with Ollanta. The resistance genes in these varieties, which expressed resistance in the seedling stage, were believed to be effective at the adult stage. Thus, seven resistance genes were identified in the four varieties. The genotypes were designated for the purposes of this study as follows: Anza, YrA YrH; Glennson 81, Yr9, YrJ, Ollanta YrL YrD; and Yecora Rojo, YrC YrD. It was recommended that these and other Yr genes be used as multiple gene complexes to increase durability of resistance to P. striiformis, an organism known to evolve virulence rapidly in field conditions. The demonstrated durability of Anza in California may be a result of its combination of resistance alleles at two loci.     

Genes for resistance to stripe rust in four spring wheat varieties

Summary Four spring wheat (Triticum aestivum L.) varieties differing in origin and reaction in the seedling stage to pathotype CDL-6 (extant in California) were intercrossed and examined in greenhouse conditions in F₁, F₂, and F₃ generations. Digenic and transgressive segregation was found in all crosses. The four varieties each had infection types (1 immune, 9 susceptible) and putative resistance genes as follows: Anza, IT 7, YrA; Glennson 81, IT 2, Yr9; Yecora Rojo, IT 6, YrC; and Ollanta, IT 4–6, YrL. Anza was classified as susceptible, Yecora Rojo and Ollanta as intermediate in seedling resistance, and Glennson 81 as resistant in the seedling stage.     

Lilium x ‘Black Beauty’—a potential bridging hybrid in Lilium

Summary Lilium Black Beauty, a rare intersectional hybrid previously reported sterile, was re-examined for pollen and ovule fertility. No pollen tubes were detected following incubation of styles pollinated with Black Beauty pollen. However, embryos varying in size from small globular to long boat-shaped and only rarely associated with endosperm, were found in 0.1–1.0% of the ovules in Black Beauty pistils pollinated with Oriental or Aurelian division lilies. Aseptic extraction and culture of these embryos on a nutritive medium resulted in growth, germination, and plantlets. It is apparent that with embryo culture, Black Beauty has unique value as a species bridge in that it accepts pollen of both Oriental and Aurelian lilies, two of the major commercial lily divisions.Scientific Journal Series Paper Number 9197 of the Minnesota Agricultural Experimental Station.     

Evaluation of maize varieties for their potential as breeding populations

Summary A 7-variety diallel of synthetic varieties that have not had selection for yield improvement and a 10-variety diallel of synthetic varieties that either resulted from recurrent selection for yield improvement or from the introgression of exotic germ plasm into adapted varieties were evaluated in six environments for yield and five other agronomic traits. The specific objective was to determine the relative potential of the synthetic varieties as germ plasm sources for breeding programs.Recurrent selection improved population yield in BSSS CO, BSK CO, and Alph CO in the varieties and also in crosses with other varieties. BSSS(R)C6 and BSSS(HT)C7 yielded 11.4% and 16.1% more than BSSS CO, and the variety crosses of BSSS(R)C6 and BSSS(HT)C7 yielded 21.6% and 22.0% more than the variety crosses of BSSS CO. Recurrent selection also improved stalk-lodging resistance for BSSS(R)C6 and BSSS(HT)C7, but root lodging for BSSS(HT)C7 was significantly higher. BS15 had 61.0% higher yields than Alph CO, with 9.3% less stalk lodging. Average heterosis of the 10-variety diallel was 1120 kg/ha (19.6%) and ranged from 800 kg/ha (13.7%) for BSK(S)C5 to 1770 kg/ha (39.4%) for BS12(HI)C5. The heterosis expressed among individual variety crosses ranged from 4.3% for BSK(S)C5 x BSTE(FR)C1 to 37.6% for BSSS(R)C6 x BS12(HI)C5, which approached the yield of the two highest yielding single-cross checks.In the 7-variety diallel of unselected varieties, BSTE CO and Late Rootworm Synthetic were superior as varieties and in crosses for yield and stalk quality. Average heterosis for the 7-variety diallel was 950 kg/ha (18.5%). Stalk lodging was important in the performance of varieties with poor stalk quality.Although recurrent selection improved yield, development of superior breeding populations also will require selection for general agronomic performance. The performance of BS16 and the yields of BSTL and Teozea and their crosses suggest that exotic germ plasm should receive greater attention.Contribution from the Agricultural Research Service, U.S. Department of Agriculture, and Journal Paper No. J-8096 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa 50010. Project No. 1897.     

