柱花草内珠被、胚柄及胚乳细胞的程序性死亡

利用石蜡切片技术对柱花草胚胎发育过程中内珠被、胚柄及胚乳细胞进行显微观察。结果表明：上述胚珠和胚体的结构成分在胚胎发育进程中相继发育然后程序性地死亡。胚珠受精作用发生后，内珠被的内表皮细胞发育形成珠被绒毡层。原胚时期，珠被绒毡层外侧的内珠被细胞退化。球形胚时期，珠被绒毡层退化。鱼雷形胚时期，胚柄退化。扩大生长胚时期，胚乳细胞退化。内珠被、胚柄及胚乳细胞的发育和程序性死亡均与不同发育时期胚的营养物质供应和形态建成相关。     

FTIR and Solid StateC NMR Spectroscopy of Proteins of Wet Cooked and Popped Sorghum and Maize

Fourier transform infrared (FTIR) and solid state¹³C NMR spectroscopic methods were used to investigate changes in maize and sorghum proteins on wet cooking and popping. FTIR spectra indicated that wet cooking led to proteins in two normal sorghums, namely NK 283 (a red hybrid) and KAT 369 (a white variety), two sorghum mutants (P850029 and P851171) and a maize hybrid (PAN 6043) assuming more antiparallel intermolecular β-sheet character, possibly at the expense of some α-helical conformation. Solid state¹³C NMR, using the technique of Cross Polarisation Magic Angle Spinning showed shifts of the protein carbonyl carbon and α-carbon resonances upfield on wet cooking in all samples, also indicating a change in protein secondary structure from α-helical to β-sheet conformation. The extent of secondary structural change on wet cooking seemed to be greater in sorghum than in maize and may have a bearing on the inferior protein digestibility of wet cooked sorghum compared to maize. Popping produced the same secondary structural change as observed for wet cooking in both sorghum and maize. However, the extent of change on popping was less than on wet cooking in sorghum and maize.     

The Selective Extraction of Glucuronoarabinoxylans from Sorghum Endosperm Cell Walls using Barium and Potassium Hydroxide Solutions

Various populations of hemicellulosic material were solubilised from water-unextractable cell wall material (WUS) of sorghum (Sorghum vulgarecv. Fara Fara) by sequential extractions with alkali. Saturated Ba(OH)₂-solutions, followed by distilled water, 1 KOH, 4 KOH and 4 KOH containing 4% (w/v) H₃BO₃ were used to extract primarily glucuronoarabinoxylans (GAX) from sorghum WUS. Cellulose remained in the residue. In total over 90% of all GAX originally present in the WUS were recovered, particularly in the saturated Ba(OH)₂, 1 KOH and 4 KOH extracts. Saturated Ba(OH)₂ was found to be the most selective of the extractants tested for GAX. (1→3), (1→4)-β- -glucans were found predominantly in the fraction obtained by washing with water after the extraction with saturated Ba(OH)₂. All extracted arabinoxylans were highly substituted (arabinose/xylose>1) and contained, besides -arabinose and -xylose, the acidic sugars -glucuronic, 4-O-methyl- -glucuronic and -galacturonic acid. The average molecular weight ranged from 210 000–1 300 000, which corresponds with DPs ofc. 1500 to 9300. The selectivity of the extractant was apparently enhanced by the presence of a bivalent cation.     

胚乳蛋白质对稻米品质影响的研究进展

蛋白质是稻米胚乳中仅次于淀粉的第二大贮藏物质,蛋白质含量、组分、形态以及分布特征对稻米品质均具有重要影响。本文梳理了胚乳蛋白质与稻米外观品质、加工品质、营养品质和蒸煮食味品质关系的研究进展,并对未来研究方向提出了展望。结果可为进一步解析胚乳蛋白质在稻米品质形成中的作用和稻米品质改良提供参考。     

固定和染色方法对水稻胚乳细胞结构观察的影响

 以扬稻6号花后3~10 d的颖果为材料,采用戊二醛 四氧化锇(GA OsO4)和高锰酸钾两种方法固定样品,Spurr树脂包埋后分别进行半薄切片和超薄切片。对半薄切片分别进行甲苯胺蓝(AMB)染色、高碘酸 希夫（PAS）法染色、多色性染液染色以及PAS AMB复染,比较了2种固定方法和4种染色方法对水稻胚乳细胞结构观察的影响。结果表明,GA OsO4固定的半薄切片染色效果整体上优于高锰酸钾,在超薄切片观察中,GA OsO4固定制样的细胞组织结构清晰,但细胞中内膜性结构不够清晰,而高锰酸钾固定制样则能较好的显示出细胞中内膜结构,但是对多糖和蛋白质的呈色较差。建议在实验中根据观察内容选择固定及染色方法。     

