Acidity is a serious limitation to plant production on many of the world's agricultural soils. Toxic aluminium (Al) cations solubilized by the acidity rapidly inhibit root growth and limit subsequent uptake of water and nutrients. Recent work has shown that the ALMT1 gene of wheat ( Triticum aestivum ) encodes a malate transporter that is associated with malate efflux and Al tolerance. We generated transgenic barley ( Hordeum vulgare ) plants expressing ALMT1 and assessed their ability to exude malate and withstand Al stress. ALMT1 expression in barley conferred an Al-activated efflux of malate with properties similar to those of Al-tolerant wheat. The transgenic barley showed a high level of Al tolerance when grown in both hydroponic culture and on acid soils. These findings provide additional evidence that ALMT1 is a major Al-tolerance gene and demonstrate its ability to confer effective tolerance to acid soils through a transgenic approach in an important crop species.
The author tired to restore the geomorphic development of alluvial coastal plains, related to the Holocene sea-level change. The Holocene shoreline had advanced seaward during the progressing period of coastal plain, since about 6, 500-7, 500yBP to the present (Matsumoto 1981a, 1981b).This paper examined the difference of the size frequency distribution between aeolian and marine sand deposits in coastal areas, to estimate the changing altitude of the former shoreline based on the grain size analysis. The samples were collected from some coastal areas in northeastern part of Honshu Island, i. e. Sendai, Ishinomaki, Akita and Shoai coastal areas (Fig. 1). Each coastal area has a long sandy bach. The sampling sites are shown in Figs. 3, 6, 8 and 10.The aeolian sands were sampled from modern sand dunes and the marine sands were sampled from swash zone and shollow marine (see Fig. 2). In the laboratory, grain size determinations were made on these smaples by conventional sieving methods, using 1/2φ sive intervals. The difference of size frequency distribution was examined in each locality. The results are shown in Figs. 4, 5, 7, 9 and 11. Aeolian sands are clearly distinguished from marine sands on each coastal area. For example, at Sendai and Ishinomaki coastal areas, the two kinds of sands are separated by the value of skewness, and at Akita and Sonai coastal areas the two kinds of sands have no difference in skewness, but they have difference in standard deviation. Statistical parameters such as mean, standard deviation and skewness of the two kinds of sands have particular boundary values in each coastal area. Then the differentiation between aeolian and marine sands should be recognized under the unique rule on each coastal area.
