Figure 6. Treatment with LAB reduces the extent of both arabinoxylan and starch degradation in the endosperm.

Transverse sections of endosperm of grains incubated for six dpi in water (a,b,e–n), or LAB (c,d,o–x) were either incubated with the LM11 antibody and processed as in Fig. 5, to visualise AX epitopes (a,c,j–n,t–x), or stained with toluidine blue and iodine solution (b,d,e–i,o–s) to visualise cellular structures and starch deposits. All sections were prepared from approximately the same position of the grain. Open arrowheads: fluorescence from AX epitopes in endosperm cell walls; closed arrowheads: interface between the sub-aleurone zone and endosperm tissue in which starch degradation has been initiated; closed arrows: aleurone layer; dashed lines (a–d,h,i,m,n,r,s,w,x) edge of the crease; asterisks (b,d): sub-aleurone zone. Results were reproducible in two separate incubations. In (a–d) letters next to the red boxes correspond to panels (e–x) as indicated. (a) Section through a grain grown in water, incubated with the LM11 antibody and viewed under a confocal microscope. The antibody decorates the cell walls of the endosperm cells around the crease of the grain, and the aleurone. (b) Section consecutive to that shown in (a), stained with toluidine blue and iodine solution. (c) As in (a) but for a grain grown in LAB. The LM11 antibody decorates cell walls in a much larger area of the endosperm surrounding the crease, compared to (a). (d) As in (b) but for a grain grown in LAB. Loss of starch from the sub-aleurone zone has not progressed to the same extent as in (b). (e–n) Close-up views of a section through a grain grown in water. The sections correspond to the five boxed areas of the grain shown in (a),(b). (e–i) were stained with toluidine blue and iodine to reveal starch; (j–n) were stained with LM11 antibody to reveal AX epitopes. (o–x) As in (e–n) but for a grain grown with LAB. (o–s) were stained with toluidine blue and iodine to reveal starch; (t–x) were stained with LM11 antibody to reveal AX epitopes. Scale bars are 100 μm (a–d) and 50 μm (e–x).