Boron (B) is an essential micronutrient for plants. Efflux-type B transporters, BORs, have been identified in Arabidopsis thaliana and rice. Here we identified BOR1 genes encoding B efflux transporters, from the hexaploid genome of wheat (Triticum aestivum L.). We cloned three genes closely related to OsBOR1 and named them TaBOR1.1, TaBOR1.2 and TaBOR1.3. All three TaBOR1s showed B efflux activities when expressed in tobacco BY-2 cells. TaBOR1-green fluorescent protein (GFP) fusion proteins were expressed in Arabidopsis leaf cells localized in the plasma membrane. The transcript accumulation patterns of the three genes differ in terms of tissue specificity and B nutrition responses. In roots, transcripts for all three genes accumulated abundantly while in shoots, the TaBOR1.2 transcript is the most abundant, followed by those of TaBOR1.1 and TaBOR1.3. Accumulation of TaBOR1.1 transcript is up-regulated under B deficiency conditions in both roots and shoots. In contrast, TaBOR1.2 transcript accumulation significantly increased in roots under excess B conditions. TaBOR1.3 transcript accumulation was reduced under excess B. Taken together, these results demonstrated that TaBOR1s are the B efflux transporters in wheat and, interestingly, the genes on the A, B and D genomes have different expression patterns.

In Thailand, boron (B) deficiency in soil is found in the north region where wheat (Triticum aestivum L.), maize (Zea mays L.) and rice (Oryza sativa L.) are promoted cereals. Physiological analysis and genetic variation in B efficiency among plant genotypes have been reported; however, the molecular and genetic mechanisms of low B tolerance remain unclear. In this present study, we investigated the molecular basis of low B tolerance in wheat, maize and rice. Transcript levels of BOR1-like genes, efflux-type B transporters, were compared between B-efficient and B-inefficient genotypes in different organs using quantitative realtime polymerase chain reaction (PCR). The results revealed that the transcript levels of BOR1-like genes are differential between two different genotypes. We found the tendency that transcripts of BOR1-like gene are accumulated to higher levels in B deficiency tolerant cultivar than the sensitive ones in most tested tissues. It is possible that the expression levels of BOR1-like genes are correlated with the B deficiency tolerance in plants. Moreover, BOR1-like genes can be useful as gene expression biomarkers for crop breeding in wheat, maize and rice by selecting appropriate tissues and growth stages.

Protoplast isolation is a first and important step for establishing a new plant with desired traits through protoplast fusion technology. This experiments were conducted to evaluate various concentration of enzymes and incubation time on protoplast yield and viability in two vetiver ecotypes, Kamphaeng Phet 2 (Vetiveria zizanioides Nash) and Prachuap Khiri Khan (V. nemoralis A.Camus). The results revealed that protoplast yields were significantly affected by different enzyme treatments. The highest protoplast yield (6.12x105 protoplasts/ml) and high viability (98.61%) in Kamphaeng Phet 2 was obtained through the process of cell wall digestion when treated with enzyme solution containing 0.5% (w/v) cellulase onozuka R-10 and 0.5% (w/v) macerozyme R-10 in combination. While, the optimal enzyme solution for protoplast isolation from leaves of Prachuap Khiri Khan was the combination of 1.0% (w/v) cellulase onozuka R-10 and 0.4% (w/v) macerozyme R-10, resulting in the highest yield (6.80x105 protoplasts/ml) and viability (96.56%) of protoplasts. Meanwhile, incubation time of 24 h with the optimal enzyme solution resulted in the highest protoplast yields of both ecotypes. Our findings have the potential to generate an efficient protocol to isolate the protoplast from leaves of vetiver which can be used for further research studies in protoplast culture and fusion for vetiver improvement. Keywords: Cellulase onozuka R-10, Macerozyme R-10, Protoplast isolation, Vetiver