Female Cultivars Research Articles

Stem Cutting Propagation and Micropropagation of Northern Bayberry

Northern bayberry [Morella (formerly Myrica) pensylvanica] is an attractive, adaptable, semievergreen, northeastern North American native shrub that is sought for landscaping but difficult to propagate clonally. The impact of timing (June, July, or August) and concentration of indole-3-butyric acid [IBA (0, 2000, 4000 or 8000 ppm)] on propagation by stem cuttings was evaluated for genotypes of northern bayberry including the female cultivars Bobzam (Bobbee™) and UConn Compact and an unnamed male. Medium formulation and cytokinin type were evaluated for micropropagation of ‘Bobzam’ and ‘UConn Compact’. Stem cuttings of ‘Bobzam’ and ‘UConn Compact’ rooted poorly (at ≤55% and ≤20%, respectively) at all timings and concentrations of IBA; however, rooting success of ≥85% was achieved for the unnamed male genotype when cuttings were taken in June. Micropropagation of ‘Bobzam’ was successful using Woody Plant medium with 4 mg·L−1 zeatin and explants taken from shoots that had expanded 12 to 18 cm on containerized stock plants. Initiated explants of ‘Bobzam’ required eight subcultures before they began to produce shoots consistently at a 2× multiplication rate and eventually reached a 3× multiplication rate. Micropropagation attempts using Murashige and Skoog medium, the cytokinins 6-benzylaminopurine, meta-topolin, and thidiazuron, or the cultivar ‘UConn Compact’ were unsuccessful. Microshoots of ‘Bobzam’ rooted at ≥80% either by in vitro prerooting or ex vitro rooting directly in trays. Rooted microcuttings easily acclimated to greenhouse conditions and grew rapidly when potted to 1.04-L containers and then into 5.68-L containers. The micropropagation protocol developed for ‘Bobzam’ can be used by propagators to expand production of this popular female cultivar.

Impact of pollination schedules on the fruit characteristics of kiwifruit

Timings of pollination are crucial for adequate fruit set, development, quality and yield of kiwifruit. A study was undertaken for three years (2020-22) to find out the effective pollination period (EPP) of commercial kiwifruit cultivars in Sikkim conditions. Ten-year-old vines of the female cultivar Monty and the male cultivar Allison were taken for the study. It was found that 8 am is the most important time to perform pollination for obtaining bigger-sized fruits. Fruit set was found to be 100% when pollination was performed at 9 am, 10 am and 3 pm. The yield was found to be the highest at 9 am (35.20 kg/plant) pollination time; TSS recorded 1.38-fold variations with the maximum at 8 am (19.1°B). Total acidity was recorded as the minimum at 9 am (0.64%) pollination. Further, ascorbic acid was recorded at to be the maximum at 9 am (118.9 mg/100g) pollination. Primary and secondary nutrients were also found to be higher in pollinated flowers from 8.00 am to 12.00 pm. Thus, efforts for producing good quality and marketable size fruits in kiwifruit the vines should the flowers should be within the 8.00 am to 12.00 pm pollination timings.

Effect of Fluraton and male cultivar on embryonic development of flowers of date palm (Phoenix dactylifera L.) C.V.‘Barhee

This study explores the influence of Fluoraton treatment and male cultivar selection on the embryonic development of offshoot flowers in tissue-cultured date palms (Phoenix dactylifera L.), specifically focusing on the 'Barhee' cultivar. Female offshoots, derived from tissue culture, were subjected to inoculation with two male cultivars, namely Al-Ghanamy Al-Akhdar and a male-seed strain. Concurrently, Fluoraton treatment, administered at concentrations of 0, 0.3, and 0.6 g L-1, was applied to the female inflorescences. Microscopic examinations unveiled significant impacts on pollen tube development, fertilization, and embryonic sac growth. These findings offer valuable insights into optimizing the pollination process, ultimately leading to enhanced fruit production. The study underscores the significance of employing Fluoraton treatment and selectively choosing certain male cultivars over others for the pollination of female cultivars, given their pivotal role in expediting the early ripening of fruits. Notably, the male was utilized in the pollination process independently of the female variety, as no discernible differences were observed between the flowers of the two female cultivars. Keywords: Fluraton, male cultivar, embryonic development, flowers, date palm, Barhi.

