Genetic analysis of resistance to whitebacked planthopper in twenty-one varieties of rice,Oryza sativa L.

Summary The inheritance of resistance to whitebacked planthopper Sogatella furcifera (Horvath) was studied in 21 rice varieties. Reactions of F₁; F₂ and F₃ progenies of the crosses of 21 resistant varieties with the susceptible variety TN 1 revealed that a single dominant gene governs resistance in Mushkan 41, Santhi, Siahnakidar 195, SM2-34, Tirisurkh 251, Zirijowaian 245, 18, 24A, 39, 76 S, 78, 180, 213 B, 267, 293, CI 6037-4, NP97, S39 JKW and Bansphul. In varieties 65 and 274 A, resistance is governed by one dominant and one recessive gene which segregate independently of each other. Tests for allelism with the Wbph 1 gene originally identified in N 22 revealed that the dominant gene present in all the test varieties is the same as Wbph 1. Further studies are required to determine the allelic relationships of the recessive gene found in varieties 65 and 274 A.     

Heritable variation in the phaseolin protein of nondomesticated common bean,Phaseolus vulgaris L.

Summary Crude protein extracts from single seeds of nondomesticated Mexican bean accessions were analysed by SDS polyacrylamide gel electrophoresis for variability in phaseolin protein. Six new phaseolin types; M1, M2, M3, M4, M5, M6, which contained polypeptides within the same range of molecular weights (51,000 to 45,000 daltons) as occur in the S, T and C phaseolin types of cultivated beans were identified. No T and C types were found among the non-domesticated Mexican accessions, and the S type occurred in less than 7% of the seeds screened. Genetic analyses of F₂ progenies from crosses between Sanilac (S), and five of the M types showed that each M phaseolin phenotype was allelic to the S type and expressed codominantly.     

Genetic analysis of two wheat cultivars, ‘Sonalika’ and ‘WL 711’ for reaction to leaf rust (Puccinia recondita)

Summary Genetic analysis for leaf rust reaction of two widely adapted cultivars, Sonalika and WL 711, has been done using 21 near isogenic Lr lines and rust culture IL004 — avirulent on the two cultivars and all the Lr lines used. The segregation pattern in the F₂ generation indicated the presence of a recessive gene in Sonalika and of a dominant gene in WL 711. These genes in cultivars Sonalika and WL 711 have been identified as Lr 11 and Lr 13, respectively. Gene Lr 13 is no longer effective in WL 711 but it continues to give field resistance in the backgrounds of Chris, Prelude and Thatcher. There has been no significant change in the virulence spectrum of the leaf rust pathogen in India with the release of WL 711. High susceptibility of WL 711 seems to be due to the evolution of more aggressive forms of the pathogen to this cultivar. The gene Lr 11, which behaves as a recessive in Sonalika, was effective against leaf rust when this cultivar was released. The high susceptibility of Sonalika is probably due to an increase in the frequency of race 77 virulent on Lr 11. Lr 11 has shown a dominance reversal in the background of Sonalika. Present results suggest that interaction of resistance genes with the background genotype must be studied for their effective use in breeding programme.     

Monosomic analysis of heading date and spikelet number in the common wheat (Triticum aestivum L.) multispikelet line ‘Noa’

Summary Genetic analysis of heading date and spikelet number was carried out in the common wheat (Triticum aestivum L.) multispikelet line Noa, by using the monosomic series of the regular line Mara. Noa's high number of spikelets was found to be controlled by a recessive major gene on chromosome 2D; a slight reduction in spikelet number was induced by another recessive gene on Noa's 7A chromosome. Noa's late heading date was found to be controlled by two recessive genes, located on chromosome 2D (a major effect) and 6B (a minor effect). The nature of the genes located on Noa's 2D chromosome and the relationship between spikelet number and heading date are discussed.     

