Intervarietal Hybrids Research Articles

Inheritance of economically valuable features in F1 hybrids of vegetable haricot bean

The aim and tasks of the study were to investigate peculiarities of inheritance of economically valuable features in intervarietal hybrids of F1 vegetable haricot bean.Material and methods. The study was conducted in 2014. The test material was 9 simple F1 hybrids. Hybrids were grown by the conventional technology for the Forest-Steppe zone. To calculate heterosis and dominance degree, formulae suggested by Chr. DaskalevandB. Griffing were used.Results and discussion. The article presents results of studying the peculiarities of inheritance of economically valuable features in intervarietal hybrids of F1 vegetable haricot bean. We identified varieties that are valuable as components for hybridization investigated some features of inheritance of economically valuable features in F1 hybrids. The study also elucidated that the growing season and its interphase period lengthsby F1 hybrids were inhe3rited via all types ofdominance, however, cross combinations with intermediate inheritance, positive dominance and overdominance prevailed. Inheritance of the lowest pod attachment height above the soil surface included all transitions from positive overdominance to intermediate inheritance. Overdominance prevailed in inheritance of productivity traits, such as "pod number per plant", "seed number per pod", "1000-seed weight", "seed number per plant", "seed weight per plant," in F1 plants.Conclusions. The study showed that the heterosis effect was the highest in F1 intervarietal haricot bean hybrids for the following productivity components: "seed number per pod", “seed and pod numbers per plant” and “seed weight per plant”

Cryopreservation of Bituminaria bituminosa varieties and hybrids

Bituminaria bituminosa (L.) C.H. Stirton is a drought tolerant, perennial legume pasture species and a source of pharmaceutical compounds. Bituminaria breeding programs aim to develop and conserve hybrids with desirable traits such as high forage quality, tolerance to biotic or abiotic stresses, and high contents of furanocoumarins. In this work we present a cryopreservation study of different B. bituminosa accessions: two varieties and eight intervarietal hybrids resulting from crosses between the three botanical varieties: var. bituminosa, var. crassiuscula, and var. albomarginata. No previous work on cryopreservation of Bituminaria species has been reported. We applied the ultra-fast cooling method, using droplet vitrification on aluminum foil strips. First, we investigated the PVS2 toxicity and cryopreservation damage in two genotypes, comparing three PVS2 treatments and two culture media. An incubation of 30min in PVS2 resulted in regeneration rates after cryopreservation higher than 80%. The MS medium was selected for optimal meristem outgrowth, in order to avoid the prominent callus formation that was observed in the presence of BAP. These conditions were subsequently used to cryopreserve eight other genotypes. The results were highly variable; 45days after cryopreservation, survival ranged between 22% and 98% while regeneration ranged between 0% and 96%, depending on the accession. A significant and positive correlation was observed between survival and regeneration. At 90days post culture plantlets could be recovered from cryopreserved explants of all genotypes. This study shows that the droplet vitrification method is promising for the cryopreservation of eight of the 10 genotypes assayed and the method can thus be applied to develop a cryobank of B. bituminosa.

Evidence for genetic incompatibilities associated with post-zygotic reproductive isolation in the human fungal pathogen Cryptococcus neoformans.

Hybridization is a potent mechanism for generating unique strains with broad host ranges and increased virulence in fungal pathogens. In the opportunistic basidiomycete pathogen Cryptococcus neoformans, intervarietal hybrids are commonly found infecting patients. The two parental varieties C. neoformans var. grubii and C. neoformans var. neoformans mate readily under laboratory conditions, but the hybrid basidiospores have germination rates about four times lower than those from intravarietal crosses. Here, we used microdissection to collect basidiospores from a hybrid cross and analysed the genotypes of germinated basidiospores to identify potentially antagonistic allelic combinations between loci that impact basidiospore germination. Our analyses showed clear evidence for Bateson-Dobzhansky-Muller (BDM) incompatibility affecting basidiospore viability. Antagonistic combinations of alleles from both two loci and three loci were found. Interestingly, most of the hybrid progeny showed segregation distortion in favour of the alleles from var. neoformans, consistent with large-scale epistatic interactions among loci affecting basidiospore viability. Our study presents the first evidence of BDM incompatibility between nuclear genes affecting post-zygotic reproductive isolation in this model basidiomycete yeast.