The Biochemical Basis and Implications of Grain Strength in Sorghum and Maize

This review deals with the biochemical basis and implications of hardness and grain strength in sorghum and maize. Grain hardness affects various aspects of the growth and processing of cereal grain from resistance to fungal infection to cooking quality. It is clear that the prolamins play an important role with the γ-prolamins being the most important. It would appear that these prolamins help shape the protein bodies and form disulphide bonds within themselves or with other proteins. The γ-prolamins form the cement while the α-prolamins are the bricks. Both prolamins are present in greater proportions in hard grains and in the vitreous portion of hard grains. Genetic and environmental effects on the amounts of the different prolamins and on their distributions within the protein body and in different parts of the endosperm also determine grain hardness. Grains that will be hard appear to deposit prolamins and antifungal proteins earlier and in greater amount than do soft grains. The cell wall composition is also different between the two types of grains while there is a higher proportions of amylose in the starch of hard than in that of soft grains. Most of the differences that exist between hard and soft grains also exist between the outer and inner portion of the grain. It is postulated that there might be a master gene controlling the onset of strength in grains by simultaneously altering the levels of various apparently unrelated biochemical events. It is also suggested that solute availability may play an important role in the regulation of expression of genes for hardness-related proteins.     

小麦籽粒胚乳细胞增殖动态及其与粒重和体积的关系

为了了解小麦在不利气候条件下的灌装机理，改善湖北小麦的产量与品质状况，作者以三种粒型小麦品种(系)为材料，研究了籽粒胚乳细胞增殖动态及其与体积和粒重的关系。结果表明，用Richards方程能较好地模拟胚乳细胞增殖动态。不同品种间胚乳细胞数有明显的差异，表现为大粒饱满品种(鄂恩1号)＞大粒不饱满品系(95A—10)＞小粒饱满品种(华走8号)。强势粒胚乳细胞分裂起始势高，达到最高增殖速率时间短，活跃分裂期长，可分裂出更多的胚乳细胞。弱势粒胚乳细胞增殖起始势低，细胞分裂速率变化缓慢，其最终胚乳细胞数显著低于强势粒。多元统计分析表明，决定籽粒体积大小的主要是胚乳细胞数和单个胚乳细胞大小，决定粒重大小的主要是胚乳细胞数和单个细胞重。     

同源四倍体水稻胚乳发育:极核融合和胚乳细胞化

利用激光扫描共聚焦显微术和塑料包埋半薄切片技术观察同源四倍体水稻极核融合及游离核进一步发育的过程,发现同源四倍体水稻约有1/3子房极核融合过程和游离核进一步发育与其二倍体原种的基本一致;2/3子房出现各种异常现象,如极核未受精、受精异常和胚乳游离核发育滞后等。应用荧光增白剂染色对胚乳细胞化过程进行观察,直接观察到胚乳初生壁的出现和形成过程以及不同部位的胚乳细胞壁的形成机理。表明同源四倍体水稻与二倍体水稻胚乳的细胞化过程基本一致,胚乳细胞初始垂周壁来源于珠孔端胚囊壁内突向心游离生长,初始平周壁来源于游离核有丝分裂产生的成膜体,而中间胚乳细胞壁则有些来源于游离核有丝分裂产生的成膜体,有些是自由生长而来。同源四倍体水稻胚乳细胞化过程也出现相当比例的异常现象,如无细胞壁形成、细胞化不同步和产生分枝状的细胞壁等。同源四倍体水稻胚乳发育过程中出现的极核融合、游离核发育和细胞化过程等异常都可能导致同源四倍体水稻的结实率降低。     

高粱体细胞抗盐系的筛选

用高粱体细胞梯度筛选法筛选了在3％NaCl培养其中能存活的体细胞系，并获得了再生植株，利用芽期和苗期抗盐鉴定和产比结果表明，高粱体细胞抗盐新品系T011有较强的抗盐能力和高配合力。     

水稻胚乳细胞发育的结构观察及其矿质元素分析

 为了探明水稻胚乳发育的过程和糊粉层形成的机理, 用光学显微镜和电子显微镜观察了水稻糊粉层细胞和内胚乳细胞在颖果发育过程中的结构变化,用能谱仪分析了胚乳细胞中元素的种类和相对含量。结果表明, 糊粉层细胞是由胚乳表层细胞转化而来的。糊粉层细胞中的P、K、Mg和Ca等矿质元素含量要明显高于内胚乳细胞。发育初期糊粉层细胞中富含线粒体、圆球体和小液泡;发育中后期小液泡积累蛋白质和矿质元素而形成糊粉粒。在发育中后期,内胚乳细胞随着细胞内淀粉体的充实,细胞核发生形变而衰亡;而糊粉层细胞的核在发育过程中不消亡。糊粉层的形成与表层细胞积聚矿质和脂类等“灌浆废物”(指非内胚乳细胞的贮藏物)有关。因而,转运灌浆物质多的胚乳背部,其糊粉层细胞的层数要比腹部和侧部多。谷物胚乳发育分为游离核期、细胞化期、分化期和成熟期四个时期。     

