Expression of late maturity α-amylase in wheat containing gibberellic acid insensitivity genes

Summary Two wheat cultivars, Spica and Lerma 52, which consistently produce high levels of -amylase during the later stages of grain development (late maturity -amylase), were crossed with a set of four near-isogenic lines carrying the tall (rht) allele or one of the dwarfing genes Rht1, Rht2 or Rht3 (GA-insensitive alleles). The F₁ and F₂ populations were developed and analysed for grain -amylase and plant height. The Rht3 gene exhibited the strongest influence on plant height and strongly inhibited new -amylase synthesis during the later part of grain ripening. By comparison, Rht1 and Rht2 had a less pronounced effect but still significantly reduced the expression of late maturity -amylase. These observations suggest that gibberellic acid is involved either directly or indirectly in this phenomenon. The implications of the effect of dwarfing genes on expression of late maturity -amylase are discussed in relation to cultivar improvement and to the identification and control of high -amylase germplasm.     

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.     

Molecular marker-assisted selection for yield-enhancing genes in the progeny of “9311×<Emphasis Type="Italic">O. rufipogon</Emphasis>” using SSR

Oryza rufipogon (IRGC105491) is a wild relative of cultivated rice, it contains two favorable yield-enhancing genes (yld1.1 and yld2.1) on chromosomes 1 and 2, respectively, which are capable of improving the yield of hybrid rice by 18 and 17%, respectively. SSR markers RM9, RM24, RM5 and RM306 are flanking yld1.1, while RM166 and RM208 are mapped in the close region to yld2.1. These molecular markers tightly linked to the two yield-enhancing genes were used to screen the plants of backcross population between 9311 (one of the top-performing parental lines in super hybrid rice seed production in China) and O. rufipogon. The results were as follows: (1) in BC₂F₁ population, the percentage of the individuals which contain both of the O. rufipogon alleles at marker loci RM166 and RM9 was 16.8%; (2) 1.5% individuals of total BC₃F₁ population have all the six linked markers (RM166, RM9, RM5, RM208, RM24, RM306); (3) in BC₄F₁ population, the percentage of the individuals which contain both of the two O. rufipogon alleles at marker loci RM166 and RM9 was 18.0%. Based on marker genotypes, the individuals, that contain multiple O. rufipogon markers, were selected and used for further backcross and self cross. Many 9311-type lines with yield-enhancing genes and high yield potential were obtained. After three times self-crossing a stable improved 9311 line was obtained. The results indicated that these molecular markers are feasible for marker-assisted selection (MAS) to screen rice individuals with high yield potential.     

Associations between three ml-o powdery mildew resistance genes and agronomic traits in barley

Summary A population of 198 chromosome-doubled haploid lines of spring barley was scored for segregation in locus ml-o (powdery mildew reaction) on chromosome 4 and in the linked loci s (rachilla hair length) and ddt (reaction to the insecticide DDT) on chromosome 7. They were also tested in a disease-free field trial for the agronomic traits: grain yield, thousand grain weight, lodging, and necrotic leaf spotting. The three mutagen-induced resistance genes ml-o5, ml-o6 (from Carlsberg II) and ml-10 (from Foma) showed no detectable differences with respect to effects on agronomic traits. They all conferred a four per cent reduction in grain yield caused mainly by lower thousand grain weight, and an increase in necrotic leaf spotting. The two original mutants of Carlsberg II had additional mutant genes affecting agronomic traits. Lines with gene S (long hair) had on average a three per cent higher thousand grain weight than those with s. The alleles in locus ddt showed no association with the agronomic traits. It is concluded i) that the associations between the three ml-o alleles and agronomic traits are caused by pleiotropy, ii) that ml-o resistant, high-yielding lines may be selected, and iii) that the association between gene s and thousand grain weight may be due to genetic linkage.Abbreviations DH-lines chromosome-doubled haploid lines     

Differential meiotic behaviour in hybrid clones of Aranda ‘Christine’ (Orchidaceae)

Summary The hybrid orchid clones of Aranda Christine show differential meiotic behaviour with respect to meiotic irregularities in the form of non-congressing chromosomes, laggards and complement fractionation. These irregularities occur in significantly variable but high frequencies, which results in the observed sterility of these hybrids. The observed differential meiotic behaviour is probably due to the transmission of a variable set of chromosomes from the third generation hybrid parent, Vanda Hilo Blue. Deviant spores, mainly polysporous and polyploid, are the end products of the meiotic aberrations. Such spores appear to be produced regularly in the intergeneric orchid hybrids.Meiosis in one of the Aranda Christine clones, C80, was found to be highly aberrant and could be unique among orchid hybrids.     

