Yoshiharu Wada

Structural and Biochemical Dissection of Photorespiration in Hybrids Differing in Genome Constitution between Diplotaxis tenuifolia (C3-C4) and Radish (C3)

We compared the structural, biochemical, and physiological characteristics involved in photorespiration of intergeneric hybrids differing in genome constitution (DtDtR, DtDtRR, and DtRR) between the C3-C4 intermediate species Diplotaxis tenuifolia (DtDt) and the C3 species radish (Raphanus sativus; RR). The bundle sheath (BS) cells in D. tenuifolia included many centripetally located chloroplasts and mitochondria, but those of radish had only a few chloroplasts and mitochondria. In the hybrids, the numbers of chloroplasts and mitochondria, the ratio of centripetally located organelles to total organelles, and the mitochondrial size in the BS cells increased with an increase in the constitution ratio of the Dt:R genome. The P-protein of glycine decarboxylase (GDC) was confined to the BS mitochondria in D. tenuifolia, whereas in radish, it accumulated more densely in the mesophyll than in the BS mitochondria. In the hybrids, more intense accumulation of GDC in the BS relative to the mesophyll mitochondria occurred with an increase in the Dt:R ratio. These structural and biochemical features in the hybrids were reflected in the gas exchange characteristics of leaves, such as the CO2 compensation point. Our data indicate that the leaf structure, the intercellular pattern of GDC expression, and the gas exchange characteristics of C3-C4 intermediate photosynthesis are inherited in the hybrids depending on the constitution ratio of the parent genomes. Our findings also demonstrate that the apparent reduced photorespiration in C3-C4 intermediate plants is mainly due to the structural differentiation of mitochondria and chloroplasts in the BS cells combined with the BS-dominant expression of GDC.

Inheritance of C3-C4 Intermediate Photosynthesis in Reciprocal Hybrids between Moricandia arvensis (C3-C4) and Brassica oleracea (C3) that Differ in their Genome Constitution

Abstract To Elucidate The Genetic Mechanisms Underlying C3―C4 intermediate Photosynthesis, We investigated The Structural and Photosynthetic Characteristics of Leaves of Reciprocal Hybrids Between The C3―C4 intermediate Species Moricandia Arvensis (L.) Dc. (Mama) and The C3 Species Brassica Oleracea L. (Cabbage; Cc), Which Differ in Genome Constitution. Moricandia Arvensis Bundle Sheath (Bs) Cells included Many Centripetally Located Chloroplasts and Mitochondria, Whereas Those of Cabbage Had Few Organelles. Hybrid Leaves Were Structurally intermediate Between Those of The Parents and Showed Stronger intermediate C3―C4 Features As The Proportion of The Ma Genome increased. The P-Protein of Glycine Decarboxylase (Gdc) Was Confined Mainly To Bs Mitochondria in M. Arvensis, But Accumulated More in The Mesophyll (M) of Cabbage. in The Hybrids, The Accumulation of Gdc in Bs Cells increased With An increasing Ma:C Ratio. Hybrids Exhibited Gradients in Structural and Biochemical Features, Even in Reciprocal Crosses. The Co2 Compensation Point of Reciprocal Hybrids With High Ma:C Ratios Was Lower Than That of Cabbage But Higher Than That of M. Arvensis. Thus, The Structural and Biochemical Features in Hybrid Leaves Reduced Photorespiration. Moricandia Arvensis Had A Higher Photosynthetic Rate Than Cabbage, But The Photosynthetic Rates of Hybrids Were intermediate Between Those of The Parents Or Comparable To That of M. Arvensis. Our Results Demonstrate That The C3―C4 intermediate Characteristics Are inherited Based On The Ratio of The Parent Genomes, and That There Is No Evidence of Cytoplasmic inheritance in These Characteristics.

Genetic Transformation of a High Molecular Weight Glutenin (Glu-1Dx5) to Rice cv. Fatmawati

Abstract In order to improve rice dough functionality, we co-transformed the Glu-1Dx5 gene encoding a high molecular weight (HMW) glutenin subunit Dx5 from bread wheat, Triticum aestivum L. and either bar gene conferring resistance to herbicide bialaphos or hpt gene conferring resistance to hygromycin B to rice callus cells of cv. Fatmawati. We molecularly characterized 9 plants regenerated from bialaphos-containing medium and 63 plants from hygromycin-containing medium. The Glu-1Dx5 gene was detected by PCR analysis in 15 transgenic T0 plants. Further analysis of T1 and T2 plants revealed that some transgenic plants carried the Glu-1Dx5 gene. Analysis of the endosperm extracts of T2 plants by SDS-PAGE revealed the existence of a protein similar in size to the wheat Glu-1Dx5 gene product, suggesting successful expression of the transgene. These plants will be incorporated into breeding program for further assessment of their benefits.

Two Alternative Methods to Predict Amylose Content of Rice Grain by Using Tristimulus CIE Lab Values and Developing a Specific Color Board of Starch-iodine Complex Solution

Abstract Amylose content was predicted by measuring tridimensional Commission Internationale de l‘Eclairage (CIE L*a*b*), L*a*b* values in starch-iodine solutions and building a regression model. The developed regression model showed a highly significant relationship (R2=0.99) between the L*a*b* values and the amylose content. Apparent amylose content was strongly and negatively correlated with L*a*b* values. This method could be used to predict amylose content in rice. The conversion of L*a*b* values to red, green, blue (RGB) values and to color hexadecimal codes allowed reproducing the colors of starch-iodine solution and making an explicit color board. Using this specific color board, we could sort entries into their respective classes and easily estimate their apparent amylose content.