不同发育时期小麦粒重性状QTL的动态分析

利用6044×01-35构建的重组自交系(RIL)群体为试验材料,对小麦粒重性状进行发育动态QTL分析。结果表明,在小麦花后子粒灌浆的7个不同时期,两个试验点共检测到16个与粒重性状相关的QTL。其中开花后20d检测到的单穗粒重QTL位于2A染色体上,解释率达12%,遗传效应超过10;两环境下控制千粒重QTL在7个时期均被检测到。花后的各个时期均能在Xgwm448-Xgpw7399标记区间定位到千粒重QTL。其中花后10d检测到1个千粒重QTL,位于2A染色体的Xgwm448-Xgpw7399标记区间,解释较大的表型变异,达到18%。Qtl8、Qtl13和Qtl14均定位在Xgwm448-Xgpw7399标记区间的同一位置,共同解释11%的表型变异。花后20d和花后25d均检测到1个QTL,位于2A染色体的Xgwm372-Xgwm95标记区间的不同位点,均能解释4%的表型变异。花后40d检测到1个QTL,位于1D染色体的Xwmc93-Xgpw2224标记区间,解释1%的表型变异。从连锁群的位置上看,控制千粒重的QTL主要集中在2A染色体的Xgwm448-Xgpw7399标记区间,这是一个控制千粒重QTL的富集区域,以期进行精细定位和图位克隆。     

The Effects of Selenium on Physiological Traits, Grain Selenium Content and Yield of Winter Wheat at Different Development Stages

The paper evaluated the effects of Se application time and rate on physiological traits, grain Se content, and yield of winter wheat by field experiment. Se application significantly increased grain Se content and yield, and the increased amount treated with 20 and 30 mg Se?L^?1 was the highest. At blooming–filling stage, Se application significantly increased grain Se content, but did not affect yield. Chlorophyll content was increased by Se application, and the increased amount at heading–blooming stage was higher than that in wheat leaves at the other stages. At four development stages, Se treatments (except for 10 mg Se?L^?1 at jointing–heading stage) significantly decreased the rate of superoxide (O₂ ^?) radical production. At heading–blooming (except for 50 mg Se?L^?1) and blooming–filling stages, hydrogen peroxide (H₂O₂) content was significantly decreased by Se treatments. The rate of O₂ ^? production and H₂O₂ content at 20 and 30 mg Se?L^?1 was the lowest. Se treatments (except for 10 mg Se?L^?1 at regreening–jointing and blooming–filling stages) also induced an evident decrease in malondialdehyde content. Proline content induced by Se treatments at jointing–heading and heading–blooming stages was higher than that in wheat leaves at regreening–jointing and blooming–filling stages. At four development stages, Se treatments all significantly increased glutathione peroxidase activity, and the treatments with 20 and 30 mg Se?L^?1 also evidently increased reduced glutathione content. These results suggested that Se application at different development stages increased antioxidant capacity of wheat, reduced oxidant stress to some extent, and the effects of Se treatments was the best if Se concentration ranged between 20 and 30 mg Se?L^?1. In addition, Se application time was more beneficial for Se accumulation and yield in wheat grain at heading–blooming stage.     

A Comparison of the Effect of High Temperature on Grain Development in Wheat and Rice

Grain weight at maturity of the wheat cultivar Banks was reducedby about 5% for each 1 °C rise in daily mean post-anthesistemperature in the range from 17.7 to 32.7 °C, using grainweight at 17.7 °C as the base. In contrast, the rice cultivarCalrose had a stable grain weight up to 26.7 °C and abovethat showed a 4.4% drop in weight per 1 °C increase in meanpost-anthesis temperatures up to 35.7 °C, using grain weightat 26.7 °C as the base. In both wheat and rice there wasa reduction in the duration of grain growth with increasingtemperature up to a mean of 26.7 °C. In this range rice,but not wheat, showed a compensating increase in the rate ofdry-matter accumulation. Above 26.7 °C the rate of dry-matteraccumulation fell in both species, although this was more stablein rice than in wheat. In wheat the duration of grain growthcontinued to decrease at temperatures above 26.7 °C, butshowed little change in rice up to 35.7°C, the maximum tested.These data are discussed in relation to the physiological, biochemicaland physical constraints that may act to regulate grain developmentin wheat and rice at high temperature. Triticum aestivum, oryza sativa, grain development, high temperature effects     

