Analysis of promoter activity of members of the PECTATE LYASE-LIKE (PLL) gene family in cell separation in Arabidopsis

Abstract

BackgroundPectate lyases depolymerize pectins by catalyzing the eliminative cleavage of α-1,4-linked galacturonic acid. Pectate lyase-like (PLL) genes make up among the largest and most complex families in plants, but their cellular and organismal roles have not been well characterized, and the activity of these genes has been assessed only at the level of entire organs or plant parts, potentially obscuring important sub-organ or cell-type-specific activities. As a first step to understand the potential functional diversity of PLL genes in plants and specificity of individual genes, we utilized a reporter gene approach to document the spatial and temporal promoter activity for 23 of the 26 members of the Arabidopsis thaliana (Arabidopsis) PLL gene family throughout development, focusing on processes involving cell separation.ResultsNumerous PLL promoters directed activity in localized domains programmed for cell separation, such as the abscission zones of the sepal, petal, stamen, and seed, as well as the fruit dehiscence zone. Several drove activity in cell types expected to facilitate separation, including the style and root endodermal and cortical layers during lateral root emergence. However, PLL promoters were active in domains not obviously programmed for separation, including the stipule, hydathode and root axis. Nearly all PLL promoters showed extensive overlap of activity in most of the regions analyzed.ConclusionsOur results document potential for involvement of PLL genes in numerous aspects of growth and development both dependent and independent of cell separation. Although the complexity of the PLL gene family allows for enormous potential for gene specialization through spatial or temporal regulation, the high degree of overlap of activity among the PLL promoters suggests extensive redundancy. Alternatively, functional specialization might be determined at the post-transcriptional or protein level.

RNA-Seq Links the Transcription Factors AINTEGUMENTA and AINTEGUMENTA-LIKE6 to Cell Wall Remodeling and Plant Defense Pathways

“…PMEs, PMEIs, PGs, PLLs, and PAEs all belong to large multigene families (Louvet et al, 2006;Pelloux et al, 2007;Sun and van Nocker, 2010;Cao, 2012;Wang et al, 2013;de Souza et al, 2014). A large number of these HGmodifying enzymes are differentially expressed and primarily down-regulated in ant ail6 inflorescences, including approximately 58% of PLLs, 55% of PMEIs, 47% of PMEs, and 40% of PGs (Table I; Supplemental Table S1).…”

POLYGALACTURONASE INVOLVED IN EXPANSION1 Functions in Cell Elongation and Flower Development in Arabidopsis

“…Pectate lyases, which cleave HG backbones via b-elimination, have been implicated in pollen tube growth, fruit softening, and susceptibility to plant pathogens (Marín-Rodríguez et al, 2002) and are expressed in a wide range of tissues (Palusa et al, 2007;Sun and van Nocker, 2010), whereas PGs, which cleave HG backbones via hydrolysis, have mainly been shown to function in cell separation events (González-Carranza et al, 2007). Two PGs, QUARTET2 (QRT2) and QRT3, function in pollen tetrad separation (Rhee and Somerville, 1998;Rhee et al, 2003), and two additional PGs, ADPG1 and ADPG2, plus QRT3, are required for cell separation events during reproductive development (Ogawa et al, 2009).…”

The Role of LORELEI in Pollen Tube Reception at the Interface of the Synergid Cell and Pollen Tube Requires the Modified Eight-Cysteine Motif and the Receptor-Like Kinase FERONIA

“…To avoid potential complications from ectopically expressed LRE-cYFP interfering with pollen development and germination, we expressed LRE-cYFP from the PECTIN LYASE-LIKE SUPERFAMILY PROTEIN3 (PLL3) promoter (Sun and van Nocker, 2010), which is preferentially induced in pollen tubes after their growth in the pistil (Qin et al, 2009) (Supplemental Figures 9A and 9B).…”