Maternal effects and cytoplasmic inheritance of oleic and linoleic acid contents in sesame

Summary Responses to selection may be affected by cytoplasmic inheritance and maternal effects. Their effect on the content of oleic and linoleic acids in sesame seed oil (Sesame indicum L.) was studied using reciprocal crosses and reciprocal backcrosses. Separation of fatty acid methyl esters was carried out by gas liquid chromatography. Cytoplasmic inheritance for oleic and linoleic acids was found to be negligible in both types of crosses. Maternal effects were not observed in reciprocal crosses, however, they were detected in reciprocal F₁'s for both oleic and linoleic acids. This may be due to differences in phenological development of the parental lines affecting reciprocal crosses, but not reciprocal backcrosses.Contribution from the Department of Botany and Plant Sciences, University of California, Riverside, CA 92521. The senior author gratefully acknowledges receipt of a Fulbright-Hays Grant to carry out this study from the Fulbright Commission for Educational Interchange between the United States of America and Chile.     

Inheritance of reduced linolenic acid content in the Ethiopian mustard mutant N2-4961

The zero erucic acid Ethiopian mustard lines developed so far are characterized by an exceptionally high linolenic acid content in the seed oil. The mutant line N2‐4961, expressing low linolenic acid content in a high erucic acid background, was developed through chemical mutagenesis. The objective of this research was to study the inheritance of low linolenic acid content in this mutant. Line N2‐4961 was reciprocally crossed with its parent line C‐101 and the linolenic acid content of the reciprocal F₁, F₂ and BC₁ generations was studied. No maternal, cytoplasmic or dominance effects were detected in the analysis of F₁ seeds and F₁ plants from reciprocal crosses. Linolenic acid content segregated in 1: 2: 1 ratios in all the F₂ populations studied, suggesting monogenic inheritance. This was confirmed with the analysis of the reciprocal backcross generation. The simple inheritance of low linolenic acid content in N2‐4961 will facilitate the transference of this trait to zero erucic acid lines of Ethiopian mustard.     

Inheritance of isoflavone contents in soybean seeds

Summary We studied the genetic basis of isoflavone content inheritance in soybean seeds. The progenitors BARC-8 (low isoflavone content), IAC-100 (high isoflavone content), the F₁ and F₂ populations derived from reciprocal crosses, and backcross populations were analyzed for isoflavone content and composition. Six isoflavones were detected: daidzin (DZ), genistin (GT), glycitin (GC), malonyldaidzin (MDZ), malonylgenistin (MGT) and malonylglycitin (MGC). DZ, GT, MDZ and MGT contents were influenced by the cytoplasm and the nuclear genes of the maternal parent. For this reason, a genetic model was considered that included the cytoplasmic effect and epistasis between nuclear and cytoplasmic genes. Except for GT, the additive effect was the most important one. For GT content the cytoplasmic effect was the most important. Except for MDZ, the epistatic effects were significant for all the isoflavone forms. Our data indicate that genetic improvement for these traits should explore the additive genetic variances in superior lines or the cytoplasmic effect and the epistatic interactions between cytoplasmic and nuclear genes to obtain the largest selection gains.     

Large yield differences between reciprocal families of Solanum tuberosum

Summary A number of reports have indicated differences in reciprocal families of Solanum tuberosum when intergroup hybrids were studied. Questions have been raised concerning the potential magnitude, frequency, and genetic basis for such differences. In this study, exact reciprocal crosses were made using parents characterized by different maturities and having different cytoplasmic sources within Solanum tuberosum in order to substantiate previous claims of reciprocal differences and to clarify the nature of such differences.Field trials revealed reciprocal differences which were large and highly significant. Reciprocal yield differences of up to 115% were observed when parents of opposite maturities were used. In seven crosses, the higher-yielding reciprocal always had the higher-yielding parent as the maternal parent. Significant reciprocal differences for flowering and vine maturity were also observed between some families. The F₂ populations were generated for one set of reciprocals and the reciprocal differences in the F₂ generation seemed to be substantially reduced relative to the F₁ generation.It is concluded that the occurrence of large reciprocal differences seems to depend more upon having parents of opposite maturity than upon the taxonomic origin of the parent's cytoplasm. This, in conjunction with the reduced F₂ reciprocal differences, suggests that observed differences may be due to very persistent maternal effects or a type of dauermodification, rather than true cytoplasmic inheritance.Cooperative Investigation of U.S. Department of Agriculture, Science and Education Administration. Agricultural Research and the Wisconsin Agricultural Experiment Station.     

