(2014) demonstrated the INRA-RU1 epitope could be detected in wheat from approximately 11 DAA using enzymatic digestion of cell wall. been reported to be associated with the formation of cell wall outgrowths during endosperm cellularisation and xyloglucan is here shown to be a component of these anticlinal extensions, happening transiently in both varieties. Pectic homogalacturonan (HG) was abundant in cell walls of maternal cells of wheat and rice grain, but only recognized in endosperm cell walls of rice in an unesterified HG form. A rhamnogalacturonan-I (RG-I) backbone epitope was observed to be temporally controlled in both varieties, recognized in endosperm cell walls from 12 DAA in rice and 20 DAA in wheat grain. Detection of the LM5 galactan epitope showed a definite variation between wheat and rice, being recognized at the earliest stages of development in rice endosperm cell walls, but not recognized in wheat endosperm cell walls, only in maternal cells. In contrast, the LM6 arabinan epitope was recognized in both varieties around MDA 19 8 DAA and was transient in wheat grain, but persisted in rice until maturity. Electronic supplementary material The online version of this article (doi:10.1007/s00425-014-2201-4) contains supplementary material, which is available to authorized users. cv. Koshihikari (bred at Fukui Prefectural Agricultural Study Facility) plants were cultivated in 15-cm diameter pots under controlled environment conditions at Rothamsted Study with 12-h MDA 19 light period at 28?C daytime temperature and 22?C nighttime temperature, 70?% relative moisture. Pots were placed in simulated paddy field conditions, where the pots are two-thirds submerged inside a deep tray of water. Seeds were germinated MDA 19 in dark moist conditions and transferred to hydroponic conditions after 7?days. Seedlings were consequently transferred to loam-based ground once they experienced reached a height of 15?cm. Caryopses were harvested at 4, 6, 8, 12, 20 and 28 DAA from the middle third of the panicle and immediately prepared for microscopy. Anthesis was defined as the point at which the middle third of the panicle experienced revealed anthers. cv. Cadenza Cd207 (bred by Cambridge Flower Breeders Ltd.) vegetation were cultivated under glasshouse conditions at Rothamsted Study, as previously explained (Tosi et al. 2004). Caryopses were harvested at 4, 6, 8, 12, 20 and 28 DAA from the middle third of the spikelet and immediately prepared for microscopy. Light microscopy and immunofluorescence analysis MDA 19 Transverse medial sections of wheat and rice grains (approximately 1?mm in thickness) were slice in fixative. Sections were fixed over night at room heat (RT) in 4?%?(w/v) paraformaldehyde and 2.5?% (w/v) glutaraldehyde in 0.1?M Sorensons MDA 19 phosphate buffer. After three rinses in buffer, the specimens were dehydrated in an ethanol series, slowly infiltrated with LR White colored resin (25, 50, 75, 100?%, (v/v); medium grade, TAAB L012) for 7 and 28?days for rice and polymerised at 55?C inside a nitrogen gas saturated environment. Semi-thin sections of 1?m thickness were cut using a ReichertCJung ultramicrotome, collected in drops of distilled water on multi-well slides coated with poly-l-lysine hydrobromide (Sigma P1399), and dried on a hot plate at 40?C. Slides with LR White-embedded grain sections were pre-incubated (50?l drop/well) in 5?% (w/v) milk powder (Marvel products) in 1xPBS at pH 7.0 for 60?min, then incubated for 2?h in main antibody. The following monoclonal antibodies were used, diluted in PBS comprising 5?% (w/v) milk powder: rat monoclonalLM5 (Jones et al. 1997),.