Roles for auxin during morphogenesis of the compound leaves of pea ( Pisum sativum )

Abstract

The goal of this study was to explore the impact of the plant growth regulator auxin on the development of compound leaves in pea. Wildtype ( WT) plantlets, as well as those of two leaf mutants, acacia ( tl) and tendrilled acacia ( uni-tac) of pea ( Pisum sativum L.), were grown on media containing the auxin-transport inhibitors 2,3,5-triiodobenzoic acid (TIBA), N-(1-naphthyl)phthalamic acid (NPA), or the auxin antagonist, p-chlorophenoxyisobutyric acid (PCIB). The resulting plantlets were carefully analyzed morphologically, by scanning electron microscopy and for Uni gene expression using quantitative reverse transcription-polymerase chain reaction. Auxin transport was measured in WT leaf parts using [(14)C]indole-3-acetic acid. Relative Uni gene expression was determined in shoot tips of a range of leaf-form mutants. Morphological abnormalities were observed for all genotypes examined. The terminal tendrils on WT plants were converted to leaflets, stubs or were aborted. The number of pinna pairs produced on leaves was reduced, with the distal forms being eliminated before the proximal ones. Some leaves were converted to simple, including tri-and bilobed, forms. These treatments phenocopy the uni-tac and unifoliata ( uni) mutants of pea. In the most extreme situations, leaf blades were completely lost leaving only a pair of stipules or scale leaves. Polar auxin transport was basipetal for all leaf parts. Uni gene expression in shoot tips was significantly reduced in 60 microM NPA and TIBA. Uni mRNA was more abundant in tl, af and af tl and reduced in the uni mutants compared to WT. These results indicate that an auxin gradient plays fundamental roles in controlling morphogenesis in the compound leaves of pea and specifically it: (i). is the driving force for leaf growth and pinna determination; (ii). is necessary for pinna initiation; and (iii). controls subsequent pinna development.

Influence of Ecklonia maxima Extracts on Growth, Yield, and Postharvest Quality of Hydroponic Leaf Lettuce

“…The sites of leaf primordium initiation are induced in the meristem by auxin peaks and by auxin-induced repression of the so-called KNOXI gene [67]; this repression enhances the effects of gibberellins, which stimulate leaflet growth and differentiation. Thus, auxins play an important role in stimulating leaflet initiation and growth [68] and have been shown to exert this role both if they come from plant biosynthesis or from exogenous applications [69][70][71][72]. This process involves also other hormones such as cytokinins.…”

Cell Polarity Signaling: Focus on Polar Auxin Transport

“…Cell polarity is a fundamental cell property important for cell function in all the cellular organisms. Development of cell polarity is critical for all aspects of the plant life, such as the development of the single cell embryo (zygote), differentiation and morphogenesis of various cell types, short and long-range transport of signaling molecules such as auxin (Benkova et al, 2003;Campanoni et al, 2003;Mattsson et al, 2003;Reinhardt et al, 2003;DeMason and Chawla, 2004;Kim et al, 2005;Lin and Wang, 2005;Santelia et al, 2005), and responses to vectorial environmental cues (e.g. light and gravity) (Blakeslee et al, 2005;Tanaka et al, 2006;Zazimalova et al, 2007) or microorganisms (Lipka et al, 2007;Kwon et al, 2008).…”

Morphology, inheritance and mapping of a compressed lamina mutant of carrot

“…2004), and pea (Gould et al. 1994, DeMason and Chawla 2004). Morphological leaf mutants of Arabidopsis , e.g.…”