Cytogenetic evidence for the origin of teosinte (Zea mays ssp. Mexicana)

Summary Cytogenetic evidence has shown that teosinte (Zea mays ssp. mexicana (Schrad.) Iltes) and maize (Zea mays L. ssp. mays) are conspecific. They hybridize readily and their offspring are generally fertile. Teosinte could not have originated as a byproduct of maize-Tripsacum hybridization. Such introgression gave rise to plants that are phenotypically maize or Tripsacum, depending on which parent was used as a pollen donor. Compartive morphological and genetical studies indicated that it is more probable that maize originated from a teosinte-like ancestor under domestication, than that a maize-like plant gave rise to teosinte through a series of mutations.Reseach supported financially by the Illinois Agricultural Experiment Station, and Grants GB-40136-X and BM573-01034 A02 from the National Science Foundation.     

Identification of QTL controlling adventitious root formation during flooding conditions in teosinte (Zea mays ssp. huehuetenangensis) seedlings

Adventitious root formation (ARF) at the soil surface is one of the most important adaptations to soil flooding or waterlogging. Quantitative trait loci (QTL) controlling ARF under flooding condition were identified in a 94 F₂ individual population by crossing maize (Zea mays L., B64) × teosinte (Z. mays ssp. huehuetenangensis). A base-map was constructed using 66 SSR and 42 AFLP markers, covering 1,378 cM throughout all ten maize chromosomes. The ARF capacity for seedlings was determined by evaluating the degree of root formation at the soil surface following flooding for 2 weeks. ARF showed continuous variation in the F₂ population. Interval mapping and composite interval mapping analyses revealed that the QTL for ARF was located on chromosome 8 (bin 8.05). Utilising a selective genotyping strategy with an additional 186 F₂ population derived from the same cross combination and 32 AFLP primer combinations, regions on chromosomes 4 (bin 4.07) and 8 (bin 8.03) were found to be associated with ARF. Z. mays ssp. huehuetenangensis contributed all of the QTL detected in this study. Results of the study suggest a potential for transferring waterlogging tolerance to maize from Z. mays ssp. huehuetenangensis.     

Evaluation of the contribution of teosinte to the improvement of agronomic,grain quality and yield traits in maize (Zea mays)

Teosinte, an ancestor to modern maize, displays an excellent performance regarding resistance to stress, but its yield potential has rarely been reported. To evaluate the potential contribution of teosinte to maize improvement, two maize–teosinte backcrossed recombination inbred line (RIL) populations and their corresponding test-cross hybrids were planted for trait assessment. In RN and ZP RIL populations, the average coefficients of variation of 31 agronomic traits were 9.14% (Range, 0.38%‒25.21%) and 6.85% (Range, 0.55%‒27.73%), respectively. The correlation coefficients of 13 common shared traits between RIL populations and test-cross hybrid populations ranged from 0.10 to 0.60 and from 0.06 to 0.72, respectively. A total of 39 and 3 recombined inbred lines, and 29 and 47 test-cross hybrids exhibited higher yields than their checks (RP125, Zheng58, CD189 and ZD958) with the BLUP data, respectively. Furthermore, four test-cross hybrids including RN034/SCML1950, ZP068/Chang7-2, ZP079/Chang7-2 and ZP122/Chang7-2 showed a more stable yield performance, with yield gains of +7.07%, +3.64%, +5.83% and +3.82% over checks, respectively. In conclusion, teosinte could serve as an alien germplasm for maize breeding.     

