Inheritance of shelf life and other quality traits of tomato fruit estimated from F<Subscript>1</Subscript>’s,F<Subscript>2</Subscript>’s and backcross generations derived from standard cultivar, <Emphasis Type="Italic">nor</Emphasis> homozygote and wild cherry tomato

A tomato cultivar with high quality fruit and a long shelf life is a main goal in tomato breeding and it would be achieved using wild germplasm. The objective of this work was to explore the inheritance for fruit quality traits, especially fruit shelf life, in three tomato crosses using a standard Argentinean cultivar (Ca, cv ‘Caimanta’), a ripening mutant (nor, homozygous for the nor gene) of Solanum lycopersicum, and a wild cherry type (Ce, LA1385 of S. lycopersicum var. cerasiforme). The wild parent had a shorter fruit shelf life than the mutant genotype but higher than Ca. When the Ce genotype was analyzed in hybrid combination, the F₁ (Ca×Ce) was similar to the wild genotype for shelf life whereas the F₁ (nor × Ce) had a longer shelf life. Both F₁ crosses and backcrosses to the cherry type genotype had significantly lower fruit weight than the cultivated genotypes but higher than the cherry type parent. In the F₂ analysis, it was found that the inheritance underlying quality traits is complex since non allelic interactions were detected. A significant additive genetic variance was found for fruit shelf life as well as for other fruit quality traits in each cross. The genetic parameters analyzed by mean values and variances in parental, F₁ and F₂ and backcross generations indicated that the cross between the normal ripening cultivar and LA1385 of S. lycopersicum var. cerasiforme offers the best possibility to obtain long shelf life tomato genotypes with good fruit quality.     

Inheritance of resistance to stripe rust (Puccinia striformis) in crosses between wild emmer (Triticum dicoccoides) and cultivated tetraploid and hexaploid wheats. I. Triticum durum

Summary Reciprocal crosses were carried out between Triticum dicoccoides sel. G-25-highly resistant to Puccinia striiformis race 20A-and Triticum durum cultivar Nursith 163-which served as susceptible parent.F₁ hybrids in one of the crosses showed a wide range of infection types to the test isolate, whereas in a repeated cross all F₁ plants proved highly resistant. The variable reaction pattern observed in the F₁ hybrids of the first cross suggests incomplete penetrance of the resistance factor in certain environmental conditions.The segregation ratio displayed by the F₂ progenies indicates that a single dominant factor for resistance to stripe rust race 20A was transferred from wild emmer to cultivated durum wheat.Contribution from the Agricultural Research Organization, Volcani Center, Bet Dagan, Israel. 1973 Series, No. 291-E.     

On the inheritance of tuber resistance of solanum tuberosum to phytophthora infestans in the field

Data on the attack of the tubers of 2,036 F₁ seedlings of 32 different cross combinations of potato varieties were collected. A survey is given of the field resistance of a large number of established varieties and of their parents.From both sets of data it appears that crossing two highly resistant parents results in a high percentage of resistant offspring. When crossing a susceptible with a resistant parent one gets a majority of resistant F₁ seedlings and even among the offspring of two susceptible varieties a few resistant seedlings are encountered.The genes R ₁ and R ₃ for hypersensivity of the leaves exert a strong influence. Preliminary data suggest that the cambial layer just below the skin in this case is a strong barrier to the penetration of the parasite as is stated also with some varieties devoid of R-genes (Bravo, Libertas and others).     

Inheritance of quality traits in processing tomato (Lycopersicon esculentum Mill.)

Summary The genetic basis of pH, colour and soluble solids in processing tomato is examined. In a first experiment, aimed at identifying the base populations with which to start selection, parents, F₁ and F₂ progenies of an 8 × 8 diallel cross without reciprocals were tested.The results indicate that additive, dominance and additive x additive epistatic effects were noticeable for the three characters. Higher order interlocus interactions were also detected.As to the soluble solids, a trait for which higher order epistatic effects were less marked, the breeding potential of the cross combinations was assessed by calculating the expected mean values at the F generation. Some cross populations having C33 or C35 as parent appeared to be superior.A second experiment was conducted to collect data on the heritability of the foregoing qualitative traits by utilizing the regressions of F₃ offspring on F₂ parents. The low heritability coefficients observed would suggest the ineffectiveness of individual selection in early generations.In both the F₂ and F₃ generations rather low correlation coefficients among the three quality traits were observed.     

