PJB-2018-86
Expression Patterns Analysis of Dehiscence Zone Core Regulatory Module SHPs-FUL Transcripts in Pod Shattering in Rapeseed
Romana Shahzadi
Abstract
Pod shattering in Brassicaceae is controlled by a cascade of more than 8 known genes. However, core regulatory module SHP-FUL is fundamental to fruit dehiscence zone and valve margin expression. The present study was envisaged to isolate the orthologs of SHATTERPROOF1/2 (SHP1and SHP2) and FRUITFULL (FUL) from local canola varieties such as Pakola (less susceptible to shattering) and Punjab Sarsoon3 (susceptible to shattering), and to study expression patterns of the isolated transcripts in different tissues. The morphological characterization revealed significant difference between pod wall thicknesses, seeds per pod and pod length between the two cultivars. PCR amplification followed by sequencing revealed that two products namely BnSHP1-like and BnSHP2-like could be identified. The sequence analysis of BnSHP1-like and BnSHP2-like demonstrated that these genes are 747 bp and 735 bp in size, respectively. The nucleotide alignments revealed 98% identity of BnSHP1-like and BnSHP2-like with BnSHP1 and BnSHP2 sequences. The sequence homology was estimated to be 95 and 96% at amino acid level for BnSHP1-like and BnSHP2-like genes, respectively. Only substitutions are found and no insertions or deletions are detectable; therefore the size remained conserved. Interestingly, all the mutations were nonsynonymous. Though mutations were mapped in the M, I and the K-domains but majority of them were accrued at the C-terminal regions. The phylogenetic reconstruction of SHP1 and SHP2 homologs from other species conglomerated BnSHP1-like and BnSHP2-like into their respective clades. Surprisingly, BnSHP2-like of canola was sister to SHP2 of Arabidopsis. Semi-quantitative RT-PCR revealed overlapping expression of both the BnSHP1-like and BnSHP2-like transcripts in flower and siliques but no expression in the leaf tissues was observed. A strong expression for FUL gene was detectable in mature silique and silique from upper portion of plant as compared to other tissues of Pakola and Punjab Sarsoon 3. Thus, BnSHP1/2-like and FUL genes have redundant expression both in the pods and flower. Our results have implications in developing transgenic plants against shattering problem in canola.
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