Agro-climatic requirements and reproductive potentials of pistachio pollinator specimens grown in warm area in North Africa

The success of pistachio production depends on the best selection of female and male trees combined with perfect flowering synchronization. In warm areas, flowering is highly affected by climate change and selecting an appropriate pollinator for a female cultivar is challenging. In this study, seventeen local pistachio pollinators were under study in the arid Central Tunisian region. Bloom timing and chilling and heat requirements were determined based on 17 years of phenology records and using the Partial Least Squares (PLS) regression. Pollen production and quality were assessed. Three pollinator groups as early-, intermediate- and late-flowering ones were delineated and their median bloom dates spanned from DOY84 to DOY110, with bloom dates spread over 27 and 37 days, allowing perfect coverage of the bloom period of the female cultivar Mateur. Within the three groups, the most interesting candidates were H23a and H26a as intermediate-flowering males, H3a, H3b, H18, H23b and H26b as late-flowering ones and H30 as an early-flowering male covering the first flowers blooming. The pollen viability was high in all the studied pollinators (92–98 %). However, great differences existed in inflorescence density (in the range of 2–4) and pollen production per inflorescence (in the range of 191–424 mg). Based on flowering synchronization, the suitable ones had less variable chilling requirements in the range of 33–37 Chill Portions (CP) in warm areas against a significant variability of the heat needs (8783–17,302 GDH). This supported the key role of increased heat accumulation to compensate for the lack of chill and when chilling requirements are not fully fulfilled in warm areas until the chill threshold value of 25 CP. A significant delayed flowering period occurred for all pistachio pollinators when chill accumulation dropped below 25 CP, which may cause asynchronous flowering, leading to poor pollination. In conclusion, bloom timing and pollen production are common variables to characterize pistachio pollinators. The agroclimatic needs could be a relevant tool for planning the best combination linked to local conditions, while estimation improvement is required for warm areas. However, pistachio cultivation in warmer areas will be viable until a certain chill level. Pistachio cultivars will be able to grow, while lack of chill will be overcome with heat accumulation key role for chill compensation until a threshold of 25CP. These findings are of high interest for the warmest orchards, which will cover many important fruit-growing regions with Mediterranean climates all over the world with the expected climate change.

Male diversity matters: genetic structuring of insular male date palm (Phoenix dactylifera L.) revealed valuable breeding and conservation resources

ABSTRACT Most male date palms available for pollinating different female cultivars have mainly originated from seed propagation resulting in many different local males that represent a source of genetic diversity. Favourable fruit production is related to the quality of pollen and its compatibility with a certain female variety. Therefore, the genetic characterisation of the male progenitors should be the first step to establish a selection programme to produce superior males through different procedures. In this study, the genetic diversity and population structure of 72 male date palm accessions were investigated using 15 microsatellite loci. The highest mean number of alleles per locus was obtained for Tozeur group. Bayesian model-based clustering analysis indicated the presence of two differentiated endemic male date palm genetic clusters, continental and insular, with the presence of introduced accessions originating from the Middle East. The diversity analysis in the insular region of Tunisia, which had never been performed before, revealed that this germplasm enclosed valuable endemic resources supporting the hypothesis of the presence of wild material. These findings are crucial for identifying interesting genotypes that can be integrated into international coordinated actions of Phoenix dactylifera L. breeding programmes and the protection and conservation of valuable resources.

Identification of genetic regions associated with sex determination in date palm: A computational approach

Sex determination of date palm seedlings is the challengeable effort for breeders. Different studies based on molecular markers and genome sequencing have provided some insight in to the genetic regions related to sex determination in date palms in general. But due to differences in cultivar population structure and also cost of whole genome sequencing, we may need a more suitable approach in developing countries for this task. Therefore, we suggest using a combination of different available molecular markers and a computational approach to identify the genetic regions involved in sex differentiation in date palm cultivars. In this study we used twenty-three cultivars including 7 male and 16 female cultivars that were examined by 30 different dominant and co-dominant molecular markers which deal with different genomic regions. Grouping of the tree samples based on 178 loci resulted in genetic differentiation of the studied male and female palm trees. Multiple correspondence analysis (MCA) bi-plot also showed genetic difference within male and female trees. Heatmap plot specified those markers which differentiate date palm trees. SSR (simple sequence repeats) and IRAP (inter retrotransposon amplified polymorphism) markers provided sex linked markers for male cultivars. In present study, we introduced sex specific alleles for Iranian male date palm cultivars as a fast track in seedlings. Different association studies performed identified the candidate genetic regions which are significantly associated with sex differentiation in date palm cultivars.

