Intraspecific Crosses Research Articles

GERMINABILIDAD Y DESARROLLO INICIAL DE NUEVOS HÍBRIDOS INTRAESPECÍFICOS DE Theobroma cacao L; MALVACEAE

El objetivo de esta investigación fue evaluar la germinabilidad de semillas y el desarrollo inicial de híbridos interclonales de Theobroma cacao L. El ensayo se estableció en el campus experimental “La Teodomira”, Manabí, Ecuador. Se realizaron cruzamientos intraespecíficos entre cinco genotipos de T. cacao, los frutos obtenidos se cosecharon aproximadamente a los 180 días. Las variables estudiadas fueron: porcentaje de germinación y de emergencia, altura de planta, diámetro de tallo, número de hojas y contenido de clorofila en el área foliar. Se obtuvo un 97.8% de germinación a los ocho días luego de desmulización e imbibición y un 86.5% de emergencia, registrándose un mayor porcentaje de germinación y emergencia en la progenie derivada del cruce L11-H19 x EET-103. A los 120 días, el mayor diámetro de tallo se registró en la familia EET-558 x CCN-5 y la mayor altura en la familia EET-103 x L11-H19. En promedio se obtuvo 15 hojas por planta y 43.5 de clorofila SPAD a los 120 días. El contenido de clorofila en las hojas está condicionado por la edad fisiológica de las plántulas. No obstante, para futuras investigaciones se recomienda realizar evaluación en campo de estas progenies, en especial de aspectos fisiológicos involucrados con la producción de hojas y contenido de clorofila, pues estos podrían ser indicadores para selección de genotipos promisorios

High-resolution mapping of Rym14Hb, a wild relative resistance gene to barley yellow mosaic disease

Key messageWe mapped the Rym14Hb resistance locus to barley yellow mosaic disease in a 2Mbp interval. The co-segregating markers will be instrumental for marker-assisted selection in barley breeding.Barley yellow mosaic disease is caused by Barley yellow mosaic virus and Barley mild mosaic virus and leads to severe yield losses in barley (Hordeum vulgare) in Central Europe and East-Asia. Several resistance loci are used in barley breeding. However, cases of resistance-breaking viral strains are known, raising concerns about the durability of those genes. Rym14Hb is a dominant major resistance gene on chromosome 6HS, originating from barley’s secondary genepool wild relative Hordeum bulbosum. As such, the resistance mechanism may represent a case of non-host resistance, which could enhance its durability. A susceptible barley variety and a resistant H. bulbosum introgression line were crossed to produce a large F2 mapping population (n = 7500), to compensate for a ten-fold reduction in recombination rate compared to intraspecific barley crosses. After high-throughput genotyping, the Rym14Hb locus was assigned to a 2Mbp telomeric interval on chromosome 6HS. The co-segregating markers developed in this study can be used for marker-assisted introgression of this locus into barley elite germplasm with a minimum of linkage drag.

Production and characterization of inter and intraspecific hybridization eggplant

ABSTRACT The eggplant is a highly valuable horticultural crop grown all over the world and it is of substantial economic importance in Asia. However, its production is severely threatened by several soil-borne and foliar diseases, insect-pests, drought, heat, and frost damage. Therefore, efforts to transfer useful resistance genes into eggplant from their wild relatives is important. In the present study, interspecific and intraspecific hybridization was carried out, that included three cultivated genotypes of eggplant (Solanum melongena MEE, Solanum melongena MEP, Solanum melongena MEB) and one wild Solanum species (Solanum incanum INC). The F1 hybrids were made by inter and intraspecific hybridization. A total of 632 possible inter and intraspecific reciprocal crosses was performed where only three were successful. The minimum days to flowering were observed in parent MEP, and maximum plant height was measured in MEE×MEB. Maximum fruit length was observed in parent MEB. Furthermore, fruit diameter, leaf width, leaf length, and fruit yield per plant were found maximum in hybrid MEExINC. Our results suggest that these materials will be of great interest for the genetic improvement of eggplant; they may have a tremendous potential to increase tolerance to abiotic stresses, such as to drought and heat, as well as increased nutrient and herbal values. Findings of this study will be helpful for the human health, ultimately contributing to the development of a new generation of plants adapted to climate.

