De novo assembly of the seed transcriptome and search for potential EST-SSR markers for an endangered, economically important tree species: Elaeagnus mollis Diels

Seeds of Elaeagnus mollis(Elaeagnaceae) produce an edible oil and contain more vitamin E(Ve) than major oil-seed crops. Despite its economic value, there is no information on its genome sequence. Here, we used the Illumina platform to determine the seed transcriptome of E.mollis to identify the genes related to Ve biosynthesis and potential simple sequence repeat(SSR) markers. In total, 100,999 unigenes were obtained with an average length of 605 bp and N50 of 985 bp. Of these unigenes,52,256(51.7%) were annotated in at least one public database(NT, NR, PFAM, Swiss Prot, KOG, KO, and GO)in searches using blastn/x. The unigene annotation identified 15 unigenes encoding six enzymes(GGR, HPPD,HPT/VTE2, MPBQ-MT/VTE3, TC/VTE1, and c-TMT/VTE4) putatively involved in Ve biosynthesis. In addition,16,810 SSRs distributed in 14,057 unigenes were mined.Of these, 2820, 583, and 3423 SSRs were located in the 50–UTR, coding sequence(CDS), and 30–UTR regions,respectively, while the remaining 9984 SSRs had undetermined physical locations. The largest group of repeat motifs comprised mononucleotide repeats(70.76%), followed by dinucleotide(15.59%) and trinucleotide(12.10%)repeats. AG/CT(8.69%) and AAG/CTT(4.15%) were the main dinucleotide and trinucleotide repeats, respectively.Furthermore, 9597 SSR-specific primer pairs were designed. Among 100 primer pairs selected randomly to determine their usefulness, 53 proved to be efficient. To the our best of knowledge, this work is the first study of the E. mollis transcriptome and constitutes valuable genomics data for future genetic engineering studies to alter the amount of Ve. The identified potential EST-SSR markers can be used for population genetics studies and assistedbreeding of E. mollis.

Dimming control scheme based on hybrid LACO-SCFDM for visible light communications

This paper proposes a hybrid layered asymmetrically clipped optical(HLACO) single-carrier frequency-division multiplexing(SCFDM) scheme for dimmable visible light communication. It designs a signal structure that combines layered asymmetrically clipped optical(LACO)-SCFDM and negative LACO-SCFDM in proportion for improving the inherent weaknesses of orthogonal frequency-division multiplexing(OFDM)-based dimmable schemes and further enhancing the system performance. Compared to the HLACO-OFDM-based dimming scheme, it obtains a lower bit error ratio and enables efficient communication over broader dimming range. Its spectral efficiency realizes 2.875 bit·s^(-1)·Hz^(-1) within the dimming range of 30%–70%, and the attainable average spectral efficiency gains exceed at least 19.21% compared to other traditional dimmable schemes.