Calcium can affect in vitro cassava storage roots formation and starch accumulation. Low concentration of calcium stimulates to induce in vitro cassava storage roots formation and the accumulation of starches. With the addition of calcium concentration, the diameter of the in vitro cassava storage roots was increased, but the induction rate and starch content was decreased. The scanning electron microscope observations SC124 in vitro cassava storage roots starch and field cultivation of cassava root starch, starch grains formed by these two different ways is very similar in size and shape. Our findings show that, apply tissue culture techniques to study the cassava starch synthesis mechanism is feasible.

Background HD-Zips (Homeodomain-Leucine Zippers) are a class of plant-specific transcription factors that play multiple roles in plant growth and development. Although some functions of HD-Zip transcription factor have been reported in several plants, it has not been comprehensively studied in peach, especially during adventitious root formation of peach cuttings. Results In this study, 23 HD-Zip genes distributed on 6 chromosomes were identified from the peach (Prunus persica) genome, and named PpHDZ01-23 according to their positions on the chromosomes. These 23 PpHDZ transcription factors all contained a homeomorphism box domain and a leucine zipper domain, were divided into 4 subfamilies(I-IV) according to the evolutionary analysis, and their promoters contained many different cis-acting elements. Spatio-temporal expression pattern showed that these genes were expressed in many tissues with different levels, and they had distinct expression pattern during adventitious root formation and development. Conclusion Our results showed the roles of PpHDZs on root formation, which is helpful to better understand the classification and function of peach HD-Zip genes.

The induction of tuberous roots of cassava in vitro is functional in MS medium containing 0.54 mM NAA, 0.44 mM BA and 3%-7% sucrose; meanwhile, the saccharide accumulation in the induced tuberous roots was increased with the sucrose content addition from 3%-7% in the inducible medium. Thus, the sucrose is an important factor for tuberous root induction in Cassava in vitro. The experimental results showed that the appropriate concentration of sucrose played a key role on the tuberous root induction in Cassava in vitro.

In this study, two encoding invertase inhibitors (INH) named as MeINH1 and MeINH2 were isolated from cassava (Manihot esculenta Crantz). TheMeINH1 contains a 583 bp fragment in length and codes a region of 172 amino acids; and the MeINH2 contains a 538 bp fragment in length and codes a region of 169 amino acids. The amino acid sequence analysis showed that both MeINH1 and MeINH2 have typical structure of invertase inhibitor proteins with a N-terminal signal peptide, four conserved cysteine residues and two disulfide bridges, respectively; whereas, they showed low homology to other organisms. This research provides a foundation for further study of the cassava INH.

In order to study the inducement pattern and regulating mechanism of MeCWINV3 in Cassava. An 1160 bp promoter region upstream of the MeCWINV3 gene (GenBank Accession No. KC905170) was isolated from Cassava (Manihot esculenta) genomic DNA using PCR methods. Sequence analysis found that it contains typical TATA box and CAAT box, and several cis-acting elements that related plant stress responses, such as ABRE, ARFAT, GAREAT, MYB and MYC transcription factors. Furthermore, transient expression in transgenic tobacco was analyzed by inserting upstream of GUS gene in expressing vector. The results showed that GUS was mainly expressed in tobacco veins. This will be the basis for further investigating the function of the MeCWINV3 gene promoter.