Evaluation of Pollen Production of Common Male Date Palms Grown in the Mexicali Valley, Mexico

The aim of this study was the evaluation of date palm (Phoenix dactylifera L.) pollen production during the 2021 and 2022 seasons in the Mexicali Valley, Mexico. Twelve seed-propagated male palms of 20 years of age and similar vigor were selected and grouped into four groups with phenotypic characteristics of the common female cultivars in the area (Medjool, Deglet Noor, Khadrawy, and Zahidi). The pollen was extracted manually, with average production among all individuals of 780.94 and 777.11 g, in 26 and 24 inflorescences, respectively, for each year. Likewise, the flowering period on average was 47 and 41 days for each year. The pollen extracted from the earliest four inflorescences averaged 38.7 and 32.55 g, while that of the latest one produced 10.70 g and 18.28 g for each year, respectively. Seedling male palms with a phenotype similar to the Deglet Noor cultivar produced the greatest amount of pollen with 1250.98 and 1114.26 g on average for each year, produced during a late, short flowering period. Likewise, those palms with phenotypes similar to the Medjool cultivar produced the second-highest amount of pollen with 851.28 and 866.43 g on average for each year, produced during an early, long flowering period. Finally, an in vivo viability test through the fruit set percentage, revealed that the use of any of these four pollen sources would be suitable for the pollination of the recipient female cultivar Medjool, the most widely cultivated variety in Mexico. These results will allow date producers to select and propagate better pollen-producing male palms.

AGAMOUS Gene as a New Sex-Identification Marker in Fig (Ficus carica L.) Is More Efficient Than RAN1.

Fig is an ancient gynodioecious fruit tree with females for commercial fruit production and hermaphrodites (males) sometimes used as pollen providers. An early sex-identification method would improve breeding efficiency. Three AGAMOUS (AG) genes were recruited from the Ficus carica genome using AG sequences from Ficus microcarpa and Ficus hispida. FcAG was 5230 bp in length, with 7 exons and 6 introns, and a 744-bp coding sequence. The gene was present in both female and male fig genomes, with a 15-bp deletion in the 7th exon. The other two AG genes (FcAG2-Gall_Stamen and FcAG3-Gall_Stamen) were male-specific, without the 15-bp deletion (759-bp coding sequence), and were only expressed in the gall and stamen of the male fig fruit. Using the deletion as the forward primer (AG-Marker), male plants were very efficiently identified by the presence of a 146-bp PCR product. The previously reported fig male and female polymorphism gene RESPONSIVE-TO-ANTAGONIST1 (RAN1) was also cloned and compared between male and female plants. Fifteen SNPs were found in the 3015-bp protein-coding sequence. Among them, 12 SNPs were identified as having sex-differentiating capacity by checking the sequences of 27 known male and 24 known female cultivars. A RAN1-Marker of 608 bp, including 6 SNPs, was designed, and a PCR and sequencing-based method was verified with 352 fig seedlings from two hybrid populations. Our results confirmed that the newly established AG-Marker is as accurate as the RAN1-Marker, and provide new clues to understanding Ficus sex determination.

