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Different types of palmyrah fruits showing carpel distribution and seed germination. a, Cross-section of one-, two-, three-and four-seeded fruits; b, Cross-section of three-seeded fruit; two seeds were separated by thin carpel; c, A bunch of palmyrah fruits; d, Elongation of apocolons from three-seeded fruit during tubular germination.
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The palmyrah palms are slow-growing dioecious perennials and have no distinguishing features to
identify the sex until flowering. The palm commences flowering only after 12–15 years of maturity. The seed
sex ratio (primary sex ratio) was estimated by germinating seeds and growing seedlings under favourable
conditions with minimal mortality until fl...
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Citations
... Several problems are encountered in the germination of seeds in Palmyrah such as poor, protracted germination and prolonged nursery period. The Palmyrah seed takes 40-60 days to initiate germination and the eophyll (first leaf) emerge out after a period of 100 days from sowing (George and Karun, 2011;Masilamani et al., 2020). Besides germination, short viability is major problem in Palmyrah (Masilamani et al., 2021). ...
Studies were carried out to find the influence of media and sowing conditions on the field emergence of Palmyrah seeds. The seeds were sown in a sunken nursery bed, raised nursery bed, and direct sowing to observe field emergence. The experiment was conducted in a Randomized Block Design with eight replications of 50 seeds sown in each treatment. The observations were recorded at monthly intervals up to 24 months after sowing. The results revealed that Palmyrah seeds sown in a raised bed containing red earth, sand and farmyard manure 2:1:1 ratio recorded the highest field emergence of 78.67 % followed by seeds sown in sand and field conditions. This study concluded that Palmyrah seeds sown in raised bed containing red earth, sand and farmyard manure 2:1:1 ratio used for sowing/multiplication purpose
... The palmyrah palms are slow-growing of the remotive tubular type and have no distinguishing features to identify the sex until flowering. The palm commences flowering only after 12-15 years of maturity (George and Karun, 2011). Palmyrah is an annual flowering type and usually flowers during November. ...
... Several problems are encountered in germination of seeds in palmyrah such as poor, protracted germination and prolonged nursery period. The palmyrah seed takes 40-60 days to initiate germination and the eophyll (first leaf) emerge out after a period of 100 days from sowing (George and Karun, 2011;Masilamani et al., 2020). The main reasons for the failure of seeds to germinate in suitable conditions are either dead or dormant. ...
Palmyrah (Borassus flabellifer L.) is a slow growing, dioecious, drought resistant palm and considered to be native of Tropical Africa. It is cultivated as well as found growing in wild in the Indian subcontinent. It is distributed in India, Burma, Africa and Sri Lanka. Several problems are encountered in germination of seeds in palmyrah such as poor, protracted germination and prolonged nursery period. The main reasons for the failure of seeds to germinate in suitable conditions are either dead or dormant. The delayed germination of palmyrah might be due to the stony endocarp acting as a physical barrier to imbibition or imposing mechanical resistance to embryo enlargement. Against this backdrop, this review focuses on seed dormancy, pre-sowing seed treatment, nursery technology, and seed storage behaviour of palmyrah.
... Male and female flower identification in fruit and seed-producing plants is crucial from the breeder's perspective. The plants in which female flower representation is more important than male flowers include Actinidia deliciosa (Shirkot et al., 2002); Phoenix dactylifera (Solliman et al., 2019); Carica papaya (Parasnis et al., 2000); Borassus flabellifer (George and Karun, 2011); Hippophae rhamnoides (Persson and Nybom, 1998;Sharma et al., 2010); Myristica fragrans (Shibu et al., 2000); Piper longum (Manoj et al., 2008); Pistacia vera (Hormaza et al., 1994;Hormaza and Wunsch, 2007), and Simmondsia chinensis (Agrawal et al., 2007(Agrawal et al., , 2011(Agrawal et al., , 2008Mohasseb et al., 2009). To achievebetter date palm production, female plants should be more than males. ...
Sex determination in the early developmental stages of dioecious crops is economically-beneficial. During this study, a human homology of SRY gene was successfully identified in dioecious crops. SRY gene sequences of date palm and jojoba were submitted to GenBank under the accession numbers KC577225 and MK991776, respectively. This is the first report regarding the novel sex-determination methodology of four dioecious plants (jojoba, date palm, papaya, and pistachios). SRY sex gene was found in all the tested dioecious plant and human samples. This novel approach is simple and of significant importance for breeders. It facilitates the unambiguous selection of jojoba and date palm female plants at an early age and reduces the plantation cost of cultivating non-productive male plants. This is a rapid sex-determination technique for dioecious plants and mammals at an early stage. This technique specifically targets the SRY sequence that has been comprehensively investigated in humans. The kit development for the SRY-based sex determination of various crops is in progress.
... The sex-specific molecular markers for Lodoicea maldivica described here are among the first to be developed for any palm species (but see Karun 2011 andCherif et al. 2013). Using these markers, we were able to determine reliably the sex of immature plants of Lodoicea sampled from across its native range on the islands of Praslin and Curieuse. ...