大红花蝴蝶兰杂交后代观赏性状分离规律研究

[目的]为研究蝴蝶兰观赏性状遗传规律,优化杂交亲本,更加高效的培育高品质的蝴蝶兰新品种。[方法]以5份大红花蝴蝶兰为材料,设计了3组正反交杂交组合,并对杂种后代花底色、花径、花朵数、花梗高度、植株冠幅等主要观赏性状进行了观测分析。[结果]结果表明,3个组合正反交杂种后代,花底色、花朵数、花梗高度等性状杂种优势明显,在花色上出现了亲本没有的花斑变化,正反交分离表现明显不同,深紫红色大红花作为母本时,获得深色杂种后代的几率更高;3个杂交组合正反交杂种后代花径分离表现不尽相同,‘T’和‘R’组合正反交杂种后代花径则表现超亲优势,而‘133’和‘62’,‘J’和‘62’正反交则表现出一定程度的衰退现象,当母本花径较大时,杂种后代花径总体较大,但获得超亲花径的比例低;3个组合正反交植株冠幅均表现一定程度的衰退现象。[结论]该研究结果初步阐明大红花杂种后代主要观赏性状的分离表现,为蝴蝶兰育种亲本的选配和新品种选育提供理论依据。     

Successful interspecific hybridization between Cucumis sativus L. and C. hystrix Chakr.

Interspecific F₁ hybrids were obtained from a cross between Cucumis sativus L. (2n = 2x = 14) and C. hystrix Chakr. (2n = 2x = 24). Controlled crossing resulted in fruit containing embryos which were excised and rescued on a Murashige and Skoog solid medium. A total of 59 vigorous plants were obtained from a fruit containing 159 embryos (37.3% regeneration rate). Hybrid plants were morphologically uniform. The multiple branching habit, densely brown hairs (especially on corolla and pistil), orange-yellow collora, and ovate fruit of F₁ hybrid plants were similar to that of the C. hystrix paternal parent. While appearance of the first pistillate flower was more similar to that of C. sativus maternal parent than to C. hystrix, staminate flower appearance was mid-parent in occurence. The diameter and internode length of stem, shape and size of leaves and flowers were intermediate when compared to the parents. An elongated green, trilobate style/stigma which was not apparent in either parent was observed in staminate flowers of F₁ plants. Similarly, the style/stigma of pistillate flower of F₁ plants were longger when compared to their parents. The brown pubescence observed on pistillate flowers of the F₁ and C. hystrix was not observed on the C. sativus parent. The somatic chromosome number of F₁ plants was 19. Two morphologically distinct groups of chromosomes were observed in the F₁ hybrid; 7 relatively large chromosomes characteristic of C. sativus, and 12 smaller chromosomes characteristic of C. hystrix. Analysis of malate dehydrogenase isozyme banding patterns provided additional comfirmation of hybridity. Reciprocal crossing of F₁ plants to either parent and self-crossing indicated that the hybrids were male and female sterile. This revised version was published online in July 2006 with corrections to the Cover Date.     