VARIABILITY, GENETIC COMPONENTS AND SELECTION RESPONSE IN SEGREGATING GENERATIONS AMONG SOME COTTON CROSSES

The successful breeding program depends on genetic variability response to selection, heritability and genetic advance. The present investigation aimed to estimate these components in two intra-specific cotton crosses (Giza 92 x Giza 87 and Giza 96 x Giza 87) during early segregating generation. Most of the studied traits showed high broad sense heritability coupled with low or moderate genetic advance as percent of mean in F2 generation. So, these traits controlled by non additive gene action. The analysis of variances for F3 families showed highly significant differences between F3 families and variance within F3 was lower than among families for all the studied traits over the two crosses. All F3 families had low intra-class correlation values over the two crosses, so selection between families is better than within families. The additive genetic variance was larger than dominance variance for all the studied traits except for seed cotton yield / plant and lint %, also, these traits showed partial degree of dominance for cross I. While, cross II has higher values of dominance genetic variance than additive variance for all traits except for boll weight and fiber length, so that showed overdominance. Selection differential and response to selection were found to be positive for all traits during F2 and F3. The probability of new recombinant lines falling outside parental range was higher in cross I than cross II for all traits except for boll weight and fiber length. The study reveals that judicious selection leads to improvement in next generation.

Quantitative comparison of three main metabolites in leaves of Coffea accessions by UPLC-MS/MS

The wild diversity of the Coffea genus is large, which is valuable for coffee plant breeding programs intended to obtain higher sensory quality varieties; but a biochemical characterization of accessions, already available in coffee germplasm banks, is still needed. In this work, a quantitative determination of caffeine, trigonelline and 5-caffeoylquinic acid (5-CQA), in coffee leaves of 80 different Coffea spp. accessions from the Coffee Germplasm Bank located in Huatusco, Veracruz, Mexico was done. These metabolic variables might be useful as quality-related selection markers in future coffee breeding programs. Fresh coffee leaves from each accession were processed and metabolites determined by UPLC-MS/MS analyses. Multidimensional Scaling (MDS), Hierarchical Cluster Analysis (HCA) and Analysis of Variance (AOV) revealed that levels of caffeine and trigonelline in leaves significantly varied among accessions, from 0.00 to 2.04% (w/w) and from 0.42 to 1.82% (w/w), respectively. While 5-CQA ranged from 0.00 to 0.66%. In C. liberica no caffeine was detected, demonstrating that coffee leaves have the potential to be used in the genetic profiling of Coffea spp. These results could be useful in formulating a proposal for intraspecific crosses in C. arabica, for the generation of F1 hybrids with good cup quality attributes, while in C. canephora they could be helpful for enhancing sensory quality traits of Robusta coffees.

Fruit quality and DNA methylation are affected by parental order in reciprocal crosses of tomato.

Reciprocal effects were found for tomato fruit quality and DNA methylation. The epigenetic identity of reciprocal hybrids indicates that DNA methylation might be one of the mechanisms involved in POEs. Crosses between different genotypes and even between different species are commonly used in plant breeding programs. Reciprocal hybrids are obtained by changing the cross direction (or the sexual role) of parental genotypes in a cross. Phenotypic differences between these hybrids constitute reciprocal effects (REs). The aim of this study was to evaluate phenotypic differences in tomato fruit traits and DNA methylation profiles in three inter- and intraspecific reciprocal crosses. REs were detected for 13 of the 16 fruit traits analyzed. The number of traits with REs was the lowest in the interspecific cross, whereas the highest was found in the cross between recombinant inbred lines (RILs) derived from the same interspecific cross. An extension of gene action analysis was proposed to incorporate parent-of-origin effects (POEs). Maternal and paternal dominance were found in four fruit traits. REs and paternal inheritance were found for epiloci located at coding and non-coding regions. The epigenetic identity displayed by the reciprocal hybrids accounts for the phenotypic differences among them, indicating that DNA methylation might be one of the mechanisms involved in POEs.

