Crossability relationships of andean potato varieties of three ploidy levels

Summary The formation of triploids in 4x×2x crosses was studied in primitive potato varieties from the Andes of Peru and Bolivia. Triploid frequencies were as high as 80–100% in some crosses, although the actual number of seeds was low. The triploid block varied according to the tetraploid parent, and was never entirely absent. The likelihood of triploid formation was studied in 4x×2x crosses where pollen from both tetraploids and diploids of known genotype was used. Even though the diploids were chosen for their non-production of 2n gametes, as detected in pollen grain size, 66% of the hybrids were tetraploid. The amount and probability of gene-flow between the tetraploid and diploid gene-pools, either directly through 2n gametes or through triploid bridges was examined. Most of the 20 cultivars of S. x chaucha produced seed in crosses with tetraploids and diploids, although the fertility of the latter crosses was four times higher. The female fertility of some of the triploids thus allows them to exchange genes with the tetraploids and diploids, although gene-flow occurs more rapidly through direct transfer from diploids to tetraploids via 2n gametes.     

A male-sterile line with ‘virescent’ marker character in Upland cotton

Summary Inheritance of 81A genetic male-sterility with virescent marker character and its cytology in Upland cotton (Gossypium hirsutum L.) are presented. The chromosome number of 81A is normal, 2n = 52, and pollen abortion occurs mainly in the late uninuclear stage. Male-sterility and virescence in 81A are controlled by one pair of recessive gene. Because male sterility and virescence showed no recombination, pleiotropy is assumed. However, very close linkage could not be ruled out. Allelic tests indicated that virescence observed in 81A is non-allelic to all virescence genes identified earlier in Upland cotton and its male-sterility is non-allelic to msc₁, msc₂ and msc₃ discovered in P.R. China. It is proposed that 81A male-sterile gene symbol be tentatively named to msc₇. The development of 81A genetic male-sterile line associated with virescence trait could raise considerably the efficiency of the hybrid seed production in cotton.     

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.     

Correlation between α-amylase gene expression and seedling vigor in rice

Summary This report examines the relationship between seedling vigor, -amylase enzyme activity and -amylase mRNA accumulation in ten varieties of rice (Oryza sativa L.) grown at two temperatures (15°C and 30°C). A significant, positive correlation was observed between seedling vigor, -amylase enzyme activity, and the accumulation of mRNA from one rice -amylase gene (RAmy1A) at both temperature regimens. The results of this study support previous experiments which have correlated -amylase enzyme activity to seedling vigor. We have extended this correlation to the expression of one of ten genes that comprise the rice -amylase multigene family. These results suggest that the expression of -amylase gene RAmy1A is an important, and possibly rate-limiting factor in determining seedling vigor in rice.     

Comparative analysis of petal proteins in red and white lines from near-isogenic Portulaca sp. ‘Jewel’ plants

Summary A couple of near-isogenic lines, JR and JW from Portulaca sp. Jewel has red and white petals respectively. The difference in petal color in the two lines is caused by an alteration of single genetic locus which is involved in the biosynthesis of betalain pigmentation. In order to detect this genetic difference at the polypeptide level, we have now attempted the comparative analysis of petal proteins between JR and JW. The protein profiles of SDS-polyacrylamid gel electrophoresis from three different stages of the developing petals, and the autoradiographic protein profiles of in vivo labeled petals howed that a 27 KD fragment strongly appeared as a characteristic of JR petal fraction. Thus, this fragment can be considered as a candidate for certain polypeptides which is associated with the betalain synthesis pathway functioning in the pigmented petals.Abbreviations SDS sodium-dodecyl sulfate - KD kilo-dalton - DOPA 3,4-dihydroxyphenylalanine     

Morphology,cytology and forage potential of Pennisetum americanum (L.) K. Schum. x P. Purpureum Schum. amphidiploids

Summary F₁ hybrids between short-day photoperiod- sensitive maiwa bulrush millet, Pennisetum americanum (2n=14), and elephant grass, P. purpureum (2n=28), are triploid (2n=21), sterile, and can only be propagated vegetatively. Fertile amphidiploids, (2n=42, with 21 bivalents) were produced by colchicine treatment. Good seed set was obtained upon selfing the amphidiploids and the progeny exhibited variable pollen fertility and bivalent univalent and multivalent formation.Reciprocal crosses between elephant grass and the colchicine-induced amphidiploid failed to produce seeds. The maiwa millet x amphidiploid cross resulted in poor seed set and the reciprocal failed. Maiwa x amphidiploid hybrids were pollen sterile with 2n=21, rather than the expected 2n=28, indicating chromosome elimination.Morphologically, the amphidiploids and maiwa x amphidiploid hybrids closely resembled elephant grass and the F₁ hybrid. The amphidiploids showed no superiority over the F₁ hybrid and elephant grass in either forage yield or quality but one maiwa x amphidiploid genotype surpassed a promising local elephant grass selection in forage dry matter yield and flowered for a relatively short period.     