Cytoplasmically controlled cold tolerance in a cytoplasmic-genetic male sterile line of rice

Summary The cytoplasmic-genetic male sterile line, Krishna-A with Kalinga-I cytoplasm was developed in rice through repeated backcrossing the completely pollen sterile F₁ of the cross Kalinga-I/Krishna with the recurrent male parent cv. Krishna. The germination percentage and root-shoot length in Krishna-A at 12°C and 9°C indicated a higher degree of tolerance to low temperature than the cold tolerant female parent Kalinga-I. The high yielding cold tolerant variety Kalinga-I was developed from a cross involving the cold tolerant variety Dunghansali and the high yielding variety IR 8. It is inferred that tolerance to low temperature during germination in Krishna-A was inherited from the cytoplasm of cv. Dunghansali through Kalinga-I besides male sterility. The cytoplasmic control of cold tolerance is reported here for the first time in rice literature. The male sterile line Krishna-A because of its tolerance to low temperature would be suitable for the development of hybrid rice especially for areas where low temperature is a problem during germination.     

Relationship between allelic variation of Glu-1 and Gli-1/Glu-3 prolamin loci and gluten strength in hexaploid wheat

Summary Allelic variation of prolamin loci was examined in the F₂ from crosses between the hexaploid wheat varieties: Cajeme 71, Yécora 70, Ablaca, Anza, Pané 247 and Axona. Different allelic blocks for gliadins and LMW glutenin subunits were determined in Gli-1, Gli-2 and Glu-3 loci. A percentage of recombination of 1.5 ± 0.3 was determined between Gli-A1 and Glu-3 in the F₂ progeny of Yécora 70 x Axona. A significant positive association was found between gluten strength, measured by SDS-sedimentation volume, and the prolamins coded by Anza Gli-D1/Glu-D3 loci and Yécora 70 Gli-A1/Glu-A3 loci. Interactions between non homeologous loci Glu-1 and Gli-1/Glu-3 were also found.     

Genetic analysis of hexaploid wheat,Triticum aestivum using intervarietal chromosome substitution lines—protein content and grain weight

Summary The 21 intervarietal chromosome substitution lines of the cultivar Hope in Chinese Spring were used to analyse the genetic differences between the two cultivars Hope and Chinese Spring in grain protein content and grain weight.Only one chromosome of Hope, 5D, significantly influenced grain protein content of Chinese Spring. Its influence was of only minor effect and was to decrease protein content expression of Chinese Spring. It has been postulated that the genetic control of protein content, in this instance, is most likely due to many genes each of small effect.Five chromosomes of Hope influenced the 1000 grain weight value of normal Chinese Spring, all increasing its expression. Chromosomes 1A, 4A and 5B were of major effect and 3A and 6A of comparatively minor effect. A minimal estimate of five genes determines the difference in grain size between these cultivars. The possible evolutionary significance of the contribution of the A genome of bread wheat to grain size determination is discussed. On the basis of certain findings of this study, proposals are made for breeding for increased grain size in hexaploid wheat.     

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.     

Inheritance of resistance to powdery mildew (Erysiphe graminis f. sp. hordei) in eleven primitive barley varieties

The inheritance of the powdery mildew resistance of eleven primitive barley varieties was investigated. crosses with varieties with identified resistance genes revealed that at least three different genes are present in a group of six genotypes from Greece (Hor736, Hor847, Hor878, Hor1159, Hor1379 and Hor1873) and one from Turkey (Hor1188). One dominant gene is common to these seve genotypes and in the Greek accessions a second gene is present. The expression of this second gene was respectively dominant in the crosses with Hor736 and Hor1159, recessive in the crosses with Hor878 and Hor1873, and depended on the employed powdery mildew isolate in the crosses with Hor847 and Hor1379. The detected genes differ from the resistance genes of the crossing partners, viz. Ml-al2, Ml-(Ab), Ml-(CP) and Ml-(1402). The accessions from China (Hor824 and Hor4021) each possess two resistance genes which differ from Ml-a12, Ml-(La) and Ml-(CP). The major gene is common to both accessions and is either identical, allelic or closely linked to a gene in the variety Nigrate. The Columbian accession Hor1894 possesses one resistance gene linked to a resistance gene in Nigrate but this gene differs from the Ml-a locus. The variety Palestine (Hor3997) possesses two resistance genes of which one is allelic or closely linked to Ml-(at).     