Agronomic performance of super-sweet corn genotypes in the north of Rio de Janeiro

We investigated the agronomic performance of super-sweet corn genotypes. Super-sweet corn genotypes were backcrossed with regionally adapted field varieties (CIMMYT 8 and Piranão 8). Eight morphological and yield-related traits were evaluated. A significant effect of interaction was observed between the five groups of genotypes (donor parents; super-sweet backcrossed parents; super-sweet intervarietal hybrids; common intervarietal corn hybrids; and field corn populations). Despite the low yield of genotype SH2Piranão, the hybrids resulting from interbreeding of the backcrossed parents for the improvement of super-sweet corn were promising. The agronomic performance of the super-sweet parents and their hybrids indicates the possibility of breeding lines with high genetic value to obtain single-cross hybrids and cultivars of super-sweet corn adapted to the northern region of the State of Rio de Janeiro.

Inheritance of economic traits of Microcerasus tomentosa thunb. intervarietal hybrids

A hybrid fund of Microcerasus tomentosa comprising 6 families with a total of 287 plants has been created. The features of the inheritance of important economic traits in hybrid offspring intervarietal hybrids Microcerasus tomentosa are defined. The hybrid family and cross combinations with high features of macrocarpa, small fruit size, dry berry separation, vitamin C, immunity and precocity are defined. During the study period of controlled hybrid offspring of crosses a number of elite seedlings was identified - Natali x Jubilejnaja, Natali x Smugljanka vostocnaja, and Natali x Rozovaja urožajnaja that combine high rates of fruit weight with other economic traits.

Hybrid Embryo Rescue: A Non-Conventional Breeding Strategy in Horticultural Crops

Production of interspecific and intergeneric hybrids is useful for transfer of desirable genes from wild species into cultivated species. In many instances, progeny from wide crosses is difficult to produce owing to several barriers. Post-zygotic barriers such as endosperm abortion and, at later stages, embryo degeneration are of common occurrence, leading to low fertility; but these have been overcome through the use of embryo rescue and several hybrids have been developed. This approach is especially useful in horticultural crops, more so in fruit crops. In our laboratory, we have developed protocols for hybrid embryo rescue in several top-of-the-line fruit crops that suffer from an inability to cross naturally (e.g., distant crosses, use of seedless parent/s) or instances where initial fruit drop is very high. Thus, interspecific, intergeneric and intervarietal hybrids have been generated in mango, banana, seedless grape, papaya and seedless citrus using embryo rescue. Culture of embryos has also been demonstrated in rose, capsicum, hot pepper, onion and tomato. Among the very important strategies under non-GM biotechnologies figure techniques of hybrid embryo rescue, and related applications like ovule/ovary/placental cultures through sequential embryo culture. Embryo culture applied to practical problems is a tissue culture technique that has proven to be of greatest value to breeders.

Heterosis over environments in crosses involving indica and tropical japonica rice cultivars

The discovery of wide compatibility genes in rice recently shifted the emphasis on enhancing heterosis from intervarietal hybrids to intersubspecific hybrids. We therefore studied the nature and magnitude of heterosis in inter- and intrasubspecific crosses involving improved tropical japonica (J) parents (BSI 10 [P1], BSI 16 [P2], B4116 [P3], and B4122 [P4]) and indica (I) parents (Govind [P5], Manhar [P6], Pant Dhan 4 [P7], Sarjoo 52 [P8], Pant Dhan 12 [P9], and Narendra 359 [P10]). We evaluated all 45 hybrids and parents in a randomized complete block design under environments with optimum sowing and high fertility (E1), optimum sowing and optimum fertility (E2), and late sowing and high fertility (E3). We studied 10 agronomic traits, including harvest index and grain yield, for heterosis, heterobeltiosis, and standard heterosis using Pant Dhan 4 as the standard variety.