An assessment of the potential of 4DS.4DL-4s l L translocation lines as a means of eliminating tall off types in semi-dwarf wheat varieties

Summary Wheat varieties tend to be chromosomally unstable producing on average 2–3% of plants with abnormal chromosome numbers. A number of semi dwarf wheat varieties, carrying the gibberellic acid insensitive dwarfing genes Rht1 or Rht2, have been seen to produce distinct tall off types due to reduction in dosage of the chromosome carrying the dwarfing gene. The UK variety Brigand, carrying Rht2 on chromosome 4D, produced very distinct tall off types when this chromosome was reduced in dosage. The frequency of tall off types was sufficiently high to cause the variety to fail United Kingdom statutory uniformity tests. An attempt to prevent the loss of chromosome 4D was made by constructing translocation chromosomes involving the short arm of chromosome 4D, which carries Rht2, and the long arm of chromosome 4S ^l from Aegilops sharonensis, which carries a gene(s) conferring preferential transmission. The work in this paper describes the field evaluation of two lines carrying 4DS.4DL-4S ^l L translocations, and demonstrates their success in preventing spontaneously occurring monosomy of chromosome 4D in semi-dwarf wheats.     

Segregation and linkage analysis of DNA markers in microspore derived and F2 populations of oilseed rape (Brassica napus L.)

Summary The segregation of RFLP and RAPD markers was compared in two oilseed rape (Brassica napus L.) breeding populations from the cross Topas x R4, the latter being a low linolenic mutation line. A total progeny of 68 F₂ and 40 microspore derived plants were studied with 25 markers. The results indicated a significant excess of Topas alleles at five RAPD loci in the microspore derived population. This suggests that genomic regions which probably affect microspore culture ability do not have identical distribution in the two population types.     

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.     

Genetic and cytogenetic studies with a male sterile mutant of common wheat (Triticum aestivum)

Summary Genetic and cytogenetic studies were done on a male sterile mutant of the wheat variety Probus. Association of the 4A chromosome carrying the ms gene was studied in the F₁ of the male sterile Probus with Chinese Spring ditelo 4AS, with Transec and with line T4AS-DRS respectively. The presumption that the genetic male sterility of the mutant was due to a terminal deletion of the short arm of chromosome 4A could be confirmed.Linkage studies showed that the ms gene was at 17 map units from the dwarfing gene (Rht3) of Minister dwarf. This allows selection of short male sterile plants at the seedling stage.     

Chromosome locations of genes controlling ‘purple leaf base’ in rye and wheat

Summary Purple leaf base is expressed only if there is anthocyanin pigmentation in coleoptiles either in rye or in rye-wheat-additions. Genes controlling purple leaf base were found to be located on chromosomes 5R (An5), 4B (Ra2) and 6B (Ra3) using the trisomic set of rye cv. Esto and autoplasmic rye-wheat-additions, respectively.     

In vitro culture variation of wheat and rye caused by genes affecting plant growth habit in vivo

Summary The influence of genes affecting the plant growth habit in wheat (Rht8 and Ppd1) and rye (ct1 and ct2) on tissue culture response was studied using immature embryos. Whereas the semi-dwarfing gene Rht8 seems to promote only a minor effect, the day-length sensitive allele ppd1 determined a major increase in callus growth and regeneration ability. With regards to their tissue culture efficiency, the four alleles studied could be ranked as follows: ppd1>Rht8>rht8>Ppd1.In contrast to wheat, the GA insensitive semi-dwarfing genes of rye (ct1 and ct2) appear not to influence in vitro response.     

Location of genes for chlorophyll synthesis on specific arms of chromosomes in Triticum aestivum

Summary An Indian hexaploid wheat var. Pb C591 has been shown to carry gene(s) for chlorophyll synthesis on chromosome 3A (Singh & Joshi, 1979). In the present study cv. Pb.C591, its monosomic 3A and diteocentrics for 3A, 3BL and 3DL of var. Chinese Spring have been used. The F₂ segregation involving crosses between Pb.C591 as male, monosomic line 3A of Pb.C591 (female) and ditelocentrics 3A, 3BL and 3DL of cv. Chinese Spring as male and female respectively has been observed. It has been found that there are two dominant genes regulating chlorophyll synthesis in cv. Chinese Spring. These genes are located on chromosomes arms 3A and 3DS respectively.These chlorophyll synthetic genes must be the same which were postulated by Sears (1956, 1957) as the normal alleles of virescent gene v ₂ (which was located on 3BS) on chromosomes 3A(v ₁) and 3D(V ₃).     

α-Tomatine and other steroidal glycoalkaloids in fruits of tomato lines resistant to the glasshouse whitefly (Trialeurodes vaporariorum Westw.)