On defining a winter wheat

Summary An international survey of wheat breeders and scientists was conducted to determine whether there was a common understanding of the term winter wheat. Response to photoperiod was mentioned by only seven of the 30 survey respondents. It was consequently suggested that it be excluded from any definition. Response to vernalization was mentioned by 28 of the 30 respondents. However, there was considerable variation in the method of quantifying this response and the degree of response necessary for wheat to be called winter. It was concluded that the only objective and internationally consistent definition of winter wheat was a genetic definition based on the complement of Vrn genes a wheat possesses. Varieties not possessing any of the dominant Vrn alleles appear to take a distinctively longer and more variable time to head when grown under non-vernalizing, long day conditions. These are genetically winter wheats.     

The relationship between powdery mildew (Sphaerotheca fuliginea) resistance and leaf chlorosis sensitivity in cucumber (Cucumis sativus) studied in single seed descent lines

Summary The genetic relation between powdery mildew resistance and sensitivity for leaf chlorosis of glasshouse cucumber was investigated. The powdery mildew resistant, leaf chlorosis sensitive hybrid variety Profito was crossed with the powdery mildew susceptible, non chlorosis sensitive hybrid variety Corona. Forty four F₆ inbred lines of this cross, produced by single seed descent, were tested for powdery mildew resistance (PMR) and leaf chlorosis sensitivity (LCS). PMR and LCS were positively correlated (r=0.59). One or more of the PMR genes probably causes LCS as a pleiotropic effect or is closely linked to LCS, but also other factors, not genetically linked to PMR can cause LCS. Five F₆ lines combined a significantly higher level of PMR than Corona with a significantly lower LCS than Profito. Three of these lines could hardly be distinguished from Corona for the level of LCS.Abbreviations LCS leaf chlorosis sensitivity - PMR powdery mildew resistance - SSD Single Seed Descent     

Molecular and biological studies on male sterile cytoplasm in Cruciferae. II. The origin of Ogura male sterile cytoplasm inferred from the segregation pattern of male sterility in the F1 progeny of wild and cultivated radishes (Raphanus sativus L.)

Summary To determine the origin of Ogura male sterile cytoplasm in radish (Raphanus sativus L.), wild and cultivated radishes were crossed. Three types of progeny resulted from the F₁ hybrids between the wild radish from Kushikino with Ogura-type mtDNA and the cultivars (Uchiki-Gensuke or Comet). The segregation patterns of the male sterility were compared with those of Ogura cytoplasm. The male sterility induced in the F₁ hybrid was maintained by crossing with Uchiki-Gensuke, that maintains Ogura male sterility. In the two types of progeny, in which Comet (a restorer of Ogura cytoplasm) was used as one of the parents, both fertile and sterile plants segregated at the predicted ratio on the assumption that a single dominant fertility restoring gene exists in the restorer. From these results, we concluded that the Ogura cytoplasm is identical to that of the wild radish, and the former originated in a population of Japanese wild radish.     

The black currant leaf curling midge,Dasyneura tetensi Rübs.; its host range,and the inheritance of resistance

Summary Established Western European black currant cultivars are susceptible to Dasyneura tetensi but the Scandinavian Sunderbyn II, Kangosfors and Hedda, and 10 out of 33 Russian cultivars showed very slight or no leaf symptoms of midge attack in the field.Of species within the black currant Section Eucoreosma, Ribes dikuscha, R. pauciflorum (probably=syn R. ussuriense), and R. americanum were not attacked, but an accession of R. bracteosum proved very susceptible. Species within other sections of the genus were not attacked.A strong dominant resistance gene in R. dikuscha, designated Dt, appeared to be linked with (a) gene(s) controlling resistance to American gooseberry mildew, Sphaerotheca mors-uvae. Resistance in Sunderbyn II and, probably, in R. pauciflorumwas oligogenic and dominant.     