Yield stability and adaptability of maize hybrids based on GGE biplot analysis characteristics

The objective of this study was to evaluate stability and adaptability of the grain yield of commercial intervarietal maize hybrids by the GGE (Genotype and Genotype by Environment Interaction) biplot and AMMI (Additive Main Effects and Multiplicative Interaction) analyses. Two intervarietal hybrids (BIO 2 and BIO4) were evaluated together with single, double and three-way cross hybrids. The performance of the intervarietal hybrid BIO 4 was superior to all double and three-way cross hybrids and outmatched the single-cross hybrids by 43%. In terms of stability, BIO 2 was more stable than BIO4, which is desirable, but biological stability, which is not necessarily desirable, was also observed, since the yield was below the environmental mean. The graphical GGE biplot analysis was superior to the AMMI1 since a greater portion of the sum of squares of GE and G+GE was captured and the predictive accuracy was higher. On the other hand, the AMMI2 graph outperformed the GGE biplot in predictive accuracy and explanation of G + GE and GE, although the difference in accuracy was smaller than between GGE2 and AMMI1.

Analysis of cpSSR in triticale plants obtained byin vitroandrogenesis

In vitro androgenesis allows haploid and double haploid homozygous plants to be obtained. However, in cereals, non-viable albino plants are often produced. This limits the use of this technique both in basic studies and in plant genetic improvement programs. We have analyzed eight microsatellites of the chloroplast genome (cpSSR) in a collection of 46 double haploid green lines derived from the intervarietal hybrid ‘Torote’ × ‘Presto’, and 49 haploid albino plants all obtained from the double haploid line ‘ATOPE-41’, in order to know the stability of this sequences after the androgenetic process. The green plants showed no variations at the analyzed loci, while two of the albino plants differed at two loci: WCt2 and WCt9. These variations notably affected the microsatellite nucleotide sequences as well as the sequences surrounding them. The changes observed consisted of insertions, deletions and nucleotide substitutions, with transition and transversion types equally common. The latter albino plants showed several alleles at the polymorphic loci, indicating the existence of heteroplasmy.

Inoculação de Azospirillum amazonense em dois genótipos de milho sob diferentes regimes de nitrogênio

A adaptabilidade de genótipos de milho a ambientes onde os nutrientes não estejam prontamente disponíveis pode ser relacionada com a adaptação à predominância, nos solos, das formas de N nítrica e amoniacal e à associação com microrganismos benéficos como as bactérias diazotróficas e, ou, promotoras de crescimento de plantas. O objetivo deste trabalho foi verificar o comportamento de dois híbridos intervarietais de milho sob diferentes doses e formas de N, assim como o efeito da inoculação com Azospirillum amazonense, em um ensaio em casa de vegetação, utilizando vasos preenchidos com vermiculita e solução nutritiva de Hoagland como fonte de nutrientes. O delineamento experimental foi de blocos ao acaso em esquema fatorial, constituindo os tratamentos em: dois híbridos intervarietais, H1 (Carioca x Eldorado) e H2 (Palha Roxa ES x Sol da Manhã); plantas inoculadas ou não inoculadas com A. amazonense, e três regimes de N, conforme doses e proporções seguintes: 126 mg semana-1 de N (75 % NH4+ : 25 % NO3-); 126 mg semana-1 de N (25 % NH4+ : 75 % NO3-), e 12,6 mg semana-1 de N (50 % NH4+ : 50 % NO3-). Vinte e cinco dias após o plantio, as plantas foram separadas em raiz e parte aérea para determinação da matéria seca, conteúdos totais de N e P, atividade das enzimas nitrato redutase e glutamina sintetase e açúcares solúveis totais. O híbrido H1, mais eficiente em avaliações preliminares em campo, produziu mais matéria seca e apresentou maior eficiência na utilização de N e P. Plantas que receberam a maior dose de N, independentemente do predomínio da forma nítrica ou amoniacal, apresentaram maior acúmulo de N (nas raízes e parte aérea) e P (na parte aérea) e maior índice de utilização de P. Com o predomínio da forma amoniacal, observou-se incremento na produção de matéria seca da parte aérea e na atividade da glutamina sintetase, bem como decréscimo na concentração de açúcares solúveis totais nas raízes. A inoculação com A. amazonense promoveu maior produção de matéria seca e acúmulo de N nas raízes.