Genetic analysis of resistance to <Emphasis Type="Italic">Fusarium</Emphasis> root rot in common bean

Fusarium root rot (FRR) is a major disease of common bean worldwide. Knowledge of the inheritance of resistance to FRR would be important in devising strategies to breed resistant varieties. Therefore, a 12 × 12 full diallel mating scheme with reciprocal crosses was performed to generate 132 F₁ progenies, which were then advanced to the F₃. The progenies were evaluated for resistance to FRR under green house conditions in Uganda. General combining ability (GCA) effects were highly significant (P ≤ 0.01) for disease scores. Specific combining ability effects were not significant (P > 0.05) in the F₁, but were highly significant (P < 0.01) in the F₃ generation. These results indicate that resistance to FRR was governed by genes with additive effects in combination with genes with non-additive effects. Reciprocal differences were also significant (P = 0.01) at F₁ and F₃, primarily reflecting a large influence of maternal effects in both these generations. In fact, susceptible parents did not differ significantly (P > 0.05) for disease scores when used as paternal parents in the F₃, but differed strongly as maternal parents (P = 0.0002). Generally, the progenies were distinctly more resistant when the resistant parent was used as the female in crosses, especially as observed in the F₃. The maternal effects were strong in the F₃ generation, suggesting a complex form of cytoplasmic–genetic interaction. The non-maternal reciprocal effects in the F₃ were significant (P < 0.05) in both the resistant × resistant diallel, and in the resistant × susceptible crosses. Mid-parent heterosis (MPH) occurred in most crosses, with average heterosis approximately equal in each of the three generations, indicating that epistasis was probably more influential than dominance of individual genes. Gene-number formulas indicated that several genes were involved in resistant × susceptible crosses. Among resistant × resistant crosses, many produced continuous distributions of F₁ progeny scores, suggesting polygenic inheritance, while bi-modal distributions were characteristic of the F₃ distributions, and fit expected ratios for two or three loci segregating in each cross. Dominant forms of epistasis favoring resistance were strongly indicated. Parent–offspring heritability estimates were moderate. Overall, the results indicate that resistant parents contain a number of different resistance genes that can be combined with the expectation of producing strong and durable resistance. The lines MLB-49-89A, MLB-48-89, RWR719 and Vuninkingi, with large and negative GCA effects, contributed high levels of resistance in crosses and would be recommended for use in breeding programs.     

Genetics of the Erucic Acid Content in Interspecific Hybrids of Ethiopian Mustard (Brassies carinata Braun) and Rapeseed (B. napus L.)

Ethiopian mustard (Brassica carinata Braun) is a potential oil crop in which genes for low erucic acid content of the seed oil have not yet been found. In order to solve this problem the potential of rapeseed (B. napus L.) varieties as a source of these genes has been tested. Reciprocal F₁ hybrids between B. carinata and a low erucic acid variety of B. napus, F₂, and backcrosses with B. carinata were obtained. The fatty acid composition was determined in half seeds of F₁ and segregating generations from reciprocal interspecific crosses. The genetic analysis indicated that the erucic acid content of the seed oil of B. carinata is controlled by two genes with no dominance and additive in action.     