Effect of High Temperature Stress at Anthesis on Grain Yield and Biomass of Field-grown Crops of Wheat

Spring wheat (Triticum aestivumL., ‘Chablis’) wasgrown under field conditions from sowing until harvest maturity,except for a 12-d period [70–82 days after sowing (DAS)coinciding with anthesis] during which replicated crop areaswere exposed to a range of temperatures within two pairs ofpolyethylene-covered temperature gradient tunnels. At 82 DAS,an increase in mean temperature from 16 to 25 °C duringthis treatment period had no effect on above-ground biomass,but increased ear dry weight from 223 to 327 g m^-2and, at 83DAS, reduced root biomass from 141 to 63 g m^-2. Mean temperatureover the treatment period had no effect on either above-groundbiomass or grain yield at maturity. However, the number of grainsper ear at maturity declined with increasing maximum temperaturerecorded over the mid-anthesis period (76–79 DAS) and,more significantly, with maximum temperature 1 d after 50% anthesis(78 DAS). Grain yield and harvest index also declined sharplywith maximum temperature at 78 DAS. Grain yield declined by350 g m^-2at harvest maturity with a 10 °C increase in maximumtemperature at 78 DAS and was related to a 40% reduction inthe number of grains per ear. Grain yield was also negativelyrelated to thermal time accumulated above a base temperatureof 31 °C (over 8 d of the treatment from 5 d before to 2d after 50% anthesis). Thus, grain fertilization and grain setwas most sensitive to the maximum temperature at mid-anthesis.These results confirm that wheat yields would be reduced considerablyif, as modellers suggest, high temperature extremes become morefrequent as a result of increased variability in temperatureassociated with climate change.Copyright 1998 Annals of BotanyCompany Triticum aestivum, spring wheat, temperature, grain number, grain yield, root growth.     

Effect of the Calcium on Polygalacturonase (PG) Activity and Synthesis at Different Ripening Stages of Tomato Fruits

It has been reported that PG is a key enzyme related to the tomato fruit ripening and that the application of calcium can dramatically decrease the PG activity and delay the ripening of fruits. In this paper the effects of calcium treament at various ripening stages on the transformation of absorbed calcium, PG activity and PG synthesis in tomato fruits were studicd. According to the analysis of calcium by atomic absorption spectroscopy, it was shown that the soluble and total calcium contents in pericarp of fruits treated with calcium at mature-green stage were increased significantly, and that more soluble calcium was transformed into bound calcium. Both the absorption and transformation of calcium decreased in fruits treated with calcium at later stage of ripening. The inhibition of calcium on PG activity was most effective by treatment at mature-green stage, but less effective at later stage of ripening. One reason for the decrease of calcium inhibition was probably due to the decline of calcium absorption as fruit ripening. The polyacrylamide gel electrophoresis of PG showed that PG with a molecular weight of 46.7 kD was absent in mature-green fruits, and PG synthesis occurred only at the later stage of ripening. It seems that the earlier the treatment was done the more effective of the calcium inhibition of PG synthesis. Based on the above results, it was concluded that the PG plays a major role in ripening and senescence of tomato fruits, and both PG synthesis and its activity were inhibited by calcium. In order to delay the ripening and senescence of tomato fruits, the treatment with calcium should be done at mature-green stage.     

The Effects of Floret Sterilization on Grain Number and Grain Weight in Wheat Ears

This paper describes the effects of sterilizing certain floretson the development of others within the ears of wheat, cultivarMaris Ranger. Sterilization of all the florets in spikelets2, 4, 6, and 8 (numbered from the base of the ear upwards) ledto more grain setting and greater grain growth in the untreatedspikelets. These compensatory increases were insufficient toprevent a depression in the yield of grain per ear. Sterilizationof more than one of the basal florets of spikelet 8 led to amore frequent setting of the grain in the distal florets onthat spikelet and to the centrally positioned grain becomingheavier. The physiological basis for the inhibitory influences of theolder and developing grain on the unfertilized florets and youngergrain is discussed.     