Intraspecific hybrid sterility in Aegilops caudata L.

Ae. caudata L. is an annual, diploid species distributed over the eastern Mediterranean. Morphologically, it is divided into two varieties, var. typica and var. polyathera Boiss. In the present work, two series of crossing experiments were carried out. Firstly, reciprocal crosses between the two varieties collected from sympatric populations were made. All F1 hybrids showed normal fertility. Secondly, crosses between accessions collected from different geographical regions were made. F1 hybrids from the crosses between most Aegean accessions and the accession from Syria (Tester A) or the accession from northern Turkey (Tester B) showed complete sterility. However, those from the crosses between the Aegean accessions and the accession from Olympia in Greece (Tester D) showed normal fertility. Contrary to this, F1 hybrids from crosses between the accession from northern Iraq and those from Syria and northern Turkey showed high fertility, while complete sterility was observed in hybrids between the Iraqi accession and the accessions from Greece and northwestern Turkey (Testers D and C). Accordingly, it is concluded that the intraspecific hybrid sterility in Ae. caudata is not a characteristic of intervarietal hybrids but is due to geographical differentiation: The factors responsible for genetic differentiation in Ae. caudata causing intraspecific hybrid sterility are not correlated with morphology but with geography.

Intraspecific hybrid sterility in Aegilops caudata L.

Ae. caudata L. is an annual, diploid species distributed over the eastern Mediterranean. Morphologically, it is divided into two varieties, var. typica and var. polyathera Boiss. In the present work, two series of crossing experiments were carried out. Firstly, reciprocal crosses between the two varieties collected from sympatric populations were made. All F1 hybrids showed normal fertility. Secondly, crosses between accessions collected from different geographical regions were made. F1 hybrids from the crosses between most Aegean accessions and the accession from Syria (Tester A) or the accession from northern Turkey (Tester B) showed complete sterility. However, those from the crosses between the Aegean accessions and the accession from Olympia in Greece (Tester D) showed normal fertility. Contrary to this, F1 hybrids from crosses between the accession from northern Iraq and those from Syria and northern Turkey showed high fertility, while complete sterility was observed in hybrids between the Iraqi accession and the accessions from Greece and northwestern Turkey (Testers D and C). Accordingly, it is concluded that the intraspecific hybrid sterility in Ae. caudata is not a characteristic of intervarietal hybrids but is due to geographical differentiation: The factors responsible for genetic differentiation in Ae. caudata causing intraspecific hybrid sterility are not correlated with morphology but with geography.

MODELOS MATEMÁTICOS PARA ESTIMAR EL CRECIMIENTO DEL FRUTO DE CHILE MANZANO (Capsicum pubescens R and P)

