Abstract
The plant-specific NAC (NAM, ATAF, and CUC) transcription factors have diverse role in development and stress regulation. A new transcript encoding NAC protein, homologous to nam-like protein 4 from Petunia was identified from an ABA-regulated subtractive cDNA library of Capsicum annuum seedling. Here, this homolog (named CaNAC2) from C. annuum was characterized and investigated its role in abiotic stress tolerance. Our results indicated that a plant-specific and conserved NAC domain was located in the N-terminus domain of CaNAC2 which was predicted to encode a polypeptide of 410 amino acids. Phylogenetic analysis showed that CaNAC2 belonged to the NAC2 subgroup of the orthologous group 4d. The protein CaNAC2 was subcellularly localized in the nucleus and it had transcriptional activity in yeast cell. CaNAC2 was expressed mainly in seed and root. The transcription expression of CaNAC2 was strongly induced by cold, salt and ABA treatment and inhibited by osmotic stress and SA treatment. Silence of CaNAC2 in virus-induced gene silenced pepper seedlings resulted in the increased susceptibility to cold stress and delayed the salt-induced leaf chlorophyll degradation. These results indicated that this novel CaNAC2 gene might be involved in pepper response to abiotic stress tolerance.
Highlights
Pepper (Capsicum annuum L.), the Solanaceae family, is an important spicy crop
One of the isolated clones showed 82% homologous to nam-like protein 4 from Petunia. This homolog was used as the initial probe to screen the Solanaceae EST database in GenBank and the full-length clone was isolated by a homology-based candidate gene method
We designated it CaNAC2 followed with CaNAC1 that had been functionally identified in C. annuum (Oh et al, 2005)
Summary
Pepper (Capsicum annuum L.), the Solanaceae family, is an important spicy crop. Pepper plants originate from tropical regions and the optimal temperature for its growth ranges between 21 and 27◦C (Deng et al, 2009). To respond to low temperature stress, plants have caused many physiological, and biochemical modifications to adapt to stress condition (Thomashow, 1999; Shinozaki et al, 2003) Such changes are intricately regulated by genes t. One of the genes cloned from the forward subtraction was homologous to Petunia nam-like protein 4 encoding NAC transcription factor Expression of this NAC homolog was significantly induced by cold stress and ABA. The function of this gene silencing in pepper plants was studied by a virus-induced gene silencing (VIGS) method These findings suggest that CaNAC2 in pepper could be involved in defense response against abiotic stress
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