Karyotypes and chromosome association in aneuploid varieties of Japanese garden iris,Iris ensata Thunb

Summary Karyotypes, chromosome association and pollen fertility of aneuploid varieties (2n=25), Ochibagoromo, Matsusakatsukasa and Isehomare in Iris ensata were analysed and compared with those of eu-diploid varieties (2n=24), Shishinden, Kachô and Asahimaru. The somatic chromosome complement of the aneuploid varieties consisted of 11 pairs and 3 singles of chromosomes and that of the eu-diploid varieties 12 pairs of chromosomes. The singles of chromosomes in the aneuploid varieties had similarity with one another and with a pair of chromosomes in the eu-diploid varieties. The high frequency of normal association was present in the eu-diploid varieties, and this indicated that 12 pairs of chromosomes had full homology between each other. In contrast, the mean chromosome association per cell in an aneuploid variety Ochibagoromo was 4.615_I+10.067_II+0.077_III+0.005_IV, indicating that the chromosome complement of this variety consisted of 11 pairs and 3 singles and that these singles had partial homology among them. The eu-diploid varieties exhibited high pollen fertility due to their regularity of chromosome association; the aneuploid varieties considerably lower fertility, i.e. 28.2% for Ochibagoromo, 31.8% for Isehomare and 43.8% for Matsusakatsukasa. The primary cause for the low fertility of these varieties seemes to be the partial homology among 3 single chromosomes. Finally, the origin and the development of the aneuploid varieties were discussed.     

Diallel analysis of yield components of snap beans exposed to two temperature stress environments

Ten snap beans (Barrier, Brio, Carson, Cornell 502, CT 70, HB 1880, Hystyle, Labrador, Opus and Venture) were selected for differential temperature tolerance and used as parents in a complete diallel mating design. The 45 F₁ hybrid lines (with reciprocals) and parents were screened at 32 C day/28 C night, and in a separate experiment, 16 C day/10 C night, during reproductive development in replicated controlled environments. Variation for yield under temperature treatments was observed among parents and hybrids, with certain hybrids exceeding parental performance. Significant (P 0.0001) general combining ability (GCA), and significant (P 0.05) specific combining ability (SCA) were observed for yield components including pod number, seed number, and seeds per pod. There was evidence that pod number and seeds per pod under temperature stress are under separate genetic control. Reciprocal effects and heterosis were not significant. GCA could not be predicted from parental performance. The breeding line Cornell 502 had the highest GCA under high temperature, and the cultivar Brio had the highest GCA under low temperature. The cross Brio × Venture was high yielding in both temperature treatments. Heat tolerance and chilling tolerance were associated in certain parents and hybrids. However, performance under high and low temperature treatments was not generally correlated in the parents and hybrids, indicating that these traits should be selected separately.     

The inheritance and association of resistance to rust,common bacterial blight,plant habit and foliar abnormalities in Phaseolus vulgaris L.

Summary No antagonistic or synergistic interaction was found between isolates of Uromyces appendiculatus var. appendiculatus and Xanthomonas campestris pv. phaseoli when inoculated to the same plant. A single dominant gene was suggested to control resistance to three isolates of rust in the crosses Pompadour Checa × Chichara and Pompadour Checa × NE W-4. A two-gene model was confirmed for the reaction to the three rust isolates for the crosses Pompadour Checa × GN Tara and Pompadour Checa × San Cristobal; a dominant (Ur _p) gene determined resistance and was epistastic to a dominant gene (Ur _t) for susceptibility. (Ur _t) was expressed only in the presence of recessive (ur _p) alleles. The reaction to common bacterial blight was quantitatively inherited and an association was detected with plant habit but not with rust reaction and leaf variegation. Plants with leaf variegation and crippled growth, were detected in the progeny of the cross Pompadour Checa × GN Tara and were controlled by duplicate recessive genes (mutatorunstable genes) and three genes, acting additively, respectively. The developmental expression of the latter trait varied considerably. Linkage was detected between genes controlling the variegated and the crippling traits.Published as Paper No. 7839, Journal Series, Nebraska Agricultural Experiment Station. Research was conducted under project No. 20-036.     