小麦内胚乳细胞及其淀粉体的发育

为了探明小麦内胚乳细胞发育和淀粉体生长的规律,以不同发育天数的小麦颖果为材料,利用树脂半薄切片和胚乳细胞分离等方法研究了内胚乳细胞及其淀粉体的形态、数目和生长过程.结果如下:(1)小麦内胚乳细胞呈不规则的多面体形态,内含大、小两种淀粉体,大淀粉体呈鹅卵石形,小淀粉体呈圆球形;(2)内胚乳细胞的生长呈“S”型曲线,花后16～24 d是细胞生长最快的时期;(3)大淀粉体的增殖和生长主要在花后4～16 d进行,小淀粉体在花后16 d大量出现并快速增殖,至胚乳发育后期小淀粉体数量占内胚乳细胞淀粉体总量的90％以上;(4)内胚乳细胞核在颖果发育中、后期发生衰亡,淀粉体在核衰亡过程中仍然能增殖和生长.     

同源四倍体水稻胚乳发育:糊粉层细胞壁纤维素物质发育、胚乳淀粉积累及胼胝质“套”的形成

 利用荧光显微术观察，发现同源四倍体水稻与其二倍体原种的糊粉层细胞壁纤维素物质都存在一个“充实”的过程。授粉后5～6 d，糊粉层开始分化形成，此时其细胞壁上未观察到纤维素物质；授粉后6～8 d，糊粉层细胞壁上开始积累纤维素物质；授粉后8～9 d，糊粉层细胞壁积累了大量的纤维素物质。胚乳淀粉的积累存在一个变化的过程：初生胚乳核周围可见一些淀粉体，随着胚乳游离核的增多，游离核周围淀粉体的数量逐渐减少，胚乳细胞化后，胚乳细胞内开始大量形成淀粉体。利用苯胺蓝染色连续切片荧光观察，发现同源四倍体水稻及其二倍体原种胚乳发育过程中，在珠心表皮和内珠被之间存在一层胼胝质物质，围绕着胚囊并包裹住珠心呈“套”状。这个结构的形成变化过程为：授粉后30 min在珠孔端珠心表皮细胞与内珠被之间开始积累少量的胼胝质，之后胼胝质逐渐增多并向合点端扩展延伸；授粉后1～2 d包裹着整个胚囊外的珠心而仅在维管束处断开；授粉后9～13 d，胼胝质“套”消失。该结构可能与胚和胚乳在发育期间的水分和养分的调节等有密切关系。同源四倍体水稻还存在糊粉层细胞壁发育不同步、糊粉层细胞壁结构异常以及胼胝质“套”不消失等异常现象。这些现象有可能会影响同源四倍体水稻的结实率。     

能源作物甜高粱和玉米对土壤重金属的富集比较

采用盆栽实验研究不同浓度重金属胁迫下(Cd、Pb、Cr)能源作物甜高粱和玉米不同器官Cd、Pb、Cr含量、富集系数以及冠部累积量。结果表明,Cd胁迫下,甜高粱不同器官Cd含量、富集系数以及冠部累积量(6.28~59.71μg)均高于玉米;Pb胁迫下,玉米不同器官Pb含量、富集系数以及冠部累积量(223.71~652.44μg)均高于甜高粱;随Cr浓度增加,甜高粱和玉米不同器官Cr含量、富集系数以及冠部累积量均呈上升趋势,在Cr胁迫下甜高粱和玉米的生物量较小,冠部Cr累积量小。相比之下,甜高粱适合修复Cd污染土壤,玉米适合修复Pb污染土壤,两种作物均不适合修复Cr污染土壤。     

低温下外源水杨酸对玉米幼苗保护酶活性的影响

0.5mmol/L水杨酸(SA)预处理玉米幼苗降低了低温胁迫期间玉米幼苗体内丙二醛(MDA)的含量及超氧阴离子(O2-.)的产生速率。酶活性分析表明,SA预处理后玉米幼苗在低温胁迫下超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性较低温对照高。常温下用0.5mmol/LSA预处理玉米幼苗,提高了保护酶的活性,从而提高了玉米幼苗的抗寒性。     

水稻胚乳发育遗传调控的研究进展

胚乳是被子植物双受精产物之一,为种子发育提供营养;同时,水稻胚乳也是人类口粮的重要来源.胚乳组织约占水稻种子干质量的70％以上,其发育直接影响稻米产量和品质.目前我们对水稻胚乳发育调控的分子机制有了较为深入的认识,克隆了一些重要基因,同时发现表观遗传调控在胚乳发育中也发挥重要作用.本文主要以水稻为例,同时穿插拟南芥和玉...     

