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SDG26(SET domain group26) is a gene encoding histone methytransferase. In the background of sdg26defective mutants, plants shows phenotypes of increased number of rossete leaves, thicker leaf lamina, robust bolt, more branching, delayed flowering and expansion of growth period. This study investigate the cellular characteristics in sdg26and analyze the sequence upstream of SDG26gene initiation codon in bioformatics. Furthermore, The content level of SOD, MDA, soluble carbohydrate and proline been investigated in sdg26upon drought or salinity stress and studied the development of root system, elucidating the changes physical and chemical parameters and resistance upon drought and salinity. The results are listed followingly,1At the beginning, the study obtained homozygous sdg26mutant by T-DNA insertion, followed by observing phenotypes and tissue dissection. Compared to Col ecotype, the mutant shows robustness, more lateral branching and higher fertility.In the paraffin dissection of shoot, we found a increase of vascular bundle in sdg26. It suggest that the thickeness of shoot may be caused by the increase of cell number.2Via investigating the sequence upstream of SDG26gene initiation codon in bioformatics, we found that there are numerous adversity-responding cis-elements in the promoter, including8WRKY710S,16ARR1AT,7NODCON2GM and27DOFCOREZM. It suggests SDG26may respond to stress closely.3In the drought stress assessment, SOD activity, MDA, soluble carbohydrate and proline level showed obvious increase in sdg26with the drought continuation(3,6,9,12,15d), furthermore, the global level of these parameters is evidently higher than that in Col control. After20days drought, Col died of dehydration while sdg26showed normal growth and enhanced resistance to drought stress.4Upon a variety of concentration of salt stress (0,50,100,150,200mmol/L NaCl), the GR of sdg26is98%,58%,17%,7%and1%respectively while GR of Col is98%,32%,7%,0.5%and0. The sdg26shows pleiotropicly higher GR than Col upon salinity stress. At the same time, SOD activity, MDA, soluble carbohydrate and proline level showed full-scale increase in sdg26compared to Col, indicating resistance in sdg26is enhanced compared to Col under salt stress.5The development of root system is one of the markers in plant resistance. At5days post exposure100mmol/L NaCl stress. Col showed retained development of root system and shorter main root fewer lateral roots than normal. And the root length reached a plateau at6to8mm, in the contrast, sdg26remained normal growth and continuous elongation of roots and more lateral roots. That indicates resistance to high salinity in sdg26is enhanced compared to Col.
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