Identification Of Elite Agronomic Traits And Tolerance To Drought Stress And Low Temperature In Seedling Stage Of Chromosome ARM Substitution Lines Of Triticum Dicoccoides In The Background Of Common Wheat

As one of the most important crops in China, wheat (Triticum aestivum) is essential for the national food security. In order to explore the elite gene resources in Triticum dicoccoides. two sets of chromosome arm substitution lines (CASL) of T. dicoccoides in the genetic background of two common wheat cultivars Bethlehem (BLH) and Chinese Spring (CS) were used for agronomic traits investigation and statistical analysis. Additionally, the tolerances to drought and low temperature stress were studied in different CASL. The main results are as follows:1. The characteristics of seed germination and seedling growth were investigated by the statistical analysis of germination rate, germination potential, and germination index, the seedling height, root length, root number and average root length. The results showed that the indexes of seed germination and seedling growth had large variation among different CASL in both backgrounds of BLH and CS. In both backgrounds, the germination rate, germination potential and germination index of CASL 5BS and 7BS were significantly higher than that of their parents, additionally, the seed germination indexes of CASL 5AS and 6AS were significantly lower than that of their parents, speculating that at least one effect QTLs controlling seed germination located on this CASL. The seedling height, taproot length and average root length of CASL 4BL and 6BL were significantly higher or longer than that of their parent;the taproot length and root number of CASL 2BS and 3AL were significantly longer and more than that of their parents; the taproot length and average root length of four CASL (5BS, 6AL, 2AS and 1AS)were significantly longer than those of their parents. The seedling height, root length and average root length of CASL 1BS were significantly lower than that of their parent; the average root length and root number of CASL 4AL were significantly shorter and less than the parents. All above results suggested that the genes related to seed germination and seedling growth might be distributed on chromosomes 1AS, 2AS, 3AL, 6AL, 2BS and 5BS in wheat.2. In the field test, several agronomic traits, such as grain morphology, spikelet number and effective tiller number, were found having significant difference in some CASL. Based on these results,chromosome arms 2AS and 1BL might have the QTLs related to grain length and width, the 6BS the QTLs of grain length, grain width and grain weight, the 7AS and 4AL the genes related to seed thickness and grain weight, the 5AL the gene regulating the pagoda-type spike, the 4AS, 4AL, 6BS and 6BL the genes inhibiting the awn growth,the 6AS and 5AL the genes regulating spike length,the 6BL,2BS, 1AS and 2AL the genes controling spikelet number, the 5AL, 2BL, 1AL and 1AS the genes related ·to effective tiller, and the 1AS, 3BS, 7AL and 3AS the genes regulating grain number per spike of wheat.3. The drought tolerance of CASL was identified during germination and seedling stage. CASL 7BS and 7AL with well developed root systems were considered as the drought resistant material,because the dry and fresh weight of over ground and underground biomass of these two CASLs were significantly greater than those of their parents in both backgrounds under drought stress. The CASL 3BL was the most drought-sensitive material in both backgrounds due to its worst drought tolerance.These results indicated that the genes related to drought existed in the chromosome arms 7BS, 7AL and 3BL.4. The seed germination and seedling growth of CASLs were investigated under growth of low temperature (4 ?). Compared with their parents, the CASL 4AL, IBS, 1AS, 7BS and 3BL had higher relative germination potential and relative germination, more overground and underground dry matter accumulation and higher resistance to low-temperature, while the CASL 5BL and 6BS had weak low-temperature resistance. These results indicated that 4AL, IBS, IAS, 7BS, 3BL,5BL and 6BS chromosome arms may involve the genes related to low-temperature resistance.This study will lay a foundation for exploring the elite genes related to seed germination and seedling growth in wild wheat and further studying the related genetic rules.