Towards sex identification of Asian Palmyra palm (Borassus flabelliferL.) by DNA fingerprinting, suppression subtractive hybridization andde novotranscriptome sequencing

Abstract

BackgroundAsian 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.MethodsDNA 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 andde novotranscriptome sequencing of male and female cDNA from inflorescences were performed to identify sex-specific genes for developing sex-linked markers.ResultsThrough 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. Althoughde novotranscriptome 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.

Integrative Analyses of Transcriptomics and Metabolomics in Sex Differentiation of Mulberry Flowers

“…In previous studies, galactose metabolism was indicated to be linked to pistil abortion, and pistil deletion of Prunus mume and Camellia sinensis ( Shi et al, 2012 ; Liu et al, 2020 ). Also, galactose metabolism appeared to differ starkly between the male and female inflorescences of Borassus flabellifer palm ( Pipatchartlearnwong et al, 2019 ). 3-ketoacyl-ACP synthase (KAS III) and alpha-galactosidase which participate in the galactose metabolism pathway were specifically expressed in male flowers of Vernicia fordii ( Mao et al, 2017 ).…”

Phytochemical Constituents and Nutritional Potential of Palmyra Palm: A Review

“…Only the female plant produces the edible by products, such as immature endosperm, matured fleshy mesocarp, and tuberous seedling (Vengaiah et al, 2017). However the male plant's inflorescence is used to harvest the delicious sap (Bondya & Bodra, 2014;Pipatchartlearnwong et al, 2019).…”

Palmyra Palm (Borassus flabellifer L., Arecaceae) as a Valuable Resource for Livelihood Security in Odisha, India

“…The plant is dioecious while the flowering and fruiting occurs usually from March to April every year. The edible products like immature endosperm, mesocarp pulp, and tuberous seedling are obtained only from the female plant [3], while the sweet sap is extracted from the inflorescence of the male plant [4,5]. The tree usually thrives in tropical and subtropical regions of the world [5,6].…”

“…The edible products like immature endosperm, mesocarp pulp, and tuberous seedling are obtained only from the female plant [3], while the sweet sap is extracted from the inflorescence of the male plant [4,5]. The tree usually thrives in tropical and subtropical regions of the world [5,6]. Archeological and historical evidence indicated the presence of Borassus flabellifer L. in Southeast Asia dating back at least 1500 years.…”