Genetic analysis of resistance to late leaf spot in interspecific groundnuts

Late leaf spot (LLS), caused by Phaeoisariopsis personata, is an important foliar fungal disease of groundnut (Arachis hypogaea L.), which causes significant economic losses globally to the crop. Inheritance of resistance to LLS disease was studied in three crosses and their reciprocals involving two resistant interspecific derivatives and a susceptible cultivar to refine strategy for LLS resistance breeding. The traits associated with LLS resistance, measured both in the field and under controlled conditions were studied following generation mean analysis. Results suggested that resistance to LLS is controlled by a combination of both, nuclear and maternal gene effects. Among nuclear gene effects, additive effect controlled majority of the variation. In JL 24 × ICG 11337 cross and its reciprocal only additive effects were important, while in JL 24 × ICG 13919 cross and its reciprocal, both additive and dominance effects contributed to the variation. Among digenic epistatic effects, additive × dominance interactions were significant. Additive–maternal effects were significant in both the crosses, while dominance–maternal effects also contributed to the variation in the crosses between the parents, JL 24 and ICG 13919. Due to significant contribution of additive effects of both nuclear and maternal inheritance to resistance to LLS, the parent, ICG 11337 would be a good donor in breeding programs. It would be worthwhile to use the resistance donor as female parent to tap maternal effects of resistance to LLS. Disease score is the best selection criterion in the field for use in breeding programs because of its high heritability and ease in measurement.     

低酚棉种仁含油量的母体效应和杂种优势分析

利用3个低酚棉品种配制的四个正、反交组合的F1、F2和回交世代对棉籽种仁含油量的母体效应和杂种优势进行了遗传分析。结果表明，棉籽的种仁含油量受母体基因型的控制，即存在母体效应，细胞质效应对种仁含油量无显著影响。用种仁含油量高的品种作母本配制的杂种一代（F1）棉籽，其种仁含油量有极显著的中亲和高亲优势，F2棉籽种仁含油量的自交衰退率虽较大，但其中亲优势仍较大，且优于用低种仁含油量品种作母本配制的杂种二代（F2）棉籽。利用杂种优势是提高棉籽种仁含油量的有效方法，其中的关键是亲本选配。此外，本文还讨论了棉籽含油量遗传研究的模型选择问题和提高棉籽含油量的育种方法问题。     

Inheritance of Dry Root Rot (Rhizoctonia bataticola) Resistance in Chickpea (Cicer arietinum)

The inheritance of resistance to dry root rot of chickpea caused by Rhizoctonia bataticola was studied. Parental F₁ and F₂ populations of two resistant and two susceptible parents, along with 49 F₁ progenies of one of the resistant × susceptible crosses were rested for their reaction to dry root rot using the blotting-paper technique. All F, plants of the resistant × susceptible crosses were resistant; the F₂ generation fitted a 3 resistant: 1 susceptible ratio indicating monogenic inheritance, with resistance dominant over susceptibility. F³ family segregation data confirmed the results. No segregation occurred among the progeny of resistant × resistant and susceptible × susceptible crosses.     

Identifying apomixis in matroclinal progeny from an interspecific crossing between <Emphasis Type="Italic">Iris domestica</Emphasis> and three different colors of <Emphasis Type="Italic">Iris dichotoma</Emphasis>

In a previous investigation on the reciprocal difference of interspecific hybridization between three different flower colors of Iris dichotoma and Iris domestica in the F₁ offspring from crosses where I. domestica was a maternal parent were similar in morphological and cytological characters to their maternal parent. This could be evidence of apomixis; however, matroclinal progeny with complete morphological similarity to the maternal parent could be attributed to the heterozygosity for these characters in the pollen parent. The F₁ plants were investigated in order to identify apomixis in I. domestica. Four matroclinal plants were randomly selected from each F₁ population produced from Iris domestica × Iris dichotoma that had three different colors of flowers and were allowed to self-pollinate to establish an F₂ population. All of the F₂ plants had no segregation to I. domestica in their morphological characters. In addition, 13 reciprocal F₁ plants were detected by 25,719 single nucleotide polymorphism (SNP) markers. When I. dichotoma plants with three different flower colors were used as maternal parents, all the progenies were genuine hybrids. When I. domestica were used as maternal parents, all the F₁ plants were apomictic progenies. Apomixis of I. domestica was successfully identified and SNP markers identified F₁ hybrids derived from six interspecific crosses between I. dichotoma and I. domestica, which provides a reference for authenticating offspring identity during Iris cross breeding in the future.     

