The elicitor-responsive gene for a GRAS family protein, CIGR2, suppresses cell death in rice inoculated with rice blast fungus via activation of a heat shock transcription factor, OsHsf23.

We show that a rice GRAS family protein, CIGR2, is a bonafide transcriptional activator, and through this function, targets the B-type heat shock protein-encoding gene OsHsf23 (Os09g0456800). CIGR2 (Os07g0583600) is an N-acetylchitooligosaccharide elicitor-responsive gene whose activity, through the direct transcriptional control of OsHsf23, is required for mediating hypersensitive cell death activation during pathogen infection. RNAi lines of CIGR2 and OsHsf23 similarly exhibited the higher level of granulation in the epidermal cells of leaf sheath inoculated with an avirulent isolate of rice blast fungus.

Loss of function of the IAA-glucose hydrolase gene TGW6 enhances rice grain weight and increases yield.

Increases in the yield of rice, a staple crop for more than half of the global population, are imperative to support rapid population growth. Grain weight is a major determining factor of yield. Here, we report the cloning and functional analysis of THOUSAND-GRAIN WEIGHT 6 (TGW6), a gene from the Indian landrace rice Kasalath.

Visual selection in rice: a strategy for the efficient identification of transgenic calli accumulating transgene products.

Fluorescent proteins such as green fluorescent protein (GFP) allow direct visualization of transformed cells without the need for exogenous substrates. Furthermore, visual selection using GFP is a powerful tool that can be used to isolate transformed cells without antibiotic or herbicide pressure and can be applied to transformation systems in plants hypersensitive to these agents. Moreover, we propose that visual selection enables isolation of calli in which the gene of interest is expressed to a high level, by selecting calli in which a strong GFP signal is observed.

Application of gene targeting to designed mutation breeding of high-tryptophan rice.

Site-directed mutagenesis via gene targeting (GT) based on homologous recombination is the ultimate mutation breeding technology because it enables useful information acquired from structural- and computational-based protein engineering to be applied directly to molecular breeding, including metabolic engineering, of crops. Here, we employed this rationale to introduce precise mutations in OASA2--an α-subunit of anthranilate synthase that is a key enzyme of tryptophan (Trp) biosynthesis in rice (Oryza sativa)--via GT, with subsequent selection of GT cells using a Trp analog. The expression level of OASA2 in plants homozygous and heterozygous for modified OASA2 was similar to that of nontransformants, suggesting that OASA2 transcription in GT plants was controlled in the same manner as endogenous OASA2, and that GT could lead to a lower risk of gene silencing than in conventional overexpression approaches.

Metabolome and photochemical analysis of rice plants overexpressing Arabidopsis NAD kinase gene.

The chloroplastic NAD kinase (NADK2) is reported to stimulate carbon and nitrogen assimilation in Arabidopsis (Arabidopsis thaliana), which is vulnerable to high light. Since rice (Oryza sativa) is a monocotyledonous plant that can adapt to high light, we studied the effects of NADK2 expression in rice by developing transgenic rice plants that constitutively expressed the Arabidopsis chloroplastic NADK gene (NK2 lines). NK2 lines showed enhanced activity of NADK and accumulation of the NADP(H) pool, while intermediates of NAD derivatives were unchanged.

Over-expression of calcium-dependent protein kinase 13 and calreticulin interacting protein 1 confers cold tolerance on rice plants.

Calcium is a ubiquitous signaling molecule and changes in cytosolic calcium concentration are involved in plant responses to various stimuli. The rice calcium-dependent protein kinase 13 (CDPK13) and calreticulin interacting protein 1 (CRTintP1) have previously been reported to be involved in cold stress response in rice. In this study, rice lines transformed with sense CDPK13 or CRTintP1 constructs were produced and used to investigate the function of these proteins.

Early infection of scutellum tissue with Agrobacterium allows high-speed transformation of rice.

Several approaches have recently been adopted to improve Agrobacterium-mediated transformation of rice, both to generate the large number of T-DNA insertion plants needed for functional analysis of the rice genome, and for production of rice with additional agronomical value. However, about 3 months of in vitro culture is still required for isolation of transgenic rice plants. Here, we report the competency of scutellum tissue from 1-day pre-cultured seeds for Agrobacterium-mediated transformation.

Constitutive expression of human lactoferrin and its N-lobe in rice plants to confer disease resistance.

The milk protein, lactoferrin, is known to have antibacterial, antiviral, and antifungal activities. To explore the possibility of conferring disease resistance in plants by expressing this protein, the gene for the full-length human lactoferrin (HLF), as well as the N-lobe, the N-terminal half molecule (HLFN), was introduced into rice plants and expressed constitutively under the control of the cauliflower mosaic virus 35S promotor. Western blot analysis of leaves from HLF-transgenic rice plants showed an 80 kDa-band, which was about 1-2 kDa less than human milk lactoferrin.

OsCDPK13, a calcium-dependent protein kinase gene from rice, is induced by cold and gibberellin in rice leaf sheath.

Calcium-dependent protein kinases (CDPKs) play an important role in rice signal transduction, but the precise role of each individual CDPK is still largely unknown. Recently, a full-length cDNA encoding OsCDPK13 from rice seedling was isolated. To characterize the function of OsCDPK13, its responses to various stresses and hormones were analyzed in this study.

RERJ1, a jasmonic acid-responsive gene from rice, encodes a basic helix-loop-helix protein.

Differential screening of a cDNA library constructed using poly(A)(+) RNA from suspension-cultured rice cells treated with jasmonic acid (JA) for 1/2h yielded a cDNA of a gene tentatively named RERJ1 that is upregulated in response to exogenous JA. Northern blot analysis indicated that the RERJ1 mRNA levels peaked at 1/2-1h after the addition of jasmonic acid and then decreased gradually. RERJ1 encodes a transcriptional regulator with a basic helix-loop-helix motif.

Characterization of calreticulin as a phosphoprotein interacting with cold-induced protein kinase in rice.

Calreticulin is an abundant endo/sarcoplasmic reticulum Ca2+-binding protein. To investigate whether calreticulin (CRO1) is involved in the cold-stress response in rice, a transgenic plant was constructed. The transcriptional level was decreased within 30 min and recovered within 2 h of a cold treatment.