Some physiological and photosynthetic characters of rice × sorghum and rice × wheat hybrids

Summary Some photosynthetic characters as-leaf anatomy, leaf photosynthetic rate and CO₂ compensation pointdistinguishing C₃ and C₄ plants and physiological characters as leaf area ratio, nitrogen content, leaf stem ratio and total shoot-to-root and deep root-to-shoot ratios have been studied in rice × sorghum and rice × wheat hybrids. Rice × sorghum 1. has lower values of photosynthetic rate, leaf nitrogen, total root and deep root-to-shoot ratio and CO₂ compensation point as of rice parent where as, rice × sorghym 2. is superior in all these characters. Both hybrids lack kranz anatomy. Though both rice × sorghum hybrids show characters of C₃ rice plant but rice × sorghum 2. has improved drought tolerance and leaf characters in relation to yield. Rice × wheat hybrid have higher assimilatory area and higher total root-to-shoot ratio. Grains of rice × wheat hybrids are identical to rice grain. However, as grains of rice × wheat hybrid does not contain seed coat, it could be exploited as novel rice germplasm after improvement.Abbreviations T CO₂ compensation point - T21 CO₂ compensation point at 21% O₂ - T2 CO₂ compensation point at 2% O₂ - dR/sR deep Root-to-shoot Ratio - LAR Leaf Area Ratio - CER photosynthetic rate - TR/SR Total Root-to-Shoot Ratio     

Searching for DNA introgressed from wheat and for wheat-like grain proteins in a rice x wheat hybridization derivative

The DNA of a putative rice x wheat hybridization derivative (X Oryticum oryzoides) from China, the DNA of its parental rice cultivar and the DNA of a wheat line were digested with ten different restriction endonucleases, resolved by agarose electrophoresis, Southern blotted and hybridized using genomic wheat DNA as a probe. Phenol extracted, ethanol and cetyltrimethylammonium bromide precipitated DNA of the putative hybrid showed a restriction fragment length polymorphism (RFLP) different from that of the parental rice. When the DNA was further purified by Qiagen chromatography, the RFLP differences were not detected. Hence the apparent RFLP differences were probably due partial digestion of the less pure DNA preparations by the restriction endonucleases. No real introgressed fragments from wheat genome could be shown. The HpaII/MspI sites were more frequently digested with MspI than with HpaII in rice and hybridization derivative DNA, but the sites were evidently more frequently methylated in wheat DNA. Thus, in terms of methylation of the DNA, the hybridization derivative was much more like the rice parent than the wheat parent. The hybridization derivative showed a single endospermal protein (mass 19 kg mol^-1) not detected in the parental rice cultivar. This minor protein was soluble in buffered 50% isopropanol and precipitable with methanol. The results indicate that there are no or only short introgressed sequences from wheat in the rice/wheat derivative, a result which might be considered in breeding efforts with the hybrid derivative.     

Parental effects on crossability,embryo differentiation and plantlet recovery in wheat x rye hybrids

Summary One hexaploid wheat cultivar (Triticum aestivem) and two tetraploid wheat lines (T. durum) were crossed with seventeen inbred lines of rye (Secale cereale). Seed set, degree of hybrid embryo differentiation at the time of excision for in vitro culture and recovery of amphihaploid plantlets from various embryo categories were studied. Degree of embryo differentiation was predominantly determined by maternal wheats, paternal rye genotypes appearing to be of minor importance. T. aestivum x rye hybrid embryos were superior to those produced from T. durum for degree of differentiation. The proportion of plantlets developing from differentiated embryos was high for all wheat parents, whereas undifferentiated embryos were mostly unsuitable for plantlet production. The results revealed that cross-incompatibility in hexaploid wheat x rye crosses was due to failure of fertilization, while in tetraploid wheat x rye crosses it was caused by lack of embryo differentiation. Correlation analyses showed that seed set provided a criterion to predict the amphihaploid plantlets to be expected from a particular wheat x rye combination.     

Yield of F1, F2 and F3 hybrids of rice (Oryza sativa L.)

Summary Yield and yield components of F₁ hybrids were studied in three experiments at 30×30 cm spacings and in one experiment at 15×15 cm spacings. In the 30×30 cm experiments, 10 of the 41 hybrids tested significantly outyielded their high parents. However, only 2 hybrids significantly outyielded the best cultivar: one hybrid yielded 23 % and the other 16 % more than their respective check cultivars. The four hybrids in the 15×15 cm experiment yielded only 59 to 92% as much as their high parents.In areas where rice is transplanted at relatively wide spacings, the observed levels of F₁ heterosis in selected hybrids may be sufficient to warrant production of hybrid rice, if enough hybrid seed can be produced. For direct-seeding at the high rates normal in the USA, the relatively small levels of heterosis and the difficulties of hybrid seed production preclude use of F₁ hybrid rice cultivars at present.None of 19 bulk F₂ and F₃ hybrids in two experiments yielded significantly more than its high parent. Similarly, none of the 12 mixtures included in one experiment yielded significantly more than its high parent. On the basis of yield alone, using bulk F₂ or F₃ or simple mixture populations is not merited.Contribution from the Western Region, Agricultural Research Service, U.S. Department of Agriculture, and the Department of Agronomy and Range Science, University of California, Davis, California 95616.     