An explication of ‘wind illness’ in Northern Thailand

Wind illness is a very common complaint among the Northern Thai, yet is rarely recognized by Thai physicians trained in biomedicine. Persons most susceptible to wind illness are adult women who have ever borne a child. Consequently, data were obtained from 415 everparous women, 43% of whom reported ever having had wind illness and 57%, never having had it. In addition, 20 individuals who had ever had the syndrome were followed for case study, and 13 indigenous healers who traditionally treat clients suffering wind illness were interviewed. Their perceptions of the etiology, symptomatology and treatment of wind illness are reported in Part I. Part II is an attempt to define wind illness in terms of biomedicine and as a consequence of fertility. Part III synthesizes the emic and etic accounts with explanations for the perdurance of wind illness despite the advances of biomedicine and the recent fertility decline in Northern Thailand.     

Are ‘multiple cross-multiple pollen hybrids’ an answer for productive populations in Brassica campestris (var.) Brown Sarson?

Summary A set of 167 mucromphs was evaluated in their F₁ generation for seven plant, four plot and five ratio characters. Methods of characterizing the parents and the hybrids on the basis of combining ability effects described in the first part were found to be efficient in identifying desirable cross combinations for pedigree breeding or generating composite populations. Order effects of multiple-pollen combinations were found to be potent for a number of character components. High x Low cross-combinations were found to produce a high frequency of heterotic crosses followed by High x High. Selected biparental progenies, single crosses, three-way crosses and elite varieties were successful female parents and combinations of pollen from two varieties, one variety and three varieties were successful male parents, in that order, in producing significant heterosis in mucromphs. The relationship between general and specific combining ability on the one hand and realised heterosis on the other was discussed.     

Photosynthetic phosphorylation

A brief history of the discovery of photosynthetic phosphorylation by chloroplasts and bacterial chromatophores is presented. Arnon early introduced the terminology of Cyclic and Non-cyclic photophosphorylation and Cyclic and Non-Cyclic electron transport to the processes observed in illuminated chloroplasts. He made major contributions to the elucidation of these processes and stressed their great biological significance. Investigations of the electron transport components of chromatophores have led to the isolation, purification and crystallization of bacterial reaction centers. The development of three-dimensional molecular structures, and the characterization of their electron transfer components have provided a great deal of information about the early reactions of bacterial photosynthesis. The electron transfer schemes presented clearly support the cyclic nature of light-induced electron transfer. Recent developments in the understanding of ATP synthesis in oxidative phosphorylation by mitochondria and in photophosphorylation by chloroplasts and bacterial chromatophores are discussed.Abbreviations ADP, ATP adenosine 5-di- and triphosphates - NADP⁺, NADPH oxidized and reduced Nicotinamide-adenine dinucleotide phosphate - RC reaction center - EPR electron paramagnetic resonance - F₀F₁ ATP-synthase (synthetase) of mitochondria, chloroplasts, and of chromatophores - F₀ membrane portion of ATP-synthase - F₁-ATPase water soluble sector of ATP-synthase     

Location of a gene regulating drought-induced abscisic acid production on the long arm of chromosome 5A of wheat

The accumulation of abscisic acid (ABA) by detached and partially dehydrated wheat leaves is known to be inherited in a quantitative manner. The location of genes having a major effect on drought-induced ABA accumulation in wheat was determined using a set of single chromosome substitution lines and populations derived from a cross between a high-ABA- and a low-ABA-producing genotype. Examination of a series of chromosome substitution lines of the high-ABA genotype Ciano 67 into the low-ABA recipient Chinese Spring showed that chromosome 5A carries gene(s) that have a major influence on ABA accumulation in a drought test with detached and partially dehydrated leaves (DLT). A similar DLT was used to examine ABA accumulation in a population of F₂ plants and doubled haploid (DH) lines derived from the cross between Chinese Spring (low-ABA) and SQ1 (high-ABA) in which the F₂ population (139 plants) and DH lines (96 lines) were also mapped partially with molecular markers. Analysis of variance of ABA accumulation between and within marker allele classes in the F₂ confirmed the location of a gene(s) regulating ABA accumulation on the long arm of chromosome 5A. MAPMAKERQTL showed the most likely position for the ABA quantitative trait locus (QTL) to be between the loci Xpsr575 and Xpsr426, about 8 cM from Xpsr426. A similar trend for high ABA accumulation was found in DH lines having the SQ1 allele at marker loci in the same region of chromosome 5AL, but the QTL effect was not significant. The function of the QTL is discussed.     