Prediction of F6 line performance from F3 families in spring oilseed rape. I. Yield and other agronomic traits

Summary The reliability of a selection among crosses based on a cross prediction in early generations was investigated in spring rapeseed. The performance of the parents, the F₂ generation, and random F₃ lines from four crosses were used to predict the probability of finding superior recombinant lines. These predictions were made for two years and compared with the observed performance of F₆ lines in the second of these two years and in an additional year. Predicted and observed performances coincided reasonably for the characters plant height, standability, maturity and an index calculated from seed yield, oil content and protein content. For seed yield and flowering time, the predictions were very unreliable. In conclusion, prediction methods may be useful in rapeseed breeding, if quality traits are of major commercial interest.     

Genetic effects on Fe, Zn, Mn and P contents in Indica black pericarp rice and their genetic correlations with grain characteristics

Complete diallel crosses with 6 varieties of black pericarp rice and 1 variety of aromatic white rice were conducted to analyze the seed, maternal and cytoplasmic genetic effects on Fe, Zn, Mn and P contents in kernels by using a genetic model for quantitative traits of seeds in parents and their F₁s and F₂s. Seed, maternal as well as cytoplasmic genetic effects controlled the contents of all the mineral elements studied. The seed genetic effects were found to be more influential than the maternal genetic effects on Fe, Zn, Mn contents. Seed additive effects constituted a major component of the genetic effects whereas the seed additive along with maternal additive and dominant effects formed the main part in the inheritance of P content. The heritabilities of seed effects on all the mineral contents were highly significant (p< 0.01). The estimated values of narrow-sense heritabilites of seed genetic effects on Fe, Zn and Mn contents were high, while those of seed and maternal effects on P content were intermediate. Single plant selection and single grain selection based on the seed mineral element contents were advocated to improve the hybrid progeny. Genetic correlations showed that there existed significant genetic correlations of seed additive, seed dominance, cytoplasm, maternal additive and maternal dominance between grain characteristics such as 100-grain weight,grain length, grain width, grain shape and mineral elements Fe, Zn, Mn and P contents. Indirect selection of grain characteristics may be one of the breeding methods to select for higher contents of Fe, Zn, Mn and P in black pericarp indica rice. This revised version was published online in July 2006 with corrections to the Cover Date.     

Compatibility between wild and cultivated common bean (Phaseolus vulgaris L.) genotypes of the Mesoamerican and Andean gene pools: Evidence from the inheritance of quantitative characters

The extent and distribution of incompatibility between gene pools (Mesoamerican and Andean) and evolutionary classes (wild, landrace and bred) of the common bean (Phaseolus vulgaris) was explored by seeking anomalous values of highly heritable quantitative traits in the progeny of crosses. Clear incompatibility (no progeny or sterile or deformed progeny) was shown by 28 crosses in a 12-parent wild × bred diallel cross, and 37 crosses in a 12-parent landrace × bred diallel cross. Incompatibility was particularly common in the progeny of certain genotypes, but was not consistently associated with the division between gene pools or evolutionary classes. When crosses showing clear incompatibility were eliminated from the data, days to flowering, number of seeds per pod, log (weight per seed) and seed roundness in the F₁ generation gave a good fit to an additive-dominance model, confirming that there is no overall tendency to incompatibility between the gene pools. There was a division between the gene pools with regard to log (weight per seed), as expected, but there was no such division, with regard either to the means of the parent lines or the distribution of the statistics V _r and W _r (which indicate the distribution of dominant alleles between genotypes), for the other quantitative variables. Differences between reciprocal crosses were strikingly widespread, and appeared generally to be due to cytoplasmic effects or cytoplasmic × nuclear interactions rather than maternal effects, indicating that the direction in which a cross is made may have a perceptible effect on the progeny that can be obtained from it. This revised version was published online in July 2006 with corrections to the Cover Date.     