短日照对墨西哥大刍草生长发育的影响

通过不同短日照处理玉米近缘种墨西哥大刍草,研究短日照对其生长发育的影响,结果表明:短日照处理可以诱导墨西哥大刍草提前抽雄开花;墨西哥大刍草接受短日感应的临界叶龄、日照长度、短日诱导天数分别为6叶龄、13h、15d;对墨西哥大刍草进行短日诱导(日照长度为12h),以处理25d主茎雄花分枝数最多和分枝最长,因此,以饲草玉米种子生产为目的,对墨西哥大刍草进行短日诱导,应从6叶龄开始进行25d以上每天12h的连续短日照处理最为有效。     

玉米（Zea mays L.）×大刍草（Zea diploperennis L.）远缘杂交选育玉米自交系的研究

为了丰富玉米遗传变异,从1990年起,我们进行了玉米(Zea mays L.)和多年生二倍体大刍草(Zea diploperennis L.)远缘杂交的研究。经过5年8个世代的杂交、回交和自交选择,目前已获得抗逆性、抗病虫能力较强,农艺性状优良的玉米自交系14个。在测配1000个杂交组合中,所选系表现出较高的一般配合力和特殊配合力。实践证明,这是一条导入外缘种质、拓宽玉米遗传基础,进一步提高杂交种增产潜力的途径之一。     

盐碱胁迫对野生地肤种子发芽和幼苗生长的影响

将中性盐NaCl、Na2SO4和NaHCO3、Na2CO3两种碱性盐按不同比例混合,模拟出30种与天然盐碱土壤相似的条件,进行野生地肤种子发芽试验和幼苗生长情况检测等7项指标,结果表明:在混合盐碱胁迫作用下,地肤种子发芽受到明显抑制,发芽率、发芽势、发芽指数等指标呈下降趋势,并随盐碱度递增,下降程度逐渐增大,高盐高碱效应较单独高盐或高碱作用大;幼苗存活率和相对含水量在不同处理组间均呈下降趋势,而MDA和可溶性糖含量则随着盐碱度的升高逐渐上升,其中可溶性糖含量在低盐浓度(50、100 mmol/L)或低pH条件下,增加幅度小于高盐浓度(200、250 mmol/L)或高pH,两者具有明显的协同作用。     

药西瓜在新疆昌吉地区引种表现及栽培技术

药西瓜自2005年在昌吉州地区引种栽培以来,于2009年在昌吉州玛纳斯县引种成功,并由多年生性状驯化为一年生,其药材性状符合<中华人民共和国卫生部药品标准一维吾尔药分册>中药西瓜标准(WS3-BW-0068-98).同时,该品种产量较高,一般水肥条件可产干药材86 kg/667 m2,同时,本品种还具有病虫害少,管理粗放的特点.     

不同暗处理对墨西哥玉米开花习性、产量及品质的影响

试验结果表明暗处理可以诱导墨西哥玉米在本地开花。在不同光照时间条件下，墨西哥玉米的单株产量有极显著差异，粗蛋白含量有显著差异，但暗处理对粗脂肪含量无显著影响。墨西哥玉米在暗处理30d前提下，以每天光照9h最为适宜，在此条件下墨西哥玉米既可以在本地开花散粉，且产量和品质没有显著影响。     

安吉白茶阶段性白化过程中光合特性的变化

为阐明安吉白茶阶段性白化过程中光合特性的变化,本研究以特殊茶树资源安吉白茶为材料,研究其阶段性白化过程中叶绿体超微结构、光合作用、光合色素和生化成分的变化。结果表明,安吉白茶白化阶段叶绿体发育受阻,已发育的叶绿体超微结构被破坏,复绿阶段则逐渐恢复正常;净光合速率、气孔导度和蒸腾作用在阶段性白化过程中整体呈上升趋势,而在白化期显著下降;胞间CO2浓度在阶段性白化过程中整体呈下降趋势,而在白化期有所升高;光合色素和茶多酚含量在阶段性白化过程中整体逐渐上升,而在白化期显著降低;总氨基酸和茶氨酸含量在阶段性白化过程中整体逐渐下降,而在白化期显著升高。为安吉白茶叶色突变和高氨基酸含量形成机制研究提供了一定的理论基础。     

夏玉米铜的吸收与器官间的分配研究

以两种不同株型夏玉米品种为材料，就不同生育时期玉米植株对铜的吸收、积累及其在不同器官之间的分配情况进行了研究。结果表明，玉米植株铜的含量在苗期较高，随生长发育的进程而逐渐降低；穗期吸收量最大，子粒灌浆期间对铜的吸收量也较多，两品种吸收铜的差异主要在花粒期，紧凑型品种在乳熟期吸收量较大，而平展型品种在子粒形成期吸收量较大。成熟期不同器官铜的积累量依次为叶片、子粒、茎秆（雌穗）、叶鞘（苞叶）、雄穗、穗柄、花丝。两品种间单株吸铜量差异不明显，单位面积吸收量的差异主要是由于密度造成的。     