Genetic diversity analysis of advanced chickpea (Cicer arietinum L.) genotypes in Ethiopia for identification of high-yielding and novel Fusarium wilt resistance sources

Chickpea (Cicer arietinum L.) is one of the most important food legumes in the world. However, Fusarium wilt is one of the major yield limiting factors in chickpea. Breeding for host plant resistance is the most cost-efficient and eco-friendly strategy to control the disease. The deployment of resistant varieties has not been extensively used due to lack of stable resistance source with desirable yield and yield-related morphological traits in cultivated chickpea with a narrow genetic base for traits’ improvement. Therefore, creating significant genetic diversity is a fundamental step to develop Fusarium wilt-resistant varieties. In this study, 47 advanced recombinant inbred lines derived from multi-parent intraspecific crosses and three checks were assessed for Fusarium wilt resistance and major yield-related morphological traits for two consecutive years. Analysis of variance showed the presence of significant difference (P < 0.05) among test genotypes for major yield-related morphological traits. Consistently, multivariate analyses showed high genetic diversity between test genotypes. Cluster analysis grouped test genotypes into four distinct clusters. The first two principal coordinates with eigenvalues greater than one accounted for 93.94% of the total variation suggesting high genetic diversity between test genotypes. Based on these, we identified 20 high-yielding and novel Fusarium wilt-resistant genotypes with mean wilt incidence of 3.83%. Therefore, these genotypes can be utilized in any chickpea breeding program as a novel Fusarium wilt resistance sources to develop wilt-resistant varieties with high yield and yield-related morphological traits.

A high-density genetic map and multiple environmental tests reveal novel quantitative trait loci and candidate genes for fibre quality and yield in cotton

A high-density linkage map of an intraspecific RIL population was constructed using 6187 bins to identify QTLs for fibre quality- and yield-related traits in upland cotton by whole-genome resequencing. Good fibre quality and high yield are important production goals in cotton (Gossypium hirsutum L.), which is a leading natural fibre crop worldwide. However, a greater understanding of the genetic variants underlying fibre quality- and yield-related traits is still required. In this study, a large-scale population including 588 F7 recombinant inbred lines, derived from an intraspecific cross between the upland cotton cv. Nongdamian13, which exhibits high quality, and Nongda601, which exhibits a high yield, was genotyped by using 232,946 polymorphic single-nucleotide polymorphisms obtained via a whole-genome resequencing strategy with 4.3-fold genome coverage. We constructed a high-density bin linkage map containing 6187 bin markers spanning 4478.98cM with an average distance of 0.72cM. We identified 58 individual quantitative trait loci (QTLs) and 25 QTL clusters harbouring 94 QTLs, and 119 previously undescribed QTLs controlling 13 fibre quality and yield traits across eight environments. Importantly, the QTL counts for fibre quality in the Dt subgenome were more than two times that in the At subgenome, and chromosome D02 harboured the greatest number of QTLs and clusters. Furthermore, we discovered 24 stable QTLs for fibre quality and 12 stable QTLs for yield traits. Four novel major stable QTLs related to fibre length, fibre strength and lint percentage, and seven previously unreported candidate genes with significantly differential expression between the two parents were identified and validated by RNA-seq. Our research provides valuable information for improving the fibre quality and yield in cotton breeding.

Intra- and Inter-Specific Crosses among Centaurea aspera L. (Asteraceae) Polyploid Relatives-Influences on Distribution and Polyploid Establishment.

How polyploids become established is a long-debated question, especially for autopolyploids that seem to have no evolutionary advantage over their progenitors. The Centaurea aspera polyploid complex includes diploid C. aspera and two related tetraploids C. seridis and C. gentilii. Our purpose was to study the mating system among these three taxa and to analyze its influence on polyploid establishment. The distribution and ploidy level of the Moroccan populations, and forced intra- and inter-specific crosses were assessed. Allotetraploid C. seridis produced more cypselae per capitulum in the intra-specific crosses. It is a bigger plant and autogamous, and previous studies indicated that selfing forces the asymmetric formation of sterile hybrids. All these characteristics help C. seridis to avoid the minority-cytotype-exclusion effect and become established. Inter-specific hybridization was possible between C. aspera and C. gentilii, and with the symmetric formation of hybrids. However, 49% of the hybrid cypselae were empty, which probably reveals postzygotic barriers. Autotetraploid C. gentilii produced the same number of cypselae per capitulum as those of the diploid parental, has an indistinguishable field phenotype, is allogamous, and symmetrically produces hybrids. Therefore, C. gentilii does not seem to have the same competitive advantages as those of C. seridis.

