Plant tissues that require structural rigidity synthesize a thick, strong secondary cell wall of lignin, cellulose and hemicelluloses in a complicated bridged structure. Master regulators of secondary wall synthesis were identified in dicots, and orthologs of these regulators have been identified in monocots, but regulation of secondary cell wall formation in monocots has not been extensively studied. Here we demonstrate that the rice transcription factors SECONDARY WALL NAC DOMAIN PROTEINs (SWNs) can regulate secondary wall formation in rice (Oryza sativa) and are potentially useful for engineering the monocot cell wall. The OsSWN1 promoter is highly active in sclerenchymatous cells of the leaf blade and less active in xylem cells. By contrast, the OsSWN2 promoter is highly active in xylem cells and less active in sclerenchymatous cells. OsSWN2 splicing variants encode two proteins; the shorter protein (OsSWN2S) has very low transcriptional activation ability, but the longer protein (OsSWN2L) and OsSWN1 have strong transcriptional activation ability. In rice, expression of an OsSWN2S chimeric repressor, driven by the OsSWN2 promoter, resulted in stunted growth and para-wilting (leaf rolling and browning under normal water conditions) due to impaired vascular vessels. The same OsSWN2S chimeric repressor, driven by the OsSWN1 promoter, caused a reduction of cell wall thickening in sclerenchymatous cells, a drooping leaf phenotype, reduced lignin and xylose contents and increased digestibility as forage. These data suggest that OsSWNs regulate secondary wall formation in rice and manipulation of OsSWNs may enable improvements in monocotyledonous crops for forage or biofuel applications.

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We sought to determine the effects of sprout-induced ␣-amylase on the pasting properties of flour and starch in wheat grain. To accomplish this, we used grain from five winter and two spring wheat cultivars obtained by significantly delaying the harvest date. Furthermore, grain from one winter wheat cultivar was soaked in water for 24 h at 5°C and then stored up to 48 h at 20°C. ␣-Amylase activity and the pasting properties of flour and starch were examined in each wheat sample mentioned above. Extremely late harvesting was associated with higher ␣-amylase activity and lower peak viscosity of flour in general. However, little change in starch peak viscosity was observed during the late stage of development in most cultivars. A wetting treatment also indicated that an excess accumulation of ␣-amylase and a marked decrease in flour peak viscosity did not coincide with a large decline in starch peak viscosity.

The effects of increase in ␣-amylase and endo-protease activities during germination on the deterioration of the breadmaking quality of hard wheat were examined using three varieties with different strengths of gluten: VictoriaINTA, Harunoakebono, and Leader. The results are summarized as follows: (1) The degradation of the breadmaking quality of flour damaged in germination differed greatly according to the gluten strength of each variety. VictoriaINTA, which has extra-strong gluten, was more tolerant of the germination damage than the other varieties with strong gluten. (2) The degradation of specific loaf volume, which is caused by lowering the gas retention of the dough, was the result of the softening of the dough that was observed as a decrease in the mixing peak time and the breaking force of the dough. (3) The ␣-amylase and endo-protease activities of flours did not seemed to influence the breadmaking quality, although there was a considerably high correlation between endo-protease activity of whole wheat flour and breadmaking quality. From these results, it would seem that the main reason that flour damaged during germination degrades breadmaking quality is the endo-protease in the wheat grain, which already causes partial gluten decomposition. Accordingly, it might be better to examine the endo-protease activity of whole wheat flour at harvest ripeness in order to estimate the value of breadmaking quality within the hard-wheat breeding system. Keywords: extra-strong variety, breadmaking quality, endo-protease activity, ␣-amylase activity Most Japanese hard wheat used for bread is grown in Hokkaido; however, pre-harvest sprouting often occurs as grain develops due to unfavorable weather. This problem is serious because wheat flour that is damaged during germination has a maximum viscosity (MV) of Amylograph that is below 300 B.U. and is unsuitable for industrial processing. Many studies on germination damage in wheat deal with starch degradation, i.e., MV of Amylograph, Falling number, ␣-amylase activity and the quality of bread (MacGregor & Matsuo, 1972; Meredith & Pomernz, 1985;MacGregor & Dushnicky, 1989). However, the deterioration of breadmaking quality in flour that has been damaged during sprouting cannot always be explained by low MV values (Yamauchi et al., 1998;Sato et al., 1999). Therefore, another practical index to estimate the value of breadmaking quality is required within the hard-wheat breeding system. On the other hand, there is some evidence that the degradation of storage protein also greatly contributes to the loss of breadmaking quality during germination. (Kruger, 1971;Bushuk & Lukow, 1987;Lukow & Bushuk, 1984;Janssen et al., 1996b;Weegels et al.,1996). Studies show that an increase in ␣-amylase and endoprotease activities in wheat may lead to degradation of endosperm starch and protein during germination and may have a deleterious effect on the quality of bread (Kiribuchi & Nakamura, 1973; Preston & Kruger, 1979;Meredith & Pomeranz, 1985;Salomonsson et al., 1989; Sun & Henson,19...