Effect of Genetically Diverse Pollen on Pollination, Pollen Tube Overgrow, Fruit Set and Morphology of Kiwiberry (Actinidia arguta)

Successful pollination and fertilization are crucial processes for obtaining a high yield, especially for dioecious plants such as A. arguta. Determination of pollen tube growth on stigma and fruit development parameters, which were investigated in this study, can enable the evaluation of male–female compatibility—one of the factors of successful pollination. Pollen quality and grain size were analysed for two years on six male cultivars of A. arguta and one of A. chinensis var. deliciosa. Results showed high pollen quality, both with parameters above 80%. Pollen germination in vivo showed differences in pollen–stigma interactions. The highest positive interactions were observed for all female cultivar crosses with male ‘Nostino’ and ‘Rubi’ and the lowest one for A. chinensis var. deliciosa ‘Tomuri’. However, fruit set and average fruit weight were equally high in most of the combinations (fruit set above 75% for the majority of combinations). Some differences were noticed in the average seed number per fruit and weight. All tested male cultivars were able to fertilize tested female cultivars, but taking into account other characteristics such as pollen efficiency, some male cultivars seemed to be more proper for commercial orchards. Using A. chinensis var. deliciosa pollen seems to be unreasonable in tested conditions.

Sea Buckthorn Leaf Powders: The Impact of Cultivar and Drying Mode on Antioxidant, Phytochemical, and Chromatic Profile of Valuable Resource.

Sea buckthorn (Hippophae rhamnoides L. (HR)) leaf powders are the underutilized, promising resource of valuable compounds. Genotype and processing methods are key factors in the preparation of homogenous, stable, and quantified ingredients. The aim of this study was to evaluate the phenolic, triterpenic, antioxidant profiles, carotenoid and chlorophyll content, and chromatic characteristics of convection-dried and freeze-dried HR leaf powders obtained from ten different female cultivars, namely ‘Avgustinka’, ‘Botaniceskaja Liubitelskaja’, ‘Botaniceskaja’, ‘Hibrid Percika’, ‘Julia’, ‘Nivelena’, ‘Otradnaja’, ‘Podarok Sadu’, ‘Trofimovskaja’, and ‘Vorobjovskaja’. The chromatic characteristics were determined using the CIELAB scale. The phytochemical profiles were determined using HPLC-PDA (high performance liquid chromatography with photodiode array detector) analysis; spectrophotometric assays and antioxidant activities were investigated using ABTS (2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) and FRAP (ferric ion reducing antioxidant power) assays. The sea buckthorn leaf powders had a yellowish-green appearance. The drying mode had a significant impact on the total antioxidant activity, chlorophyll content, and chromatic characteristics of the samples; the freeze-dried samples were superior in antioxidant activity, chlorophyll, carotenoid content, and chromatic profile, compared to convection-dried leaf powder samples. The determined triterpenic and phenolic profiles strongly depend on the cultivar, and the drying technique had no impact on qualitative and quantitative composition. Catechin, epigallocatechin, procyanidin B3, ursolic acid, α-amyrin, and β-sitosterol could be used as quantitative markers in the phenolic and triterpenic profiles. The cultivars ‘Avgustinka’, ‘Nivelena’, and ‘Botaniceskaja’ were superior to other tested cultivars, with the phytochemical composition and antioxidant activity.

Optimization of in vitro pollen germination and viability testing of some Australian selections of date palm (Phoenix dactylifera L.) and their xenic and metaxenic effects on the tissue culture–derived female cultivar “Barhee”

Optimization of in vitro pollen germination and viability testing of some Australian selections of date palm (Phoenix dactylifera L.) and their xenic and metaxenic effects on the tissue culture–derived female cultivar “Barhee”

