2. Materials and methods
2.1. Constructs for E. coli transformation
The coding sequence of tomato BHY1 (Ronen et al., 2000) was
cloned between the HindIII and XbaI sites of the plasmid pUC19.
Similarly, the BHY coding sequences from C. zofingiensis, H. pluvialis,
Pantoea ananatis, and Arabidopsis were cloned between the same sites
of pUC19. For co-expression of CrBKT with different BHYs in E. coli,
polycistronic plasmids were constructed by adding a Shine–Dalgarno
(SD) sequence (AGGAGGACAGCC) upstream of the first ATG of CrBKT
(Zhong et al., 2011) which was then inserted between the XbaI and
SacI sites of the BHY-harboring PUC19 plasmids resulting in polycistronic
plasmids. E. coli JM109 carrying pACCAR16ΔcrtX was used as
the host for functional analysis of the cooperation of CrBKT with
various BHYs and tomato BHY1, respectively.
2.2. Constructs for plant transformation
pBI-SlTpCrBKT was derived from pBI121-CRBKT (Zhong et al.,
2011) by replacing the transit peptide sequence of Arabidopsis
RBCS with tomato one (GenBank No. M15236) using PCR-based
cloning techniques. The CrBKT of pBI-SlTpCrBKT was replaced by
HpBHY coding sequence (GenBank No. BD250390) to create pBISlTpHpBHY.
The CaMV35S::SlTpHpBHY::nos cassette was amplified
and inserted in the pBI121-SlTpCRBKT at the ClaI site resulting in
pBI-SlTpHpBHY-SlTpCrBKT.