Parâmetros genéticos e teste de paternidade em progênies de Euterpe oleracea produto da hibridação espontânea com Euterpe edulis em clima subtropical

O objetivo deste estudo foi avaliar o sistema de fecundação e a distribuição da variabilidade molecular entre e dentro de três grupos de progênies de polinização aberta de Euterpe oleracea, além de realizar um teste depaternidade para identificação dos genitores masculinos e promover a certificação genética das plântulasbífolioladas. Para tal, foram utilizados seis loci microssatélites em 306 amostras. Os grupos de progênies sãoresultado de um sistema misto de fecundação, com ausência de cruzamentos entre aparentados, sendoalógamos (tm e ts = 1,0), com correlação de autofecundação (rt) igual a 0,110. Foram constatados diferentesgraus de parentescos (rp), entre 15,5 a 26,1% de irmãos completos. A paternidade foi atribuída para 51% e 24% das amostras, com 80 e 95% de confiança respectivamente. Foram identificados 22 doadores de pólen e uma autofecundação, verificou-se que o morfotipo bífoliolado não é garantia de cruzamento intraespecifico, já que quatro progênies foram identificadas como híbridos interespecíficos. Foram detectados em média 7 a 12,3 alelos por locus e uma heterozigosidade média observada entre 0,382 a 0,898 e a esperada entre 0,354 a 0,693. O índice de fixação foi entre -0,053 a -0,319. A variação entre os grupos foi de 5%, sendo 95% dentro deles. Os resultados indicam boas perspectivas para realização de trabalhos futuros relacionados à predição de ganhos genéticos a partir da seleção entre e dentro dos grupos de progênies.

A New Intra-Specific and High-Resolution Genetic Map of Eggplant Based on a RIL Population, and Location of QTLs Related to Plant Anthocyanin Pigmentation and Seed Vigour.

Eggplant is the second most important solanaceous berry-producing crop after tomato. Despite mapping studies based on bi-parental progenies and GWAS approaches having been performed, an eggplant intraspecific high-resolution map is still lacking. We developed a RIL population from the intraspecific cross ‘305E40’, (androgenetic introgressed line carrying the locus Rfo-Sa1 conferring Fusarium resistance) x ‘67/3’ (breeding line whose genome sequence was recently released). One hundred and sixty-three RILs were genotyped by a genotype-by-sequencing (GBS) approach, which allowed us to identify 10,361 polymorphic sites. Overall, 267 Gb of sequencing data were generated and ~773 M Illumina paired end (PE) reads were mapped against the reference sequence. A new linkage map was developed, including 7249 SNPs assigned to the 12 chromosomes and spanning 2169.23 cM, with iaci@liberoan average distance of 0.4 cM between adjacent markers. This was used to elucidate the genetic bases of seven traits related to anthocyanin content in different organs recorded in three locations as well as seed vigor. Overall, from 7 to 17 QTLs (at least one major QTL) were identified for each trait. These results demonstrate that our newly developed map supplies valuable information for QTL fine mapping, candidate gene identification, and the development of molecular markers for marker assisted selection (MAS) of favorable alleles.

SUPERIOR LINES FOR AGRO-TECHNOLOGICAL TRAITS IN SAFFLOWER (Carthamus tinctorius L.)

In safflower (Carthamus tinctorius L.) breeding, determining superior pure lines after crossing for agro-technological traits is the first step to improve new cultivar candidates. Therefore, aim of the study was to determine superior pure lines of sufflower in F9-10 derived three intraspecific crosses evaluating the agronomical and technological (quality) traits. A total of 25 safflower genotypes including 15 pure lines was compared with 10 standard cultivars (Dincer 5-18-1, Centennial, Remzibey-05, Balci, Linas, Olas, Gelendost-2, Gokturk, Montola 2000 and W6 9822) and genotypes along with parents of lines for two years in 2017-2018. GEMO-20 had higher 1000-seed weight, GECE-8 and GEMO-20 had higher oil content, GEMO-19, 28 and GEW6-7 had higher oil yield, GEMO-28 and GEW6-7 had higher seed yield than standard cultivars. According to 1000-seed weight, oil content, seed and oil yield traits, GEMO-19, GEMO-20, GEMO-28 and GEW6-7 lines were identified as superior lines.