Performance inheritance and combining ability of spring barley accessions

Purpose and objectives. To establish the gene interaction types in the performance inheritance, to evaluate the combining abilities and effects of genes for this trait in spring barley accessions.
 Materials and methods. We investigated 75 F1 spring barley hybrid combinations derived from crossing 25 female forms with three male ones (chaffy and naked). Crossing was conducted in accordance with topcross design. F1 seeds and parents were sown with a cassette breeding planter SKS-6A. Grain pea was the forecrop. The plot area was 0.20 m2. The interrow distance was 0.20 m; the inter-plot tracks were of 0.50 m. Crossings were performed in two replications. Plants were harvested manually, with roots.
 For structural analysis, 20 typical plants were chosen from each F1 hybrid population, and the performance inheritance was determined by dominance degree (hp). The obtained data were grouped and gene interaction types were determined as per G.M. Beil and R.E. Atkins’s classification. Using two-factor analysis of variance in STATISTICA 10, we found significant differences between the GCA and SCA variances for the performance and evaluated the combining ability effects.
 Results and discussion. In 2019–2020, the features of 22 spring barley cultivars and three lines were described in terms of the gene interaction types in the performance inheritance and combining ability. On this basis, the prospects of biotype selections were evaluated. In the arid conditions of 2019, F1 only showed positive over dominance, while in favorable 2020 the inheritance types varied from positive to negative overdominance. In the two years, the general combining ability was high in female cultivars Khors and Troian. The male components did not show consistently high GCA for the both years. Hybrids between accessions with a high GCA and accessions with a lower or intermediate GCA may be promising in breeding due appearance of positive transgressions in the offspring. In 2019, the SCA effects were significantly strong in female forms Troian, Datcha, Gladys, Grace, Gatunok, Modern, and Herkules and in male forms Ahrarii and Scrabble.
 Conclusions. The study found that the gene interaction types in the spring barley performance inheritance depended on cross combinations and growing conditions. In unfavorable 2019, F1 only showed positive overdominance (heterosis), while in favorable 2020, positive overdominance, positive dominance and intermediate inheritance were observed. In 2019–2020, the high GCA was seen in female cultivars Khors and Troian. The strong SCA effects were noticed in female components Troian, Datcha, Gladys, Grace, Gatunok, Modern, and Herkules and male forms Agrarii and Scrabble. The hybrid combinations with the maximum probability of producing transgressive segregants have been selected

Molecular Mechanism Underlying Derepressed Male Production in Hexaploid Persimmon

Sex expression in plants is often flexible and contributes to the maintenance of genetic diversity within a species. In diploid persimmons (the genus Diospyros), the sexuality is controlled by the Y chromosome-encoded small-RNA gene, OGI, and its autosomal counterpart, MeGI. Hexaploid Oriental persimmon (Diospyros kaki) evolved more flexible sex expression, where genetically male individuals carrying OGI can produce both male and female flowers (monoecy). This is due to (semi-)inactivation of OGI by the Kali-SINE retrotransposon insertion on the promoter region and the resultant DNA methylations. Instead, flower sex determination in Oriental persimmon is also dependent on DNA methylation states of MeGI. Here, we focused on a cultivar, Kumemaru, which shows stable male flower production. Our results demonstrated that cv. Kumemaru carries OGI with Kali-SINE, which was highly methylated as well as in other monoecious cultivars; nevertheless, OGI gene could have a basal expression level. Transcriptomic analysis between cv. Kumemaru and 14 cultivars that predominantly produce female flowers showed differentially expressed genes (DEGs) specific to cv. Kumemaru, which is mainly involved in stress responses. Co-expression gene networks focusing on the DEGs also suggested the involvement of stress signals, mainly via gibberellin (GA), salicylic acid (SA), and especially jasmonic acid (JA) signal pathways. We also identified potential regulators of this co-expression module, represented by the TCP4 transcription factor. Furthermore, we attempted to identify cv. Kumemaru-specific transcript polymorphisms potentially contributing to derepressed OGI expression by cataloging subsequences (k-mers) in the transcriptomic reads from cv. Kumemaru and the other 14 female cultivars. Overall, although the direct genetic factor to activate OGI remains to be solved, our results implied the involvement of stress signals in the release of silenced OGI and the resultant continuous male production.

Uniparental Inheritance of Salinity Tolerance and Beneficial Phytochemicals in Rice