Relationship between heterosis and genetic distance based on morphological traits and AFLP markers in pepper

Genetic diversity is considered as one of the criteria for the selection of parents for hybrid breeding. The present study was undertaken to evaluate genetic divergence among seven pepper cultivars and to assess the relationship between heterosis and parental genetic distance. Twenty‐one F₁ hybrids and seven parents were evaluated for 15 morphological characters in a greenhouse and in the field. The parents were examined for DNA polymorphisms using six amplified fragment length polymorphism (AFLP) primer combinations. Cluster analysis using two genetic distance measures grouped the seven parents differently. Mid‐parent and high‐parent heterosis was observed for most characters. Most hybrids outperformed the parental lines for fruit yield, earliness and plant height. Morphological and AFLP‐based distance measurements were efficient enough to allocate pepper genotypes into heterotic groups. The correlations of morphological distances with mid‐parent heterosis were significant for days to flowering and maturity, suggesting earliness can be predicted from morphological distances of parental lines. However, the correlations of AFLP‐measured genetic distances with mid‐ and high‐parent heterosis were non‐significant for all characters, except for fruit diameter, and proved to be of no predictive value.     

Shading of plants facilitates selection for powdery mildew resistance in Squash

Summary Powdery mildew development was assessed on squash (Cucurbita pepo) plants of a susceptible cultivar, a resistant accession, their F₁, and their F₂ in an early summer planting in the field, covered or not covered with a shading net. Three reaction types were observed: susceptible, powdery mildew on stems and on both, the upper and lower leaf surfaces, as in the susceptible parent; resistant, no powdery mildew on leaves or stems, as in the resistant parent; and partially resistant, powdery mildew on upper leaf surfaces only, as in the F₁. Disease presence on the stem was associated with susceptibility. Shading hastened the appearance of powdery mildew and increased the severity of infection on partially resistant and susceptible plants, facilitating identification of resistant individuals in the F₂ population.Contribution No. 1613-E from the Agricultural Research Organization, Bet Dagan, Israel     

A study of diallel crosses between varieties of nicotiana tabacum L. for yield components

To predict the behaviour of selections in the F₁ generation itself before taking them to the advanced generations for further screening, the applicability of diallel cross analysis was studied.For this purpose four N. tabacum varieties were crossed in all combinations to constitute a diallel system and data collected on green leaf, saleable leaf i.e. sum of bright leaf and medium leaf yields, number of days taken for flowering, length and breadth of the middle leaves at maturity of the F₁ plants were subjected to Jinks and Hayman method of analysis.The results showed that Delcrest is a good combiner in throwing better recombinations. It always improved the yielding potential of the poorer parent. In the light of the graphical analysis, the results were discussed in relation to the improvement of the crop and predictions made as to which cross throws better strains. The characters studied are mostly additive in gene action. The scope of this method in the breeding projects to evolve superior strains was outlined.     

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.     

甘蓝型油菜黄化突变体的光合特性及叶绿素荧光参数分析

调查油菜自发黄化突变体(NY)、野生型(NG)及其正反交后代材料(F₁和rF₁)的光合色素含量、光合特性、叶绿素荧光参数及农艺性状,分析五叶期各参数的变化规律。表明,突变体叶绿素a、叶绿素b、类胡萝卜素和总叶绿素均大幅减少,其中叶绿素b减幅最大;净光合速率显著降低,胞间CO₂浓度升高,但气孔导度与野生型等相当,表明光合速率不受气孔限制;光补偿点和光饱和点升高,暗呼吸速率与野生型等相当,表观量子效率和光补偿点处量子效率显著降低;CO₂补偿点、光呼吸速率和羧化效率均显著降低,CO₂饱和点则显著升高;突变体的荧光参数,包括F_o、F_m、F_v/F_m、F_v'/F_m'、Φ_PSII、q_p、NPQ和ETR均显著降低,说明光合色素含量降低导致PSII反应中心捕光能力弱和光化学转化效率低,使叶片光合速率降低。突变体的黄化持续时间较长,对生长发育产生影响较大,单株籽粒产量只有野生型的57.09%,但与正常材料组配F₁的光合特性和农艺性状均能恢复到正常水平。     