Summary The total steroidal alkaloid compositions of the mature-harvested fruits of the tomato cultivar Allround (Lycopersicon esculentum), of the species L. hirsutum glabratum, resistant to the glasshouse whitefly (Trialeurodes vaporariorum), and of four resistant lines were determined by capillary gas chromatography. The contents of -tomatine in the red-ripe fruits of Allround and in those of the lines were low (5 mg/kg fresh weight). The green-mature fruits of the wild species had a high content (3390 mg/kg fresh weight) of -tomatine. The total alkaloid profiles of Allround and of the lines were similar. Comparison of flame ionisation detector response with thermoionic detector response indicated that in addition to tomatidine, the aglycone of -tomatine, a small amount of one other steroidal alkaloid might be present in Allround and in the lines. The wild species contained five compounds which possibly are steroidal alkaloids.The safety level of -tomatine in tomatoes is discussed. It was concluded that, in respect of the glycoalkaloids of the mature-harvested fruits, the resistant tomato breeding lines are as safe for human cosumption as the standard cultivar.     

Embryo development in two barley genotypes after self pollination and pollination with Hordeum bulbosum L.

Summary Embryo development in vivo was compared in the two barley genotypes VK 16032 and Vogelsanger Gold after self pollination and after pollination with H. bulbosum. Embryo growth in VK 16032 after crossing with H. bulbosum showed a similar growth pattern to that of the self pollinated embryos, although the size increase was smaller. The hybrid embryos continued to grow until day 18 after pollination. The embryos from the cross between Vogelsanger Gold and H. bulbosum ceased to grow 8 days after pollination. Arrested embryo growth with subsequent abortion in Vogelsanger Gold was associated with a very early depletion and break down of the endosperm. Use of barley genotypes less sensitive to the genomic disturbances after crossing with H. bulbosum in combination with genotypes like Vogelsanger Gold is recommended in haploid breeding work.     

A rapid method for early generation selection of dwarf genotypes in wheat

Summary In the early generations of a breeding programme to incorporate the successful Norin 10 semidwarfing genes into adapted tall or standard lines, the bread and durum wheat breeder must be able to recognise and discard those lines that are not homozygous for the dwarfing gene. A method which exploits the gibberellin insensitive reaction of lines carrying the genes combined with a single seed descent technique is described in which most unwanted genotypes may be removed as F2 seedlings.     

Inheritance of contorted growth in hazelnut

Summary The contorted hazelnut, Corylus avellana L. f. contorta (Bean) Rehder, is an ornamental tree prized for its twisted trunk and branches. Crosses of normal growth habit cultivars and Contorta, as it is commonly called, produced all normal growth habit seedlings. Sib matings of these normal seedlings of Contorta produced offspring in the ratio of 3 normal: 1 contorted, while backcrosses to Contorta segregated 1 normal: 1 contorted. These segregation ratios indicate control of contorted growth by a single recessive gene for which we propose the name twisted and the symbol tw. Progenies segregating simultaneously for growth habit and leaf anthocyanin indicated that the two loci are independent.     

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.     

Inheritance studies of characters associated with floating habit and their linkage relationship in rice

Summary Deep water rice varieties in general have certain peculiar characters which are associated with floating habit. These characters are (i) early nodal differentiation, (ii) nodal rooting, (iii) spreading habit, (iv) awned grains, (v) brown hull colour, (vi) red pericarp (red rice), and (vii) seed dormancy. Inheritance of these characters and linkage relationship of genes governing these characters were studied in a cross between Pankaj (non floating) and Nageribao (floating) rice varieties. Nageribao, a cultivar from Assam possesses these characters.Early nodal differentiation was observed to be controlled by a single dominant gene, designated as Nd. Nodal rooting was controlled by two dominant complementary genes, designated as Nr ₁ and Nr ₂. We found an inhibitory factor for spreading habit and one for brown hull colour in Pankaj; the operation of two dominant duplicate genes An ₁ and An ₂ for controlling awning characters, a single dominant gene Rd for red pericarp colour and a single dominant gene Gd for grain dormancy. Joint segregations between these characters resulted in the assignment of genes in the X linkage group of indica rices with estimated map distances based on the cross-over values. The genes An (awning), Es (spreading habit), Nr (nodal rooting) and Nd (nodal differentiation) were observed to be associated with each other. The gene for red pericarp (Rd) was observed to be linked with the grain dormaney gene Gd.     

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.     

Genetics of resistance to five strains of turnip mosaic virus in Chinese cabbage

Summary Inheritance of resistance to turnip mosaic virus (TuMV) strains C1, C2, C3, C4, and C5 in Chinese cabbage (Brassica campestris subsp. pekinensis) was evaluated using monoclonal antibodies. Crosses were made between a resistant line, 0–2, and four susceptible line. Seoul (SE),SSD31 (SS), Cheongbang (CH), and Yaki 1 ho (YA), to determine the inheritance of resistance of 0–2 in different genetic backgrounds. Resistance to TuMV was controlled by a single dominant gene or double dominant genes depending on the strain and cross. The resistance genes of 0–2 were modified by susceptible parents such that a single dominant gene was involved in the SS×0–2 combination, but double dominant genes in the SE×0–2 against TuMV-C3 or TuMV-C5. ELISA tests using inoculated and noninoculated leaves in the same plant suggested that the dominant resistance genes inhibit virus movement rather than virus multiplication.