Combining ability for yield,protein and oil of peanut lines from South American centers of diversity

Summary Ten peanut (Arachis hypogaea L.) lines, two from each of five centers of diversity in South America, and the F₂ generation of all possible crosses among them were used to characterize the variation for yield, fruit and seed traits and protein and oil content and to determine the breeding potential of the parents. Two of the parental lines belong to subspecies hypogaea and the other eight to subspecies fastigiata.Several crosses gave heterotic responses for yield. The parents of the crosses with significant heterosis generally came from different centers of diversity.Variation among both general and specific combining abilities was significant for all traits with the exception of the SCA estimate for protein percent. The component of variation for GCA was larger than the SCA component for all traits.A Spanish line and a Valencia-like intermediate line from the Guarani region had the highest GCA effects for fruit yield, seed yield and meat content and transmitted consistently their characteristics to their F₂ progeny. Some lines showed significant but small maternal effects for oil, protein and oil + protein percent. Differences between reciprocal crosses were significant for fruit length, fruit weight and oil + protein percent.A significant portion of the variation among crosses was explained by differences among parental lines within centers of diversity. This supports the fact that centers are founded because of the diversity of the peanuts grown there.The performance of parental lines per se was useful in predicting the performance of the lines in hybrid combination for all traits except fruit yield.Paper number 6141 of the Journal Series of the North Carolina Agricultural Research Service (USA). This work was partially supported by CSRS Research Agreement 701-15-51.     

Genetic analysis of resistance to bacterial leaf streak caused by Xanthomonas campestris pv. undulosa in bread wheat

Summary The inheritance of resistance to bacterial leaf streak or black chaff of wheat was studied under field conditions, with an artificial epidemic of Xanthomonas campestris pv. undulosa. A complete series of crosses between five parents, differing in reaction to X. c. pv. undulosa, was generated. Disease was recorded at two different stages of growth. No evidence of cytoplasmic effect was found from the comparison between reciprocal F₁ crosses. The study of the F₃ generations attested that five genes were involved in resistance to bacterial leaf streak. Separate analyses carried out for the two scoring dates were mutually consistent: genotypes, number of genes, and their action and relative importance were verified. The genes differed in strength of expression of resistance. One of the two strongest genes, Bls1, is present in all three superior parents, Pavon 76, Mochis T88 and Angostura F88. Resistance was not complete, and proved to be stable over the season.     

Inheritance of seed resistance to bruchids in cultivated mungbean (Vigna radiata, L. Wilczek)

Bruchid beetles or seed weevils are the most devastating stored pests of grain legumes causing considerable loss to mungbean (Vigna radiata (L.) Wilczek). Breeding for bruchid resistance is a major goal in mungbean improvement. Few sources of resistance in cultivated genepool were identified and characterized, however, there has been no study on the genetic control of the resistance. In this study, we investigated the inheritance of seed resistance to Callosobruchus chinensis (L.) and C. maculatus (F.) in two landrace mungbean accessions, V2709BG and V2802BG. The F₁, F₂ and BC generations were developed from crosses between the resistant and susceptible accessions and evaluated for resistance to the insects. It was found that resistance to bruchids in seeds is controlled by maternal plant genotype. All F₁ plants derived from both direct and reciprocal crosses exhibited resistance to the bruchids. Segregation pattern of reaction to the beetles in the F₂ and backcross populations showed that the resistance is controlled by a major gene, with resistance is dominant at varying degrees of expressivity. Although the presence of modifiers was also observed. The gene is likely the same locus in both V2709BG and V2802BG. The resistant gene is considered very useful in breeding for seed resistance to bruchids in mungbean.     

Effect of genetic background on the target fatty acids of acyl-ACP thioesterase transgenes in Brassica napus

