Download AB123Abstract - PSI AOAPO 2016 Conference

Secretome profiling of chickpea identifies a leaderless Bet v1-like protein that
participates in stress response
Vijay Wardhan, Subhra Chakraborty and Niranjan Chakraborty*
National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi 110067, India
Secreted proteins maintain cell structure and biogenesis, besides acting in signaling events
crucial for cellular homeostasis during stress adaptation. To better understand the underlying
mechanism of stress-responsive secretion, the suspension-cultured cells of chickpea were
subjected to water-deficit conditions. Cell viability of the suspension culture remained unaltered
until 96 h, which gradually declined at later stages of dehydration. Proteomic analysis led to the
identification of 215 differentially regulated proteins, involved in multivariate cellular processes
that include metabolism, cell defence and signal transduction suggesting their concerted role in
stress adaptation. One-third of the secreted proteins displayed no N-terminal secretion signals
suggesting a nonclassical secretion route. Screening of the secretome identified a leaderless
Bet v 1-like protein, designated CaRRP1, the export of which was inhibited by brefeldin A. We
investigated the gene structure and genomic organization, and demonstrated that CaRRP1 may
be involved in stress response. The transcript abundance of CaRRP1 was significantly and
positively correlated to stresses caused by both abiotic and biotic factors.
Functional
complementation of CaRRP1 could rescue the growth defects in yeast mutant, deficient in
vesicular transport indicating a partial overlap of protein secretion and stress response. Our
study provides the most comprehensive analysis of dehydration-responsive plant secretome
and the complex metabolic network operating in plant extracellular space.