Transcriptome Profiling Provides Insight into the Genes in Carotenoid Biosynthesis during the Mesocarp and Seed Developmental Stages of Avocado (Persea americana)

Abstract

Avocado (Persea americana Mill.) is an economically important crop because of its high nutritional value. However, the absence of a sequenced avocado reference genome has hindered investigations of secondary metabolism. For next-generation high-throughput transcriptome sequencing, we obtained 365,615,152 and 348,623,402 clean reads as well as 109.13 and 104.10 Gb of sequencing data for avocado mesocarp and seed, respectively, during five developmental stages. High-quality reads were assembled into 100,837 unigenes with an average length of 847.40 bp (N50 = 1725 bp). Additionally, 16,903 differentially expressed genes (DEGs) were detected, 17 of which were related to carotenoid biosynthesis. The expression levels of most of these 17 DEGs were higher in the mesocarp than in the seed during five developmental stages. In this study, the avocado mesocarp and seed transcriptome were also sequenced using single-molecule long-read sequencing to acquired 25.79 and 17.67 Gb clean data, respectively. We identified 233,014 and 238,219 consensus isoforms in avocado mesocarp and seed, respectively. Furthermore, 104 and 59 isoforms were found to correspond to the putative 11 carotenoid biosynthetic-related genes in the avocado mesocarp and seed, respectively. The isoform numbers of 10 out of the putative 11 genes involved in the carotenoid biosynthetic pathway were higher in the mesocarp than those in the seed. Besides, alpha- and beta-carotene contents in the avocado mesocarp and seed during five developmental stages were also measured, and they were higher in the mesocarp than in the seed, which validated the results of transcriptome profiling. Gene expression changes and the associated variations in gene dosage could influence carotenoid biosynthesis. These results will help to further elucidate carotenoid biosynthesis in avocado.

Analysis of Centranthera grandiflora Benth Transcriptome Explores Genes of Catalpol, Acteoside and Azafrin Biosynthesis

“…This suggests that one gene may have different transcripts which may come from variable splicing, alleles, different copies of the same gene, homologs, orthologs, etc. The mean length of transcripts and genes were 1895 bp and 2115 bp, respectively, and the N50 of the transcripts and genes were 2902 and 2936 bp, respectively (Table 2), which were higher than that in Dendrobium huoshanense , Persea Americana , and R. glutinosa [18,71,72]. These results implied that our assembly quality was suitable for subsequent analyses.…”

Molecular and biochemical analyses of avocado (Persea americana) reveal differences in the oil accumulation pattern between the mesocarp and seed during the fruit developmental period

“…Avocado fruit is rich in oil, which is mainly stored in the mesocarp and seed. The fruit developmental period has been divided into five stages based on the days after full bloom (DAFB) [51], with the fruit considered to be physiologically mature at 215 DAFB. The oil content in the mesocarp continued to accumulate throughout the fruit developmental period (Fig.…”

Molecular Markers and a Quality Trait Evaluation for Assessing the Genetic Diversity of Avocado Landraces from China

“…Avocado (Persea americana Mill. ), which is a member of the family Lauraceae of the order Laurales, is one of the most economically important subtropical/tropical fruit crops worldwide [1][2][3]. Avocado is a highly diverse species with local variations that have resulted in various ecological races [4].…”

“…Number of observed alleles, 2 effective number of alleles,3 observed heterozygosity,4 expected heterozygosity, and5 Shannon's information index.…”