转Bar基因玉米基因漂移的研究

转基因植物发生基因漂移可能引起的生态环境安全性问题已经引起广泛关注,本试验采用转Bar基因抗除草剂玉米为试材,进行了外源基因遗传漂移距离和频率的研究。结果表明,转基因玉米的漂移率与距离成正相关,最大漂移频率为37.78％,隔离距离以150 m以上为好。     

Effect of intercropping on rhizosphere population in maize (Zea mays L.) and soybean (Glycine max Merill)

Comparative studies on the rhizosphere and non-rhizosphere bacterial and fungal populations of maize and soybean both under solecropping and intercropping were conducted. Intercropping increased the bacterial R : S ratio of maize and soybean, whereas fungal R : S ratio showed a decrease in both cases when compared to solecrop condition. Intercropping of maize with soybean increased the maize yield by 34% and decreased the soybean yield by 51% when compared with their respective yields under solecrop conditions. The dominant fungal species in the rhizosphere and non-rhizosphere soils were also affected by plant species and cropping systems.     

Zinc biofortification of maize (Zea mays L.): Status and challenges

Zn deficiency is one of the leading health problems in children and women of developing countries. Different interventions could be used to overcome malnutrition, but biofortification is most impactful, convenient, sustainable and acceptable intervention. Maize is one of the major crops grown and consumed in the regions with prevalent Zn malnutrition; therefore, this is suitable target for Zn biofortification. Zn biofortification of maize could be achieved through agronomic and genetic approaches. Discussion of agronomic approaches with genetic approaches is prerequisite because soils in developing countries are deficit of Zn and availability of Zn in soils is mandatory for estimating the genetic responses of maize genotypes through genetic approaches. Seed priming, foliar and soil applications are agronomic tools for biofortification, but solo and combined applications of these treatments have different effects on Zn enrichment. Genetic approaches include the increase of Zn bioavailability or increase of kernel Zn concentration. Zn bioavailability could be increased by reducing the anti‐nutritional factors or by increasing the bioavailability enhancers. Kernel Zn concentration could be improved through hybridization and selections, whereas genetically engineered attempts for improving Zn uptake from soil, loading in xylem, remobilization in grains and sequestration in endosperm can further improve the kernel Zn concentration. Key challenges associated with dissemination of Zn biofortified maize are also under discussion in this draft. Current review emphasized all of above‐mentioned contents to provide roadmap for the development of Zn biofortified maize genotypes to curb the global Zn malnutrition.     

不同处理对NaCl胁迫下野生地肤萌发的缓解效应

以赤霉素、水杨酸及吸湿-回干法分别对野生地肤种子进行盐胁迫缓解效应的研究。结果表明:300 mmol/L(350 mmol/L)NaCl胁迫下,200 mg/L(250 mg/L)赤霉素对野生地肤盐胁迫伤害有明显的缓解效应;5 mmol/L水杨酸对野生地肤盐胁迫伤害缓解效果最佳;300 mmol/L(350 mmol/L)NaCl胁迫下吸湿-回干法处理可以明显改善种子的萌发能力。3种不同处理方法中,以赤霉素处理效果最好,其次是水杨酸。再次为吸湿-回干法。     

Bar基因的玉米花粉管通道法转化

通过花粉管通道法利用抗除草剂基因（bar）转化3个玉米自交系,D0代获得35株GUS阳性植株．其中17株PCR阳性植株,除草剂筛选获得抗性植株13株。研究发现DNA溶液浓度影响转化率,当浓度为100μg／ml时,转化率最高,为2．61％。DNA导入时间距人工授粉时间的延长,结实率升高,但转化率显著下降,人工授粉后1d导入DNA产生的转化株最多,为19株,平均转化率为1．35％。     

