QTL Mapping Of Transpiration Related Traits In Rice Under Salt And Alkali Stress

Rice is the main food crops in the world,along with the population increasing and the continuous improvement of living standards,people demand for rice yield increase gradually,become people to focus on the problem of food supply.In recent years,due to the accelerated urbanization and environmental degradation,lead to the per capita arable land area is decreasing,the land salinization degree aggravate gradually.Therefore,how to excavating the main effect QTL of salt and alkaline tolerance,using salt-tolerant rice breeding,expanding the planting area of rice on saline area,is more and more important to improve rice production and ensure food safety.In this study,180 recombinant inbred line?RIL?population derived from a cross Dongnong425 and Changbai 10,and a genetic linkage map containing 102 SSR markers and 113 Indel markers was constructed.In 2016 and 2017,the water solution of NaCl with a concentration of 6ds·m^-1 and the Na₂CO₃ solution with pH=9.0 were treated in whole growth stage,and normal water irrigation was controlled.In rice heading stage of sword leaf transpiration rate?Tr?,stomatal conductance?Sc?,canopy temperature?Ct?,leaf length?Ll?,leaf width?Lw?,leaf area?Lar?and leaf curl?Lri?transpiration related traits are measured,and additive of target traits QTL mapping and epistatic and environment interaction analysis.The main results are as follows:1.Under the condition of salt and alkali stresses both parent and RIL population transpiration related traits affected by intimidation,transpiration rate,stomatal conductance,leaf length,leaf width and leaf area were reduced,canopy temperature and leaf curl.Under alkaline stress,the change range is greater than that of salt stress.Under the conditions of salt stress and natural ratio and alkali stress and natural ratio,the average two-year transpiration rate of RIL population respective are 0.86 and 0.80,The average values of stomatal conductance respective are 0.91 and0.91,The average leaf length respective are 0.77 and 0.73,The average leaf width respective are0.88 and 0.84,The average leaf area respective are 0.66 and 0.61,The average canopy temperature respective are 1.04 and 1.08,The average leaf curl respective are 1.13 and 3.76.2.Under two years of salt stress,thousand grain weight and panicle weight per plant were positively correlated with transpiration rate,leaf length and leaf area.Under two years of alkali stress,thousand grain weight was significantly or significantly positively correlated with transpiration rate and leaf area.There is significant or significant positive correlation between single ear weight and transpiration rate,leaf length and leaf area.The results showed that the transpiration characters influenced yield characters under the condition of salinity stress.Salinity and alkalinity stress conditions in the two years,with the exception of transpiration rate and leaf length,leaf area and leaf length has negative correlation significantly positively related to outside,the rest of the transpiration related traits under salt stress and various characters under alkali stress both showed no significant correlation,that rice transpiration characteristics on the resistance to salt and alkali resistance might exist different genetic mechanisms.3.QTL was performed with LOD=2.5 as the threshold by using the QTLIciMappingV4.0.A total of 93 additive QTLs were detected in two years,distributed on 12 chromosomes.Among them,qRLl2,qCt7,qTr6,qRSc8,qlar8-2,qct9-3,qRLw9 and qRLw12 have not been detected by predecessors.qCt7 in natural condition and at the same time under the condition of salt and alkali stresses has already been detected,repeat two years qTr8 under natural and salt stress conditions at the same time two years repeat are detected,qTr6 under salt stress and alkali stress at the same time two years repeat are detected,qLl9 is repeatedly detected under salt stress for two years,and qTr10 and qLl8 are simultaneously detected under alkali stress for two years.Among them,qLl9and qTr10 have a high contribution rate,with an average value of 21.16%and 19.37%respectively.4.Use of QTL Network2.1 software mixed linear model?MCIM?,P=0.05 for critical threshold,the RIL population for two years,a total of 6 environmental analysis of the additive and the environment interaction effect,24 additive QTL were detected,distribution in 1,3,4,5,6,7,8,9,10,and 12 chromosomes,including 19 QTL were also IciMapping V4.0 software detected.All the 24 additive QTLS has environmental interaction effects.qLl9 and qTr10 ICIM and MCIM two genetic model were detected at the same time,and the contribution rate is higher,qLl9 is to control the main effect of rice transpiration under salt stress related traits QTL,qTr10 is to control the main effect of rice transpiration related traits under alkali stress QTL.5.Using MCIM model to carry on the upper level and environmental interaction effect analysis of rice transpiration related traits,36 pairs of epistatic QTL has been detected,and 33 of them had interaction effects on QTL and environment.The epistemic and environmental interactions affect the genetic expression of the transpiration related QTL.6.Some control different traits QTL are positioned to the same interval,chromosome 3RM1324-RM517 range positioning to qTr3-2,qLl3,qLri3-2 and qRLri3,chromosome 5 Indel42-Indel46 range positioning to qTr5,qSc5 and qLri5-2,because the QTL there may be a pleiotropic or close chain phenomenon.7.Indel35-Indel37,RM1324-RM517 range at the same time the QTL detection to control salt stress and alkali stress,to show that the transpiration related traits under salt stress and alkali stress exists partial genetic overlap phenomenon,salt,alkali rice transpiration under the two stress related traits,the genetic mechanism of existing differences also exist.