Identification of genes for drought resistance and prediction of gene candidates in soybean seedlings based on linkage and association mapping

Drought is one of the primary abiotic stress factors affecting the yield,growth,and development of soybeans.In extreme cases,drought can reduce yield by more than 50%.The seedling stage is an important determinant of soybean growth:the number and vigor of seedlings will affect growth and yield at harvest.Therefore,it is important to study the drought resistance of soybean seedlings.In this study,a recombinant inbred line(RIL)population comprising 234 F_(6:10)lines(derived from Zhonghuang35×Jindou 21)and a panel of 259 soybean accessions was subjected to drought conditions to identify the effects on phenotypic traits under these conditions.Using a genetic map constructed by single nucleotide polymorphism(SNPs)markers,18 quantitative trait loci(QTL)on 7 soybean chromosomes were identified in two environments.This included 9 QTL clusters identified in the RIL population.Fifty-three QTL were identified in 19 soybean chromosomes by genome-wide association analysis(GWAS)in the panel of accessions,including 69 significant SNPs(-log_(10)(P)≥3.97).A combination of the two populations revealed that two SNPs(-log_(10)(P)≥3.0)fell within two of the QTL(qPH7-4 and qPH7-6)confidence intervals.We not only re-located several previously reported drought-resistance genes in soybean and other crops but also identified several non-synonymous stress-related mutation site differences between the two parents,involving Glyma.07 g093000,Glyma.07 g093200,Glyma.07 g094100 and Glyma.07 g094200.One previously unreported new gene related to drought stress,Glyma.07 g094200,was found by regional association analysis.The significant SNP CHR7-17619(G/T)was within an exon of the Glyma.07 g094200 gene.In the RIL population,the DSP value of the"T"allele of CHR7-17619 was significantly(P<0.05)larger than the"G"allele in different environments.The results of our study lay the groundwork for cloning and molecular marker-assisted selection of droughtresistance genes in soybeans at the seedling stage.

QTL mapping of drought tolerance traits in soybean with SLAF sequencing

Drought stress is an important factor affecting soybean yield.Improving drought tolerance of soybean varieties can increase yield and yield stability when the stress occurs.Identifying QTL related to drought tolerance using molecular marker-assisted selection is able to facilitate the development of drought-tolerant soybean varieties.In this study,we used a high-yielding and drought-sensitive cultivar‘Zhonghuang 35’and a drought-tolerant cultivar‘Jindou 21’to establish F6:9 recombinant inbred lines.We constructed a highdensity genetic map using specific locus amplified fragment sequencing(SLAF-Seq)technology.The genetic map contained 8078 SLAF markers distributing across 20 soybean chromosomes with a total genetic distance of 3780.98 c M and an average genetic distance of0.59 c M between adjacent markers.Two treatments(irrigation and drought)were used in the field tests,the Additive-Inclusive Composite Interval Mapping(ICIM-ADD)was used to call QTL,and plant height and seed weight per plant were used as the indicators of drought tolerance.We identified a total of 23 QTL related to drought tolerance.Among them,seven QTL(q PH2,q PH6,q PH7,q PH17,q PH19-1,q PH19-2,and q PH19-3)on chromosomes 2,6,7,17,and 19 were related to plant height,and five QTL(q SWPP2,q SWPP6,q SWPP13,q SWPP17,and q SWPP19)on chromosomes 2,6,13,17,and 19 were related to seed weight and could be considered as the major QTL.In addition,three common QTL(q PH6/q SWPP6,q PH17/q SWPP17,and q PH19-3/q SWPP19)for both plant height and seed weight per plant were located in the same genomic regions on the same chromosomes.Three(q PH2,q PH17,and q PH19-2)and four novel QTL(q SWPP2,q SWPP13,q SWPP17,and q SWPP19)were identified for plant height and seed weight per plant,respectively.Two pairs of QTL(q PH2/q SWPP2 and q PH17/q SWPP17)were also common for both plant height and seed weight per plant.These QTL and closely linked SLAF markers could be used to accelerate breeding for drought tolerant cultivars via MAS.

Change of retinal nerve fiber layer thickness in patients with nonarteritic inflammatory anterior ischemic optic neuropathy

In this study, 16 patients （19 eyes） with nonarteritic anterior ischemic optic neuropathy in the acute stage （within 4 weeks） and resolving stage （after 12 weeks） were diagnosed by a series of complete ophthalmic examinations, including fundus examination, optical coherence tomography and fluorescein fundus angiography, and visual field defects were measured with standard automated perimetry. The contralateral uninvolved eyes were used as controls. The retinal nerve fiber layer thickness was determined by optical coherence tomography which showed that the mean retinal nerve fiber layer thickness and the retinal nerve fiber layer thickness from temporal, superior, nasal and inferior quadrants were significantly higher for all measurements in the acute stage than the corresponding normal values. In comparison, the retinal nerve fiber layer thickness from each optic disc quadrant was found to be significantly lower when measured at the resolving stages, than in the control group. Statistical analysis on the correlation between optic disc nerve fiber layer thickness and visual defects demonstrated a positive correlation in the acute stage and a negative correlation in the resolving stage. Our experimental findings indicate that optical coherence tomography is a useful diagnostic method for nonarteritic anterior ischemic optic neuropathy and can be used to evaluate the effect of treatment.

The Introduction of Specific Water and Maximum Airborne Specific Water &the Improvement of Dynamic Equations on Non-Uniform Saturated Moist Atmosphere

To eliminate the irrational supposition that condensed liquid water always falls immediately, specific water m?and maximum airborne specific water mm are introduced into the dynamic framework on non-uniform saturated moist atmosphere (m?is the ratio of the airborne liquid water mass to the moist air mass in unit cubage moist air, mm is its maximum value with , , and are airborne coefficient, vertical velocity and saturated specific humidity respectively). The balance equation between water vapor and airborne liquid water is derived. From the balance equation, a new formula of precipitate rate is got. The analysis shows that in the air stream with some upward vertical velocity ( ), the condensed liquid water can precipitate under the condition with (q is specific humidity) and? only, otherwise it is detained in the air and becomes airborne liquid water. Not only does precipitating liquid water contain condensed liquid water, but also contains converged and existing airborne liquid water. Following above discussion, improved dynamic equations on non-uniform saturated moist atmosphere are provided.