Assessment of genetic diversity of tea (Camellia sinensis (L.) O. Kuntze) by inter-simple sequence repeat polymerase chain reaction

Twenty-five diverse tea (Camellia sinensis(L.) O. Kuntze) cultivars were analyzed using the simple sequence repeat anchored polymorearse chain reaction (SSR-anchored PCR) or Inter SSR-PCR (ISSR). Out of the 45 primers 12were chosen for final study. These amplified a total of 130 bands out of which108 (84%) were polymorphic. A dendrogram was constructed using UPGMA method revealed three distinct clusters of Cambod, Assamand China type, which concur with the known taxonomical classification of tea. These results suggest that the ISSR-PCR method is potentially useful for genetic fingerprinting and molecular taxonomic classification of tea genotypes. This revised version was published online in August 2006 with corrections to the Cover Date.     

玉米种子休眠性的QTL定位

选用两个种子休眠性差异较大的普通玉米自交系R08与A318组配的F2群体共331个单株,构建了包含137个SSR标记的分子遗传连锁图谱,覆盖玉米基因组2 076.7 cM,平均图距15.2 cM。采用复合区间作图法对F_2:3家系种子休眠性数据进行分析,共检测到7个QTL,分别位于玉米第1、3、5和10染色体上。7个QTL的贡献率在2.45%~26.     

玉米幼胚培养能力性状QTL分析

以18-599（红）和R15组配的F₂群体,构建了含88对SSR标记的玉米遗传连锁图谱,覆盖基因组1 636.6 cM,标记间平均距离为18.6 cM。结合幼胚组织培养试验将幼胚发生胚性愈伤组织诱导率和胚性愈伤组织绿苗再分化数作为反映玉米培养过程中胚性愈伤组织诱导力和胚性愈伤组织绿苗再分化力的性状指标,以此调查玉米幼胚培养能力。利用复合区间作图法进行QTL分析,共检测到5个与胚性愈伤组织诱导率有关的QTL,位于第1、3、7和8染色体上,可解释5.25%～23.4%的表型变异;检测到1个与胚性愈伤组织绿苗发生数有关的QTL,位于第3染色体上,可解释表型变异率为13.42%。     

玉米茎秆弯曲性能与抗倒能力的研究

为探讨不同玉米品种茎秆抗倒伏相关的力学特点, 选用不同抗倒性品种登海3719、京科519和农大108, 设置3.00、5.25、7.50、9.25和12.00万 hm-2 5个密度, 分别于玉米抽雄前和蜡熟期取样, 用WDW3020型电子万能试验机对茎秆第3、5、7节间进行悬臂梁弯曲试验, 同时测定节间形态特征。结果表明, 随密度的增加, 茎秆基部节间直径变细、节间长度增长。品种间有一定的差异, 在3个品种中登海3719的平均直径和长度均低于其他2个品种; 品种间茎秆惯性矩也有较大差异。基部节间弹性模量、最大抗弯应力均随生育进程而增加, 但随群体密度的增加和节位的上升而逐渐降低, 登海3719在两个生育期均为最大, 且随密度增加的下降幅度较小。以京科519最低, 其对密度反应较敏感, 下降幅度大, 易发生倒伏。在玉米抽雄期, 基部节间平均弹性模量为40.0 MPa, 最大抗弯应力为2.8 MPa, 可能是茎秆抗折力学指标的下限。茎秆弹性模量与最大抗弯应力极显著相关, 茎秆直径与弹性模量和最大抗弯应力在抽雄前显著正相关, 而到蜡熟期相关不显著。它们与田间倒伏率呈极显著负相关。茎秆弯曲弹性模量反映茎秆的耐密能力, 茎秆最大抗弯应力反映品种茎秆的抗折能力, 而茎秆直径不能作为评价茎秆抗弯强弱的主要指标。玉米抽雄前期与蜡熟期茎秆抗弯性状的变化规律基本一致, 因此利用抽雄前茎秆基部弯曲力学性能鉴定与评价玉米茎秆抗倒、耐密性是可行的。