Abstract
Rice is more sensitive to salinity, particularly at its early vegetative and later productive stages. Wild plants growing in harsh environments such as wild barley from Qinghai-Tibet Plateau adapt to the adverse environment with allelic variations at the loci responsible for stressful environment, which could be used for rice genetic improvement. In this study, we overexpressed HsCBL8 encoding a calcium-sensor calcineurin B-like (CBL) protein in rice. The gene was isolated from XZ166, a wild-barley (Hordeum spontanum) line originated from Qinghai-Tibet Plateau. We found that XZ166 responded to high NaCl concentration (200 mM) with more HsCBL8 transcripts than CM72, a cultivated barley line known for salinity tolerance. XZ166 is significantly different from CM72 with nucleotide sequences at HsCBL8. The overexpression of HsCBL8 in rice resulted in significant improvement of water protection in vivo and plasma membrane, more proline accumulation, and a reduction of overall Na+ uptake but little change in K+ concentration in the plant tissues. Notably, HsCBL8 did not act on some genes downstream of the rice CBL family genes, suggesting an interesting interaction between HsCBL8 and unknown factors to be further investigated.
Highlights
High salinity is one of the most prevalent abiotic stresses that pose severe reduction in plants’ growth and productivity of crops such as rice (Oryza sativa) grown in coastal and irrigated lands (Martínez-Atienza et al, 2007)
To obtain insight about the salt stress responses in rice related to elite gene(s) from wild barley, we selected the HsCBL8 gene and thoroughly analyzed its functional relations with other genes in response to the salt stress regime
We conducted the phylogenetic analysis of HsCBL8 and revealed that the encoded protein belongs to the group of calcineurin B-like (CBL) proteins only modified with N-myristoylation or S-acylation (Batistic et al, 2012), (Figure 2A)
Summary
High salinity is one of the most prevalent abiotic stresses that pose severe reduction in plants’ growth and productivity of crops such as rice (Oryza sativa) grown in coastal and irrigated lands (Martínez-Atienza et al, 2007). 6% (800 million hectares) of world’s total land area has been reported as salt affected (Romeza and Flowers, 2008), mainly contributed by accumulation of salts over time in arid and semiarid regions, salts from oceans brought in by wind and rain, and weathering of the rocks (Rengasamy, 2002). The responses of rice to salt stress could involve the regulation of membrane integrity, ionic compartmentation, osmotic adjustment and accumulation of macromolecules (Hu et al, 2012). To cope with deleterious effects of salt stress, efforts have been made to map QTLs that respond to salt stress in rice and barley (Gao and Lin, 2013; Long et al, 2013; Ahmadi-Ochtapeh et al, 2015; Das and Rao, 2015), clone genes based on mapping and transfer elite genes from wild barley into rice (Ellis et al, 2000).
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