Lodoicea maldivica (coco de mer) is a long-lived dioecious palm in which male and female plants are visually indistinguishable when immature, only becoming sexually dimorphic as adults, which in natural forest can take as much as 50 years. Most adult populations in the Seychelles exhibit biased sex ratios, but it is unknown whether this is due to different proportions of male and female plants being produced or to differential mortality. In this study, we developed sex-linked markers in Lodoicea using ddRAD sequencing, enabling us to reliably determine the gender of immature individuals. We screened 589 immature individuals to explore sex ratios across life stages in Lodoicea. The two sex-specific markers resulted in the amplification of male-specific bands (Lm123977 at 405 bp and Lm435135 at 130 bp). Our study of four sub-populations of Lodoicea on the islands of Praslin and Curieuse revealed that the two sexes were produced in approximately equal numbers, with no significant deviation from a 1:1 ratio before the adult stage. We conclude that sex in Lodoicea is genetically determined, suggesting that Lodoicea has a chromosomal sex determination system in which males are the heterogametic sex (XY) and females are homogametic (XX). We discuss the potential causes for observed biased sex ratios in adult populations, and the implications of our results for the life history, ecology and conservation management of Lodoicea.
... Previously, there were only two reports that attempted to develop sex identification markers in Asian Palmyra palm. George et al. (2007) presented a male-specific OPA-06 600 marker after screening 180 RAPD primers using ten male and ten female samples from several populations in India and later used this marker to verify the sexes of more than 100 seedlings (George & Karun, 2011). Vinayagam et al. (2009) reported another attempt, but could not identify any sex-linked marker after screening up to 130 ISSR markers (with 65 polymorphic bands) based on 20 accessions from another population in India. ...
... Because the genome size of Asian Palmyra palm has not yet been reported, it is difficult to estimate the number of screening primers to cover the genome for effective screening. Considering that our experiment used an extensive set of 1,204 primer pairs among ten techniques and there was only a single sex-linked marker identified in the previous attempts using up to 180 RAPD and 130 SSR primers (Vinayagam et al., 2009;George & Karun, 2011), this demonstrated a complexity in identifying sex-linked loci in Asian Palmyra palm. ...
Background:
Asian Palmyra palm, the source of palm-sugar, is dioecious with a long juvenile period requiring at least 12 years to reach its maturity. To date, there is no reliable molecular marker for identifying sexes before the first bloom, limiting crop designs and utilization. We aimed to identify sex-linked markers for this palm using PCR-based DNA fingerprinting, suppression subtractive hybridization (SSH) and transcriptome sequencing.
Methods:
DNA fingerprints were generated between males and females based on RAPD, AFLP, SCoT, modified SCoT, ILP, and SSR techniques. Large-scale cloning and screening of SSH libraries and de novo transcriptome sequencing of male and female cDNA from inflorescences were performed to identify sex-specific genes for developing sex-linked markers.
Results:
Through extensive screening and re-testing of the DNA fingerprints (up to 1,204 primer pairs) and transcripts from SSH (>10,000 clones) and transcriptome data, however, no sex-linked marker was identified. Although de novo transcriptome sequencing of male and female inflorescences provided ∼32 million reads and 187,083 assembled transcripts, PCR analysis of selected sex-highly represented transcripts did not yield any sex-linked marker. This result may suggest the complexity and small sex-determining region of the Asian Palmyra palm. To this end, we provide the first global transcripts of male and female inflorescences of Asian Palmyra palm. Interestingly, sequence annotation revealed a large proportion of transcripts related to sucrose metabolism, which corresponds to the sucrose-rich sap produced in the inflorescences, and these transcripts will be useful for further understanding of sucrose production in sugar crop plants. Provided lists of sex-specific and differential-expressed transcripts would be beneficial to the further study of sexual development and sex-linked markers in palms and related species.
... Some research results done using RAPD technique is able to provide enough information to help in the selection related to sex of Borassus flabellifer L. (George and Karun, 2011); Trichosanthes dioica Roxb (Sing, Kumar, Sing, Ram, and Kalloo (2002); asparagus (Jamsari, et al., 2003), Piper longum (Manoj, et al., 2005). The research aims to get the primer that can produce specific banding pattern related to the control of kapulasan female sex with DNA amplification technique by in vitro using Polymerase Chain Reaction (PCR). ...
Kapulasan is one of horticultural plants derived from tropical region that has significant economic value. One of the obstacles in cultivating the plant is that kapulasan has flowering type of androdioceus, i.e. the male and the female flowers are separated. Female flowers produce hermaphroditic flowers that can produce fruits while the male ones will not produce fruits. In the cultivation of the plant, it is very difficult to determine the female flowers if they are propagated by seeds. It takes up to 7 years to determine the nature of the flowering. One of the important steps that can be done is through a system of early detection using molecular marks. RAPD technique as a simple technique can be used to distinguish the characteristics. The results of the research show that of the 250 primers used, the OPM-09 primer produces female sex bands related to the controller of the female kapulasan plants of which the ribbon produced is 512 bp in size.
