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sur le développement des zones arides et semi-arides

Titre : Association Panel Development and Dissection of Molecular Markers Related to Drought Resistance in Arachis Hypogaea L.

Auteur : 张秀荣；

Grade : Doctoral Dissertation 2017

Université : Shandong Agricultural University

Résumé
Peanut(Arachis hypogaea L.)is an important oil and cash crop that is grown worldwide.The producing regions are mainly distributed in arid and semi-arid areas,making drought stress the key limiting factor that affects peanut yield and quality.Drought resistance,affected by the micro effect of multiple genes and environmental effect,is a very complex quantitative trait,so it is of great value to improve the drought-resistant breeding efficiency by using marker-assisted selection(MAS)technology.An association mapping population was built from hundreds of peanut germplasm,and both phenotypic and genetic variation evaluation were performed in our study.Using the population as experimental materials,drought resistance and multiple drought-resistant traits were identified.Association analysis was performed to find drought related markers,and allelic phenotypic effects were also analyzed.A series of elite drought resistance alleles were excavated,and the drought tolerance mechanism of the selected excellent germplasm was preliminarily dissected.The main findings are as follows :(1)A total of 268 peanut lines were constructed for association analysis.The coefficient of variation of 20 agronomic,yield and quality-related traits were ranging from 4.36% to 49.94%,and all traits were normal distribution.The results from genetic estimation showed that the diversity level of irregular type was lower than that of others,and population structure analysis was consistent with genetic clustering,results of which were closely related to botanical types and geographical distribution.The average r2 value of syntenic marker pairs with significant LD(p<0.01)was 0.1453,suggesting that the population had a relatively higher genomic LD level.Model comparison showed familial relatedness had greater influence on association analysis in this panel,and Q+K model was most suitable for association analysis.(2)There were significant differences in drought resistance among individuals,and average DC and DI in the entire population were 0.76-1.33 and 0.28-1.59,respectively.The results showed that the coefficient of variation of 13 yield and drought-resistant traits were ranging from 8.38% to 50.97% under both watering ang stress conditions.Range of some traits were minished under drought stress,sucha as 100 PW,100SW,SP,while some were become wider,such as yield,PWP,PN500,MSH,etc.The drought-resistant traits were clustered into two categories : yield related traits,PWP,MPR,SP,PNP,100 PW and 100 SW,were positively correlated with drought resistance,while traits of PN500,MSH,LBL,TNB,NPB,and EBL were negatively correlated with drought resistance.(3)The 260 markers used for association analysis in the study were distributed onto 20 linkage groups,covering 75% of the whole genome,and amplified a total of 1270 polymorphic bands with an average of 4.885,ranging from 2 to 15 alleles per locus.The MAF varied from 0.194 to 0.989 with an average of 0.620.The mean value of GD was 0.488,ranging from 0.022 to 0.864.The PIC for all the markers ranged from 0.022 to 0.853 with an average of 0.424.(4)Using association analysis,8 molecular markers were significantly associated with DC and DI,among which markers AHGS1525 and AHGS1422 were repeatable with phenotypic variation explanation from 7.87 to 13.66%.There were 27 associated markers were detected only under stress,and phenotypic variation explanation of 11 markers were more than 5%.There were 27 markers were detected to be associated with drought-resistant traits under both conditions,and 19 markers were repeatable in three or more environments and 18 markers were identified with phenotypic variation explanation more than 5%.We also found 56 markers significantly associated with relative value of drought-resistant traits,among which 12 markers were repeatable.In total,42 important markers related to drought were obtained from our study,and they were found to be clustered and unevenly distributed on the peanut integrated genetic map,where the B06 linkage group had the most significant markers.(5)Based on allele variation analysis,14 positive and 18 negative alleles for drought resistance were identified from 11 specific markers detected only under stress,respectively.We identified 45 positive and 53 negative alleles for drought resistance from 27 stable markers associated with drought-resistant traits,respectively.Another 7 positive and 6 negative alleles for drought resistance were identified from markers associated with relative values.In total,113 drought related alleles were identified from our study,among which 52 were positive for drought resistance and 61 were negative.(6)Using Luhua11(DC=1.00,DI=1.20)as standard variety for strong drought resistance,47 excellent drought-resistant lines with high and stable yield were screened out according to DC and DI,including 31 important breeding parents and peanut varieties which were widely grown for production.Preliminary analysis showed that the excellent drought-resistant lines were mostly the carriers of alleles that had positive effect on yield and drought resistance.Conversely,the elite lines carried few alleles that had bad effects on yield and drought resistance.Alleles of different excellent peanut lines were aslo much different,indicating they may had variable response mechanism to drought stress.

Mots clés : peanut； germplasm resources； association mapping population； drought resistance； drought-resistant trait； molecular marker； SSR；

Présentation (CNKI)