Apple pepper inter-varietal hybrid (Capsicum pubescens R y P) “Puebla x Zongolica” is high-yielding due to its volume, pericarp thickness, and fruit weight. Fruit yield is explained mainly by its size, and it is of interest to describe fruit growth dynamics. Fruit growth analysis generally has been based on destructive sampling since it is impossible to use the same fruit throughout the growing season. Competition among the different plant organs decrease fruit size and weight, negatively affecting fruit quality and yield. For these reasons, this study was conducted to assess and identify mathematical models that describe fruit growth without destructive sampling. Simple linear regression, multiple linear regression, and four non-linear models were tested. The hypothesis was that one of the six models efficiently explains fruit growth using the independent variable volume of displaced water. Chili plants were cultivated under an intensive production system in 2004 and 2005. The dependent variable was fresh fruit weight and the independent variables were fruit growth time, and average fruit length and width at shoulder, volume of displaced water and fruit volume. Significant differences were found between the means of the evaluated variables in the two sampling periods (Pd”0.0). The models that best explained fruit growth were simple linear regression (only in 2004) in function of volume of displaced water and fruit volume and the multiple linear regression model which adequately describes growth using, besides the above mentioned variables, growth time and average length and width, in both 2004 and 2005. However, the monomolecular method (in both sampling periods) estimates fresh fruit weight simply and precisely using a single non-destructive variable, either the volume of displaced water or volume, making this model the most practical for the description of fruit growth.

Selection index and molecular markers in reciprocal recurrent selection in maize

Reciprocal recurrent selection among full-sib families is one of the outstanding methodologies of maize improvement, since gains are possible in the per se and/or in cross populations. Here the selection index proposed by Smith and Hazel was used in the cited methodology; besides, an additional phase involving RAPD markers was introduced to preserve the genetic variability of the selected genotypes and identify contaminants before their recombination. Multivariate techniques of grouping and discriminant analyses were used for this purpose, to assure the continuance of the improvement program and amplify the genetic distance between the populations Cimmyt and Piranao, which were used for an intervarietal hybrid. The molecular technique proved useful to identify contaminants and helpful in the choice of the genotypes to be recombined to maximize heterosis among populations. The technique can be included in recurrent selection programs, mainly those that target the development of hybrids.

Selección de progenitores de maíz para la obtención de semilla híbrida por pequeños agricultores.

The seed of actual high yielding hybrids are very expensive and local farmers tend to use advanced generations to reduce costs. Abetter choice is to produce seed of maize intervarietal hybrids. The objective of this research was to describe the experience of a group of maize producers in the seed production, utilization and improvement of their parents of intervarietal hybrids. The study was conducted in Nayarit State, Mexico. In 1996, a group farmers, supported by a technical researcher, evaluated two maize intervarietal crosses. The cross B840xC343 yielded better than nine commercial hybrids. This motived the farmers to produce 20 tons of seed in eight intervarietal crosses during the winter season of 1997/98. The cost of the seed production was 50% less than the cost of commercial hybrid seed. The eight intervarietal crosses were commercial planted in about 400 hectars and were evaluated in four experiments by the farmers. The results showed that two crosses, P3028xA7573 and C385xD880, had the best results. The first cross had a heterosis of 4.1% over the high yielding parent and the second a heterosis of 30% over a parent. Since 1999, the parents of the best intervarietal cross is being improved by reciprocal recurrent selection of half siblings, two years per cycle.

Genetic Diversity and Origin of Weedy Rice (Oryza sativa f. spontanea) Populations Found in North-eastern China Revealed by Simple Sequence Repeat (SSR) Markers

Weedy rice (Oryza sativa f. spontanea) is one of the most notorious weeds occurring in rice-planting areas worldwide. The objectives of this study are to determine the genetic diversity and differentiation of weedy rice populations from Liaoning Province in North-eastern China and to explore the possible origin of these weedy populations by comparing their genetic relationships with rice varieties (O. sativa) and wild rice (O. rufipogon) from different sources. Simple sequence repeat (SSR) markers were used to estimate the genetic diversity of 30 weedy rice populations from Liaoning, each containing about 30 individuals, selected rice varieties and wild O. rufipogon. Genetic differentiation and the relationships of weedy rice populations were analysed using cluster analysis (UPGMA) and principle component analysis (PCA). The overall genetic diversity of weedy rice populations from Liaoning was relatively high (H(e) = 0.313, I = 0.572), with about 35 % of the genetic variation found among regions. The Liaoning weedy rice populations were closely related to rice varieties from Liaoning and japonica varieties from other regions but distantly related to indica rice varieties and wild O. rufipogon. Weedy rice populations from Liaoning are considerably variable genetically and most probably originated from Liaoning rice varieties by mutation and intervarietal hybrids. Recent changes in farming practices and cultivation methods along with less weed management may have promoted the re-emergence and divergence of weedy rice in North-eastern China.

