Comparative proteomic analysis of eggplant (Solanum melongena L.) heterostylous pistil development

Abstract

Heterostyly is a common floral polymorphism, but the proteomic basis of this trait is still largely unexplored. In this study, self- and cross-pollination of L-morph and S-morph flowers and comparison of embryo sac development in eggplant (Solanum melongena L.) suggested that lower fruit set from S-morph flowers results from stigma-pollen incompatibility. To explore the molecular mechanism underlying heterostyly development, we conducted isobaric tags for relative and absolute quantification (iTRAQ) proteomic analysis of eggplant pistils for L- and S-morph flowers. A total of 5,259 distinct proteins were identified during heterostyly development. Compared S-morph flowers with L-morph, we discovered 57 and 184 differentially expressed proteins (DEPs) during flower development and maturity, respectively. Quantitative real time polymerase chain reactions were used for nine genes to verify DEPs from the iTRAQ approach. During flower development, DEPs were mainly involved in morphogenesis, biosynthetic processes, and metabolic pathways. At flower maturity, DEPs primarily participated in biosynthetic processes, metabolic pathways, and the formation of ribosomes and proteasomes. Additionally, some proteins associated with senescence and programmed cell death were found to be upregulated in S-morph pistils, which may lead to the lower fruit set in S-morph flowers. Although the exact roles of these related proteins are not yet known, this was the first attempt to use an iTRAQ approach to analyze proteomes of heterostylous eggplant flowers, and these results will provide insights into biochemical events taking place during the development of heterostyly.

Biostimulant Application Enhances Fruit Setting in Eggplant—An Insight into the Biology of Flowering

“…Observations with the use of a fluorescence microscope allowed us to verify the correct growth of pollen tubes in the styles of all types of pistils but their number was significantly affected by flower type and biostimulant treatment and by cultivar to a lesser extent. This observation is contrary to the results of Wang et al [11], who determined that the structure of the stigmatic surface in short-styled flowers inhibited pollen germination. On the grounds of highly genotype-dependent heterostyly expression in eggplant, results on short-styled pistil performance may be divergent.…”

“…The higher fruit setting efficiency of this phenotype results from well-developed nodules with high pollen absorption capacity. However, the development of the ovules and their position in the placenta, as well as pollen grain shape, size, and amount in anthers, were nondifferentiated among long-, medium-, and short-styled pistils [6,10], although Wang et al [11] demonstrated that lower fruit setting from short-styled flowers resulted from stigma-pollen incompatibility. The bumblebee (Bombus terrestris) is the most effective eggplant pollinator for plants under covers.…”

Temporal Distinction between Male and Female Floral Organ Development in Nicotiana tabacum cv. Xanthi (Solanaceae)

“…In angiosperms, various factors affect the successful pollination and subsequent fertilization of the egg in the female gametophyte (i.e., embryo sac). The mating patterns are greatly influenced by the phenotypic variations in floral traits, such as herkogamy (the spatial separation of anthers and stigma) and dichogamy (the temporal separation of male and female phases) [1][2][3][4][5][6][7][8], cleistogamy (the self-fertilization within a permanently closed flower) [3,9], and heterostyly (styles of different lengths relative to the stamens in the flowers of different plants) [10,11]. The diversity of functional floral traits is defined by the genetic and developmental mechanisms controlling the differentiation of these reproductive organs during floral ontogeny.…”