... Some research results done using RAPD technique is able to provide enough information to help in the selection related to sex of Borassus flabellifer L. (George and Karun, 2011); Trichosanthes dioica Roxb (Sing, Kumar, Sing, Ram, and Kalloo (2002); asparagus (Jamsari, et al., 2003), Piper longum (Manoj, et al., 2005). The research aims to get the primer that can produce specific banding pattern related to the control of kapulasan female sex with DNA amplification technique by in vitro using Polymerase Chain Reaction (PCR). ...
... Likewise, no clear phenotypic variations among the population have been identified. Furthermore, the genetic study of this species in India, as thought to be the origin of B. flabellifer in Southeast Asia, using RAPD markers also showed low genetic diversity [15,16,[40][41][42][43]. Simulation for the minimum number of founders estimated that 3-4 individuals settled in the southern and northeastern Thailand represent the founders of the cluster I and II, respectively. ...
Background:
Borassus flabellifer or Asian Palmyra palm is an important crop for local economies in the South and Southeast Asia for its fruit and palm sugar production. Archeological and historical evidence indicated the presence of this species in Southeast Asia dating back at least 1500 years. B. flabellifer is believed to be originated in Africa, spread to South Asia and introduced into Southeast Asia through commercial routes and dissemination of cultures, however, the nature of its invasion and settlement in Thailand is unclear.
Results:
Here, we analyzed genetic data of 230 B. flabellifer accessions across Thailand using 17 EST-SSR and 12 gSSR polymorphic markers. Clustering analysis revealed that the population consisted of two genetic clusters (STRUCTURE K = 2). Cluster I is found mainly in southern Thailand, while Cluster II is found mainly in the northeastern. Those found in the central are of an extensive mix between the two. These two clusters are in moderate differentiation (F ST = 0.066 and N M = 3.532) and have low genetic diversity (HO = 0.371 and 0.416; AR = 2.99 and 3.19, for the cluster I and II respectively). The minimum numbers of founders for each genetic group varies from 3 to 4 individuals, based on simulation using different allele frequency assumptions. These numbers coincide with that B. flabellifer is dioecious, and a number of seeds had to be simultaneously introduced for obtaining both male and female founders.
Conclusions:
From these data and geographical and historical evidence, we hypothesize that there were at least two different invasive events of B. flabellifer in Thailand. B. flabellifer was likely brought through the Straits of Malacca to be propagated in the southern Thailand as one of the invasive events before spreading to the central Thailand. The second event likely occurred in Khmer Empire, currently Cambodia, before spreading to the northeastern Thailand.
... In addition, with the availability of genome sequence of date palm (Phoenix dactylifera) (Al-Dous et al., 2011;Al-Mssallem et al., 2013), a closely related species to Asian Palmyra palm, the numbers of transferable markers for the Asian Palmyra palm could be further expanded. The genetic study of the Asian Palmyra palm was, so far, limited to a few markers, for example, RAPDs developed for sex determination (George and Karun, 2011;George et al., 2007), and ISSRs used for diversity assessment in India (Vinayagam et al., 2009). These, however, were unable to provide a genetic resolution for the population structure of the Asian Palmyra palm because of their limitation as dominant markers. ...
Asian Palmyra palm, found throughout south and southeast Asia, is important for local economies, especially for sugar palm production. Unlike its related species, such as oil palm and coconut, only a few genetic markers are available for Asian Palmyra palm. In this study, we tested the transferability of molecular markers derived from oil palm, and a set of selected markers were used for evaluating the diversity of Asian Palmyra palm growing in Thailand. From 545 primer pairs of expressed sequence tagsimple sequence repeat (EST-SSR) and genomic simple sequence repeat (gSSR) markers, 317 (58.17%) primer pairs were able to amplify the Asian Palmyra palm DNA, and 19 (5.99%) pairs were polymorphic. After extensively genotyping 164 samples from 12 populations, we obtained 25 loci with the polymorphic information content (PIC) average of 0.37 and allele numbers ranging from one to five. The observed and expected heterozygosity ranged from 0 to 1 and 0 to 0.76, respectively. A dendrogram showed separation of the palm populations into two clades, between north-eastern and southerncentral regions. This study provides a set of microsatellite markers for use in further genetic studies of Asian Palmyra palm. © 2017, American Society for Horticultural Science. All rights reserved.
... One male-specific RAPD primer was identified and it was found to produce a polymorphic DNA band of *600 bp in the male plant . Further study by the same group was carried out for early determination of sex in one, two and three-seeded fruits of B. flabellifer L. using the same primer as before (George and Karun 2011). ...
A number of dioecious species are grown across India and some of those plants play a crucial role in the agro-based economy of the country. The diagnosis of sex is very difficult in the dioecious plant prior flowering wherein sex identification at the seedling stage is of great importance to breeders as well as farmers for crop improvement or production purpose. A comprehensive approach of sex determination comprising morphological, biochemical, cytological and molecular attributes is a must required for gender differentiation in dioecious plant species. In the present review, we highlighted the economical, medicinal as well as industrial importance of most of the dioecious species extensively grown in Indian subcontinent. In addition to that, the cytogenetic, genetic as well as molecular information in connection to their sex determination were critically discussed in this review.
