Genome-wide analysis of WOX gene family in rice, sorghum, maize, Arabidopsis and poplar.

WUSCHEL-related homeobox (WOX) genes form a large gene family specifically expressed in plants. They are known to play important roles in regulating the development of plant tissues and organs by determining cell fate. Recent available whole genome sequences allow us to do more comprehensive phylogenetic analysis of the WOX genes in plants. In the present study, we identified 11 and 21 WOXs from sorghum (Sorghum bicolor) and maize (Zea mays), respectively. The 72 WOX genes from rice (Oryza sativa), sorghum, maize, Arabidopsis (Arabidopsis thaliana) and poplar (Populus trichocarpa) were grouped into three well supported clades with nine subgroups according to the amino acid sequences of their homodomains. Their phylogenetic relationship was also supported by the observation of the motifs outside the homodomain. We observed the variation of duplication events among the nine sub-groups between monocots and eudicots, for instance, more gene duplication events of WOXs within subgroup A for monocots, while, less for dicots in this subgroup. Furthermore, we observed the conserved intron/exon structural patterns of WOX genes in rice, sorghum and Arabidopsis. In addition, WUS (Wuschel)-box and EAR (the ERF-associated amphiphilic repression)-like motif were observed to be conserved among several WOX subgroups in these five plants. Comparative analysis of expression patterns of WOX genes in rice and Arabidopsis suggest that the WOX genes play conserved and various roles in plants. This work provides insights into the evolution of the WOX gene family and is useful for future research.

Zhang X ，Zong J ，Liu J ，Yin J ，Zhang D ... -  《-》

A genome-wide analysis of the ERF gene family in sorghum.

Yan HW ，Hong L ，Zhou YQ ，Jiang HY ，Zhu SW ，Fan J ，Cheng BJ ... -  《Genetics and Molecular Research》

Small auxin upregulated RNA (SAUR) gene family in maize: identification, evolution, and its phylogenetic comparison with Arabidopsis, rice, and sorghum.

Small auxin-up RNAs (SAURs) are the early auxin-responsive genes represented by a large multigene family in plants. Here, we identified 79 SAUR gene family members from maize (Zea mays subsp. mays) by a reiterative database search and manual annotation. Phylogenetic analysis indicated that the SAUR proteins from Arabidopsis, rice, sorghum, and maize had divided into 16 groups. These genes were non-randomly distributed across the maize chromosomes, and segmental duplication and tandem duplication contributed to the expansion of the maize SAUR gene family. Synteny analysis established orthology relationships and functional linkages between SAUR genes in maize and sorghum genomes. We also found that the auxin-responsive elements were conserved in the upstream sequences of maize SAUR members. Selection analyses identified some significant site-specific constraints acted on most SAUR paralogs. Expression profiles based on microarray data have provided insights into the possible functional divergence among members of the SAUR gene family. Quantitative real-time PCR analysis indicated that some of the 10 randomly selected ZmSAUR genes could be induced at least in maize shoot or root tissue tested. The results reveal a comprehensive overview of the maize SAUR gene family and may pave the way for deciphering their function during plant development.

Chen Y ，Hao X ，Cao J 《-》

Genome-wide analysis of the MADS-box gene family in Populus trichocarpa.

Populus trichocarpa (poplar) is distinguished from its herbaceous counterparts Arabidopsis and rice by its woody structure, perennial life cycle, and dioecious, two-whorled flowers. MADS-box genes are known to be involved in many important processes during plant development. Investigation of the poplar genome revealed 105 putative functional MADS-box genes and 12 pseudogenes. These numbers are comparable to those in Arabidopsis. However, poplar has 64 type II MADS-box genes, implying a higher birth rate when compared with Arabidopsis (64 vs.47). In addition to duplications for floral organ identity genes, TM3-like, StMADS11, ANR1 and Bs clades were significantly increased. As indicated by the phylogenetic analysis, there exist at least two MIKC* MADS-box genes in the poplar genome. In contrast, only 41 putative functional type I genes and 9 pseudogenes were found, suggesting that the poplar type I MADS-box genes have experienced a lower rate in both birth and death. Poplar MADS-box genes were distributed on all linkage groups (LGs), except LG XIX. Like other gene families, poplar MADS-box gene family has expanded through tandem gene duplication and segmental duplication events as demonstrated by two genomic regions where clustered MADS-box genes exhibited high similarities in the MADS-box domains. A survey of poplar EST sequences showed that MADS-box genes were expressed in wood and cambium tissues, which are specific to woody plants. The expression of common MADS-box gene in tree-specific tissues suggests that the novel function combinations of a set of genes similar to those in herbaceous plants may account for the development of woody characteristics in poplar.

Leseberg CH ，Li A ，Kang H ，Duvall M ，Mao L ... -  《GENE》

Genome-wide analysis of heat shock transcription factor families in rice and Arabidopsis.

The heat shock transcription factors (HSFs) are the major heat shock factors regulating the heat stress response. They participate in regulating the expression of heat shock proteins (HSPs), which are critical in the protection against stress damage and many other important biological processes. Study of the HSF gene family is important for understanding the mechanism by which plants respond to stress. The completed genome sequences of rice (Oryza sativa) and Arabidopsis (Arabidopsis thaliana) constitute a valuable resource for comparative genomic analysis, as they are representatives of the two major evolutionary lineages within the angiosperms: the monocotyledons and the dicotyledons. The identification of phylogenetic relationships among HSF proteins in these species is a fundamental step to unravel the functionality of new and yet uncharacterized genes belonging to this family. In this study, the full complement of HSF genes in rice and Arabidopsis has probably been identified through the genome-wide scan. Phylogenetic analyses resulted in the identification of three major clusters of orthologous genes that contain members belonging to both species, which must have been represented in their common ancestor before the taxonomic splitting of the angiosperms. Further analysis of the phylogenetic tree reveals a possible dicot specific gene group. We also identified nine pairs of paralogs, as evidence for studies on the evolution history of rice HSF family and rice genome evolution. Expression data analysis indicates that HSF proteins are widely expressed in plants. These results provide a solid base for future functional genomic studies of the HSF gene family in rice and Arabidopsis.

Guo J ，Wu J ，Ji Q ，Wang C ，Luo L ，Yuan Y ，Wang Y ，Wang J ... -  《Journal of Genetics and Genomics》