Phenolic Compounds and Antioxidant Activity of Md2 Pineapple (Ananas comosus L.) Variety at Three Stages of Ripening

MD2 pineapple fruits with different ripening stages (stage 1-green skin, stage 2- 50% yellowing of skin, and stage 3-100% yellowing of skin), were used to determine the total phenolic, total flavonoid content, and condensed tannins using Folin-Ciocalteu, aluminum chloride, and acid butanol assays, respectively. Assessment of the antioxidant activity of the pineapple flesh was performed using ABTS and DPPH radical assays. Total phenolic content, total flavonoids and condensed tannins of the flesh varied among samples with 160.7 to 197.4 mg GAE/ 100 g DW, 7.7 to 14.7 mg CE/ 100 g DW, and 77.1 to 124.2 mg tannin eq./ 100 g DW, respectively. In the peel, the total phenolics, total flavonoids, and condensed tannins showed significant differences among the samples as ripening stages increased. ABTS radical scavenging activity of the flesh samples showed weak correlation against total phenolic, total flavonoids, and condensed tannins but peel samples showed moderate correlation. DPPH radical scavenging activity of the flesh and peel samples showed strong positive correlation with total phenolics, total flavonoids, and condensed tannins. These results suggest that pineapple is a potential source of phytochemicals with antioxidant activities

RNA-Seq Reveals Differentially Expressed Genes Associated with High Fiber Quality in Abaca (<i>Musa textilis</i> Nee)

Despite the importance of and current demand for abaca (Musa textilis Nee) fiber, there has been limited study that capitalizes on RNA-seq to identify candidate genes associated with high fiber quality and bunchy top virus (AbBTV) resistance. Three varieties (Abuab, Inosa, and Tangongon), one wild banana variety (Musa balbisiana Colla) Pacol, and two developed backcrosses (Abuab × Pacol BC2 and BC3) were grown at the Institute of Plant Breeding (IPB), Laguna, Philippines. The pseudostems of 3-month-old suckers of each genotype were sampled for RNA-seq. Datasets were analyzed for differential expression (DE) implementing various model frameworks, including pairwise, genotypic and non-DE models. Results indicate that Abuab and BC3 induce the highest proportion (70%) of abaca-specific genes. Gene ontology (GO) enrichment analysis showed several genes associated with cellulose synthase activity, callose synthase, ß-glucosidase activity, glucan biosynthetic process, etc. KEGG pathway analysis showed several genes encoding for enzymes involved in the lignin biosynthetic pathway. Analysis using genotypic DE (GDE) between abaca bunchy top virus (AbBTV)-resistant and -susceptible groups revealed genes such as pathogenesis-related protein and NBS-LRR. As the genotypes were not infected with the pathogen, these genes are yet to be confirmed for their roles in disease resistance and are an interesting subject for further investigation

Assessing Loss of Regulatory Divergence, Genome&ndash;Transcriptome Incongruence, and Preferential Expression Switching in Abaca &times; Banana Backcrosses

The Musa textilis var. Abuab has high fiber quality (FQ) but is susceptible to abaca bunchy top virus (AbBTV); the Musa balbisiana var. Pacol has low FQ but is resistant against AbBTV. Their backcrosses (BC2 and BC3) possess both desirable traits. Analysis using RNA-seq showed that the regulatory divergence of Abuab and Pacol is largely explained by cis differences with 27.4% and 22.3% if we are to assess it using BC2 and BC3, respectively. Cis differences between the two genotypes are significantly reduced from BC2 to BC3 due to changes in genomic constitution. Trans, on the other hand, is robust to changes in allelic composition. All these are attributed to the loss of heterozygosity in BC3 relative to BC2. Further analysis showed that both backcrosses exhibited genome-wide preferential expression of Pacol- over Abuab-specific alleles, despite the wider genetic presence of the latter in the hybrids. The ratio of the two genotype-specific expressed transcripts and the ratio of their corresponding genetic make-up are significantly disproportionate, a phenomenon that we refer to here as &ldquo;genome&ndash;transcriptome incongruence&rdquo;. We also observed preferential expression switching in which several genes prefer the Abuab- (or Pacol-) specific allele in BC2 but switched to the Pacol- (or Abuab-) specific allele in the BC3 genome

Towards the Understanding of Important Coconut Endosperm Phenotypes: Is there an Epigenetic Control?

The coconut is a major crop of many tropical countries, with the endosperm being one of its main products. The coconut soft-endosperm variants, the Makapuno and the Lono, are emerging as economically important. This review describes this crop, its salient endosperm phenotypes and the prevailing hypotheses associated with these. We also collate the literature on the Makapuno and provide a comprehensive review of the scarce information on the Lono. We review the current tenets of plant DNA methylation and provide examples of altered phenotypes associated with such methylation changes. We explore how the changes in the methylome affect endosperm development and the tissue culture process. We further cite the epigenetic basis of an altered endosperm phenotype of a closely related species to the coconut, the oil palm. We discuss how such modifications could affect coconut endosperm development, yielding the Makapuno and Lono phenotypes