Heterosis in crosses among white grain maize populations with high quality protein

The objective of this work was to investigate heterosis and its components in 16 white grain maize populations presenting high quality protein. These populations were divided according to grain type in order to establish different heterosis groups. The crosses were carried out according to a partial diallel cross design among flint and dent populations. Seven agronomic traits were evaluated in three environments while four leaf diseases and incidence of corn stunt were evaluated in one. Least square procedure was applied to the normal equation X'Xbeta = X'Y, to estimate the model effects and their respective sum of squares. Among the heterosis components, in diallel analysis, significance for average heterosis in grain yield, number of days to female flowering and to all evaluated diseases was detected. Specific heterosis was significant for days to female flowering and resistance to Puccinia polysora. Results concerned to grain yield trait indicate that populations with superior performance in dent group, no matter what flint population group is used in crosses, tend to generate superior intervarietal hybrids. In decreasing order of preference, the dent type populations CMS 476, ZQP/B 103 and ZQP/B 101 and the flint type CMS 461, CMS 460, ZQP/B 104 and ZQP/B 102 are recommended to form composites.

ネギ品種間Ｆ１の初期生育におけるヘテロシスとＡＦＬＰに基づく遺伝的距離との関係

ネギ品種間Ｆ１の初期生育におけるヘテロシスとＡＦＬＰに基づく遺伝的距離との関係

Topics on the genetics of maize yield stability

Diallel experiments were carried out in several environments to investigate the genetic control of maize yield stability. The analyses used the methodology developed by Pacheco (1997) which is useful when the genotype x environment interaction is significant and the genetic effects are not consistent across environments. The 28 population diallel assessed in ten environments allowed the following conclusions: a) dominance deviations were the main cause of yield instability; b) populations selected under environmental stress conditions, such as Saracura, produced more stable intervarietal hybrids through a reduction in the deviations from regression due to specific combining ability; c) selection for yield followed by selection for stability would increase the breeding program efficiency if the initial populations had high General and Specific Combining Abilities, broad adaptability and regression deviations close to zero.

An assessment of doubled haploid production in soft red winter wheat by wheat x corn wide crosses

Feasibility of wheat x corn hybridization to produce doubled haploids (DHs) for soft red winter wheat (SRWW) breeding was assessed. Seven interparietal wheat hybrids were pollinated with the same corn genotype (Seneca 60) in a greenhouse, followed by 2,4-D application, 6–24 hours post-pollination, embryo rescue at the end of third week after pollination and chromosome doubling by colchicine in the media at 1–2 leaf stage of the plantlets. The plantlets were transferred to soil, maintained in a growth chamber for two weeks and then grown in the greenhouse. There was no seed set without 2,4-D treatment and 81–90% (mean 87%), including proliferated ovaries, with 100 ppm 2,4-D treatment. Wheat hybrids differed significantly for percent seed set with corn pollination and for percent seeds with embryos but not for differentiation of cultured embryos. Haploid seed development was better in coin envelops than in glassine bags. 16% seeds had embryos, 37% embryos had normal organogenesis, 50% seedlings survived to maturity and 25% of them set seed. Wheat hybrid 5156 was the best with 86% seed set, 35% seeds with embryos, 54% embryos producing plantlets of which 57% survived to maturity and 50% of the survivors set seed. Overall, if 100 DHs are needed for selection of desirable segregants, enough intervarietal wheat hybrid seed would be required to have 289 plants of an intervarietal cross for pollination with corn.