胚乳裂纹对玉米种子活力指标的影响

以玉米杂交种种子为试验材料,研究胚乳无裂纹、胚乳单裂纹、胚乳双裂纹和胚乳龟裂纹种子的发芽势、发芽率、发芽指数、活力指数变化。结果表明,24 h内的吸水率表现为龟裂纹种子的吸水率最高,无裂纹种子的吸水率最低。随着胚乳裂纹数的增加其种子发芽势、发芽率、发芽指数和活力指数均呈降低的变化趋势。胚乳无裂纹的种子发芽势、发芽率、发芽指数和活力指数显著高于胚乳龟裂纹的种子发芽势、发芽率、发芽指数和活力指数。种子胚乳无裂纹的幼苗干重显著高于胚乳龟裂纹的幼苗干重。胚乳龟裂纹是导致种子活力降低的原因之一,在种子生产中应该减少胚乳龟裂纹产生。     

Effect of Chemical Treatments on Polyphenols and Malt Quality in Sorghum

Tannin-containing sorghums, Chirimaugute and DC-75, and a tannin-free sorghum, SV2, were steeped in water, HCl (0·25 ), formaldehyde (0·017 ) and NaOH (0·075 ) for 8 and 24 h. Germination was carried out for 2 and 5 d. Steeping in NaOH enhanced water uptake of the grains compared with the other treatments. All treatments reduced the polyphenol content of the raw grain. Treatment with NaOH or formaldehyde (HCHO) was more effective than water or HCl. Malt quality was measured in terms of diastatic power (DP). Potential DP, determined after the peptone extraction, indicated higher amylase activity in DC-75 malt than in Chirimaugute and SV2 malt. Available DP, determined after water extraction, was low in malt from the tannin-containing varieties that had been treated with water or HCl. Malting alone was not an effective method of reducing the enzyme inhibitory power of the sorghum tannins. Available DP was markedly improved by the NaOH and HCHO treatments of the tannin-containing varieties. It is concluded that steeping in dilute NaOH is effective in detoxifying high-tannin sorghums, reducing the steeping period and enhancing malt quality. Steeping in NaOH appears to be a safer alternative to HCHO for treatment of high-tannin sorghums in the malting industry and for other food uses.     

Biochemical Basis of Kernel Milling Characteristics and Endosperm Vitreousness of Maize

Chemical characteristics of 18 normal maize grain samples, having a wide range of physical properties (endosperm vitreousness, kernel friability and milling characteristics), were analysed and related to physical properties. Measurement of damaged starch showed that starch behaved as a passive filler in endosperm. Endosperm protein content and class, as determined from extractability properties and reversed-phase high-performance liquid chromatography, were correlated with kernel physical properties. Endosperm vitreousness and kernel mechanical properties (kernel friability and milling characteristics) were related to different components, however. Vitreousness seems to be linked to the proportion (%) of the two γ-zein fractions, whereas friability increased when α-zein content decreased and when salt extractable protein content increased.     

Cellularization of the Free Nuclear Endosperm in Rice Caryopsis Revealed by Light and Electron Microscopy

Summary

Events during the early development of rice endosperm were studied cyto-histologically. Attempts were made to clarify the sequential changes during the early developmental stages of endosperm to reveal the ultrastructural details of the first-anticlinal wall formation and the subsequent cellularization. Early development of nuclear endosperm rapidly proceeded after anthesis and a large number of free nuclei proliferated until 48 HAA. In a large central cell, phragmoplasts arose as a result of alignment of vesicles appeared between the free nuclei located in the peripheral cytoplasm layer along nucellus. The phragmoplasts initially fused with wall of the nucellus and formed the initials of anticlinal wall. The initial wall grew toward a large central vacuole and reached tonoplast of central vacuole. Thereby, alveolar typed cell compartments ensued. Furthermore, the anticlinal wall continuously arose to form a large number of alveolar typed compartments. The cellularization of compartments including a free nucleus was achieved during 48 to 72 HAA. Microtubules and Golgi apparatus seemed to contribute to cellularization. Lastly, the process forming first-anticlinal wall is followed on a representative diagram and compared with the cellularization in other cereal endosperms.     

高粱叶角遗传研究

利用高粱骨干不育系、恢复系和自选紧凑型恢复系,采用不完全双列杂交设计对高粱叶角性状进行遗传研究。分析表明,高粱叶角性状是由基因加性效应和显性效应共同作用的结果,大叶角具有不完全显性作用,基因加性效应起主要作用,高粱叶角遗传符合加性—显性遗传模型。在叶角的方差中,一般配合力方差占主要地位,所以在培育紧凑型品种时,直接选择是非常有效的。广义遗传力和狭义遗传力都很高,表明叶角受环境影响所造成的表型变异较小,在早代进行单株选择是有效的。