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.     

Floral biology and artificial pollination in Dioscorea alata L.

Summary Floral biology of Dioscorea alata L. was studied. Anthesis occurred in male flowers by 12.30 h and in female flowers between 13.00 h and 14.30 h. Male flowers remained open for 4–5 hours and female flowers for 9–11 days.Natural pollination was practically absent but parthenocarpic fruit development was observed in rare cases. For hand pollination a simple and efficient pencil method was standardised. Pollen remained viable for 4–5 hours whereas stigma receptivity lasted for 9–10 days. The optimum time of pollination was found to be between 12.00 h and 15.00 h. Several factors like high relative humidity, atmospheric temperatures below 30°C and non-bagging the female flowers were found to promote fruit set.     

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.     

Heritability of β-glucan, groat percentage, and crown rust resistance in two oat crosses

Summary Parent-offspring regression was used to estimate heritability for three traits (-glucan content, groat percentage, and resistance to crown rust (Puccinia coronata Cda. f. sp. avenae Eriks.) in oat (Avena sativa L.). The populations used were derived from two crosses, Nova x Marion QC and Sylva x Marion QC. Marion QC was used as a parent because other research had shown that it is relatively high in -glucan, a trait for which heritability had not previously been estimated. Nova and Sylva are similar in adaptation to Marion QC, and Sylva may be a source of general resistance to crown rust. Random F₅ plants were grown in a greenhouse, and their F₆ and F₇ progeny were grown in replicated field trials. Heritability estimates for the two grain quality traits were based on regression of F₆ values on F₅ values, F₇ values on F₆ values, and F₇ values on F₅ values. Heritability estimates for -glucan content were between 0.27 and 0.45. The highest estimate was the one based on the F₆ and F₇ generations of Sylva x Marion QC: 0.45, compared to estimates of 0.32 or less for earlier generations of the same cross, and to estimates of 0.35 or less for all generations of Nova x Marion QC. Heritability estimates for groat percentage were all between 0.23 and 0.32. The F₆ and F₇ generations were evaluated for resistance to crown rust resistance. The Sylva x Marion QC cross seemed to segregate for heritable resistance (h ²=0.31) but the Nova x Marion QC cross did not (h ²=0.07). Several lines from the Sylva x Marion QC cross had low symptoms in both the F₆ and F₇ generations. There were no strong genetic correlations among the traits.     

Heritabilities and genetic variation for preharvest sprouting in progenies of Clark's Cream white winter wheat

Summary Preharvest sprouting resistance is a major breeding criterion in many regions where white wheat (Triticum aestivum L.) is produced. Availability of genetic sources of sprouting resistance should significantly advance this goal. Objectives of the present investigation were to determine heritabilities and genetic variation of sprouting resistance in progeny of six susceptible genotypes and Clark's Cream, a cultivar with excellent sprouting resistance. Sixty-five randomly selected F₂:F₃ lines from the six parental combinations were evaluated in blocks-within-replication designs at two locations during 1984–85. Falling number, -amylase activity, and sprouting percentage in simulated rain were usually more favorable in F₂:F₄ grain than in grain of the susceptible parents and frequently equalled levels in grain of the resistant parent. Broad sense heritability estimates were moderate to high for falling number and -amylase activity, low to moderate for visual sprouting, and inconsistent for embryo germination in ABA. Phenotypic correlations with sprouting were significant most often for falling number and least often for the agronomic traits, days to heading and kernel weight. We concluded that increased preharvest sprouting resistance is an attainable objective when genetic sources of strong resistance and appropriate selection criteria, such as sprouting after simulated rain, are used.     

Transformation of lily by Agrobacterium

Summary Lily cv. Harmony was inoculated with several Agrobacterium strains to study its susceptibility to Agrobacterium infection and transformation. Tumorous tissue formation on inoculated stem internodes of sterile-grown plantlets, as well as expression of a -glucuronidase marker gene interrupted by an intron in cells of inoculated stem nodes, indicate that the monocotyledon Lilium is a host for Agrobacterium.     