Genetic control of heading date and spikelet number in common wheat (T. aestivum L.) line ‘Noa’

Summary The phenology and build-up of spikelet number under 10 h day-length were studied in five wheat lines: the multispikelet line Noa, the regular line Mara, the F₁ hybrid between them and monosomics 2D of Mara and of this hybrid (lacking the 2D chromosome of Mara). Noa had a longer spike development phase, a higher initial number of spikelet primordia and a slower rate of spikelet production than Mara. The F₁ hybrid was similar to Noa in its high initial number of spikelets and to Mara in its high rate of spikelet production. This hybrid had a shorter spikelet phase than both parents. Deletion of one dose of the Mara 2D chromosome from either Mara or the F₁ hybrid caused a reduction in the rate of spikelet production and an increase in the duration of the spikelet phase. These effects were due to the reduced dosage of the 2D chromosome. However, in the F₁ hybrid this deletion also caused an increase in the spike development phase — an indication that Noa carries on its 2D chromosome a recessive gene for late heading date which acts on the spike development phase. This gene of Noa is independent of the day-length sensitive gene ppd, and is different from Noas dominant gene for large initial number of spikelets.     

A partial genome assay for quantitative trait loci in wheat (Triticum aestivum) using different analytical techniques

F₁ plants between two intervarietal chromosome substitution lines of European spring wheat varieties, Sicco (Chinese Spring 5B) and Highbury (Chinese Spring 5B), were used to produce 114 doubled haploid lines, 45 by the Hordeum bulbosum technique and 69 by anther culture. These two sets of lines were characterized for variation at a range of morphological, isozyme and RFLP marker loci, and genetic maps were developed with emphasis on chromosomes 6B, 7A, 7B and 7D. A subset of lines, scored for production traits in field trials in 1986 and 1987, were analysed for quantitative trait loci (QTL). The performance of the lines for the quantitative traits studied showed no overall differences due to the method of production of the lines. QTL were located on the linkage map for ear emergence time, height, tiller weight, yield and 50-grain weight using four analytical methods. Many of these effects showed genotype x year interaction.     

Sources and inheritance of resistance to leaf curl virus in Lycopersicon

Summary One hundred and twenty-two varieties, lines and wild accessions of Lycopersicon were screened under three different regimes during the autumn/winter season of 1982–83 and 1983–84 for resistance to tomato leaf curl virus (TLCV). L. hirsutum f. glabratum (B6013) and L. hirsutum f. typicum (A1904) proved to be highly resistant to TLCV in all three environments. Various accessions of L. peruvianum were also highly resistant. L. pimpinellifolium (A1921) exhibited no TLCV symptoms within 90 days. Of the cultivated varieties, Acc 99 exhibited the minimim score for susceptibility; AC 142, Collection No. 2, Kalyanpur Angurlata and HS 101 had a low rating for virus incidence. The inheritance of resistance was studied in the interspecific crosses between a TLCV resistant line of L. pimpinellifolium (A1921) and five (HS 101, HS 102, HS 110, Pusa Ruby and Punjab Chhuhara) susceptible cultivars of L. esculentum. Parents, F₁, F₂ and backcross progenies were artificially inoculated with local strains of TLCV using vector the viruliferious whitefly, Bemisia tabaci (Genn.). Data indicated that the resistance of L. pimpinellifolium (A 1921) is monogenic and incompletely dominant over susceptibility.     

