Overexpression of maize anthocyanin regulatory gene Lc affects rice fertility.

Seventeen independent transgenic rice plants with the maize anthocyanin regulatory gene Lc under control of the CaMV 35S promoter were obtained and verified by molecular identification. Ten plants showed red spikelets during early development of florets, and the degenerate florets were still red after heading. Additionally, these plants exhibited intense pigmentation on the surface of the anther and the bottom of the ovary. They were unable to properly bloom and were completely sterile. Following pollination with normal pollen, these plants yielded red caryopses but did not mature normally. QRT-PCR analysis indicated that mRNA accumulation of the CHS-like gene encoding a chalcone synthase-related protein was increased significantly in the sterile plant. This is the first report to suggest that upregulation of the CHS gene expression may result in rice sterility and affect the normal development of rice seeds.

Molecular Mechanisms Underlying γ-Aminobutyric Acid (GABA) Accumulation in Giant Embryo Rice Seeds.

To uncover the molecular mechanisms underlying GABA accumulation in giant embryo rice seeds, we analyzed the expression levels of GABA metabolism genes and contents of GABA and GABA metabolic intermediates in developing grains and germinated brown rice of giant embryo rice 'Shangshida No. 5' and normal embryo rice 'Chao2-10' respectively. In developing grains, the higher GABA contents in 'Shangshida No. 5' were accompanied with upregulation of gene transcripts and intermediate contents in the polyamine pathway and downregulation of GABA catabolic gene transcripts, as compared with those in 'Chao2-10'. In germinated brown rice, the higher GABA contents in 'Shangshida No. 5' were parallel with upregulation of OsGAD and polyamine pathway gene transcripts and Glu and polyamine pathway intermediate contents and downregulation of GABA catabolic gene transcripts. These results are the first to indicate that polyamine pathway and GABA catabolic genes play a crucial role in GABA accumulation in giant embryo rice seeds.

High expression of tocochromanol biosynthesis genes increases the vitamin E level in a new line of giant embryo rice.

'Shangshida No. 5' is a new variety of giant embryo rice derived from a single-point mutation of the giant embryo gene (ge) in 'Chao2-10' rice. This study quantified the levels of eight vitamin E homologues (α-, ß-, γ-, and δ-tocopherol and α-, ß-, γ-, and δ-tocotrienol) in brown rice, embryos, endosperm, and developing seeds of giant embryo and normal embryo rice using a normal phase high-performance liquid chromatographic method. Quantitative RT-PCR analysis was conducted to reveal the different expression patterns of the ge gene and tocochromanol biosynthesis genes in developing giant and normal embryo seeds. The total vitamin E content in 'Shangshida No. 5' brown rice was 52.54 mg α-tocopherol equivalent (α-TE)/kg, of which α-tocopherol constituted 49.14 mg/kg, which was approximately 2.2-fold greater than that in 'Chao2-10' brown rice. In giant embryo seeds, the expression level of the ge gene was higher than that in normal embryo seeds during early developmental stages. These results are the first to indicate that coup-regulated expression of the OsHPPD, OsHPT, and OsMPBQ MT2 genes might be the primary reason for the large accumulation of α-tocopherol in giant embryo rice seeds. The different transcription pattern of the tocochromanol biosynthesis genes in 'Shangshida No. 5' rice seeds compared with 'Chao2-10' rice seeds is attributable to the ge mutation and the different expression level of the ge gene in giant embryo seeds.

[Studies on improving crop nutritional quality through gene engineering].

This paper summarizes the studies on improving crop nutritional quality including protein, saccharide and lipid through gene engineering in recent 10 years. Special emphasis is laid upon the improvement of protein contains and amino acid components. The food safety caused probably by gene engineering and some ways to solve the problem are introduced briefly.