title: Proteomic Identification of Differentially Expressed Proteins during Alfalfa (Medicago sativaL.) Flower Development.
abstract: Flower development, pollination, and fertilization are important stages in the sexual reproduction process of plants; they are also critical steps in the control of seed formation and development. During alfalfa (Medicago sativaL.) seed production, some distinct phenomena such as a low seed setting ratio, serious flower falling, and seed abortion commonly occur. However, the causes of these phenomena are complicated and largely unknown. An understanding of the mechanisms that regulate alfalfa flowering is important in order to increase seed yield. Hence, proteomic technology was used to analyze changes in protein expression during the stages of alfalfa flower development. Flower samples were collected at pre-pollination (S1), pollination (S2), and the post-pollination senescence period (S3). Twenty-four differentially expressed proteins were successfully identified, including 17 down-regulated in pollinated flowers, one up-regulated in pollinated and senesced flowers, and six up-regulated in senesced flowers. The largest proportions of the identified proteins were involved in metabolism, signal transduction, defense response, oxidation reduction, cell death, and programmed cell death (PCD). Their expression profiles demonstrated that energy metabolism, carbohydrate metabolism, and amino acid metabolism provided the nutrient foundation for pollination in alfalfa. Furthermore, there were three proteins involved in multiple metabolic pathways: dual specificity kinase splA-like protein (kinase splALs), carbonic anhydrase, and NADPH: quinone oxidoreductase-like protein. Expression patterns of these proteins indicated that MAPK cascades regulated multiple processes, such as signal transduction, stress response, and cell death. PCD also played an important role in the alfalfa flower developmental process, and regulated both pollination and flower senescence. The current study sheds some light on protein expression profiles during alfalfa flower development and contributes to the understanding of the basic molecular mechanisms during the alfalfa flowering process. These results may offer insight into potential strategies for improving seed yield, quality, and stress tolerance in alfalfa.
authors.affiliation: Beijing Key Laboratory of Grassland Science, Forage Seed Lab, China Agricultural UniversityBeijing, China; Chifeng Academy of Agricultural and Animal SciencesChifeng, China.
authors.forename: Lingling
authors.initials: L
authors.lastname: Chen
authors.affiliation: Chengdu Municipal Development and Reform Commission Chengdu, China.
authors.forename: Quanzhu
authors.initials: Q
authors.lastname: Chen
authors.affiliation: Beijing Key Laboratory of Grassland Science, Forage Seed Lab, China Agricultural University Beijing, China.
authors.forename: Yanqiao
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Beijing Key Laboratory of Grassland Science, Forage Seed Lab, China Agricultural University Beijing, China.
authors.forename: Longyu
authors.initials: L
authors.lastname: Hou
authors.affiliation: Beijing Key Laboratory of Grassland Science, Forage Seed Lab, China Agricultural University Beijing, China.
authors.forename: Peisheng
authors.initials: P
authors.lastname: Mao
keywords: MAPK; PCD; alfalfa; flower; pollination; proteomics; senescence