Immunogold-EM analysis reveal brefeldin a-sensitive clusters of auxin in Arabidopsis root apex cells

Abstract

Immunogold electron microscopy (EM) study of Arabidopsis root apices analyzed using specific IAA antibody and high-pressure freeze fixation technique allowed, for the first time, vizualization of subcellular localization of IAA in cells assembled intactly within plant tissues. Our quantitative analysis reveals that there is considerable portion of IAA gold particles that clusters within vesicles and membraneous compartments in all root apex cells. There are clear tissue-specific and developmental differences of clustered IAA in root apices. These findings have significant consequences for our understanding of this small molecule which is controlling plant growth, development and behavior.

Relative Contribution of PIN-Containing Secretory Vesicles and Plasma Membrane PINs to the Directed Auxin Transport: Theoretical Estimation

“…While several studies have claimed to provide experimental evidence to support this concept since [9,10,11], their conclusions are currently greatly debated in the field [12,13]. Hence the question whether vesicular secretion significantly contributes to intercellular auxin transport remains unresolved.…”

“…Several studies claimed to have proven the vesicular transport of IAA [9,10,11]. However, the validity of the evidence presented in most of these studies has been questioned by many researchers in the field, and thus the hypothesis of vesicular transport of auxin remains controversial [12,13].…”

Relative Contribution of PIN-containing Secretory Vesicles and Plasma Membrane PINs to the Directed Auxin Transport: Theoretical Estimation

“…The hypothesis of vesicular secretion of auxin was postulated more than 15 years ago [6,7]. While several studies have claimed to provide experimental evidence to support this concept since [8][9][10], their conclusions are currently greatly debated in the field [11,12]. Hence the question whether vesicular secretion significantly contributes to intercellular auxin transport remains unresolved.…”

“…This process is analogous to neurotransmitter release in animals, and is important for the transport of auxin as suggested by previous reports [6,7] (Figure 1). Several studies claimed to have proven the vesicular transport of IAA [8][9][10]. However, the validity of the evidence presented in most of these studies has been questioned by many researchers in the field, and thus the hypothesis of vesicular transport of auxin remains controversial [11,12].…”

Seeing is better than believing: visualization of membrane transport in plants

“…Immunolocalization of transport substrates ABA [73,74], IAA [22] and CK [75] have been visualized in different plant species by whole-mount immunolocalization using polyclonal and monoclonal antisera (Figure 2; [76]). Despite requiring of fixation, some of these antisera have become successful tools for the in situ localization of local maxima [75,77] or the translocation of hormones in plants [78][79][80][81][82]. Anti-IAA antibody signals were reported to recapitulate signals found with the DR5 reporter in the mature and lateral root [77,79].…”