Cytological observations in some hybrids between the rice species Oryza sativa L. and O. glaberrima Steud.

Summary Several hybrids between Oryza sativa and O. glaberrima and their backcrosses with O. sativa were studied. Their seed sterility was very different; large differences were also observed in the level of pollen sterility and in the earliness of microspore failure. The proportion of aborted embryo sacs was much lower than the rate of sterile male gametophytes. The backcross populations were much more sterile than the corresponding F₁ hybrids. On the base of our observations and according to the literature, we may conclude that genic unbalance is the main cause of sterility of these hybrids, but that physiological factors may also be involved. Thus a restoration of fertility is generally possible by selection. On the other hand, male-sterile lines could be bred from some of these hybrids.     

Spontaneous wheat/rye translocations from female meiotic products of hybrids between octoploid triticale and wheat

Summary Heptaploid hybrids between octoploid triticale and wheat were backcrossed as female parents with wheat to examine the rye chromosome distribution in the resultant progenies using genomic in situ hybridization (GISH). One hundred and one backcross (BC) seeds were examined and whole rye chromosome additions and substitutions, wheat/rye centric and noncentric translocations and rye telocentric chromosomes were detected. Dicentric wheat/rye translocated chromosomes were also observed. Comparisons were made with previous results on the rye chromosome distribution from male gametes of the same cross and differences were found, where in the female derived population a deficit of plants with more than two rye chromosomes was apparent relative to the anther derived population.     

Anther culture of tropical japonica × indica hybrids of rice (Oryza sativa L.)

Summary Nine japonica × indica F1 hybrids of rice involving 6 indica and 3 japonica tropical varieties, were large scale anther cultured. The frequency of callusing anthers averaged 18.7%. The microspore-derived calli produced green plants with a mean frequency of 8.7%. Albino plants represented 61% of the shoot forming calli. Monitoring of the green and albino plant regenerating capabilities of calli arising between week 4 and week 8 of incubation of the anthers showed no increase of the albino/green ratio and a slow decrease of the shoot forming ability of the transferred calli after the sixth week of culture. Spontaneous doubled haploids (SDH) represented 46% of the regenerated green plants in 4 hybrids. However, a high frequency of partially sterile regenerants was noticed among 132 SDH plants generated from a hybrid.     

Expression of barley yellow dwarf virus and Russian wheat aphid resistance genes in and fertility of spring wheat × triticale hybrids and backcross lines

Summary The Barley Yellow Dwarf Virus disease (BYDV) and the Russian wheat aphid (RWA) Diuraphis noxia (Mordvilko) have caused significant losses to wheat and barley in several areas of the world. Important sources of resistance to both BYDV and RWA have been found in Triticale. Different generations of interspecific wheat x Triticale crosses were produced and the progenies were screened for BYDV and RWA tolerance. Plants with equal chromosome numbers showed different levels of fertility. A significant correlation was observed between pollen fertility and seed set in primary florets (r=0.57). In generaL, pollen fertility, seed set and the number of euploid plants (2n=42) increased from one generation to the next. The expression of BYDV tolerance varied from population to population. Additive effects were predominant in F₁ and some backcross populations. A dominant effect of rye tolerance genes was also observed in few populations. A monogenic trait or a quantitative (polygenic) character would not agree with the observed segregation patterns. The heritability of this oligogenic tolerance was quite different between populations and in many populations the tolerance genes were only partially expressed. Some transgressive segregation for tolerance and sensitivity was demonstrated. The genes controlling tolerance to RWA in Triticale lines, Muskox 658 and Nord Kivu were not expressed in advanced lines resistant to BYDV. This indicates that tolerance genes for BYDV and RWA in these lines are located on different chromosomes.     