Genotypic Analysis for Retrieval of MYMV Resistant Progenies from Certain Crosses of Mungbean [Vigna radiata (L.) Wilczek

The present investigation was conducted to study the nature of inheritance of MYMV among intra-specific crosses among three MYMV susceptible and five MYMV resistant genotypes of green gram. The molecular screening and hotspot evaluation is carried out in fifteen F1 progenies and 8 F2 families, respectively. The yellow mosaic-affected leaf samples gave positive results with MYMIV specific primer pairs YFP1/YRP1 and YFP2/YRP2 amplified fragments having size of 704bp and 648 bp, respectively. Coat protein gene sequence analysis revealed that the identified virus is homologous to MYMV. The inheritance study based on F2 data indicated the ratio of MYMV resistant plants and susceptible plants showed a good fit to expected 3:1 (Susceptible: Resistant) suggesting a typical monogenic recessive gene governing resistant reaction to MYMV besides resting the susceptibility from the susceptible parents.

Strain comparison on reproductive performance, growth and survival in two wild &lt;i&gt;Clarias Gariepinus&lt;/i&gt; (Burchell 1822) and their reciprocal hybrids

A strain comparison experiments was carried out in wild Clarias gariepinus with the aim of evaluating the reproductive performance, (in terms of percentage fertility and hatchability) growth and survival for choice of strain in selective breeding. Live samples of wild C. gariepinus collected from River Argungu, Kebbi state (KB) and Eleyele dam, Oyo state (OY), Nigeria were crossbred and mated in pure parental and reciprocal crosses generating four mating combinations (generic crosses) replicated three times in completely randomized design (CRD) manner. The F1 generations were reared indoor for 56 days. The hybrids revealed higher characters compared to the progeny of pure parental groups in fertilization rate (84.000±0.270%; 78.265±0.135% compared to 88.400±0.130%; 71.465±0.265%), hatching (77.305±0.405%;72.235±0.465% compared to 80.995±0.025%; 64.555±0.615%) and survival of larvae (100.000±0.000%; 98.582±1.418% compared to 98.840±0.581%; 73.371±0.157%). On the other hand, fertilization and hatching rate among the hybrids and the pure crosses were statistically significant (P&lt;0.05). Similarly, significant difference (P&lt;0.05) was observed between the two reciprocal hybrids. However, the hybrid crosses showed intermediate characters between the pure crosses in mean weight gain (MWG), specific growth rate (SGR) and survival of fingerlings. Though the crosses of pure Oyo species displayed significantly higher value in MWG (5.583±0.058g) and SGR (10.319±0.051g) than other groups, fingerling survival (73.371±0.157%) was found to be lowest. The growth parameters like MWG (4.884±0.001g) and SGR (10.231±0.130g) of the hybrids of Oyo fingerlings were found to be higher than pure Kebbi crosses, while survival (100.000±0.000%) of hybrid of Kebbi fingerlings were higher than pure Kebbi (98.840±0.581%). Therefore, this is considered as heterosis (hybrid vigour) for the hybrids they have achieved better traits either one of the pure groups. Intra-specific cross of female wild C. gariepinus from Kebbi and male wild C. gariepinus from Oyo (KB♀ × OY♂) be practiced for optimum performance used in commercial production. This will ensure high fertility, hatchability, growth and survival rate.&#x0D; Key words: Clarias gariepinus, growth, reproductive performance, Strain comparison, survival.

Estimation of gene effects for yield attributing traits in mungbean (Vigna radiata) and urdbean (Vigna mungo) for intra and interspecific crosses

