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Small heat shock proteins (sHSPs), the intra cellular chaperons respond to high temperatures and other stresses, are expressed under the control of the heat shock factors, which recognize highly conserved cis-regulatory elements (CREs). The present study was designed to identify and compare nine different sHSP gene promoters from rice on the basis of their location on chromosomes, sequence similarities, evolutionary relationship and putative binding sites of transcription factors. Additionally, they were analyzed for their functional importance in the regulation of sHSP genes. For this, 5′ upstream region of nine sHSP genes from Oryza sativa was amplified, sequenced and analyzed. RFLP mapping approach using molecular linkage maps of three-way cross-population showed that OsHSP 16.9A, OsHSP 16.9B, OsHSP 16.9C and OsHSP C-II genes were clustered on the short arm of chromosome 1 with a 1238-bp overlapped sequence between OsHSP 16.9A and OsHSP 16.9B, whereas OsHSP 17.3, OsHSP 17.7, OsHSP 17.9, OsHSP 18.0 and OsHSP 26 genes were clustered on chromosome 3 with a 420-bp overlapped sequence between OsHSP 17.3 and OsHSP 18.0. Evolutionary analysis revealed that sHSPs that clustered on different chromosomes in the same specie showed high sequence similarity and evolved prior to the divergence of their localization. Eighteen CREs remained conserved among all sHSP gene promoters during evolution. These common regulatory elements are related to disease resistance, hormonal responses, light responses, seed storage proteins, tissue-specific expression, pollen development and other environmental stresses. Moreover, CCAATBOX1 was also found in all sHSP gene promoters involved in the regulation of heat shock response. Conclusively, promoter region of sHSP genes seems to be capable of driving genes expression during stress and genetic manipulation might be helpful in producing better quality rice.

The most recent classification proposed by Harley et al. in 2004 recognized seven subfamilies within the family Lamiaceae (Symphorematoideae, Viticoideae, Ajugoideae, Prostantheroideae, Scutellarioideae, Lamioideae and Nepetoideae). Symphorematoideae (formerly as part of Verbenaceae) is recognized as a subfamily of Lamiaceae for the first. Recognition of Viticoideae is one of the major modifications introduced in Harley’s treatment but yet it is the least satisfactory circumscribed subfamily which appeared to be clearly non-monophyletic. Subsequent studies based on molecular analysis also reported the non-monophyly of Viticoideae. New combinations are proposed in later studies at the generic level in subfamily Ajugoideae and Prostantheroideae. Suprageneric relationships among the Lamioideae remained poorly understood providing no tribal ranks in the Harley’s classification. Therefore, new tribes have been erected in the recent investigations to reflect improved phylogenetic undersanding of the Lamioideae. Subtribal delimitation of Mentheae (Nepetoideae) according to recent studies is not congruent with the Harley’s and new subtribes are recommended to establish the monophyly of Mentheae. Although the clade structure is relatively well established in the Lamiaceae, but tribal compositions remain unclear and needs to be further investigated to transform their taxonomy into a more ‘natural’ classification.