Inheritance and allelism of resistances to the Russian wheat aphid in seven wheat lines

Summary Studies were conducted to determine the inheritance and allelic relationships of genes controlling resistance to the Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), in seven wheat germplasm lines previously identified as resistant to RWA. The seven resistant lines were crossed to a susceptible wheat cultivar Carson, and three resistant wheats, CORWA1, PI294994 and PI243781, lines carrying the resistance genes Dn4, Dn5 and Dn6, respectively. Seedlings of the parents, F₁ and F₂ were screened for RWA resistance in the greenhouse by artificial infestation. Seedling reactions were evaluated 21 to 28 days after the infestation using a 1 to 9 scale. All the F₁ hybrids had equal or near equal levels of resistance to the resistant parent indicating dominant gene control. Only two distinctive classes were present and no intermediate types were observed in the F₂ segregation suggesting major gene actions. The resistance in PI225262 was controlled by two dominant genes. Resistance in all other lines was controlled by a single dominant gene. KS92WGRC24 appeared to have the same resistance gene as PI243781 and STARS-9302W-sib had a common allele with PI294994. The other lines had genes different from the three known genes.     

Analysis of ATPase and succinic dehydrogenase in F1 hybrids of rice (Oryza sativa L.)

Summary Activities of ATPase and succinic dehydrogenase were assessed in three F₁ hybrids of rice and their parental lines during boot leaf stage, flowering, on 10th and 20th days after flowering. ATPase activity showed increase at the flowering and on 20th day after flowering. Succinic dehydrogenase activity continued to rise till 10th day after flowering and declined on 20th day after flowering. Hybrids with high yield were generally endowed with more positive heterosis for these two enzymes. Correlation coefficient of grain yield per panicle was significantly positive with ATPase activity at all the stages studied. Heterosis for ATPase activity might serve a reliable criterion for the selection of efficient F₁ combinations.     

The derivation of compensating translocations involving homoeologous group 3 chromosomes of wheat and rye

Summary The Sr27 translocation in WRT238 was found to consist of chromosome arms 3RS of rye and 3AS of common wheat. An attempt was made to purposely produce compensating translocations having 3RS and a wheat homoeologous group 3L arm. To achieve this, plants, double monosomic for 3R and a wheat homoeologous group 3 chromosome, were irradiated (7.5 Gy gamma rays) or left untreated before being used to pollinate stem rust susceptible testers. Segregation for stem rust resistance was studied to identify F₂ families with Sr27-carrying translocated chromosomes, these were confirmed by means of C-banding. Compensating translocations 3RS3AL and 3RS3BL) were obtained readily and at similar frequencies from untreated and irradiated plants (respectively, 7.2% and 9.3%). Both translocation types have impaired transmission and segregate approximately 3: 2 (present: absent) in the F₂.     

The effect ofGlu-B1 high molecular weight glutenin subunits on biscuit-making quality of wheat

Summary The aim of this study was to assess the effect of specificGlu-B1 HMW-GS on biscuit-making quality. Three soft spring wheat cultivars with the sameGlu-A1 andGlu-D1 HMW-GS, but differentGlu-B1 HMW-GS were used in crosses. F₂₄ derived lines were developed from these crosses.Glu-B1 HMW-GS 6+8 and 17+18; and 7+9 and 17+18 were compared. Lines with HMW-GS 6+8 versus those with HMW-GS 17+18 had a higher flour protein- and alveograph P/L ratio, shorter mixograph mixing time, more vitreous kernels, and a lower alveograph distensibility and strength (all values significant at p=0.05). Lines with HMW-GS 7+9 compared to those with 17+18 showed significant differences for flour extraction and biscuit diameter. The presence of HMW-GS 17+18 was significantly correlated with several biscuit-making quality characteristics in the Dirkwin/Zaragosa F₂₄ lines but not in the Waverley/Zaragosa F₂₄ lines, therefore the effect of HMW-GS 17+18 was modified by the genetic background in which they were expressed.     

The chromosomal location of the embryo plus scutellum alcohol dehydrogenase isozymes in the hexaploid wheat kernel

Summary Analysis of individual parts of Triticum aestivum L. and T. turgidum var. durum kernels showed two classes of alcohol dehydrogenase patterns: 1) A three banded pattern (ADH-1, ADH-2 and ADH-3) for endosperm (Ed) and 2) a seven banded pattern (ADH-F1, ADH-F2, ADH-1, ADH-2, ADH-3, ADH-S1 and ADH-S2) for embryo (E), scutellum (S) and embryo plus scutellum (E+S). The use of nullitetrasomic and ditelosomic series of Chinese Spring wheat allows alcohol dehydrogenase to be associated with arms 4A, 4BL and 4DS.A five subunit forming dimer hypothesis is postulated to explain the newly reported seven isozyme pattern. Subunits , and are coded by chromosome arms 4A, 4BL and 4DS respectively, and the newly postulated and are coded also by chromosome arm 4BL.     

