AUTHOR=Tang Jun , Lin Jing , Li Hui , Li Xiaogang , Yang Qingsong , Cheng Zong-Ming , Chang Youhong 

TITLE=Characterization of CIPK Family in Asian Pear (Pyrus bretschneideri Rehd) and Co-expression Analysis Related to Salt and Osmotic Stress Responses

JOURNAL=Frontiers in Plant Science

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2016.01361

DOI=10.3389/fpls.2016.01361

ISSN=1664-462X

ABSTRACT=<p>Asian pear (<italic>Pyrus bretschneideri</italic>) is one of the most important fruit crops in the world, and its growth and productivity are frequently affected by abiotic stresses. Calcineurin B-like interacting protein kinases (CIPKs) as caladium-sensor protein kinases interact with Ca<sup>2+</sup>-binding CBLs to extensively mediate abiotic stress responses in plants. Although the pear genome sequence has been released, little information is available about the <italic>CIPK</italic> genes in pear, especially in response to salt and osmotic stresses. In this study, we systematically identified 28 <italic>CIPK</italic> family members from the sequenced pear genome and analyzed their organization, phylogeny, gene structure, protein motif, and synteny duplication divergences. Most duplicated <italic>PbCIPK</italic>s underwent purifying selection, and their evolutionary divergences accompanied with the pear whole genome duplication. We also investigated stress -responsive expression patterns and co-expression networks of CIPK family under salt and osmotic stresses, and the distribution of stress-related <italic>cis</italic>-regulatory elements in promoter regions. Our results suggest that most <italic>PbCIPK</italic>s could play important roles in the abiotic stress responses. Some <italic>PbCIPK</italic>s, such as <italic>PbCIPK22</italic>, <italic>-19</italic>, <italic>-18</italic>, <italic>-15</italic>, <italic>-8</italic>, and <italic>-6</italic> can serve as core regulators in response to salt and osmotic stresses based on co-expression networks of <italic>PbCIPK</italic>s. Some sets of genes that were involved in response to salt did not overlap with those in response to osmotic responses, suggesting the sub-functionalization of <italic>CIPK</italic> genes in stress responses. This study revealed some candidate genes that play roles in early responses to salt and osmotic stress for further characterization of abiotic stress responses medicated by <italic>CIPK</italic>s in pear.</p>