A self-fertile trigeneric hybrid,Triticum aestivum ×Agropyron michnoi ×Secale cereale

Trigeneric hybrids between the (Triticum aestivum ×Agropyron michnoi) F₁ (CM, 2n=5x=35; ABDPP) and two winter rye (Secale cereale L., 2n=2x=14; RR) cultivars, Wugong 774 and AR-132, were synthesized. Such trigeneric hybrids could be used to transfer resistance genes for powdery mildew from rye to CM and subsequently to common wheat and to identify (1) the effects of the P genome ofAgropyron on the self-fertility of the hybrids and (2) the differences in genetic background between rye cultivars with marked differences in pollinating habit. The trigeneric hybrids varied widely in morphology and showed a high level of resistance to such diseases as barley yellow dwarf virus (BYDV), stripe rust, leaf rust, stem rust, and powdery mildew. Selfed and many backcross derivatives were obtained from the trigeneric hybrids. The results indicated that rye cvs Wugong 774 and AR132 arose from different gene pools and that the P genome ofAgropyron carries gene(s) responsible for chromosome segregation, leading to functional gamete formation and self-fertility of the hybrids. The F₂ and BC₁ plants could be obtained in two ways — fusion of the unreduced gametes and the assumed apomixis of unreduced female gametes in the trigeneric hybrid plant II-4 — which indicates that this trigeneric hybrid may be a special genetic stock. Chromosome pairing in the trigeneric hybrids and ways of producing wheat/rye and wheat/Agropyron translocations are discussed.     

Inheritance of resistance to potyviruses in Phaseolus vulgaris L. II. Linkage relations and utility of a dominant gene for lethal systemic necrosis to soybean mosaic virus

Summary A single dominant factor, Hss, that conditions a rapid lethal necrotic response to soybean mosaic virus (SMV) has been identified in Phaseolus vulgaris L. cv. Black Turtle Soup, line BT-1. Inoculated plants carrying this factor developed pinpoint necrotic lesions on inoculated tissue followed by systemic vascular necrosis and plant death within about 7 days, regardless of ambient temperature. BT-1 also carries dominant resistance to potyviruses attributed to the tightly linked or identical factors, I, Bcm, Cam, and Hsw, so linkage with Hss was evaluated. No recombinants were identified among 381 F₃ families segregating for potyvirus susceptibility, thus if Hss is a distinct factor, it is tightly linked to I, Bcm, Cam, and Hsw. BT-1 was also crossed reciprocally with the line Great Northern 1140 (GN 1140) in which the dominant gene, Smv, for systemic resistance to SMV was first identified. Smv and Hss segregated independently and are co-dominant. The (GN 1140 x BT-1) F₁ populations showed a seasonal shift of the codominant phenotype. Evaluation of the (GN 1140 x BT-1) F₂ population under conditions where Smv is partially dominant allowed additional phenotypic classes to be distinguished. Pathotype specificity has not been demonstrated for either Smv or Hss. Genotypes that are homozygous for both dominant alleles are systemically resistant to the virus and in addition show undetectable local viral replication or and no seed transmission. This work demonstrates that a gene which conditions a systemic lethal response to a pathogen may be combined with additional gene(s) to create an improved resistant phenotype.     

The inheritance of host plant resistance and its effect on the relative infection efficiency of Magnaporthe grisea in rice cultivars

The inheritance of host plant resistance and its effect on the relative infection efficiency for leaf blast was studied in the crosses IR36/CO39 (partially resistant × highly susceptible) and IR36/IR64 (both partially resistant). On the natural scale, gene action appeared multiplicative. After log transformation, additive effects described most of the genetic variation in the cross IR36/CO39, while additive and dominance effects were about equal in magnitude in the cross IR36/IR64. Dominance was towards increased resistance. No transgressive segregation occurred in the cross IR36/CO39. The number of genes that reduce lesion number was estimated to be zero in CO39 and five or more in IR36. The cross IR36/IR64 showed transgressive segregation in both directions, and IR36 and IR64 each contain at least one gene that is not present in the other cultivar. The heritabilities (narrow sense) in the F₂ were low (range 0.06–0.16), while narrow sense heritabilities based on F₃ lines were much higher (range 0.41–0.68). Lesion numbers in F₃ lines were reasonably correlated with those in F₅ progenies derived from the same F₂ plant (r was±0.6 in both crosses). Partial resistance can be effectively improved by selecting the most resistant plants from the most resistant F₃ lines.     

