Journal of Genetics and Genomics

Cytological analysis and genetic control of rice anther development

Dabing Zhang, Xue Luo, Lu Zhu

2011, 38(9): 379-390. doi: 10.1016/j.jgg.2011.08.001

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Abstract:
Microsporogenesis and male gametogenesis are essential for the alternating life cycle of flowering plants between diploid sporophyte and haploid gametophyte generations. Rice (Oryza sativa) is the world’s major staple food, and manipulation of pollen fertility is particularly important for the demands to increase rice grain yield. Towards a better understanding of the mechanisms controlling rice male reproductive development, we describe here the cytological changes of anther development through 14 stages, including cell division, differentiation and degeneration of somatic tissues consisting of four concentric cell layers surrounding and supporting reproductive cells as they form mature pollen grains through meiosis and mitosis. Furthermore, we compare the morphological difference of anthers and pollen grains in both monocot rice and eudicot Arabidopsis thaliana. Additionally, we describe the key genes identified to date critical for rice anther development and pollen formation.

Glutamine analogs promote cytoophidium assembly in human and Drosophila cells

Kangni Chen, Jing Zhang, Ömür Yilmaz Tastan, Zillah Anne Deussen, Mayte Yu-Yin Siswick, Ji-Long Liu

2011, 38(9): 391-402. doi: 10.1016/j.jgg.2011.08.004

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Abstract:
CTP synthase is compartmentalized within a subcellular structure, termed the cytoophidium, in a range of organisms including bacteria, yeast, fruit fly and rat. Here we show that CTP synthase is also compartmentalized into cytoophidia in human cells. Surprisingly, the occurrence of cytoophidia in human cells increases upon treatment with a glutamine analog 6-diazo-5-oxo-l-norleucine (DON), an inhibitor of glutamine-dependent enzymes including CTP synthase. Experiments in flies confirmed that DON globally promotes cytoophidium assembly. Clonal analysis via CTP synthase RNA interference in somatic cells indicates that CTP synthase expression level is critical for the formation of cytoophidia. Moreover, DON facilitates cytoophidium assembly even when CTP synthase level is low. A second glutamine analog azaserine also promotes cytoophidum formation. Our data demonstrate that glutamine analogs serve as useful tools in the study of cytoophidia.

Age- and gender-dependent obesity in individuals with 16p11.2 deletion

Yongguo Yu, Haitao Zhu, David T. Miller, James F. Gusella, Orah S. Platt, Bai-Lin Wu, Yiping Shen

2011, 38(9): 403-409. doi: 10.1016/j.jgg.2011.08.003

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Abstract:
Recurrent genomic imbalances at 16p11.2 are genetic risk factors of variable penetrance for developmental delay and autism. Recently, 16p11.2 (chr16:29.5 Mb–30.1 Mb) deletion has also been detected in individuals with early-onset severe obesity. The penetrance of 16p11.2 deletion as a genetic risk factor for obesity is unknown. We evaluated the growth and body mass characteristics of 28 individuals with 16p11.2 (chr16:29.5 Mb–30.1 Mb) deletion originally ascertained for their developmental disorders by reviewing their medical records. We found that nine individuals could be classified as obese and six as overweight. These individuals generally had early feeding and growth difficulties, and started to gain excessive weight around 5–6 years of age. Thirteen out of the 18 deletion carriers aged 5 years and older (72%) were overweight or obese, whereas only two of 10 deletion carriers (20%) younger than five were overweight or obese. Males exhibited more severe obesity than females. Thus, the obesity phenotype of 16p11.2 deletion carriers is of juvenile onset, exhibited an age- and gender-dependent penetrance. 16p11.2 deletion appears to predispose individuals to juvenile onset obesity and in this case are similar to the well-described Prader–Willi syndrome (PWS). Early detection of this deletion will provide opportunity to prevent obesity.

Characterization of a novel high-tillering dwarf 3 mutant in rice

Bosen Zhang, Feng Tian, Lubin Tan, Daoxin Xie, Chuanqing Sun

2011, 38(9): 411-418. doi: 10.1016/j.jgg.2011.08.002

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Abstract:
Tiller number and culm length are important components of plant architecture and determinate grain production in rice. A line SIL046, derived from an introgression lines population developed by an accession of common wild rice (Oryza rufipogon Griff.) and a high-yielding indica cultivar Guichao 2 (Oryza sativa L.), exhibits a higher tiller number and shorter culm length phenotype than the recipient parent Guichao 2 (GC2). Genetic analysis showed that the high-tillering dwarf phenotype was controlled by a novel single recessive gene, referred to as thehigh-tillering dwarf 3 (htd3), which located within the genetic distance of 13.4 cM between SSR makers RM7003 and RM277 on chromosome 12. By means of fine-mapping strategy, we mapped HTD3 gene within the genetic distance of 2.5 cM and the physical distance of 3100 kb in the centromere of chromosome 12. Further identification of HTD3 gene would provide a new opportunity to uncover the molecular mechanism of the development of culm and tiller, two important components of yields in rice.

DNA methylation changes detected by methylation-sensitive amplified polymorphism in two contrasting rice genotypes under salt stress

Wensheng Wang, Xiuqin Zhao, Yajiao Pan, Linghua Zhu, Binying Fu, Zhikang Li

2011, 38(9): 419-424. doi: 10.1016/j.jgg.2011.07.006

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Abstract:
DNA methylation, one of the most important epigenetic phenomena, plays a vital role in tuning gene expression during plant development as well as in response to environmental stimuli. In the present study, a methylation-sensitive amplified polymorphism (MSAP) analysis was performed to profile DNA methylation changes in two contrasting rice genotypes under salt stress. Consistent with visibly different phenotypes in response to salt stress, epigenetic markers classified as stable inter-cultivar DNA methylation differences were determined between salt-tolerant FL478 and salt-sensitive IR29. In addition, most tissue-specific DNA methylation loci were conserved, while many of the growth stage-dependent DNA methylation loci were dynamic between the two genotypes. Strikingly, salt stress induced a decrease in DNA methylation specifically in roots at the seedling stage that was more profound in IR29 than in the FL478. This result may indicate that demethylation of genes is an active epigenetic response to salt stress in roots at the seedling stage, and helps to further elucidate the implications of DNA methylation in crop growth and development.

GWAS 2011: Opportunities and challenges

Jian-Jun Liu, Xue-Jun Zhang

2011, 38(9): 425-427. doi: 10.1016/j.jgg.2011.09.001

Abstract (80) HTML PDF (1)

Abstract:

2011 Vol. 38, No. 9