We report the first whole genome sequence (WGS) assembly and annotation of a dwarf coconut variety, ‘Catigan Green Dwarf’ (CATD). The genome sequence was generated using the PacBio SMRT sequencing platform at 15X coverage of the expected genome size of 2.15 Gbp, which was corrected with assembled 50X Illumina paired-end MiSeq reads of the same genome. The draft genome was improved through Chicago sequencing to generate a scaffold assembly that results in a total genome size of 2.1 Gbp consisting of 7,998 scaffolds with N50 of 570,487 bp. The final assembly covers around 97.6% of the estimated genome size of coconut ‘CATD’ based on homozygous k-mer peak analysis. A total of 34,958 high-confidence gene models were predicted and functionally associated to various economically important traits, such as pest/disease resistance, drought tolerance, coconut oil biosynthesis, and putative transcription factors. The assembled genome was used to infer the evolutionary relationship within the palm family based on genomic variations and synteny of coding gene sequences. Data show that at least three (3) rounds of whole genome duplication occurred and are commonly shared by these members of the Arecaceae family. A total of 7,139 unique SSR markers were designed to be used as a resource in marker-based breeding. In addition, we discovered 58,503 variants in coconut by aligning the Hainan Tall (HAT) WGS reads to the non-repetitive regions of the assembled CATD genome. The gene markers and genome-wide SSR markers established here will facilitate the development of varieties with resilience to climate change, resistance to pests and diseases, and improved oil yield and quality.

Background In the past, simple sequence repeat (SSR) marker development in coconut is achieved through microsatellite probing in bacterial artificial chromosome (BAC) clones or using previously developed SSR markers from closely related genomes. These coconut SSRs are publicly available in published literatures and online databases; however, the number is quite limited. Here, we used a locally established, coconut genome-wide SSR prediction bioinformatics pipeline to generate a vast amount of coconut SSR markers. Results A total of 7139 novel SSR markers were derived from the genome assembly of coconut ‘Catigan Green Dwarf’ (CATD). A subset of the markers, amounting to 131, were selected for synthesis based on motif filtering, contig distribution, product size exclusion, and success of in silico PCR in the CATD genome assembly. The OligoAnalyzer tool was also employed using the following desired parameters: %GC, 40–60%; minimum ΔG value for hairpin loop, −0.3 kcal/mol; minimum ΔG value for self-dimer, −0.9 kcal/mol; and minimum ΔG value for heterodimer, −0.9 kcal/mol. We have successfully synthesized, optimized, and amplified 131 novel SSR markers in coconut using ‘Catigan Green Dwarf’ (CATD), ‘Laguna Tall’ (LAGT), ‘West African Tall’ (WAT), and SYNVAR (LAGT × WAT) genotypes. Of the 131 SSR markers, 113 were polymorphic among the analyzed coconut genotypes. Conclusion The development of novel SSR markers for coconut will serve as a valuable resource for mapping of quantitative trait loci (QTLs), assessment of genetic diversity and population structure, hybridity testing, and other marker-assisted plant breeding applications.

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Banana is a major fruit crop in the Philippines and remains to be a large contributor to the country & prime dollar reserve. Among the main hindrances in global banana production, diseases such as Banana bunchy top disease (BBTD) caused by BBTV can bring catastrophic loss to any banana plantation. To elucidate the resistance mechanism and understand the interplay of host factors in the presence of the invading pathogen, we implemented RNA-seq-based comparative transcriptomics analyses of mock- and BBTV-inoculated resistant (wild M. balbisiana) and susceptible (M. acuminata & Lakatan & banana genotypes. Similar patterns of expression for 119 differentially expressed genes (DEGs) were observed on both genotypes, representing the typical defense response of banana to BBTV. A set of 173 DEGs specific to the susceptible ′Lakatan′ banana cultivar revealed potential host factors and susceptibility mechanisms involved in successful BBTV infection. Further, differential transcriptomic analysis revealed 268 DEGs exclusive to the resistant wild M. balbisiana, unraveling insights into the complex resistance mechanisms involved in BBTV defense such as pathogen perception, phytohormone action, reactive oxygen species (ROS), hypersensitive response (HR), production of secondary metabolites, and cell wall modification. The DEGs identified in this study will aid in the design of foreground markers for the precise integration of resistance genes during marker-assisted breeding programs. Furthermore, the application of these results will also enable the foreseen deployment of genome-edited banana cultivars targeting the resistance and host factor genes towards a future-proof banana industry.