Zoysia is a warm-season turfgrass, which comprises 11 allotetraploid species (2n = 4x = 40), each possessing different morphological and physiological traits. To characterize the genetic systems of Zoysia plants and to analyse their structural and functional differences in individual species and accessions, we sequenced the genomes of Zoysia species using HiSeq and MiSeq platforms. As a reference sequence of Zoysia species, we generated a high-quality draft sequence of the genome of Z. japonica accession ‘Nagirizaki’ (334 Mb) in which 59,271 protein-coding genes were predicted. In parallel, draft genome sequences of Z. matrella ‘Wakaba’ and Z. pacifica ‘Zanpa’ were also generated for comparative analyses. To investigate the genetic diversity among the Zoysia species, genome sequence reads of three additional accessions, Z. japonica ‘Kyoto’, Z. japonica ‘Miyagi’ and Z. matrella ‘Chiba Fair Green’, were accumulated, and aligned against the reference genome of ‘Nagirizaki’ along with those from ‘Wakaba’ and ‘Zanpa’. As a result, we detected 7,424,163 single-nucleotide polymorphisms and 852,488 short indels among these species. The information obtained in this study will be valuable for basic studies on zoysiagrass evolution and genetics as well as for the breeding of zoysiagrasses, and is made available in the ‘Zoysia Genome Database’ at .

Expression controls of the carbon acquisition system in marine diatoms in response to environmental factors are an essential issue to understand the changes in marine primary productivity. A pyrenoidal β-carbonic anhydrase, PtCA1, is one of the most important candidates to investigate the control mechanisms of the CO2 acquisition system in the marine diatom Phaeodactylum tricornutum. A detailed functional assay was carried out on the putative core regulatory region of the ptca1 promoter using a β-glucuronidase reporter in P. tricornutum cells under changing CO2 conditions. A set of loss-of-function assays led to the identification of three CO2-responsive elements, TGACGT, ACGTCA, and TGACGC, at a region −86 to −42 relative to the transcription start site. Treatment with a cyclic (c)AMP analog, dibutyryl cAMP, revealed these three elements to be under the control of cAMP; thus, we designated them, from 5′ to 3′, as CO2-cAMP-Responsive Element1 (CCRE1), CCRE2, and CCRE3. Because the sequence TGACGT is known to be a typical target of human Activating Transcription Factor6 (ATF6), we searched for genes containing a basic zipper (bZIP) region homologous to that of ATF6 in the genome of P. tricornutum. Gel-shift assays using CCRE pentamers as labeled probes showed that at least one candidate of bZIP proteins, PtbZIP11, bound specifically to CCREs. A series of gain-of-function assays with CCREs fused to a minimal promoter strongly suggested that the alternative combination of CCRE1/2 or CCRE2/3 at proper distances from the minimal promoter is required as a potential target of PtbZIP11 for an effective CO2 response of the ptca1 gene.

Our previous study showed that three CO 2 /cAMP-responsive elements (CCRE) CCRE1, CCRE2, and CCRE3 in the promoter of the chloroplastic b-carbonic anhydrase 1 gene in the marine diatom Phaeodactylum tricornutum (Pptca1) were critical for the cAMPmediated transcriptional response to ambient CO 2 concentration. Pptca1 was activated under CO 2 limitation, but the absence of light partially disabled this low-CO 2 -triggered transcriptional activation. This suppression effect disappeared when CCRE2 or two of three CCREs were replaced with a NotI restriction site, strongly suggesting that light signal cross-talks with CO 2 on the cAMP-signal transduction pathway that targets CCREs. The paralogous chloroplastic carbonic anhydrase gene, ptca2 was also CO 2 /cAMP-responsive. The upstream truncation assay of the ptca2 promoter (Pptca2) revealed a short sequence of 2367 to 2333 relative to the transcription-start site to be a critical regulatory region for the CO 2 and light responses. This core-regulatory region comprises one CCRE1 and two CCRE2 sequences. Further detailed analysis of Pptca2 clearly indicates that two CCRE2s are the cis-element governing the CO 2 /light response of Pptca2. The transcriptional activation of two Pptcas in CO 2 limitation was evident under illumination with a photosynthetically active light wavelength, and an artificial electron acceptor from the reduction side of PSI efficiently inhibited Pptcas activation, while neither inhibition of the linear electron transport from PSII to PSI nor inhibition of ATP synthesis showed an effect on the promoter activity, strongly suggesting a specific involvement of the redox level of the stromal side of the PSI in the CO 2 /light cross talk.

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