Cross compatibility between Abelmoschus esculentus and A. moschatus

Interspecific cross compatibility between cultivated and wild okra (Abelmoschus esculentus and A. moschatus) and pollen tube growth behaviour in the crosses among a local cultivar of A. esculentus, A. moschatus and their F₁s were studied. Fruit set was observed in all the crosses except one and seed setting was absent in two of the crosses which set fruit. All seed produced were shrivelled but F₁ plants were obtained from two crosses where cultivated okra was used as the seed parent. The F₁ plants were perennial in nature with very low pollen viability and seed set. A high percentage of pollen germination and profuse pollen tube penetration in the style were observed in the cross A. esculentus × A. moschatus but low pollen tube penetration with abnormal pollen tubes was observed in the reciprocal cross. The number of pollen tubes was very low but they appeared to be normal in the backcross A. esculentus × F₁, but were generally abnormal in the reciprocal cross. Both pre- and postzygotic barriers seemed to occur in crosses between the two species. The present studies indicate that these barriers can be overcome and desirable characters from A. moschatus transferred to cultivated okra using conventional hybridisation techniques. This revised version was published online in July 2006 with corrections to the Cover Date.     

Some notes on the association between fruit dimensions and fruit weight in Capsicum annuum L.

Summary Previous reports on the inheritance of fruit dimensions in Capsicum suggested two contradictory views: independent inheritance of individual dimensions vs inheritance of a shape index, i.e., length/width ratio.The F₂ of a cross between parent lines that differed in fruit size and weight but had similar shape indices exhibited intermediate dominance in fruit weight and in fruit width for small size. The correlation between fruit shape (as measured by the length to width ratio) and fruit weight in the F₂ was small and not significantly different from zero. The two variables, fruit width and fruit length, accounted for 90% of the variation in fruit weight. Apparently one can select for fruit weight in the F₂ independently of fruit shape.     

Variation in flower abscission of peppers under stress shading conditions

Summary Seedlings from 77 accessions including inbreds, F₁ hybrids and seven F₂ populations were exposed to approximately 60% shading for 35 days following transplanting into the field.Most of the lines did not set fruit under the shading due to heavy abscission of flowers. A few exceptional lines, hybrids and F₂ segregants showed resistance to abscission and set normal fruits under the shading regime. This procedure is suggested for screening against stress-induced flower abscission. An association is suggested between resistance to shading and to high temperatures and its genetic control.Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel No. 1209-E, 1993 series.     

光子陆地棉种质资源主要性状的遗传评价

以102份光子陆地棉材料为母本,分别与遗传标准系TM-1杂交,获得102个F₁群体。采用随机区组设计,设置3个重复,对光子陆地棉材料主要性状进行遗传评价。结果表明,调查的11个性状表型差异均较大,材料间产量性状(株高、果枝数、铃数、铃重、衣分和子指)差异大于纤维品质性状(纤维长度、纤维强度、马克隆值、整齐度和伸长率),特别是衣分、铃数等性状差异更明显; 除果枝数、马克隆值、伸长率以外,光子亲本群体其他性状的平均值都小于F₁群体。而亲本群体所有性状的变异系数均大于F₁,不同光子材料的杂种优势有很大差别,中亲优势和超亲优势也有很大的差别,有些种质某些性状的中亲、超亲优势为负值,其后代性状表现劣势; 纤维品质性状的中亲、超亲优势与毛子程度均呈负相关,而产量性状的中亲、超亲优势与毛子程度均呈正相关,说明可利用光子材料杂种优势改良纤维品质,而其后代产量性状的杂种优势利用受到限制; SSR分子标记遗传相似系数与各个性状的中亲、超亲优势的相关都不显著,说明在光子材料的育种中,杂种优势是不能通过亲本之间的遗传背景相似程度来预测的。     

Studies on the breeding of self-pollinating cereals

The behaviour of 19 varieties of spring wheat under different environmental conditions is discussed in terms of the following five characters: weight per grain, grains per spikelet, spikelets per ear, ears per plant and yield of grain per plant. The first four of these characters (the components of yield) are shown by correlation analyses to be largely independent of each other.Four varieties, chosen because they each showed extreme values of one or more of the components of yield, were crossed in all possible combinations. The F₁ and F₂ of this diallel set of crosses was analysed for each character according to the method of Jinks and Hayman. The results are discussed in relation to crop improvement and predictions are made for each character as to which cross or crosses are likely to be the most profitable for the breeder. The future handling of this material in order to test these predictions is outlined.     

