水稻Wxmp背景下SSⅡa和SSⅢa等位变异及其互作对蒸煮食味品质的影响

为了明确Wxmp基因背景下不同半糯粳稻品质差异的原因,以淀粉合成酶基因SSⅡa和SSⅢa表现多态性而其他淀粉合成相关基因无多态性的武粳13和关东194 (Milky Princess)杂交后代衍生的64个半糯品系为材料,分析了Wxmp基因背景下, SSⅡa和SSⅢa基因等位变异对直链淀粉含量(amylose content, AC)、胶稠度(gel consistency, GC)、糊化温度(gelatinization temperature,GT)及RVA谱特征值的影响。结果表明,SSⅡa和SSⅢa等位变异对AC、GC、GT和RVA谱特征值都有显著影响,且2个基因间存在互作效应。SSⅡa2和SSⅢa2 (2表示该基因来源于非半糯亲本武粳13)有使AC增高的趋势,分别使AC提高1.87%和1.23%, 2年结果基本接近。单个SSⅡa和SSⅢa等位变异对GT无显著影响,而基因型SSⅡa1SSⅢa1(1表示该基因来源于半糯亲本关东194)的GT比SSⅡa2SSⅢa2高1.34℃,达显著水平,表明2个基因的互作对GT有显著影响。GC在不同基因型间均存在极显著差异, SSⅡa2和SSⅢa1可分别使GC增加8.74mm和9.62mm。从2个基因的互作效应来看,基因型SSⅡa2SSⅢa1的GC比基因型SSⅡa1SSⅢa2和SSⅡa2SSⅢa2分别增加10.64 mm和16.95 mm。SSⅡa2使最高黏度、热浆黏度、冷胶黏度、崩解值增加,回复值和消减值下降;而SSⅢa2的效应则相反。2个基因的互作效应,最高黏度、热浆黏度和冷胶黏度均以SSⅡa2SSⅢa1最大,崩解值和回复值均以SSⅡa2SSⅢa2最大,消减值SSⅡa2SSⅢa1最小。本研究结果为半糯粳稻蒸煮食味品质的改良提供了一定的理论依据。

Wx^mp基因背景下可溶性淀粉合成酶基因SSⅡa和去分支酶基因PUL对水稻蒸煮食味品质的影响

【目的】分析在同一主效基因(Wx^mp)背景下可溶性淀粉合成酶基因SSⅡa和去分支酶基因PUL对稻米蒸煮食味品质的影响,以期为水稻品质遗传改良提供依据。【方法】选择在SSⅡa和PUL存在多态性而其他淀粉合成酶相关基因没有多态性的半糯品系宁0145和粳稻品种武运粳21进行杂交,获得F2群体与F3株系。利用分子标记,选择含有Wx^mp基因的F2单株与F3株系,将这些F2单株与F3株系分成SSⅡa^nPUL^n、SSⅡa^nPUL^w、SSⅡa^wPUL^n和SSⅡa^wPUL^w4种基因型(n和w分别表示该基因来源于宁0145和武运粳21),分析不同基因型蒸煮食味品质性状的差异,探讨同一Wxmp基因背景下不同SSⅡa和PUL等位基因对蒸煮食味品质性状的影响。【结果】不同基因型间蒸煮食味品质性状均存在显著差异,来源于武运粳21的SSⅡa^w基因和PUL^w基因分别使直链淀粉含量增加0.29%~1.00%和0.62%~1.18%,且PUL的效应大于SSⅡa,两者间存在互作效应。SSⅡa^w基因和PUL^w基因降低胶稠度和崩解值,提高了热浆黏度、冷胶黏度、消减值和回复值,对糊化温度、峰值黏度和峰值时间的作用较小。【结论】明确了Wx^mp背景下SSⅡa和PUL基因对稻米蒸煮食味品质的遗传效应,该研究结果为SSⅡa和PUL基因的分子标记辅助选择改良稻米品质提供了理论依据。

Impacts of heavy metals on 1,2-dichloroethane biodegradation in co-contaminated soil

1,2-Dichloroethane (DCA), a potential mutagen and carcinogen, is commonly introduced into the environment through its industrial and agricultural use. In this study, the impact of lead and mercury on DCA degradation in soil was investigated, owing to the complex co-contamination problem frequently encountered in most sites. 1,2-Dichloroethane was degraded readily in both contaminated loam and clay soils with the degradation rate constants ranging between 0.370-0.536 week1 and 0.309-0.417 week1, respectively. The presence of heavy metals have a negative impact on DCA degradation in both soil types, resulting in up to 24.11% reduction in DCA degradation within one week. Both biostimulation and treatment additives increased DCA degradation, with the best degradation observed upon addition of glucose and a combination of diphosphate salt and sodium chloride, leading to about 17.91% and 43.50% increase in DCA degradation, respectively. The results have promising potential for effective remediation of soils co-contaminated with chlorinated organics and heavy metals. However, the best bioremediation strategy will depend on the soil types, microbial population present in the soil matrices, nutrients availability and metal forms.

