opaque2对糯玉米子粒食味和营养品质的影响分析

玉米opaque2(o2)是胚乳发育的核心调控基因，对子粒发育至关重要。基于9组糯玉米o2近等基因系(o2-NILs)及对应轮回亲本，对鲜食期和成熟期子粒的种皮厚度、总淀粉含量、可溶性糖含量等性状进行分析。结果表明，黄糯2/o2o2和中63-2/o2o2鲜食期子粒的食味品质性状均有提高，其他o2-NILs子粒品质变化不一。鲜食期o2突变对种皮厚度影响较大，但与成熟期无直接相关性。o2突变使玉米子粒赖氨酸含量增加，营养价值提高，但多数近等基因系成熟期淀粉含量和百粒重降低，仅糯2/o2o2、淀粉含量和百粒重均不受影响。糯2/o2o2、SY1-2/o2o2、赵OP-6/o2o2中27 KD γ-zein表达量显著增加、子粒饱满度与轮回亲本相近，但均表现为粉质胚乳，因此认为，优质蛋白糯玉米硬质胚乳的恢复需多个o2胚乳修饰基因协同作用。     

玉米opaque2突变体子粒表型及营养成分分析

通过回交转育构建o2突变型的近等基因系CAL58/o2,对其子粒进行扫描电镜和透射电镜观察,发现与CAL58相比,CAL58/o2中淀粉颗粒排列松散,形状更加规则,CAL58/o2子粒中蛋白体体积变小。分析子粒的营养成分,CAL58/o2赖氨酸含量极显著提高了55.88%,氨基酸总量显著减少9.79%,粗蛋白显著减少8.86%,粗脂肪显著增加30.96%,粗淀粉显著增加5.87%。同时,提取成熟子粒醇溶蛋白进行比较,CAL58/o2子粒的α、β-醇溶蛋白含量明显降低,γ-醇溶蛋白含量增加。     

o2与淀粉合成突变基因互作对子粒赖氨酸含量的影响

以o2、sh2、su1、wx 4个基因的郑58近等基因系品质基因聚合材料为研究对象,对聚合材料子粒中赖氨酸含量进行定量测定,分析o2与淀粉合成突变基因互作对子粒赖氨酸含量的影响。结果表明,聚合材料赖氨酸含量介于0.35%~1.05%,郑58子粒赖氨酸含量为0.28%,存在显著差异。o2与淀粉合成缺陷型突变基因(sh2、su1)互作可以显著增加赖氨酸含量,3个基因聚合的基因型o2sh2su1赖氨酸含量最高,为1.05%;其次为sh2o2和su1o2基因型,聚合材料粒重均不同程度下降。o2与淀粉修饰型突变基因(wx)互作赖氨酸含量未发生明显变化。su1o2以及su1o2wx既具有相对较高的赖氨酸含量,又保持一定的粒重。     

玉米胚乳突变基因ae1和du1的遗传效应

利用玉米ae1和du1隐性纯和突变自交系与普通玉米自交系48-2的杂交F₁、F₂代子粒为研究材料,通过单粒法测定子粒的直链淀粉含量和重量,用于分析玉米胚乳突变基因ae1和du1的遗传效应。结果表明：F₂代中具有ae1或者du1纯和突变的子粒表皮皱缩,重量明显下降,直链淀粉含量显著提高。在ae1与du1的杂交后代中,子粒的单粒重和直链淀粉含量没有显著变化,表明ae1与du1双突变并不能导致直链淀粉含量增加。单突变的ae1和du1群体内各子粒间的直链淀粉含量和重量差异较大,说明遗传背景中存在影响直链淀粉含量的修饰基因,表明在选育高直链淀粉玉米品系时,应当重视遗传背景的选择和修饰基因的累加。采用单粒法技术对分离后代进行直链淀粉含量和重量选择,有利于积累高直链淀粉修饰基因,是选育子粒饱满、高粒重的高直链淀粉玉米自交系的有效方法。     

