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Germin-like proteins (GLPs) are involved in biotic and abiotic stress tolerance in different plant species. Rice ( Oryza sativa L.) genome contains about 40 GLP family member proteins in nine chromosomes. Although some of the rice GLP ( OsGLP ) promoters have been studied through in silico analysis as well as experimentally, studies regarding the distribution pattern of the biotic and abiotic stress associated transcription factor binding sites (TFbs) in the promoter regions of OsGLP genes have not been attempted thoroughly. Several transcription factors (TFs) namely NAC, WRKY, bHLH, bZIP, MYB and AP2/ERF act as major TFs concerned with biotic as well as abiotic stress responses across various plant species. In the present study the in silico analysis was carried out using the 1.5 kilobases (kb) promoter regions from 40 different OsGLP genes for the presence of NAC, WRKY, bHLH, bZIP, MYB and AP2/ERF TFbs in it. Among various OsGLP gene promoters, OsGLP8-11 was found to contain highest number of tested TFbs in the promoter region whereas the promoter region of OsGLP5-1 depicted least amount of TFbs. Phylogenetic study of promoter regions of different OsGLP genes revealed four different clades. Our analyses could reveal the evolutionary significance of different OsGLP gene promoters. It can be presumed from the present findings as well as previous reports that OsGLP gene duplications and subsequent variations in the TFbs in OsGLP gene promoter regions might be the consequences of neofunctionalization of OsGLP genes and their promoters for biotic and abiotic stress tolerance in rice.

Germin-like proteins (GLPs) are evolutionary conserved ubiquitous plant glycoproteins belonging to the cupin superfamily. A large number of GLP family members have been identified from different higher and lower plant species, and those have been classified into different subfamilies. Although three histidine residues (H) and one glutamate residue (E) in germin box B and C were conserved among all the GLP subfamily members, how the sequences of one subfamily member differ from the other is unclear. Progress in the field of genomics, transcriptomics, and proteomics has made it possible to understand the variation at gene level among different GLP members from diverse genera and also their biological significances. GLPs from different plant species were found to have various enzymatic properties including oxalate oxidase (OxO), superoxide dismutase (SOD), ADP glucose pyrophosphatase/phosphodiesterase (AGPPase), and polyphenol oxidase (PPO) activities. 'Omics' study demonstrated the expression as well as involvement of GLP family members in almost every part of higher plants as well as in lower plants. Additionally, GLPs from different species were reported to be involved in biotic as well as abiotic stresses and also in the growth and development. This review describes the present research status of GLPs from different plant species, their expressions, and functional significances. Sequence variation was detected among GLP subfamily members at the amino acid level, and based on the sequence variation and phylogenetic analyses, two new GLP subfamilies have been proposed in this review.

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