Salinity stress is one of the most problematic constraints to significantly reduce rice productivity. The Saltol QTL (quantitative trait locus) has been known as one among many principal genes/QTLs responsible for salinity tolerance in rice. However, the introgression of the Saltol QTL from the donor (male) into the recipient (female) cultivars induces great recessions from the progeny generation, which results in heavy fieldwork and greater cost and time required for breeding. In this study, the F1 generation of the cross TBR1 (female cultivar, salinity tolerant) × KD18 (male cultivar, salinity susceptible) was preliminarily treated with N-methyl-N-nitrosourea (MNU) to induce the mutants M1. Results on physiological traits show that all the M2 (self-pollinated from M1) and M3 (self-pollinated from M2) individuals obtain salinity tolerant levels as the recurrent TBR1. Twelve SSR (simple sequence repeat) markers involved in the Saltol QTL (RM493, RM562, RM10694, RM10720, RM10793, RM10852, RM13197, RM201, RM149, RM508, RM587, and RM589) and other markers related to yield-contributing traits and disease resistance, as well as water and nitrogen use, have efficacy that is polymorphic. The phenotype and genotype analyses indicate that the salinity tolerant Saltol QTL, growth parameter, grain yield and quality, pest resistance, water and nitrogen use efficacy, and beneficial phytochemicals including antioxidants, momilactone A (MA) and momilactone B (MB) are uniparentally inherited from the recurrent (female) TBR1 cultivar and stabilized in the M2 and M3 generations. Further MNU applications should be examined to induce the uniparental inheritance of other salinity tolerant genes such as OsCPK17, OsRMC, OsNHX1, OsHKT1;5 to target rice cultivars. However, the mechanism of inducing this novel uniparental inheritance for salinity tolerance by MNU application needs elaboration.

UC pistachio cultivars show improved nut quality and are ready for harvest earlier than ‘Kerman’

California pistachio growers have traditionally grown only one female cultivar (‘Kerman’) and one male pollenizer (‘Peters’). Starting in 2005, the UC breeding program released several improved cultivars, which are being planted on increasing acreage — and tested now under commercial conditions at multiple sites over multiple years. We conducted six experimental trials in the San Joaquin Valley to evaluate the performance of the UC cultivars ‘Gumdrop’, ‘Golden Hills’ and ‘Lost Hills’ and their associated UC male pollenizers ‘Famoso’, ‘Randy’ and ‘Tejon’ against the performance of the traditional pair, ‘Kerman’ and ‘Peters’. The new cultivars demonstrated a range of earlier bloom and harvest dates than ‘Kerman’ and some improved nut quality characteristics, such as a higher percentage of split, in-shell nuts. Results indicate that by growing the new female cultivars and synchronous pollenizers, producers can avoid the peak harvest period for ‘Kerman’, when equipment and processing facilities are limited, and maintain or improve their yield and nut quality.

Characterization of Flowering Time and Pollen Production in Jojoba (Simmondsia chinensis) towards a Strategy for the Selection of Elite Male Genotypes

The seeds of the dioecious shrub jojoba (Simmondsia chinensis (Link) Schneider) yield a liquid wax that is in high demand for the cosmetics industry. While elite female cultivars of this species are currently clonally propagated, male plants are grown from seed, resulting in large variations in both the flowering period and the pollen viability, and hence large variation in yields. We characterized the existing male plant material in a local plantation as a platform for future selection of elite male cultivars that would produce sufficient amounts of viable pollen throughout the extended flowering period of the female cultivars. Using as a guide the number of viable pollen grains per 1-m branch, defined here as the calculated effective pollen productivity (EPP), we identified plants with an elevated EPP that flower concurrently with the female cultivars.

Construction of an anchoring SSR marker genetic linkage map and detection of a sex-linked region in two dioecious populations of red bayberry

Red bayberry (Morella rubra) is an evergreen fruit tree found in southern China whose whole-genome sequence has recently been published. We updated the linkage map of the species by adding 118 SSR markers and the female-specific marker MrFT2_BD-SEX. The integrated map included eight linkage groups and spanned 491 cM. Eleven sex-associated markers were identified, six of which were located in linkage group 8, in agreement with the previously reported location of the sex-determining region. The MrFT2_BD-SEX marker was genotyped in 203 cultivated accessions. Among the females of the accessions, we found two female-specific alleles, designated W-b (151 bp) and W-d (129 bp). We previously found that ‘Dongkui’, a female cultivar, could produce viable pollen (we refer to such plants ‘Dongkui-male’) and serve as the paternal parent in crosses. The genotypes of the MrFT2_BD-SEX marker were W-b/Z in ‘Biqi’ and W-d/Z in ‘Dongkui-male’. The progeny of a cross between these parents produced a 3:1 female (W-) to male (ZZ) ratio and the expected 1:1:1:1 ratio of W-b/W-d: W-b/Z: W-d/Z: Z/Z. In addition, the flowering and fruiting phenotypes of all the F1 progeny fit their genotypes. Our results confirm the existence of ZW sex determination and show that the female phenotype is controlled by a single dominant locus (W) in a small genomic region (59 kb and less than 3.3 cM). Furthermore, we have produced a homozygous “super female” (WW) that should produce all-female offspring in the F2 generation, providing a foundation for commercial use and presenting great potential for use in modern breeding programs.

