Analysis of DNA extraction buffer components from plant tissue by polymerase chain reaction

RNAi effects on regulation of endogenous acid invertase activity in potato (Solanum tuberosumL.) tubers

In plants, acid invertases are known to be the key enzymes cleaving sucrose into reducing sugars (RS) (glucose and fructose). To improve the quality of potato (Solanum tuberosumL.) chips, which is largely influenced by RS accumulation in tubers stored at low temperature, a part of acid invertase cDNA with hairpin RNA (hpRNA) structure was transformed into potato cv. N2. Detection of polymerase chain reaction (PCR) amplification and Northern blotting suggested that the RNA interference (RNAi) vector was successfully transformed into cv. N2. The analysis of acid invertase activity in the plantlets and microtubers of RNAi transgenic lines indicated that the expression of the acid invertase was significantly repressed by the activity of RNAi of plantlets by an average 69.8% (with the exception of line Ni-1) with a maximal decrease of 78% (line Ni-4), and the highest decrease of activity in microtubers of 68%. Compared with that of well-inhibited antisenseinvtransgenic plants, the comparative downregulation of RNAi suggests a distinct alteration of endogenous acid invertase activity and a potential strategy for post-transcriptional gene silencing (PTGS) in modulation of cold-sweetening in potato.

A role of OsGA20ox1 , encoding an isoform of gibberellin 20-oxidase, for regulation of plant stature in rice

Gibberellin (GA) 20-oxidase (GA20ox) is a key enzyme that normally catalyzes the penultimate steps in GA biosynthesis. One of the GA20ox genes in rice (Oryza sativa L.), OsGA20ox2 ( SD1 ), is well known as the "Green Revolution gene", and loss-of function mutation in this locus causes semi-dwarfism. Another GA20ox gene, OsGA20ox1, has also been identified, but its contribution to plant stature has remained unclear because no suitable mutants have been available. We isolated a mutant, B142, tagged with a T-DNA containing three CaMV 35S promoters, which showed a tall, GA-overproduction phenotype. The final stature of the B142 mutant reflects internode overgrowth and is approximately twice that of its wild-type parent. This mutant responds to application of both GA3 and a GA biosynthesis inhibitor, indicating that it is a novel tall mutant of rice distinct from GA signaling mutants such as slr1 . The integrated T-DNAs, which contain three CaMV 35S promoters, are located upstream of the OsGA20ox1 open reading frame (ORF) in the B142 mutant genome. Analysis of mRNA and the endogenous GAs reveal that biologically active GA level is increased by up-regulation of the OsGA20ox1 gene in B142. Introduction of OsGA20ox1 cDNA driven by 35S promoter into the wild type phenocopies the morphological characteristics of B142. These results indicate that the elongated phenotype of the B142 mutant is caused by up-regulation of the OsGA20ox1 gene. Moreover, the final stature of rice was reduced by specific suppression of the OsGA20ox1 gene expression. This result indicates that not only OsGA20ox2 but also OsGA20ox1 affects plant stature.