玉米子粒性状和子粒赖氨酸含量的相关及通径分析

以28份玉米自交系为材料,对9个子粒性状与子粒赖氨酸含量进行了相关和通径分析。结果表明,油分、胚重、胚比(胚重与胚乳重的比值)、胚乳硬度等级与赖氨酸含量呈显著或极显著正相关;淀粉含量、密度(粒重与体积之比)、胚乳重与赖氨酸含量呈显著或极显著负相关;百粒重和粗蛋白含量与赖氨酸含量相关不显著。各子粒性状对赖氨酸含量的直接影响力大小依次为胚比>胚重>胚乳重>胚乳硬度等级>密度>油分>淀粉含量>粗蛋白含量>百粒重。其中,胚比对子粒赖氨酸含量起关键作用。     

郑58/opaque2近等基因系中opaque2基因突变位点分析与高效分子标记开发

opaque2突变体材料是最常用的高赖氨酸玉米供体。对已获得的郑58/o2近等基因系研究表明,胚乳发育不同时期22-kDα-醇溶蛋白的积累均明显低于郑58。荧光定量PCR结果表明,α-醇溶蛋白家族基因Z1A、Z1B、Z1C和Z1D的表达均显著低于郑58。郑58/o2胚乳发育不同时期Opaque2基因均正常表达。测序分析发现,郑58/o2中o2基因ATG后713 bp处缺失10个碱基,ORF预测Opaque2蛋白翻译提前终止。针对突变缺失位点开发基因内分子标记o2-indel-1,利用该标记进行回交转育,结果表明,o2-indel-1与o2突变表型完全连锁,错选率为0。opaque2基因突变位点的解析有助于高效分子标记的开发,有效降低错选率,提高优质蛋白鲜食玉米多基因聚合育种的选择效率。     

玉米自交系齐319空间诱变系的生物学效应分析

以两份玉米子粒类型空间诱变系SP-M1、SP-M2以及野生型玉米自交系齐319为试验材料,对田间农艺性状、穗部性状、子粒的营养品质性状和胚乳内部显微结构进行分析。结果表明,与野生型相比,两个诱变系在株高、穗位高、粒长、百粒重等田间农艺性状和穗部性状上发生显著或极显著变异,且变异方向不同,SP-M1和SP-M2赖氨酸含量显著高于野生型,SP-M2淀粉含量显著高于野生型,蛋白质含量显著低于野生型。2个诱变系与齐319在胚乳边缘组织、胚乳内部组织、淀粉粒、基质蛋白等结构存在差异,淀粉粒的组成比例和排列顺序是影响胚乳超微结构差异的主要原因。     

Opaque-2基因导入各类隐性纯合体玉米早代子粒粒重和含油率的效应研究

选用微胚乳等各类隐性纯合体玉米为试验材料,利用杂交法把opaque-2基因导入各类隐性纯合体玉米,并以被导原隐性纯合体为对照,分析各类玉米杂交导入o2后的早代o2隐性纯合体子粒粒重和含油率的变化。结果表明,在导入opaque-2后的微胚乳等各类隐性纯合体玉米杂交早代中,整粒重、胚和非胚部重、整粒含油率、胚和非胚部含油率都发生了增减两个方向的变异,效应随不同类玉米及子粒不同部位而异。导入o2后的o2微胚乳玉米(o2we)的粒重和含油率都极显著降低,表明o2基因对所选用的微胚乳玉米早代的粒重和含油率都具极显著的减少效应。o2bw(39)、o2w(45)、o2w(49)、o2w(51)和o2w(53)等玉米整粒重极显著增加;o2hw(27)、o2w(45)、o2w(49)、o2w(51)和o2w(53)等玉米胚重极显著增加;o2hw(27)、o2bw(39)、o2w(49)和o2w(53)等玉米整粒含油率显著或极显著增加;o2w(49)和o2w(53)玉米胚含油率显著或极显著增加;o2hw(27)、o2bw(39)和o2w(53)等玉米非胚部含油率显著或极显著增加。表明导入o2后对这几类玉米部分材料的粒重和含油率具有显著的改良效应,通过选择有望获得相应的优良品系。     