Inheritance of late maturity α-amylase in wheat

Summary Two wheat cultivars that consistently show high levels of grain -amylase at harvest ripeness, in the absence of preharvest sprouting, were crossed with a control, low -amylase cultivar, and F₁, F₂ and BC₁ populations were developed. Grain of these populations was analysed for -amylase activity at harvest ripeness. Distribution and segregation patterns were consistent with control at a single locus with high -amylase the recessive allele. This mode of inheritance would make it extremely difficult to differentiate homozygous low -amylase lines from heterozygotes (low -amylase phenotype but carriers of high -amylase) and has important implications for wheat breeders. High -amylase, termed late maturity -amylase, was not linked with the awned inhibitor gene, B2, located on the long arm of chromsome 6B.     

Inheritance of root traits and phosphorus uptake in common bean (Phaseolus vulgaris L.) under limited soil phosphorus supply

Heterosis is an important way to improve yield and quality for many crops. Hybrid rice and hybrid maize contributed to enhanced productivity which is essential to supply enough food for the increasing world population. The success of hybrid rice in China has led to a continuous interest in hybrid wheat, even when most research on hybrid wheat has been discontinued in other countries for various reasons including low heterosis and high seed production costs. The Timopheevii cytoplasmic male sterile system is ideal for producing hybrid wheat seeds when fertility restoration lines with strong fertility restoration ability are available. To develop PCR-based molecular markers for use in marker-assisted selection of fertility restorer lines, two F₂ populations derived from crosses R18/ND36 and R9034/ND36 were used to map fertility restoration genes in the two elite fertility restorer lines (R-lines) R18 and R9034. Over 678 SSR markers were analyzed, and markers closely linked to fertility restoration genes were identified. Using SSR markers, a major fertility restoration gene, Rf3, was located on the 1B chromosome in both populations. This gene was partially dominant in conferring fertility restoration in the two restorer lines. SSR markers Xbarc207, Xgwm131, and Xbarc61 are close to this gene. These markers may be useful in marker-assisted selection of new restorer lines with T. timopheevii cytoplasm. Two minor QTL conferring fertility restoration were also identified on chromosomes 5A (in R18) and 7D (in R9034) in two R-lines.     

Microprotoplast fusion technique: a new tool for gene transfer between sexually-incongruent plant species

Summary Various aspects of a microprotoplast fusion technique and the strategies followed for intergeneric partial genome transfer (one or a few chromosomes) and alien genes from sexually-incongruent donor species to recipient species are described. The essential requirements of the microprotoplast fusion technique are the induction of micronuclei at high frequencies, as well as the isolation and enrichment of sub-diploid microprotoplasts in donor species, efficient fusion of the donor microprotoplasts with normal recipient protoplasts and stable regeneration of plants from fusion products. The results on the production of microprotoplast hybrid plants between the transformed donor lines of Solanum tuberosum and Nicotiana Plumbaginifolia carrying various genetic markers, and a recipient line of Lycopersicon peruvianum or Nicotiana tabacum, and on the transfer and expression of alien genes (kanamycin resistance, -glucuronidase) are presented. The data obtained on microprotoplast hybrid plants between S. tuberosum and L. peruvianum showed that many of the hybrids contained one potato chromosome carrying nptII and GUS, and 24 or 48 L. peruvianum chromosomes (monosomic additions), and that they were male-and female-fertile. Various applications of chromosome transfer by this technique, especially for economically-important traits (e.g. disease or stress resistance) from sexually-incompatible wild species, for construction of chromosome-specific DNA libraries through microdissection and microcloning of chromosomes, or by flow-sorting of chromosomes for genome analysis, are discussed.     

Variation for plant characters and for performance of softwood cuttings of Rosa canina ‘Inermis’ seedlings

Summary Thirty, one-season-old Rosa canina Inermis seedlings (8–12 mm in diameter) were grown in the greenhouse. After 5 months, single-node softwood cuttings were made of each plant. Analysis of variance demonstrated marked differences between the internode length, number of leaflets per leaf and the leaf area of the original seedling, and between the time of axillary bud-break, axillary sprout length and weight of adventitious roots of their 23-day-old cuttings. Clonal root weight of cuttings was highly significantly correlated with: number of leaflets per leaf (r=–0.65), leaf area (r=+0.65), and days to axillary bud-break (r=+0.62). The origin of heterogeneity among Inermis seedling rootstocks, its probable effect on the flower production of cut roses and its possible use in the selection for clonal rootstocks are discussed.     