Aerobic dechlorination of cis- and trans-dichloroethenes by some indigenous bacteria isolated from contaminated sites in Africa

The innate toxicity of dichloroethenes(DCEs) and their tendency to be reduced to vinyl chloride(VC)(a known human carcinogen) is a cause for environmental concern. Aerobic bacteria capable of growth on cis- and trans-DCEs as sole carbon and energy sources were isolated by enrichment culture technique and identified to belong to the genera; Bacillus, Pseudomonas and Acinetobacter. Axenic and mixed cultures of the bacterial isolates utilized DCEs at concentrations above the maximum contaminant level allowable in drinking water by the Environmental Protection Agency. Their specific growth rate constant ranged significantly(P<0.05) between 0.346—0.552 and 0.461—0.667 d -1; while the maximum specific substrate utilization rate ranged significantly(P<0.05) between 20.01—29.79 and 31.40—42.83 nmol h -1 (mg of protein) -1 in cis- and trans-DCE, respectively. The optimum growth was observed at 30℃ and at a pH of 7.0 with up to 96% of the stoichiometric-expected chloride released. Serial adaptation positively affected the growth yields and dehalogenase activities of the organisms with multiple antibiotic patterns also demonstrated by the isolates. These findings therefore indicated the important roles that these organisms may play in the bioremediation of sites polluted with chlorinated ethene compounds in Africa.

Effects of soluble starch synthase genes on eating and cooking quality in semi waxy japonica rice with Wx^(mp)

The purpose of this study is to reveal the genetic mechanism of the variation of amylose content among different semi waxy or glutinous japonica rice in the background of Wxmp gene.Sixty-four semi waxy lines derived from the hybrid progenies of Wujing 13 and Milky Princess(Kantou 194)with polymorphism in soluble starch synthase gene SSIIa(SSII-3)and SSIIIa(SSIII-2)but no polymorphism in other starch synthase related genes were used as test materials.The genotypes of SSIIa and SSIIIa allele were identified by molecular markers,and the allelic effects of SSIIa and SSIIIa gene on amylose content(AC),gel consistency(GC),gelatinization temperature(GT)and rapid visco analyzer(RVA)profile characteristics were analyzed.The significant effects of SSIIa and SSIIIa alleles and the interactive effects between two genes on AC,GT,GC and RVA profile characteristics were found.The SSIIa and SSIIIa alleles from Wujing13 shown positive effects on AC with an average increase of 1.87 and 1.23%in 2 years respectively.There was no significant effect on GT for SSIIa or SSIIIa allele but remarkable influence on GT when the co-existence of the two genes.The genotype SSIIa^(mp)SSIIIa^(mp) shown 1.34℃higher GT than genotype SSIIawjSSIIIawj(mp and wj indicated that the gene was derived from Milky Princess and Wujing 13 respectively,the same as in the below).Different genes and alleles resulted in significant different GC.The genetic effect of SSIIawj and SSIIIamp on GC was 8.74 and 9.62mm respectively.The GC of SSIIa^(wj)SSIIIa^(mp) was 10.64 and 16.95mm higher than that of SSIIa^(mp)SSIIIa^(wj) and SSIIawjSSIIIawj,respectively.The allele SSIIa^(wj) could increase the peak viscosity(PKV),hot paste viscosity(HPV),cool paste viscosity(CPV)and breakdown viscosity(BDV),while decrease the consistency viscosity(CSV)and setback viscosity(SBV).However for the allele SSIIIa^(wj) the opposite was true.The genotype SSIIa^(wj)SSIIIa^(mp) had the largest PKV,HPV and CPV,the genotype SSIIa^(wj)SSIIIa^(wj) had the largest BDV and CSV,but the genotype SSIIa^(wj)SSIIIa^(mp) had the least SBV.According to the comprehensive effect of each trait,the genotype SSIIawjSSIIIamp was the best.The allelic variation and interaction effect of SSIIa and SSIIIa genes have important reference value for improving cooking and eating quality of semi waxy japonica rice.