鲜食糯玉米品质差异及适宜采收指标的研究

以8个鲜食糯玉米品种为试验材料,研究授粉后17～29 d不同采收期百粒鲜重、子粒粗淀粉含量、含水率与鲜穗蒸煮品评分的变化及关系。结果表明：4项均值在不同品种间及不同采收期间差异极显著;最佳品质期在授粉后的时期及长短、最佳品质时的百粒鲜重占最大粒重的比例、子粒粗淀粉含量在品种间均存在差异;推迟采收有利于增加百粒鲜重;子粒含水率在59%～64%时可作为鲜穗最适采收期。     

玉米胚乳突变基因ae1和du1的遗传效应

利用玉米ae1和du1隐性纯和突变自交系与普通玉米自交系48-2的杂交F1、F2代子粒为研究材料,通过单粒法测定子粒的直链淀粉含量和重量,用于分析玉米胚乳突变基因ae1和du1的遗传效应.结果表明:F2代中具有ae1或者du1纯和突变的子粒表皮皱缩,重量明显下降,直链淀粉含量显著提高.在ae1与du1的杂交后代中,子粒的单粒重和直链淀粉含量没有显著变化,表明伽ae1与du1双突变并不能导致直链淀粉含量增加.单突变的ae1和du1群体内各子粒间的直链淀粉含量和重量差异较大,说明遗传背景中存在影响直链淀粉含量的修饰基因,表明在选育高直链淀粉玉米品系时,应当重视遗传背景的选择和修饰基因的累加.采用单粒法技术对分离后代进行直链淀粉含量和重量选择,有利于积累高直链淀粉修饰基因,是选育子粒饱满、高粒重的高直链淀粉玉米自交系的有效方法.     

Analyses of albumins, globulins and amphiphilic proteins by proteomic approach give new insights on waxy wheat starch metabolism

Starch is composed of two types of glucose polymers: amylose and amylopectin. The Waxy (Wx) locus controls amylose synthesis in the wheat kernel. Hexaploid wheat has three Wx loci located on chromosomes 7A (Wx-A1), 4A (Wx-B1), and 7D (Wx-D1). Eight near isogenic lines (NILs) of Triticum aestivum cv. Tremie with one, two or three Wx null alleles were used. The albumin–globulin fraction, and amphiphilic proteins were separated using 2-dimensional electrophoresis (2DE) allowing the changes in the waxy kernel to be identified. Albumin–globulin fraction showed overexpression of sucrose synthases in the waxy NILs compared to the normal form of Tremie and a decrease in many proteins related to stress and defence metabolism such as serpins. A subunit of ADP-glucose pyrophosphorylase (AGPase), which is known to play a major role in starch synthesis, was also shown to be down regulated in the waxy NILs. Amphiphilic proteins confirmed the observations made on the albumin–globulin fraction with a decrease in a stress-related protein. These different regulations linked to observations made on wheat kernel (thousand kernel weight (TKW), protein amount per grain, size and distribution of the starch granules) led to formulation of the hypothesis that waxy endosperm does not reach maturity of the wild-type endosperm.     

玉米不同部位子粒灌浆特性与粒重的关系研究

以郑单958(ZD958)和登海661(DH661)为试验材料,研究在4.5万、7.5万、10.5万株/hm2种植密度下玉米上部及中下部子粒灌浆特性和粒重的关系。结果表明,穗粒数和千粒重是决定子粒最终产量的重要因素,两者均随着密度的增加而显著降低。同一密度下,穗位层光照自开花当天(0 d)先降低后升高,总体呈"高-低-高"的变化趋势,底层光照则持续升高。上部子粒的起始生长势、灌浆速率、胚乳细胞数及淀粉含量均低于中下部子粒。相关及通径分析表明,影响粒重的主要因素是灌浆速率、胚乳细胞数目和淀粉含量,其相关系数分别为0.959 66**、0.981 91**和0.877 76*。光照(包括穗位层和底层)主要通过灌浆速率和淀粉含量来间接影响粒重。     

Characterisation of Starch from Inner and Peripheral Parts of Normal and Waxy Barley Kernels

A previous microscopical examination of barley kernels indicated an uneven distribution of amylose in the waxy cultivar SW7142-92, where the subaleurone layer was strongly stained by iodine. To explain these results, starch was isolated from fractions of inner and peripheral parts of kernels of the waxy cultivar and a cultivar with normal starch. Analyses of amylose content showed a higher concentration of amylose in starch from the outer part of the waxy barley kernel, where the amylose, determined by a colorimetric method, made up 8·6% of the starch compared with 5·9% in the middle and 2·2% in the innermost part of the waxy kernel. This difference in amylose distribution was not observed in the normal starch kernel. The results were confirmed by gel permeation chromatography. No differences in amylopectin chain length distribution were detected by size exclusion HPLC and HPAEC-PAD of amylopectins from different parts of the barley kernels.     