Resolution of components of non-photochemical chlorophyll fluorescence quenching in barley leaves

Non-photochemical chlorophyll fluorescence quenching (qN) in barley leaves has been analysed by monitoring its relaxation in the dark, by applying saturating pulses of light. At least three kinetically distinct phases to qN recovery are observed, which have previously been identified (Quick and Stitt 1989) as being due to high-energy state quenching (fast), excitation energy redistribution due to a state transition (medium) and photoinhibition (slow). However, measurements of chlorophyll fluorescence at 77 K from leaf extracts show that state transitions only occur in low light conditions, whereas the medium component of qN is very large in high light. The source of that part of the medium component not accounted for by a state transition is discussed.Abbreviations ATP adenosine 5-triphosphate - DCMU 3[3,4-dichlorophenyl]-1,1 dimethylurea - pH trans-thylakoid pH gradient - F_o, F_m room-temperature chlorophyll fluorescence yield with all reaction centres open, closed - F_v variable fluorescence = F_m–F_o - LHC II Light harvesting complex II - PS I, PS II Photosystem I, II - P700, P680 primary donor in photosystem I, II - qP photochemical quenching of variable fluorescence - qN non-photochemical quenching of variable fluorescence - qN_e, qN_t, qN_i non-photochemical quenching due to high energy state, state transition, photoinhibition - qN_f, qN_m, qN_s components of qN relaxing fast, medium, slow - q_r quenching of r relative to the dark state - tricine N-tris[hydroxymethyl]methylglycine - r ratio of fluorescence maximum from photosystem II to that from photosystem I at 77 K     

Cytogenetic studies of the F1 hybrids of Capsicum annuum with C. chinense and C. baccatum

Summary Partially sterile interspecific hybrids were obtained between C. annuum var. cerasiformis and C. chinense var. mishme (H₁), and C. annuum var. cerasiformis and C. baccatum var. pendulum (H₂). Morphologically the F₁ hybrids were intermediate between the corresponding parents. Meiosis was irregular in the two F₁ hybrids. Cytological analysis of the two F₁ hybrids revealed that the genome of C. annuum differs from C. chinense by two translocations and some minor structural alterations and from C. baccatum by two translocations, a single inversion and some minor structural alterations. Isolation barriers such as hybrid inviability, weakness and hybrid breakdown in the H₁ hybrid and, inaddition, desynapsis in the H₂, were operative in these taxa. The differences between the present findings and those reported earlier on the two F₁hybrids were attributed to differences in the genetic architecture of the taxa employed in hybridization.     

Transmission of primary trisomics in pearl millet

Summary Transmission rates of extra chromosomes found in the full set of trisomics of pearl millet (Pennisetum americanum) (2n = 14) were estimated by examining the progeny of selfed trisomics and the progeny of trisomics crossed to disomics. When the trisomics were selfed, dark green and tiny had the highest transmission rate (23.8% and 23.3%, respectively) and pseudonormal the lowest (13.8%). Other trisomics had an intermediate rate of transmission. When the trisomics were used as females in crosses with disomics, both dark green and tiny again had the highest transmission rate and pseudonormal the lowest. When the trisomics were used as males in crosses to disomics, no trisomic was transmitted to the progeny except for spindle, and this occurred with a very low frequency (2.0%). A variation in transmission rate was observed from plant to plant and season to season for the same trisomic type. A study of the transmission rate of the extra chromosomes indicated that the following factors were probably contributing to the lower rate of transmission: small- or light-weight seeds tended to have a higher proportion of trisomics than heavier seeds; lighter seeds had a lower percentage germination; a positive and significant correlation was noticed between trivalent frequency and transmission rate. Plants with reduced vigour produced a higher frequency of trisomics. Though trisomics involving longer extra chromosomes showed a high degree of pollen and ovule sterility, they were highly transmissible. This has resulted in a close relationship between gametic sterility and transmission rate of extra chromosome.     