The present investigation was carried out at Research Farm of Tirhut College of Agriculture, Dholi, Muzaffarpur, Bihar. The experimental material consisted of three genotypes of resistant mungbean and urdbean donor each viz., HUM-16, TMB-37, Samrat and Pant U-31, Uttara, Sekhar, respectively; with a susceptible donor of LGG 450 and Barabanki local for mung and urd, respectively. Six intraspecific and four interspecific crosses were made and P1, P2, F1, F2 BC1, BC2 population were grown in RBD design with three replications. The observations were recorded for thirteen different quantitative as well qualitative traits viz., Days to 50 flowering, Plant height (cm), Number of primary branches, Cluster per plant, pods per cluster, Number of pods per plant, Days to maturity, Pod length (cm), Grains per pod, 100 seed weight (g), Harvest index, Phenol content (mg) and Grain yield per plot (kg).n Basedon the joint scaling test few intraspecific combinations showed the presence of epistasis; whereas in most of the interspecific crosses epistasis was observed. As per the three parameters model additive and/or dominant components seems to play an important role in the inheritance of most of the yield attributing traits in intra and interspecific crosses. As evident from the six parameter model, preponderance of significant reducing (-ve) additive gene effects in intraspecific crosses were observed, whereas additive and dominance components were equally important in interspecific crosses for the expression of most of the yield attributing traits. Among epistatic interactions additive x additive gene effects for days to 50 per cent flowering and dominant x dominant gene effect for 100 seed weight in four intraspecific crosses, whereas in interspecific crosses all three types of epistatic interactions were observed for the expression of most of the yield attributing traits. In most of the intra as well as interspecific crosses, duplicate type of epistasis was observed.

Genotyping by Sequencing Revealed QTL Hotspots for Trichome-Based Plant Defense in Gossypium hirsutum.

Cotton possesses certain physical features, including leaf and stem trichomes that help plants deter damage caused by insect pests, and to some extent, from abiotic factors as well. Among those features, trichomes (pubescence) hold a special place as a first line of defense and a managemental tool against sucking insect pests of cotton. Different insect pests of cotton (whiteflies, aphids, jassids, and boll weevil) severely damage the yield and quality of the crop. Likewise, whiteflies, aphids, jassids, and other insect pests are considered as potential carriers for cotton leaf curl viruses and other diseases. Genotyping by sequencing (GBS) study was conducted to understand and explore the genomic regions governing hairy (Pubescence) leaves and stem phenotypes. A total of 224 individuals developed from an intraspecific cross (densely haired cotton (Liaoyang duomao mian) × hairless cotton (Zong 128)) and characterized phenotypically for leaf and stem pubescence in different environments. Here we identify and report significant QTLs (quantitative trait loci) associated with leaf and stem pubescence, and the response of plant under pest (aphid) infestation. Further, we identified putative genes colocalized on chromosome A06 governing mechanism for trichome development and host–pest interaction. Our study provides a comprehensive insight into genetic architecture that can be employed to improve molecular marker-assisted breeding programs aimed at developing biotic (insect pests) resilient cotton cultivars.

Seed set in inter specific crosses of male sterile Mentha spicata with Mentha longifolia

Mentha is one of the most important genera of the Lamiaceae with a wide geographical distribution and considerable commercial importance. The general aim of this work was to group 34 accessions from four species of mint using ISSR molecular markers to select some accessions to estimate the potential cross-ability of mints valuable in breeding and phytochemical research. The reproductive characteristics including the type of flower, petal color, sepal and petal lengths, length of stamen and pistil as well as the number of free and living pollen grains in the anther were also studied to find out cross-ability patterns and the possible reproductive barriers. Analysis of molecular variance (AMOVA) among and within species showed more intra-specific variation (92.24%) in comparison with inter-species variation (7.76%). Results of cluster analysis based on ISSR data grouped the mint genotypes into five clusters. By this, the greatest genetic similarity was found between Ms12 from M. spicata and Ml29 from M. longifolia. The genotype Ms12 along with Ms22, the other genotype from M. spicata, were found to be male sterile due to stopped stamen development. These two had higher combining ability (seed set) when used as the female parent in intra-specific crosses and when crossed with M. longifolia compared to the other genotypes in diallel crosses. The highest number of hybrid seeds was obtained where Ml29 was crossed as the male parent with male sterile Ms12 as the female one. This high success rate of seed set in interspecific crosses between M. spicata and M. longifolia could be related to their genomic similarity confirmed by ISSR molecular data. Therefore, producing hybrid seeds and subsequent generations from crosses between these species, utilizing male sterility mechanism, can be a source of new genetic variation for mint.

Genetic Analysis of the Transition from Wild to Domesticated Cotton (Gossypium hirsutum L.).