Male-sterility in nigerian bulrush millets (Pennisetum americanum (L.) K. Schum)

Summary The occurrence of three male-sterile plants is reported. One in a population of ex-Bormu, an improved recommended variety of day-length neutral gero bulrush millet and the two others in the selfed progeny of a population of maiwa bulrush millet, a short-day photoperiod-sensitive type. Tests confirmed the cytoplasmic-genic nature of the male-sterility in the gero population. No tests could be conducted for maiwa.The transfer of male-sterility from the male-sterile Tift 23A bulrush millet, obtained from the United States, into a maiwa population is also reported. After six backcrosses the maiwa genotype appeared to have been reconstituted against the background of a male-sterility inducing cytoplasm. Maiwa male-sterility maintainer plants have also been identified.     

Chromosomal location of genes controlling 6-phosphogluconate dehydrogenase,glucose-6-phosphate dehydrogenase and glutamate dehydrogenase isozymes in cultivated rye

Summary The 6-phosphogluconate dehydrogenase (6-PGD), glucose-6-phosphate dehydrogenase (G-6-PD) and glutamate dehydrogenase (GDH) zymogram phenotypes of wheat, rye and their aneuploid derivates were determined. At least three genes involved in the production of 6-PGD isozymes were located on chromosome arms 4RL, 6RL and 2RL of Imperial rye, King II rye and Dakold rye. Evidence was obtained that at least one gene located on chromosome arm 5RS controls G-6-PD isozyme activities in these varieties of rye and one gene involved in the production of GDH isozymes was located on chromosome arm 2RS of Imperial, King II and Dakold rye. The results indicate that the 6-PGD isozymes exist as dimers and monomers. No possible structure of the G-6-PD and GDH could be determined.     

Accumulating polygenes for partial resistance in barley to barley leaf rust,Puccinia hordei. I. Selection for increased latent periods

Summary The barley cultivar Cebaba Capa was crossed to the cultivar L94, which is assumed to carry no genes for increased latent periods, and Vada, which is assumed to carry five to six minor genes for a longer latent period (LP). In the F2 selection was carried out for short and long LP's in the young flag leaves to Puccinia hordei in both crosses. In the F3, F4 and F5 the selection for short as well as for long LP continued by selecting the extreme plants in the extreme lines, a typical pedigree selection approach.The LP's are given relative to those of L94, set at 100 and of Vada, set at 185. From the cross with L94 homogeneous lines were obtained with relative LP's of 100 and of 220. From the cross with Vada the extreme lines had LP's of 135 and around or even beyond 300.Cebaba Capa is thought to carry four to six minor genes with an average gene effect slightly larger than those of the five to six minor genes in Vada. From the four to six minor genes one or two may be identical to or closely linked with minor genes of Vada, the others appeared to be different. In the lines with LP's of close to 300 or even more the number of minor genes accumulated is thought to be in the order of eight or nine. These gene number estimates are based on independent assortment. If linkage occurs the number of genes involved may be larger.Because of the high correlation between LP in the young flag leaf and the partial resistance in the field the selected lines are assumed to have a partial resistance to barley leaf rust far beyond that of Vada, which represents almost the highest level of partial resistance in European cultivars.     

An assessment of thein vitro germination capacity of pollen grains of five tea hybrid rose cultivars

Summary Germination trials of pollen grains of the tea hybrid rose cultivars: Ferry Porche, Bronze Masterpiece, Queen Elizabeth, John F. Kennedy and Lady X, were carried outin vitro, to determine whether these cultivars are suitable as pollen donors in a breeding programme.Pollen grains of all five cultivars germinated poorly in a medium containing sucrose only. Addition of boric acid in the medium improved the germination percentages. The highest germinability was observed in Ferry Porche and Lady X on 15% sucrose+50 ppm boric acid, and 20% sucrose+100 ppm boric acid, respectively. Addition of calcium nitrate in the medium reduced germination percentages in all cultivars.The effect of pH of the medium on pollen grain germinability depended on the cultivar and the composition of the medium. On a medium free of boric acid, the pH values between 5.5 and 7.0 caused a significant increase in the germination percentages of pollen grains of Lady X and Queen Elizabeth. The addition of boric acid decreased the responsiveness of the pollen of all cultivars to the pH changes of the medium.The germination capacity of pollen grains of Lady X and Ferry Porche was not affected by incubation temperatures ranging between 20°C and 30°C.On the basis of the above results Lady X and Ferry Porche are considered the most suitable for pollen donors.