Study On Relationship Between Drought Resistance And Deep Rooting Characteristics Of Different Wheat Cultivars,and Cloning And Expression Analysis On Resistance Gene TaSABP2 In Wheat(Triticum Aestivum L.)

The aim of the study is to clarify the relationship between drought resistance and physiological characteristics with different wheat cultivars,clone resistance gene TaSABP2 from wheat.Using Luohan 6,Luohan 8?two drought-resistant wheat cultivars?,Ai'kang 58,Xi'nong 979?two medium-drought-resistant wheat cultivars?and Zhengmai 366,Zhengmai 9023?two weak-drought-resistant wheat cultivars?as the experimental materials,the soil cylinder experiment,field cultivation experiment were conducted to study the relationship between root growth and drought resistance,grain yield and physiological characteristics of wheat cultivars under different water treatments.Clone the drought resistance-related wheat resistance gene TaSABP2,analysis its sequence and real-time quantitative expression detection using molecular biology techniques.The results show:?1?Under the condition of column planting,root depth of winter wheat reached the maximum at flag-leaf expansion stage,and root grew fastest from wintering stage to flag-leaf expansion stage.Difference in the maximum root depth among three wheat cultivars with different drought resistance was significant both at flag-leaf expansion stage and heading stage.The maximum root depth of a drought-resistant cultivar was deeper than that either of a medium or a weak-drought-resistant cultivar.Compared with a weak-drought-resistant cultivar,a drought-resistant cultivar had less total dry root weight per plant and less dry weight of deep-soil-layer roots,but had stronger root vigor.At grain-filling stage,the stronger drought resistance a wheat cultivar had,the stronger vigor of deep-soil-layer roots was.?2?Under the condition of field experiment,the yield reduction of drought-resistant wheat cultivars was lower,the drought resistance coefficient wasbigger,and the yield reduction of weak-drought-resistant wheat cultivars was higher yield and the drought resistance coefficient was smaller.The difference in the yield level between the treatments in the early drought period was mainly caused by the difference in the number of spikes.The difference in the yield level between the treatments in the late drought period was mainly caused by the difference of the grain weight.The value,change value?or change percentage?of the yield components,grain wet gluten content,plant height,tiller number per plant,number of secondary roots per plant in drought conditions were determined by the characteristics of the cultivars.They have no obvious correlation with the strength of drought resistance.At the same sampling time and water treatment,the drought-resistant cultivars had higher root vigor than those with weak drought resistance.?3?The full-length sequence of TaSABP2 consists of 878 bp with an intact open reading frame of 807 bp,encoding a polypeptide of 268 amino acids.The molecular weight of TaSABP2 was 29.6 k D,p I was 5.91,total number of atoms was4165 and the formula was C1338H2081N353O378S15.Homology analysis showed that the TaSABP2 nucleotide sequences and deduced amino acids were highly homologous to that of SABP2 gene in Brachypodium distachyon?XP₀03567195?.TaSABP2 contained two functional domains of Abhydrolase and PLN02211 and enzyme active site sequence?VVLVGHSLGG?,and it was one member of Abhydrolase superfamily.TaSABP2 was most likely to be located in the chloroplast and cytoplasm,without signal peptide and leader peptide.And it was non-trans membrane and soluble protein.Besides,TaSABP2 had twelve serine phosphorylation sites,five threonine phosphorylation sites and three tyrosine phosphorylation sites.Random coil was the maximum structural part in the protein secondary structure of TaSABP2,?-Heli,?-Turn extended and strand dispersed in whole protein,N-terminal region was presented mainly in the form of random coil,and C-terminal domain was existed in the form of extended strand.The multiple sequence alignment based on the deduced amino acid sequences of TaSABP2 and other PALs of 9 plants showed the functional region was conserved.Phylogenetic tree analysis indicated that TaSABP2 was very closely related to Salicylic acid binding protein 2 of Brachypodium distachyon.The main structural element in TaSABP2 protein tertiary structure was ?-Helix and random coil,less in ?-Turn and strand dispersed.Real-time PCR analysis revealed that the expression of TaSABP2 gene in different tissues was anther> pistil> ear> glume> root> leaf> stem;The expression of the gene increased rapidly under foliar spraying ABA,BR and drought,low temperature,salt stress treatment.In summary,a drought-resistant wheat cultivar may not necessarily have more dry weight of roots per plant and dry weight of deep-soil-layer roots,but surely have the deepest rooting depth and stronger vigor of roots,especially the root vigor during the late growing period,within different layer of soil.The value,change value?or change percentage?of the yield components,grain wet gluten content,plant height,tiller number per plant,number of secondary roots per plant in drought conditions were determined by the characteristics of the cultivars.They have no obvious correlation with the strength of drought resistance.The successful clonal wheat TaSABP2 gene had a certain effect on wheat resistance,and provided a theoretical basis for improving drought resistance of crops.