Proteomic changes associated with the development of açaí (Euterpe oleracea Mart.) seeds.

Açaí palm (Euterpe oleracea Mart.) seeds are a rich source of mannans, which can be used to generate bioethanol or be converted to high-value D-mannose, in addition to being a source of polyphenols with beneficial health properties. Here, we present a quantitative proteome dataset of açaí seeds at four stages of development (S1, S2, S3, and S4 stages), in which 2465 high confidence proteins were identified and 524 of them show statistically different abundance profiles during development. Several enzymes involved in the biosynthesis of nucleotide-sugars were quantified, especially those dedicated to the formation of GDP-mannose, which showed an increase in abundance between stages S1 and S3. Our data suggest that linear mannans found abundantly in endosperm cell walls are initially deposited as galactomannans, and during development lose the galactosyl groups. Two isoforms of alpha-galactosidase enzymes showed significantly increased abundances in the S3 and S4 stages. Additionally, we quantified the enzymes participating in the central pathway of flavonoid biosynthesis responsible for the formation of catechin and epicatechin, which are subunits of procyanidins, the main class of polyphenols in the açaí seeds. These proteins showed the same pattern of deposition, in which higher abundances were seen in the S1 and S2 stages.

Proteomic Analysis of Embryo Isolated From Mature Jatropha curcas L. Seeds.

Jatropha curcas L. is a non-edible oilseed containing almost 40% of seed oil and is famous as the best source of raw material for biofuel production. J. curcas seeds contain three main tissues, such as inner integument, endosperm, and embryo. To best understand the physiological events related to specific tissues, it is important to perform the proteome analysis of these tissues. Previously we have explored the pattern of reserves deposition and tissue-specific biological pathways by analyzing the proteome of the inner integument and endosperm and organelles, such as plastids and gerontoplasts isolated from these tissues. The focus of the present study was to perform the proteomic analysis of embryo isolated from the mature seeds of J. curcas. This analysis resulted in the identification of 564 proteins of which 206 are not identified previously from any other tissue of this plant. The identified proteins were functionally classified using the MapMan classification system revealing various proteins involved in different functionalities. The proteins involved in transport functions and those with proteolytic activity were determined through the Transporter Classification Database (TCDB) and MEROPS database, respectively. In addition to identify a large number of proteins participating in various metabolic processes, we found several proteins involved in defense functions, such as the members of chaperones and the ubiquitin-proteasome system. Similarly, members of the legumin and vicilin family of seed storage proteins (SSPs) were identified which in addition to their storage function, are involved in defense. In addition, we have reported that proteases belonging to different mechanistic classes and are involved in diverse physiological functions. Last but not the least, several classes of transport-related proteins were identified that are discussed concerning their function in the transportation of different nutrients across the embryo. To the best of our knowledge, this study reported the highest number of proteins identified from the embryo of mature J. curcas seeds, most of which are essential for seed germination, reflecting the fact that many proteins required for germination are already present in the mature embryo.

Proteome dynamics of the cotyledonary haustorium and endosperm in the course of germination of Euterpe oleracea seeds.

The role of the cotyledonary haustorium (CH) in the mobilization of nutrient reserves in the endosperm of species of the palm family Arecaceae is a moot question. To shed light on this matter, we present here an analysis of the quantitative proteome changes associated with four developmental stages of CH and three of endosperm during germination. Together, a total of 1965 proteins were identified, being 1538 in the CH and 960 in the endosperm. Both in the CH and endosperm proteomes, we observed an increase in the diversity of hydrolases as the CH and endosperm develops. Qualitative proteomics analysis of four CH developmental stages indicated that each stage is populated by a unique set of proteins and the quantitative analysis showed an increase in the relative abundance of hydrolases, particularly mannan degrading enzymes, as development progresses. These results add weight to the hypothesis that the CH in the seeds of E. oleraceaacts both as a conduit of carbon and nitrogen sources generated by the hydrolysis of the reserves in the endosperm and as a source of hydrolases that will contribute to the mobilization of these reserves.

Proteome Dynamics of the Developing Açaí Berry Pericarp (Euterpe oleracea Mart.).

Quantitative proteome analysis of four developmental stages of pericarp tissues of the açaí berry (Euterpe oleracea Mart.) was performed by the isobaric labeling of peptides with iTRAQ 4-plex, hydrophilic interaction liquid chromatography pre-fractionation of labeled peptides, and high-performance mass spectrometry analysis. This analysis resulted in the identification of 4286 proteins, of which 476 presented differential abundance between the stages. The differential abundance of these proteins was seen to be coordinated with the metabolic demands during cell division, lignification, and cell expansion at developmental stages 1 and 2 as well as phenolic acid accumulation and metabolic changes in the fruit maturation at developmental stages 3 and 4. The distinct accumulation of anthocyanins observed in the pericarp at developmental stage 4 was correlated with the increase in abundance of some key biosynthetic enzymes, such as leucoanthocyanidin dioxygenase, anthocyanidin O-3-glycosyltransferase, and UDP-glycosyltransferase. Here, evidence is also provided for the presence in the açaí berry of secondary metabolites not previously described in açaí, such as pterostilbene, matairesinol, and furaneol. Together, these results will pave the way for studies aimed at the genetic improvement of the nutritional properties of this important fruit crop.

Seed development of Jatropha curcas L. (Euphorbiaceae): integrating anatomical, ultrastructural and molecular studies.

KEY MESSAGE: This work provides a detailed histological analysis of the development of Jatropha curcas seeds, together with an assessment of the role of programmed cell death in this process. Seeds of Jatropha curcas are a potential source of raw material for the production of biodiesel, but very little is known about how the architecture of the seeds is shaped by the coordinated development of the embryo, endosperm and maternal tissues, namely integuments and nucellus. This study used standard anatomical and ultrastructural techniques to evaluate seed development and programmed cell death (PCD) in the inner integument was monitored by qPCR. In these studies, we found that the embryo sac formation is of the Polygonum type. We also found that embryogenesis is a slow process and the embryo is nourished by the suspensor at earlier stages and by nutrients remobilized from the lysis of the inner integument at later stages. Two types of programmed cell death contribute to the differentiation of the inner integument that begins at early stages of seed development. In addition, the mature embryo presents features of adaptation to dry environments such as the presence of four seminal roots, water absorbing stomata in the root zone and already differentiated protoxylem elements. The findings in this study fill in gaps related to the ontogeny of J. curcas seed development and provide novel insights regarding the types of PCD occurring in the inner integument.