A Fertilization-Independent Developmental Program Triggers Partial Fruit Development and Senescence Processes in Pistils of Arabidopsis

Abstract

The pistil is the specialized plant organ that enables appropriate pollination and ovule fertilization, after which it undergoes growth and differentiation to become a fruit. However, in most species, if ovules are not fertilized around anthesis the pistil irreversibly loses its growth capacity. We used physiological, molecular, and transcriptomic tools to characterize the postanthesis development of the unfertilized Arabidopsis (Arabidopsis thaliana) pistil. Surprisingly, developmental processes that have been previously described in developing Arabidopsis fruits, such as the collapse of the adaxial epidermis, differentiation of a sclerenchyma layer in the adaxial subepidermis and the dehiscence zone, and valve dehiscence, were also observed in the unfertilized pistil. We determined that senescence is first established in the transmitting tract, stigma, and ovules immediately after anthesis, and that the timing of senescence in the stigma and ovules correlates with the loss of fruit-set responsiveness of the pistil to pollen and the hormone gibberellin (GA), respectively. Moreover, we showed that mutants with altered ovule development have impaired fruit-set response to the GA gibberellic acid, which further indicates that the presence of viable ovules is required for fruit-set responsiveness to GAs in the unfertilized pistil. Our data suggest that a fertilizationindependent developmental program controls many of the processes during post-anthesis development, both in unfertilized pistils and seeded fruits, and point to a key role of the ovule in the capacity of pistils to undergo fruit set in response to GA.

Comprehensive Tissue-Specific Transcriptome Analysis Reveals Distinct Regulatory Programs during Early Tomato Fruit Development

“…S6E), consistent with a general down-regulation of ethylene-related expression after anthesis (Vriezen et al, 2008;Wang et al, 2009). Pollination is known to induce a burst of ethylene in tomato ovaries accompanied by a transient increase in ACO gene expression (Llop-Tous et al, 2000), and it has been suggested that ethylene is involved in controlling ovule senescence and the fruit-set response (Carbonell-Bejerano et al, 2010). By spatially resolving gene expression, our data implicate the ovule as a likely site of ethylene biosynthesis in ovaries, with specific ACO isoforms, such as ACO4 (Fig.…”

Entire Photodamaged Chloroplasts Are Transported to the Central Vacuole by Autophagy

“…The level of 18S rRNA was measured as an internal standard (Izumi et al, 2012). The gene-specific primers were used in previous studies (Baena-González et al, 2007;Carbonell-Bejerano et al, 2010;Izumi et al, 2012;Maruta et al, 2012;Ramel et al, 2012;Shao et al, 2013;Wang and Blumwald, 2014). The sequences of primers for qRT-PCR analysis are shown in Supplemental Table 1.…”

HALF FILLED promotes reproductive tract development and fertilization efficiency in Arabidopsis thaliana

“…In addition to their importance in controlling cell death in the transmitting tract, HAF, BEE1 and BEE3 also influence cell death in the stigma (Carbonell-Bejerano et al, 2010). Stigmatic cells degenerate soon after pollination in wild type, but remain intact in haf bee1 bee3 mutants even 7 days post-anthesis.…”

“…It seemed possible that delayed cell death in mutant stigmata might prolong pollen receptivity (Carbonell-Bejerano et al, 2010). Wild-type carpels have been reported to be receptive to pollination and fertilization for up to 4 days after the flower has opened at anthesis (Vivian-Smith et al, 2001).…”