The effect of temperature on seed set and embryo development in reciprocal crosses of wheat and barley

Summary The effect of temperature on seed set and embryo development in reciprocal crosses of barley and wheat was assessed in crosses involving two spring barley varieties (Betzes, Martonvásári 50) and one wheat variety (Chinese Spring). Detached tillers placed in nutrient solution were pollinated in controlled environments at constant day-night temperature regimes (12, 15, 18 and 21° C) with a light intensity of 30,000 lux and a relative humidity of 80%. When barley was used as the female, lower temperatures (12 and 15° C) produced the maximum seed set, whereas for the reciprocal cross, the highest temperature (21° C) produced the best seed set in the Chinese Spring × Betzes combination.Low temperature retarded the embryo development. The highest numbers of hybrid plants were produced at 18° C and 21° C in the barley × wheat cross and in the wheat × barley cross, respectively. Embryos of about 1.5 mm length in the barley × wheat cross, and of about 1.0 mm length in the wheat × barley cross germinated successfully. The smallest embryo giving rise to hybrid plants was 0.57 mm in the barley × wheat cross and 0.51 mm in the wheat × barley cross.     

Selection for white kernel color in the progeny of red/white wheat crosses

Summary Data are presented which support early generation selection for white kernel color in the progeny of red/white kernel wheat crosses which are segregating at 12 or more loci for yield (or any other trait of interest). The optimum generation for selecting white kernels is determined by the frequency of seeds produced with the potential to produce plants having desired quantitative alleles from both parents, and by the frequency of white kernels produced. The F₂-produced seed (F₃ embryo) is shown to be the optimum generation for selecting white kernels, given that 12 or more loci are segregating for a quantitative character such as yield. When the red parent is a 2 or 3 loci red genotype, selection among F₄-produced seed for white kernel color may be desirable when 5 or fewer genes are segregating for the second trait. The results have direct application for all highly heritable, recessive, sporophytic traits.Contribution from the Cornell Agricultural Research Station, Cornell Univ., Ithaca, NY 14853. Paper No. 723. Research supported by Hatch project 419     

The relationships of hardening period and the expression of frost resistance in chromosome substitution lines of wheat

Summary The highly frost resistant wheat variety Cheyenne (donor) and the poorly frost resistant variety Chinese Spring (recipient) were frozen at –9° C and –11° C at various stages of hardening, as were a number of substitution lines of these two varieties (CS/Ch 3A, CS/Ch 5A, CS/Ch 7A, CS/Ch 2B, CS/Ch 4B, CS/Ch 5B, CS/Ch 4D, CS/Ch 5D). Chromosomes 5A, 5B, 5D, 4B and 7A of Cheyenne increased the frost resistance of the recipient variety to varying extents. However, the frost resistance changed not only as a function of the different chromosomes, but also as a function of the duration of hardening, indicating that genes responsible for frost resistance are expressed differently during different phases of the hardening process.     

Comparison of fertility between the F1, F2 and anther derived lines in the crosses of indica/japonica and japonica/indica in rice (Oryza sativa L.)

Summary Response of anthers in in vitro culture was examined in the indica-japonica hybrids of rice (Oryza sativa L.). Significant genotypic differences were observed for callus induction and regeneration among the different interracial hybrids of indica-japonica races. Induction frequency of haploids ranged from 57.7 to 72.9 per cent and doubled haploid androgenic lines ranged from 27.1 to 42.3 per cent in the anther culture of the different hybrids. The indica-japonica hybrids recorded partial pollen grain and spikelet fertility in F1 (29.9 to 41.5% and 19.4 to 48.7% respectively) as well as in F2 (42.7 to 50.6% and 37.1 to 54.4% respectively). In contrast, the androgenic doubled haploid lines recorded significant increase and the pollen grain and spikelet fertility was 76.3 and 78.6 per cent respecitively. The results suggested that the sterility barriers for realising genetic recombinants and fixation of fertile homozygous lines in indica-japonica hybridization programme could be overcome through F1 anther culture technique.Abbreviations BAP Benzyl Amino Purine - 2,4-D 2,4-Dichlorophenoxy acetic acid - MS Murashige & Skoog medium - IAA Indole Acetic Acid     

The crossing of common wheat (Triticum aestivum L.) with cultivated rye (Secale cereale L.). II. Fertilization and early post-fertilization developments

Summary Fertilization and early seed development was studied in the variety Chinese Spring of common wheat (Triticum aestivum L.) after pollination with rye (Secale cereale L.) and selfing, and in the common wheat variety Hope after selfing. In all three combinations the first pollen tube reached the micropyle in about 40 min after pollination. When pollinated with rye the migration of the sperm nuclei to the egg cell and the polar nuclei was delayed by about an hour. In the subsequent development until 72 hours after pollination the average cellular and nuclear doubling times of embryo and endosperm were about 16 and 8 hours for the interspecific combination. 18 and 9 hours for Chinese Spring selfed and 20 and 12 hours for Hope selfed.