Mutant induction through adventitious buds of Kohleria

Summary Freshly cut leaves of Kohleria eriantha and K. x Longwood were exposed to a wide range of gamma irradiation doses and allowed to root and form adventitious buds. K. Eriantha could not be successfully propagated from leaf half cuttings. Longwood produced a small number of adventitious plantlets as compared to other Gesneriads. Colchicine treatments reduced leaf half survival in Longwood by more than 50%. Leaf halves exposed to low and moderate doses of gamma irradiation showed increased overall plantlet production compared to nonirradiated leaf halves.Of the mutation parameters calculated, the number of mutants per 100 surviving leaf halves appears to be the most useful since it relates the number of mutants within a dose to the number of surviving leaf halves, the number of mutants to the number of plants produced, and the number of mutants within doses to control values.Using the criteria, number of mutants per 100 surviving leaf halves, optimum production of all mutants, of useful and of dwarf mutants was obtained at 2.5 kR for noncolchicine treated leaf halves and 1.5 to 3.0 kR for colchicine treated leaf halves.Of the adventitious plantlets produced, 13.8% were classified as mutant types. Mutant plants were found in radiation dose levels up to 5.5 kR. The array of mutants produced was skewed toward plant habit and flower characteristic mutants with several leaf characteristic, lethal, and polyploid mutants observed. A high frequency of mutants, 10 of 93 plants, occurred in the nonirradiated controls. Four sectorial chimeras were identified from both control and irradiation exposed groups. Several potentially useful flower color and dwarf mutants have been selected for further study. Adventitious buds may have developed from callus at petiole and leaf-vein bases. Colchicine treatments severely inhibited adventitious plantlet production and because of this could not be used as a criterion to identify the origin of adventitious buds. Conclusive determination of the organogenesis of adventitious buds from Longwood leaf halves could not be made. Mutant plantlets formed from adventitious buds on detached leaf halves of Longwood appear to arise from single cells as has been found with other Gesneriads.Scientific Journal Series Article No. 10 330 of the Minnesota Agricultural Experiment Station.     

Inheritance and allelic relationships of fertility restoration genes for seven new sources of male-sterile cytoplasm in sunflower

The inheritance of fertility restoration of six mitomycin C and streptomycin‐induced cytoplasmic male‐sterile (cms) mutants and one cms line derived from Native American cultivar PI 432513 in sunflower was evaluated. These seven new cms sources were also compared with the commercially used cms PET1 (Helianthus petiolaris Nutt.) cytoplasm, using USDA inbred lines with restoration genes (Rf₁) specific for cms PET1 and new restoration lines identified for cms PI 432513. Restoration genes for cms PI 432513 were found in ‘Armavir’, VNIIMK, P21 and male‐fertile (MF) plants of PI 432513. F₂ and F₃ segregation ratios of crosses between cms PI 432513 and these restoration sources indicated a single dominant gene controlled fertility restoration. Progenies of cms PI 432513 testcrossed with F₁’s of half‐diallel crosses among the respective four homozygous restoration lines and RHA 274 suggested that the restoration genes of RHA 274, VNIIMK, P21 and PI 432513 were at the same locus. Restoration genes from VNIIMK, P21 and PI 432513 satisfactorily restored pollen stainability in the heterozygous condition. A very weak expression of the Rf gene in ‘Armavir’ was observed in the heterozygous condition. Fertility restoration capability of these genes for the six mutant cms HA 89 and cms HA 89 (in PET1 cytoplasm) was observed. The mutant cms HA 89 lines were also restored completely by RHA 266, RHA 274, RHA 280 and RHA 296, and F₂’s segregation ratios indicated single dominant gene control, implying a common cytoplasmic male sterility in all lines. F₁’s of half‐diallel crosses among RHA 266, RHA 273, RHA 274, RHA 280 and RHA 296 were testcrossed onto the cms lines, and their all MF progenies among lines, except RHA 280, confirmed that fertility restoration was controlled by a single Rf₁ gene locus. The restoration gene in confection line RHA 280, namely Rf₃, was at a different locus than Rf₁ and was equally capable of restoring all the cms lines. Cms HA 89 mutants and cms PI 432513 are in H. annuus cytoplasm, and are agronomically equal in hybrid performance to the cms PET1 used in commercial sunflower hybrids. These new cms lines will provide immediate alternative cms sources for reducing the genetic vulnerability resulting from the exclusive use of the single cms source PET1 in sunflower hybrid production.