Many reference genes are used by different laboratories for gene expression analyses to indicate the relative amount of input RNA/DNA in the experiment. These reference genes are supposed to show least variation among the treatments and with the control sets in a given experiment. However, expression of reference genes varies significantly from one set of experiment to the other. Thus, selection of reference genes depends on the experimental conditions. Sometimes the average expression of two or three reference genes is taken as standard. This review consolidated the details of about 120 genes attempted for normalization during comparative expression analysis in 16 different plants. Plant species included in this review are Arabidopsis thaliana, cotton (Gossypium hirsutum), tobacco (Nicotiana benthamiana and N. tabacum), soybean (Glycine max), rice (Oryza sativa), blueberry (Vaccinium corymbosum), tomato (Solanum lycopersicum), wheat (Triticum aestivum), potato (Solanum tuberosum), sugar cane (Saccharum sp.), carrot (Daucus carota), coffee (Coffea arabica), cucumber (Cucumis sativus), kiwi (Actinidia deliciosa) and grape (Vitis vinifera). The list includes model and cultivated crop plants from both monocot and dicot classes. We have categorized plant-wise the reference genes that have been used for expression analyses in any or all of the four different conditions such as biotic stress, abiotic stress, developmental stages and various organs and tissues, reported till date. This review serves as a guide during the reference gene hunt for gene expression analysis studies.

The 42-kDa endochitinase (cht42) gene from the mycoparasitic fungus, Trichoderma virens, driven by CaMV 35S promoter, was introduced into rice by Agrobacterium-mediated transformation. Eight transgenic plants harboring single copies of complete T-DNA were identified by Southern blot analysis. Homozygous transgenic plants were identified for five lines in the T(1) generation by Southern blot analysis. Homozygous T(2) plants constitutively accumulated high levels of the cht42 transcript, showed 2.4- to 4.6-fold higher chitinase activity in total leaf extract and 1.6- to 1.8-fold higher chitinase activity in the extracellular fluid. Infection assays performed on the homozygous T(2) plants with Rhizoctonia solani showed up to 62% reduction in the sheath blight disease index.

Transgenic rice (Oryza sativa L. subsp. indica cv. White Ponni) constitutively expressing the rice thaumatin-like protein gene (tlp-D34, PR-5) individually or in combination with the rice chitinase gene (chi11, PR-3) was generated using an Agrobacterium vir helper strain with multiple copies of pTiBo542 virB and virG. Transformation with the tlp-D34 gene alone and tlp-D34 + chi11 genes yielded five and seven single-copy transgenic lines, respectively. Southern blot analysis with two probes, one flanking the right T-DNA border and the second flanking the left T-DNA border, confirmed that all transgenic plants harboured single and complete T-DNA copies. Homozygous transgenic lines were first identified in the T 1 generation by Southern blot analysis and were subsequently confirmed by segregation analysis of T 2 plants. Accumulation of transcripts encoded by the transgenes was confirmed in T 0 plants and homozygous T 2 plants by Northern blot analysis. The homozygous T 2 plants harbouring tlp-D34 + chi11 genes showed 2.8-to 4.2-fold higher chitinase activity. Western blot analysis revealed the accumulation of thaumatin-like protein and chitinase in the respective transgenic plants. Upon infection with Rhizoctonia solani, the disease index reduced from 100 % in control plants to 65 % in a T 3 homozygous transgenic line T4 expressing the tlp-D34 gene alone. In a T 2 homozygous transgenic line CT22 co-expressing tlp-D34 and chi11 genes, the disease index reduced to 39 %.

The skin is the main interface between the individual and the environment. It therefore has essential physiological functions which allow the individual to live safely, even under changing external conditions which might pose potential threats. The most important physiological function of the skin is protection against various forms of noxious stimuli including physical and chemical trauma, micro-organisms and radiation. The skin and its appendages such as hair are also vital for thermoregulation. Several modalities of sensation are mediated via the skin allowing the individual to recognize the context of their relationship to the environment. The skin is a significant water storage organ, particularly in the hypodermis layer. Although it mainly acts as a barrier, the skin does have some ability to absorb various substances, particularly lipophilic compounds. Emotions such as fright, anger or joy can be expressed via the skin, due to changes in blood supply, the position of hairs, or movements of those muscles which insert directly into the skin. Synthesis of vitamin D occurs in sunexposed skin and is the major site of production in normal health. It is important for surgeons to understand the functions of the skin in order to recognize when clinical problems occur and to appreciate how patients with disordered skin physiology are likely to respond to traumatic or surgical injury.

A male sterile transgenic rice plant TC-19 harboured a novel T-DNA integration in chromosome 8 with two interchromosomal translocations of 6.55 kb chromosome 3 and 29.8 kb chromosome 9 segments. We report a complex Agrobacterium T-DNA integration in rice (Oryza sativa) associated with two interchromosomal translocations. The T-DNA-tagged rice mutant TC-19, which harboured a single copy of the T-DNA, displayed male sterile phenotype in the homozygous condition. Analysis of the junctions between the T-DNA ends and the rice genome by genome walking showed that the right border is flanked by a chromosome 3 sequence and the left border is flanked by a chromosome 9 sequence. Upon further walking on chromosome 3, a chromosome 3/chromosome 8 fusion was detected. Genome walking from the opposite end of the chromosome 8 break point revealed a chromosome 8/chromosome 9 fusion. Our findings revealed that the T-DNA, together with a 6.55-kb region of chromosome 3 and a 29.8-kb region of chromosome 9, was translocated to chromosome 8. Southern blot analysis of the homozygous TC-19 mutant revealed that the native sequences of chromosome 3 and 9 were restored but the disruption of chromosome 8 in the first intron of the gene Os08g0152500 was not restored. The integration of the complex T-DNA in chromosome 8 caused male sterility.