Molecular characterization and transcriptome profiling of expansin genes isolated from Calotropis procera fibers

Abstract

The Calotropis procera seed fibers provide an excellent model system to study the genes involved in fiber elongation, fineness and strength. Expansins constitute one of the important gene families involved in plant cell expansion and other cell wall modification processes. Four homologs of Expansin A gene i.e. CpEXPA1, CpEXPA2, CpEXPA3 and CpEXPA4 were isolated from the cDNA library obtained from fast growing Calotropis procera fibers. These homologs represented typical Expansin A family. Each of them had two conserved domains including GH45 like domain and the putative polysaccharide binding domain. The deduced amino acid sequences of the homologs indicated three conserved motifs: i) eight cysteine residues at N-terminus, ii) four tryptophan residues at C-terminus and iii) a Histidine-Phenylalanine-Aspartate motif in the center of the sequence. The presence of N-terminal signal peptide consisting of hydrophobic amino acids and a transmembrane region in all these expansin isoforms suggests their cotranslational insertion into the endoplasmic reticulum and then transportation to the cell wall by secretory pathway. The relative quantification of the four expansins in root, stem, fiber and leave tissues indicated that the transcripts of CpEXPA1, CpEXPA2, CpEXPA3 and CpEXPA4 are variably transcribed in these tissues. The lowest transcription of all the four Expansin A isoforms was observed in elongating roots indicating that root tissue might be having specific expansins other than those confined to air grown organs.

The Phenological Characterization of Calotropis procera (Ait) and its Potential for Domestication for Wool Production in Drylands

“…The 25-105 fruits per plant obtained in this study was relatively high compared to [10] average of 23 fruits per plant. [22], in a study on flowering and fruiting ecophysiology of C. procera, reported an even lower number of ripened fruits that ranged between 4-18 fruits/plant.…”

“…The observed 1-3 fruits per flower cluster noted in this study has also been documented elsewhere. For example, [10] reported that the fruit number of C. procera varies from 1-3 per inflorescent.…”

“…The fruit attains maximum length in 20-25 days in early fruiting though this period can increase when fruiting occurs late. C. procera fruit takes 30-35 days to mature [10]. [11]- [13] recorded continuous flowering with annual peaks.…”

Identification and characterization of plasma membrane aquaporins isolated from fiber cells of Calotropis procera

“…It may be assumed that the fiber cell elongation in C. procera is turgor pressure driven by aquaporin activity in cooperation with other fiber-related gene families like expansins, lipid transfer proteins, tubulins, arabino-galactan proteins, and actins (Cheema et al, 2010;Indrais et al, 2011).…”

“…It produces long and fine fibers on its seeds for wind dispersal. C. procera fibers can reach up to 45 mm in length (Cheema et al, 2010).…”