Effects of inhibition of starch branching enzymes on starch ordered structure and component accumulation in developing kernels of rice

Three rice varieties, Te-qing (TQ), Wu-xiang 9915 (WX) and Guang-ling-xiang-nuo (GLXN) with different amylose contents, and their derived lines with inhibition of starch branching enzyme I and IIb (SBEI/IIb) (GLXN-, WX- and TQ-SBEI/IIb^–) were used to investigate and compare the starch ordered structure and component accumulation in developing kernels. The starches in developing kernels of TQ, WX and GLXN all showed a typical A-type crystallinity and had similar short-range ordered structure, but their relative crystallinities gradually decreased in TQ and WX and had no significant change in GLXN with kernel development. For wild-type rices, starch components gradually increased in developing kernels. With inhibition of SBEI/IIb, the accumulation of amylose and amylopectin long branch-chains in kernels was slightly affected, but amylopectin short branch-chains seriously decreased, resulting in a significantly lower dry weight and starch content in kernel. The B-type crystallinity in developing starch gradually accumulated with kernel development of TQ-, Wx- and GLXN-SBEI/IIb^– lines. The inhibition of SBEI/IIb decreased the relative crystallinity but increased the short-range ordered structure of starches. The effects of inhibition of SBEI/IIb on starch ordered structure and component accumulation mainly appeared after 10 days after flowering, and were the most conspicuous for indica rice TQ. Though the inhibition of SBEI/IIb influenced the ordered structure and component accumulation of starch, the starch content and components in developing kernels all showed significantly positive correlations with kernel dry weight.     

Wx基因对灌浆期小麦不同叶位叶片光合特性的影响

为了解Wx基因对小麦光合作用的影响,对8个小麦Wx近等基因系的不同叶位叶片光合参数进行了测定和分析。结果表明,小麦叶片净光合速率、气孔导度、胞间CO2浓度和蒸腾速率在叶位和基因型间均有极显著差异,缺失单个Wx基因使叶片光合参数下降,且降幅表现为Wx-D1Wx-A1Wx-B1;胞间CO2浓度不影响光合作用,不同叶位叶片光合参数明显呈旗叶倒二叶倒三叶,但WxABD(糯小麦)光合参数在叶位间没有显著差异;Wild type和WxABD总体光合能力和产量相对较高。以上结果说明,Wx基因的缺失会引起叶片光合能力下降,不利于小麦产量形成。     

灌浆前期高温对小黑麦籽粒淀粉积累及其合成相关酶活性的影响

为探讨灌浆前期高温对六倍体小黑麦籽粒淀粉积累及其相关合成酶活性的影响,以4个春性小黑麦品种（系）为材料,在开花后5~14 d于田间搭建温棚进行高温胁迫,对其籽粒淀粉积累动态、淀粉合成相关酶活性进行了研究。结果表明,开花后5~14 d高温胁迫导致小黑麦千粒重和容重均显著下降,其中,千粒重下降5.95%~20.47%,容重下降3.33%~9.49%;籽粒中的总淀粉、支链淀粉与直链淀粉含量均显著降低,依次下降6.84%~17.97%、7.70%~24.60%及2.27%~7.17%,直/支链淀粉比有所升高,但差异不显著。在高温胁迫期间,小黑麦籽粒中与淀粉合成相关的腺苷二磷酸葡萄糖焦磷酸化酶（AGPP）、可溶性淀粉合成酶（SSS）、淀粉分支酶（SBE）及淀粉去分支酶（DBE）活性均较对照有所上升,高温胁迫结束后,AGPP、SSS、DBE的活性均较对照有所下降。推测灌浆前期高温胁迫导致灌浆中后期小黑麦籽粒中淀粉合成相关酶活性的下降是籽粒中淀粉含量降低以及千粒重、容重下降的主要原因。