Adaptive Expansion of the Maize Maternally Expressed Gene (Meg) Family involves Changes in Expression Patterns and Protein Secondary Structures of its Members

dc.contributor.utaustinauthorKim, Eun-Deoken_US
dc.contributor.utaustinauthorSung, Sibumen_US
dc.creatorXiong, Yuqingen_US
dc.creatorMei, Wenbinen_US
dc.creatorKim, Eun-Deoken_US
dc.creatorMukherjee, Krishanuen_US
dc.creatorHassanein, Hatemen_US
dc.creatorBarbazuk, William Braden_US
dc.creatorSung, Sibumen_US
dc.creatorKolaczkowski, Bryanen_US
dc.creatorKang, Byung-Hoen_US
dc.description.abstractThe Maternally expressed gene (Meg) family is a locally-duplicated gene family of maize which encodes cysteine-rich proteins (CRPs). The founding member of the family, Meg1, is required for normal development of the basal endosperm transfer cell layer (BETL) and is involved in the allocation of maternal nutrients to growing seeds. Despite the important roles of Meg1 in maize seed development, the evolutionary history of the Meg cluster and the activities of the duplicate genes are not understood. Results: In maize, the Meg gene cluster resides in a 2.3 Mb-long genomic region that exhibits many features of non-centromeric heterochromatin. Using phylogenetic reconstruction and syntenic alignments, we identified the pedigree of the Meg family, in which 11 of its 13 members arose in maize after allotetraploidization similar to 4.8 mya. Phylogenetic and population-genetic analyses identified possible signatures suggesting recent positive selection in Meg homologs. Structural analyses of the Meg proteins indicated potentially adaptive changes in secondary structure from alpha-helix to beta-strand during the expansion. Transcriptomic analysis of the maize endosperm indicated that 6 Meg genes are selectively activated in the BETL, and younger Meg genes are more active than older ones. In endosperms from B73 by Mo17 reciprocal crosses, most Meg genes did not display parent-specific expression patterns. Conclusions: Recently-duplicated Meg genes have different protein secondary structures, and their expressions in the BETL dominate over those of older members. Together with the signs of positive selections in the young Meg genes, these results suggest that the expansion of the Meg family involves potentially adaptive transitions in which new members with novel functions prevailed over older members.en_US
dc.description.departmentCellular and Molecular Biologyen_US
dc.description.sponsorshipAgriculture and Food Research Initiative Competitive Grant from the USDA's National Institute of Food and Agriculture 2010-0496en_US
dc.description.sponsorshipPlant Biology Programen_US
dc.description.sponsorshipNational Science Foundation ISO 1025976en_US
dc.identifier.citationXiong, Yuqing, Wenbin Mei, Eun-Deok Kim, Krishanu Mukherjee, Hatem Hassanein, William B. Barbazuk, Sibum Sung, Bryan Kolaczkowski, and Byung-Ho Kang. "Adaptive expansion of the maize maternally expressed gene (Meg) family involves changes in expression patterns and protein secondary structures of its members." BMC plant biology, Vol. 14, No. 1 (Aug., 2014): 204.en_US
dc.relation.ispartofserialBMC Plant Biologyen_US
dc.rightsAdministrative deposit of works to Texas ScholarWorks: This works author(s) is or was a University faculty member, student or staff member; this article is already available through open access or the publisher allows a PDF version of the article to be freely posted online. The library makes the deposit as a matter of fair use (for scholarly, educational, and research purposes), and to preserve the work and further secure public access to the works of the University.en_US
dc.subjectendosperm transfer cellen_US
dc.subjectdefensin-like genesen_US
dc.subjectantimicrobial peptidesen_US
dc.subjectphylogenetic analysisen_US
dc.subjectnutrient allocationen_US
dc.subjectplant sciencesen_US
dc.titleAdaptive Expansion of the Maize Maternally Expressed Gene (Meg) Family involves Changes in Expression Patterns and Protein Secondary Structures of its Membersen_US

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