The evolution and domestication of cotton is of great interest from both economic and evolutionary standpoints. Although many genetic and genomic resources have been generated for cotton, the genetic underpinnings of the transition from wild to domesticated cotton remain poorly known. Here we generated an intraspecific QTL mapping population specifically targeting domesticated cotton phenotypes. We used 466 F2 individuals derived from an intraspecific cross between the wild Gossypium hirsutum var. yucatanense (TX2094) and the elite cultivar G. hirsutum cv. Acala Maxxa, in two environments, to identify 120 QTL associated with phenotypic changes under domestication. While the number of QTL recovered in each subpopulation was similar, only 22 QTL were considered coincident (i.e., shared) between the two locations, eight of which shared peak markers. Although approximately half of QTL were located in the A-subgenome, many key fiber QTL were detected in the D-subgenome, which was derived from a species with unspinnable fiber. We found that many QTL are environment-specific, with few shared between the two environments, indicating that QTL associated with G. hirsutum domestication are genomically clustered but environmentally labile. Possible candidate genes were recovered and are discussed in the context of the phenotype. We conclude that the evolutionary forces that shape intraspecific divergence and domestication in cotton are complex, and that phenotypic transformations likely involved multiple interacting and environmentally responsive factors.

Evaluation of some Intraspecific Cotton Crosses for some Quantitative Characters at Three Locations

The objectives of this study were to determine the heterosis, combining abilities, proportional contributions, genetic components and heritability measurements of some yield, its components and fiber quality characters for six genotypes belong to Gossypium barbadense, L viz., Giza 95 (L1), Giza 87 (L2), and Giza 93 (L3), which used as a parental lines (L) as well as, Suvin (T1), Karshenky (T2), and 10229 (T3) which used as a testers (T), by using line x tester analysis (LxT) across three locations i.e. Sakha, Sids and Shandweel during 2017 and 2018 seasons. The variances due to the genotypes, locations (Loc.), parents (P), crosses (C), (P vs. C), L, T, (parents x loc.) and (P vs. C x loc.) were significant for most traits under study. Among the parents, Giza 95 (L1) and Karshenky (T2) were highest yielding parents for most studied yield traits, Giza 87 (L2) and Suvin (T1) for most studied fiber traits. According to useful heterosis and desirable specific combining ability effects estimations, the promising recombination's i.e., (L1xT1), (L2xT2), (L3xT1), (L3xT2) and (L3xT3) were the highest values for most studied traits. Proportion contribution of testers were the high values for No. of bolls/plant, seed cotton yield per plant, boll weight and fiber strength traits. Meanwhile, lines contributions were the highest for other traits. The non-additive genetic effect was larger than additive ones for NB/P, SCY/P, LY/P and length uniformity index. Meanwhile, heritability in broad sense (h2b %) were higher than the values of narrow sense (h2n %) for all characters under study.

Adaptation of common bean lines to high temperature conditions: genotypic differences in phenological and agronomic performance

The common bean is the most important legume for human consumption and is grown in areas under conditions of varied rainfall and temperature that limit its yield. The objective of the present study was to identify genotypic differences in adaptation of 91 bean genotypes to high temperature under environmental conditions of a tropical dry forest ecosystem. We quantified differences among genotypes in terms of phenology, dry matter partitioning indices and grain yield. Common bean lines were derived from interspecific and intraspecific crosses among Phaseolus species of P. vulgaris, P. acutifolius, P. coccineus and P. dumosus. We identified three germplasm accessions of P. acutifolius (G 40001, G 40027, G 40141); two lines from the cross of P. vulgaris × P. acutifolius (INB 837, SIN 524); two lines from the cross of P. vulgaris × P. acutifolius × P. coccineus (SEF 14, SEF 42) and eight lines of P. vulgaris (BFS 10, SEN 46, SEN 48, SEN 70, SMN 99, SMC 140, SMR 139-1G, AMADEUS-EAP-9510-77) that are better adapted to higher temperature stress conditions, evidencing the significant contribution of P. acutifolius to heat tolerance derived from interspecific crosses in common beans. We also found a few Andean lines of growth habit I (SAP 1, SAP 1-15, SAP 1-16, G 122, SAB 618, DAB 525) with superior level of adaptation to heat stress. The superior performance of all these above identified genotypes under higher temperature conditions was attributed to early maturity, high pollen viability and greater ability to partition dry matter to reproductive growth together with greater grain filling.