The inheritance of white fruit and stem color in summer squash Cucurbita pepo L.

Summary White fruited plants from the variety White bush were crossed to green and striped fruit in order to study the inheritance of white fruit in summer squash. The genetic ratio suggested that green fruit is controlled by two genes, C and R, and that one (C) has a dominant epistatic control. The white fruit is determined as ccrr. A third fruit color group appeared in the F₂, F₃ and BC₁, having white fruit after anthesis which changed to green during development. The genetic control for this fruit is suggested to be ccR..The green striped fruit showed a simple dominance (St) over the plain white.The dark stem of the Zucchini variety showed single gene dominance (D) over the light green stem.It was found that an association exists between the nonpersistent fruit color and dark green stem, and between white fruit and light green stem.Contribution from the Volcani Institute of Agricultural Research, Bet Dagan, Israel. 1968 Series; No. 1437E.     

库尔勒香梨部分果实性状遗传的研究

库尔勒香梨是中国久负盛名的梨果佳品。却存在着果个小、果心大的缺陷。为了传承香梨品质优势,克服其弱点,本课题组于1971年开始香梨为亲本的杂交育种工作。以6个梨的杂交组合、351株实生树为试材,进行了各组合亲本和后代的性状分析,探讨了各主要性状的遗传趋势。结果表明,杂交后代果实形状、肉质遗传倾向于亲本,倾亲率分别为68.09%和51.38%。梨果实大小为数量性状,杂种后代果个分离广泛,杂种后代果实普遍变小,各组合的遗传传递力在68.91%~117.51%之间,平均遗传传递力为93.11%。梨果实可溶性固形物含量呈数量性状遗传,杂种后代分离较广,其组合传递力平均为97.49%。     

Transfer of stem rust seedling resistance from wild diploid einkorn to tetraploid durum wheat by means of a triploid hybrid bridge

Summary Transfer of stem rust resistance from diploid wild einkorn, Triticum boeoticum, to susceptible Mindum and Spelmar, varieties of cultivated T. durum, was achieved by means of a triploid hybrid bridge and subsequent backcrossing to the tetraploid parent. Seedlings of the second hybrid generation segregated for resistance to race 14 of Puccinia graminis f.sp. tritici which was used as test race in this investigation. The F₃ and F₄ progenies included segregants which displayed seedling resistance also to races 17, 19, 21, 40, 53, 194, 222, 315 and 322. Since these were the same races which proved avirulent to the T. boeoticum donor but virulent to the T. durum recipients, it was concluded that the full pattern of resistance determined in the wild diploid parent of this cross was transferred to the tetraploid durum-like hybrid derivatives.Joint contribution from The Volcani Institute of Agricultural Research, Bet Dagan, 1970 Series, No. 1801-E, the Tel Aviv University, and the Hebrew University of Jerusalem, Israel.     

Interspecific hybrids in the genus Elaeis II. vegetative growth and yield of F1 hybrids E. guineensis x E. oleifera

Summary Yield and morphology of F₁ hybrids E. guineensis x E. oleifera are discussed. Yield of the hybrids in terms of total fruit weight is promising but the oil content of the mesocarp is intermediate between the parental species and lower than in E. guineensis. E. oleifera has a marked tendency towards the production of parthenocarpic fruits. This character is fully dominant in the hybrid. Because of this the percentage fruit per bunch in the hybrids therefore tends to become higher than in E. guineensis partly offsetting the lower percentage oil on mesocarp.The oil composition of the parental species and hybrids are compared.Height increment of the hybrids is substantially lower than of E. guineensis but annual frond production is approximately the same. There is some hybrid vigour for frond area. For most morphological, vegetative and reproductive characteristics E. oleifera exhibits complete dominance over E. guineensis.