Systematic Spatial Analysis of Gene Expression during Wheat Caryopsis Development

Abstract

The cereal caryopsis is a complex tissue in which maternal and endosperm tissues follow distinct but coordinated developmental programs. Because of the hexaploid genome in wheat (Triticum aestivum), the identification of genes involved in key developmental processes by genetic approaches has been difficult. To bypass this limitation, we surveyed 888 genes that are expressed during caryopsis development using a novel high-throughput mRNA in situ hybridization method. This survey revealed novel distinct spatial expression patterns that either reflected the ontogeny of the developing caryopsis or indicated specialized cellular functions. We have identified both known and novel genes whose expression is cell cycle-dependent. We have identified the crease region as important in setting up the developmental patterning, because the transition from proliferation to differentiation spreads from this region to the rest of the endosperm. A comparison of this set of genes with the rice (Oryza sativa) genome shows that approximately two-thirds have rice counterparts but also suggests considerable divergence with regard to proteins involved in grain filling. We found that the wheat genes had significant homology with 350 Arabidopsis thaliana genes. At least 25 of these are already known to be essential for seed development in Arabidopsis, but many others remain to be characterized.

Maternal Gametophytic baseless1 Is Required for Development of the Central Cell and Early Endosperm Patterning in Maize (Zea mays)

“…This is most likely the case in other cereals and thus far a growing number of future transfer cell-specific transcripts that are localized in a polar fashion within barley and wheat syncytial endosperms have been identified (Doan et al 1996;Drea et al 2005). Interestingly, we found irregular distributions of basal-specific endosperm transcripts in syncytia segregating the bsl1 mutation, yet we did not detect any morphological abnormalities in these endosperms.…”

“…On the basis of current genetic evidence, endosperm patterning occurs in two main phases . The first, pivotal phase leads to the establishment of the proximal-distal axis, which is reflected by the polarized localization of transcripts (Doan et al 1996; 1 Gomez et al 2002;Drea et al 2005;Ingouff et al 2005a), and, in Arabidopsis, the cytological organization of syncytial endosperm domains (Boisnard-Lorig et al 2001;Brown et al 2003). These early events are most likely regulated by several maternally required genes (for example, Springer et al 2000;Grini et al 2002;Holding and Springer 2002), including members of the Polycomb Group complex (Pc-G).…”

A T‐DNA mutation in the RNA helicase eIF4A confers a dose‐dependent dwarfing phenotype in Brachypodium distachyon

“…Wax-embedded grains were sectioned (10 lm thick) on a Leica microtome (http:// www.leica.com/) and organized sequentially on slides coated with poly-lysine. After overnight incubation at 42°C, slides were de-waxed as described by Drea et al (2005), and used for staining.…”

Maize early endosperm growth and development: From fertilization through cell type differentiation

“…Nuclei continue to proliferate within the micropylar and peripheral endosperm, whereas free nuclei in the chalazal endosperm form nodules of individual nuclei and a multinucleate cyst. At the coenocytic stage in cereals, the only region that has been identifi ed is a basal sector of transfer cell precursors ( Doan et al, 1996 ;Costa et al, 2003 ;Drea et al, 2005 ;GutierrezMarcos et al, 2006 ).…”