小麦地方品种小白冬麦抗白粉病基因分子标记

小麦农家品种小白冬麦对小麦白粉病具有良好抗性,对病原菌拥有较广的抗谱,并与其他已知抗白粉病基因的抗谱不同,遗传分析证实小白冬麦的苗期抗性由一个隐性抗白粉病基因控制。为了寻找与小白冬麦所携带抗白粉病基因连锁的分子标记,采用小白冬麦和感病品种Chancellor（CC）正反交组合,在2个F2群体125和107个单株上进行验证。结果显示,抗白粉病基因mlxbd与引物Xgwm577、Xgwm1267等紧密连锁,通过中国春及其第7部分同源群缺体-四体系,双端体系和缺失系将其定位在7B染色体长臂末端区域（7BL-10,Bin0.78-1.00）,利用与mlxbd最近的引物Xgwm577扩增23个含有已知抗白粉病基因的小麦品种,检测发现这个引物不能单独用于分子标记辅助选择育种。

Variations in Phytic Acid Content and Their Relationship with Protein Content and Kernel Morphological Characters of Chinese Winter Wheat Cultivars

[Objective] The aim of this study was to determine the variation of phytic acid content （PAC） and its frequency distribution, as well as the relationship between PAC and protein content, kernel characteristics in 161 Chinese winter wheat cultivars from four regions. [Method] One hundred and sixty-one winter wheat varieties from China Wheat Zones I, II, III and IV （Table 1） were grown in a randomized block de- sign, in the 2009-2011 cropping season; and then the indexes for describing the grain morphological characteristics such as the thousand kernel weight （TKW）, kernel length （KL）, kernel width （KW） and kernel thickness （KT） were measured; the phytic acid content （PAC）, protein content and sedimentation value were also determined; finally, the relationship between PAC and protein content, kernel characteristics were analyzed. [Result] The PAC in the cultivars tested ranged from 0.92% to 1.95% with a mean value of 1.41%. Protein content ranged from 12.60% to 19.20%, with a mean of 15.24%. Most （53.4%） of the wheat genotypes had a PAC value in the range of 1.25% to 1.55%. No significant correlation was found between PAC and protein content, sedimentation value, while protein content and SDS sedimentation value was significant correlated, which suggested the possibility of breeding wheat cultivars that have a low PAC but a high protein content and good gluten quality. There was a high correlation between TKW and KW （,.=0.79）, KL （r=0.50） and KT （r=0.64）. PAC was found having no significant correlation with TKW, KW, KL and KT. [Conclusion] The result suggests the possibility of breeding wheat cultivars that have a low PAC but high kernel weight.

Predicting Grain Yield and Protein Content in Winter Wheat at Different N Supply Levels Using Canopy Reflectance Spectra

A field experiment using a split-plot randomized complete block design with three replications was carried out to determine relationships between spectral indices and wheat grain yield （GY）, to compare the performance of four vegetation indices （VIs） for GY prediction, and to study the feasibility of VI to estimate grain protein content （GPC） in winter wheat. Two typical winter wheat （Triticum aestivum L.） cultivars ＇Xuzhou 26＇ （high protein content） and ＇Huaimai 18＇ （low protein content） were used as the main plot treatments and four N rates, i.e., 0, 120, 210, and 300 kg N ha^-1, as the sub-plot treatments. Increasing soil N supply significantly increased GY and GPC （P ≤ 0.05）. For the two cultivars combined, significant and positive correlations were found between four VIs and GY, with the strongest relationship observed when using the green ratio vegetation index （GRVI） at mid-filling. Cumulative VI estimates improved yield predictions substantially, with the best interval being heading to maturity stage. Similar results were found between VI and grain protein yield. However, when using cumulative VI, GPC showed no significant improvement. The strong relationship between leaf N status and GPC （R2 =0.9144 for ＇Xuzhou 26＇ and R2 = 0.8285 for ＇Huaimai 18＇） indicated that canopy spectra could be used to predict GPC. The strong fit between estimated and observed GPC （R2 = 0.7939） indicated that remote sensing techniques were potentially useful predictors of grain protein content and quality in wheat.

Accumulation of High Molecular Weight Glutenin Subunits in Superior and Inferior Grains of Winter Wheat

The difference in accumulation of high molecular weight glutenin subunits （HMW-GS） in superior and inferior grains results in the non-uniformity of grain quality in winter wheat （Triticum aestivum L.）. The HMW-GS accumulation and glutenin macropolymer （GMP） content were studied in superior and inferior grains during the grain filling period, using the sodium dodecyl sulfate polyacrylamide gel electrophoresis （SDS-PAGE）. Compared to inferior grains, HMW-GS was formed earlier and total accumulation amount was higher in superior grains. The total HMW-GS content was higher in superior grain than that in inferior grain except at maturity. For individual HMW-GS types, the accumulation and content of subunit 7 were the highest, followed by subunit 12, while that of subunit 8 were the lowest, followed by subunit 2 in superior grain. In contrary, the accumulation and content of subunit 7 at maturity were significantly higher than subunit 8, but they were similar between subunit 2 and subunit 12 in inferior grain. Moreover, the accumulation of subunit 7 and 12 in superior grain were significantly higher than that in inferior grain. However, compared to the inferior grain, the GMP accumulation was higher, while content was lower in superior grain at maturity.

Impact of Cutting a Clover Crop on the Nitrogen Supplied to Winter Wheat in an Intercropping System

The major function of clover in a winter wheat–white clover intercropping system is to supply nitrogen （N） for the wheat. A field experiment was conducted at Yucheng Comprehensive Station of the Chinese Academy of Sciences, to evaluate the effect of cutting white clover on N fixation and the transfer of fixed N to the associated winter wheat. A method of 15N natural abundance was used to determine the nitrogen dynamics in the intercropping system. The results showed that the amount of N transferred from the clover to the wheat, throughout the growing season, varied between 34.4 and 57.5 kg ha-1. Compared to leaving the clover standing, cutting the clover increased the amount of N that accumulated in the soil and also resulted in reduced N concentrations in the leaves and stems of the wheat. Using the cut clover as mulch between wheat rows led to decreased N concentrations in the wheat plants’ leaves and stems. The present study provides preliminary information on the amount of N transferred from clover to wheat in an intercropping system.