Inheritance of early elongation ability in floating rice revealed by diallel and QTL analyses

In floating rice, stem elongation begins much earlier than in non-floating rice, which is the major survival mechanism for flooding. Inheritance of this early elongation ability was studied using diallel and quantitative trait locus (QTL) analyses. The diallel analysis was undertaken using a set of 6×6 half-diallel crosses involving four floating (Goai, Habiganj Aman VIII, Badal 106, and Oryza rufipogon strain W120) and two non-floating (Latisail and Patnai 23) parents. The additive gene effects were higher than the dominant effects. The dominant alleles were concentrated in the cultivated floating parents (Goai, Habiganj Aman VIII, and Badal 106), whereas the recessive alleles were in the wild floating parent (W120). A QTL analysis using a Patnai 23 × Goai F₂ population detected two putative QTLs. Of these QTLs, the one on chromosome 12 behaved as a partially dominant major gene that explained more than half of the total genetic variation.Communicated by D.J. Mackill     

Meiosis and fertility of F1 hybrids between hexaploid bread wheat and decaploid tall wheatgrass (Thinopyrum ponticum)

As the first step in the transfer of barely yellow dwarf virus resistance and salt tolerance from decaploid tall wheatgrass (Thinopyrum ponticum) into hexaploid bread wheat (Triticum aestivum L.), octoploid intergeneric hybrids (2n = 8x = 56) were synthesized by crossing the tall wheatgrass cultivar Alkar with wheat cvs. Fukuhokomugi (Fuko) and Chinese Spring. (Fuko x Alkar) F₁ hybrids were studied in detail. The F₁ hybrids were perennial and generally resembled the male wheatgrass parent with regard to morphological features and gliadin profile. Most hybrids were euploid with 56 chromosomes and showed high chromosome pairing. On an average, in 6 hybrids 83.6% of the complement showed chiasmatic association, some between wheat and wheatgrass chromosomes. Such a high homoeologous pairing would be obtained if Ph1, the major homoeologous pairing suppressor in wheat, was somehow inactivated. Some of the Fuko x Alkar hybrids had high pollen fertility (18.5–42.0% with a mean of 31.5%) and high seed fertility (3–29 seeds wtih a mean of 12.3 seeds per spike), offering excellent opportunities for their direct backcrossing onto the wheat parent.     

F1 hybrid versus 32 selected F7 lines performance of common winter wheat (Triticum aestivum ssp. vulgare)

Summary One F₁ common wheat hybrid (Zlatna Dolina x Primépi) which had exhibited significant heterosis in a previous study was compared with 32 F₇ lines selected from the same cross. The yield test was planted in the 1976–1977 season at two locations: Zagreb, Yugoslavia (optimal environment) and Hutchinson, Kansas, USA (stress environment). The purpose of this experiment was to determine if a homozygous segregant superior to the F₁ hybrid could be obtained from the same cross combination.Heading date, plant height, disease incidence, grain yield and its components, protein content, and sedimentation value were examined at Zagreb. Germination, winterhardiness and grain yield were determined at Hutchinson.At Zagreb, the F₁ hybrid exhibited significant heterosis in grain yield, even though two of the three yield components were intermediate to parent values. Heterotic effects were greater in the stress environment (Hutchinson), mainly due to the poor winterhardiness and lower yield of one parent variety. At Zagreb, grain yield of the f₁ hybrid was significantly better than the best F₇ line. However at Hutchinson, the two leading F₇ Unes outyielded the f₁ hybrid, but differences were not significant.It can be concluded that genes involved in heterosis in the hybrid, Zlatna Dolina x Primépi, were not fixed in the homozygous lines selected from the same cross.