Acyl‐acyl carrier protein (ACP) thioesterase (TE) is involved in the biosynthetic fatty acid pathway of plants. Conventional canola lines transformed individually with the bay‐TE (Uc FatB1), elm‐TE (Ua FatB1), nutmeg‐TE (Mf FatB1) or Cuphea‐TE transgene (Ch FatB1), produce seed oil with modified fatty acid compositions. This study assessed the effects of genetic background, cytoplasm, maternal parent, and interaction of different TE transgenes, on the target fatty acids using F1 seeds and double haploid (DH) lines. The F₁ seeds were produced by crossing four TE transgenic parental lines and three non‐transgenic cultivars with distinct fatty acid compositions. The DH lines were developed from microspores of F₁ plants. DH lines from different crosses showed that genetic background does not have an effect on the relative levels of the target fatty acids of the same TE, indicating the stability of the substrate specificity of the TE within canola. However, significant effects of genetic background on the content of the major target fatty acids, lauric acid (C12:0) or palmitic acid (C16:0) depending on the TE, were observed. Expression of the TE in low erucic acid (C22:1) genotypes resulted in higher target fatty acid levels than expression in high C22:1 genotypes. Reciprocal crosses showed maternal effects, but not cytoplasmic effects. In addition, co‐expression of two different TE transgenes in the same seeds was observed. These results indicate the importance of selection for appropriate genetic backgrounds in order to maximize the expression of the target fatty acids of TE transgenes, and also indicate potential uses of TE co‐expression in modifying canola seed oil.     

Inheritance of neurotoxin (ODAP) content, flower and seed coat colour in grass pea (Lathyrus sativus L.)

Summary A strong epidemiological association is known to exist between the consumption of grass pea and lathyrism. A neurotoxin, -N-Oxalyl-L-, -diaminopropanoic acid (ODAP) has been identified as the causative principle. This study was undertaken to investigate the mode of inheritance of the neurotoxin ODAP, flower and seed coat colour in grass pea. Five grass pea lines with low to high ODAP concentration were inter-crossed in all possible combinations to study the inheritance of the neurotoxin. Parents, F₁ and F₂ progenies were evaluated under field condition and ODAP analyzed by an ortho-phthalaldehyde spectrophotometric method. Many of the progenies of low x low ODAP crosses were found to be low in ODAP concentration indicating the low ODAP lines shared some genes in common for seed ODAP content. The F₁ progenies of the low ODAP x high ODAP crosses were intermediate in ODAP concentration and the F₂ progenies segregated covering the entire parental range. This continuous variation, together with very close to normal distribution of the F₂ population both of low x low and low x high ODAP crosses indicated that ODAP content was quantitatively inherited. Reciprocal crosses, in some cases, produced different results indicating a maternal effect on ODAP concentration. Blue and white flower coloured lines of grass pea were inter-crossed to study the inheritance of flower colour. Blue flower colour was dominant over the white. The F₂ progenies segregated in a 13:3 ratio indicating involvement of two genes with inhibiting gene interactions. The gene symbol LB for blue flower colour and LW for white flower colour is proposed.     

Diallel analysis of callus formation ability in linseed anther culture

In linseed, the time needed to obtain pure lines can be reduced by using in vitro anther culture. The technique has been improved but there are no reports on the inheritance of the characters (callogenesis and regeneration) involved in the response. To shed some light on this aspect, anthers of four linseed varieties and their F₁ were cultivated in vitro. Callogenesis response was analysed according to a full diallel model. Among 7811 anthers, the percentage of callogenesis ranged from 27.40 to 82.04%, with the parental lines being around the average. The differences between specific hybrid combinations were significant and general and specific combining ability were highly significant. As well as dominant effects, additive and non‐additive effects are probable components of the heritability of this character, although additive effects would be more important than non‐additive. Differences between reciprocal crosses would indicate that cytoplasmic factors could also be involved in the determination of the character.     

棕色棉与白色棉杂交F1代吐絮期光合特性的杂种优势研究

 选择4个棕色棉品种（系）与5个白色棉品种进行不完全双列杂交,得正反交组合各20个,测定了吐絮期正反交组合的净光合速率、胞间CO₂浓度、叶绿素含量,叶绿素a/b、PSII的最大光化学效率,分析杂交F₁代光合参数的杂种优势表现与正反交之间的差异。结果表明：吐絮期杂种F₁各项光合参数没有明显的正向中亲优势、正向超亲优势。正反交组合之间,除胞间CO₂浓度存在显著差异外,其它光合参数差异不显著,胞间CO₂浓度受到细胞质效应影响。正交组合F1叶绿素含量与胞间CO₂浓度存在显著正相关,反交组合F₁净光合速率与胞间CO₂浓度存在极显著正相关。