Inheritance of seed size by hybrid populations of pea (F1, F2)

Pea (Pisum sativum L.) is one of the ancient and valuable high-protein leguminous cultures in the world. Breeding of new high-yielding cultivars is the main reserve to increase production of pea seeds. At the present time, intraspecific hybridization has a great importance in selection of new cultivars of pea. However, consistent patterns of inheritance of a number of economically valuable traits by hybrids are still insufficiently investigated. The objective of this research work was to study inheritance of seed size (1000-kernel weight) by pea hybrids of the first and second filial generations (F1, F2). The crossing and back-crossing (reciprocal crossing) were conducted. In our experiments, the first filial generation hybrids (F1) had a lower 1000-kernel weight than the large-seeded parental cultivars. Herewith the large-seeded genotype of the female parental cultivar had more influence on displaying of this trait in hybrids than of the male parental cultivar. In the second filial generation hybrids (F2) showed intermediate inheritance of seed size. The results of our experiments attest high efficiency of seed size selection in segregating generations of hybrids, obtained from crosses between cultivars carrying genes of seed size.

Identification of dominant genetic markers relevant to male sex determination in mulberry (Morus alba L.)

Morus alba (white mulberry) is a cultivated species of mulberry that exists as both dioecious and monoecious plants in nature. Although it has been cultivated for years as an essential crop for sericulture, and although various cultivars are readily available, its sex determination mechanisms are not yet clear. In the present study, we aimed to elucidate sex determination mechanisms of mulberry using both genetic and genomic approaches. Female and male cultivars of dioecious M. alba were crossed, and the segregation of sex was analyzed in the F1 plants. In the F1 plants, female and male plants were segregated at an almost equal ratio. By comparing the restriction site associated DNA sequencing analysis data between female- and male-bulked DNA of these F1 plants, the male-bulk-specific RAD tags were predominantly identified. Thus, we presumed that the male M. alba is heterogametic whereas the female M. alba is homogametic. Based on the corresponding sequences of male-bulk-specific RAD tags, putative male-specific markers were developed, and these markers exhibited linkage with the male sex in individual F1 plants. However, genotypes of these markers did not always show an association with sex in the cultivars of M. alba, M. bombycis, and M. lhou. Around half of the analyzed female cultivars showed identical marker genotypes to male, whereas all the analyzed male and monoecious cultivars showed a consistent genotype. According to these results, the DNA markers developed in this study were found to be relevant to male flower determination, and are thus expected to be helpful for elucidating the mechanisms underlying the evolutionary and sex determination systems of mulberry plants.

Identification of Genetic Variation of Male and Female Date Palm (Phoenix dactylifera L.) Cultivars Using Morphological and Molecular Markers

Date palm (Phoenix dactylifera L.) is a monocot, dioecious and high longevity tropical plant greatly considered due to its high economic importance in Middle East. This investigation was carried out to detect genetic relations among 34 cultivars of Iranian date palm, both males and females, using ISSR markers. Accordingly, total DNA was extracted using CTAB method and was subjected to PCR amplification using 12 ISSR primers. Analysis of ISSR data indicated that PIC value varied from 0.3695 to 0.4998 with average of 0.4497. The highest PIC value belonged to (CT)10 G primer (0.4498). Totally, 112 alleles were recognized. According to morphological attributes and ISSR markers, the 34 studied date cultivars divided into eight main groups and different sub-groups, and no significant correlation between grouping made by morphological and molecular markers. Unlike ISSR markers that produced a clear-cut among male and female cultivars, no distinct border was seen among male and female cultivars using morphological attributes. Furthermore, PCA analysis confirmed the grouping made by ISSR markers. In conclusion, ISSR markers have been useful to separate date palm cultivars.