刈割对冬小麦再生积温需求及其籽粒产量和品质的影响

对黄土高原塬区冬小麦‘陇育216’于分蘖期、拔节期及孕穗期进行刈割处理,以不刈割为对照,测定冬小麦再生生长发育的积温需求及籽粒产量及其品质,探究刈割利用时间对冬小麦再生生长积温需求及产量构成的影响。结果表明:(1)分蘖中期(6个分蘖)前刈割利用,小麦再生各阶段的有效积温需求较对照无显著差异,在收获小麦青干草0.9～1.5t/hm2的同时,能保证籽粒、秸秆产量及其品质较对照均无显著下降;分蘖期后期(9个分蘖)及其后刈割利用,拔节至开花及成熟期的有效积温需求显著减少,尽管较分蘖期可多收获60%的青干草,但籽粒、秸秆产量较对照均显著降低。(2)通径分析发现,刈割主要通过降低再生植株高度及减少单位面积穗数而导致冬小麦籽粒减产。研究表明,为维持冬小麦再生生长节律、籽粒产量及品质形成的稳定,冬小麦刈割利用的时期应不迟于分蘖中期(6个分蘖)。     

Evaluation of Wheat Chromosome Translocation Lines for High Temperature Stress Tolerance at Grain Filling Stage

High temperature (HT, heat) stress is detrimental to wheat (Triticum aestivum L.) production. Wild relatives of bread wheat may offer sources of HT stress tolerance genes because they grow in stressed habitats. Wheat chromosome translocation lines, produced by introgressing small segments of chromosome from wild relatives to bread wheat, were evaluated for tolerance to HT stress during the grain filling stage. Sixteen translocation lines and four wheat cultivars were grown at optimum temperature (OT) of 22/14°C (day/night). Ten days after anthesis, half of the plants were exposed to HT stress of 34/26°C for 16 d, and other half remained at OT. Results showed that HT stress decreased grain yield by 43% compared with OT. Decrease in individual grain weight (by 44%) was the main reason for yield decline at HT. High temperature stress had adverse effects on leaf chlorophyll content and Fv/Fm; and a significant decrease in Fv/Fm was associated with a decline in individual grain weight. Based on the heat response (heat susceptibility indices, HSIs) of physiological and yield traits to each other and to yield HSI, TA5594, TA5617, and TA5088 were highly tolerant and TA5637 and TA5640 were highly susceptible to HT stress. Our results suggest that change in Fv/Fm is a highly useful trait in screening genotypes for HT stress tolerance. This study showed that there is genetic variability among wheat chromosome translocation lines for HT stress tolerance at the grain filling stage and we suggest further screening of a larger set of translocation lines.     

Plant Uncoupling Mitochondrial Protein Activity in Mitochondria Isolated from Tomatoes at Different Stages of Ripening

In the present study we have observed a higher state of coupling in respiring mitochondriaisolated from green as compared to red tomatoes (Lycopersicon esculentum, Mill.). Greentomato mitochondria produced a membrane potential () high enough to phosphorylate ADP,whereas in red tomato mitochondria, BSA and ATP were required to restore to the levelof that obtained with green tomato mitochondria. This supports the notion that such uncouplingin red tomato mitochondria is mediated by a plant uncoupling mitochondrial protein (PUMP;cf. Vercesi et al., 1995). Nevertheless, mitochondria from both green and red tomatoes exhibitedan ATP-sensitive linoleic acid (LA)-induced decrease providing evidence that PUMP isalso present in green tomatoes. Indeed, proteoliposomes containing reconstituted green or redtomato PUMP showed LA uniport and LA-induced H⁺ transport. It is suggested that the higherconcentration of free fatty acids (PUMP substrates) in red tomatoes could explain the lowercoupling state in mitochondria isolated from these fruits.     

Effects of Favorable Alleles for Water-Soluble Carbohydrates at Grain Filling on Grain Weight under Drought and Heat Stresses in Wheat

Drought, heat and other abiotic stresses during grain filling can result in reductions in grain weight. Conserved water-soluble carbohydrates (WSC) at early grain filling play an important role in partial compensation of reduced carbon supply. A diverse population of 262 historical winter wheat accessions was used in the present study. There were significant correlations between 1000-grain weight (TGW) and four types of WSC, viz. (1) total WSC at the mid-grain filling stage (14 days after flowering) produced by leaves and non-leaf organs; (2) WSC contributed by current leaf assimilation during the mid-grain filling; (3) WSC in non-leaf organs at the mid-grain filling, excluding the current leaf assimilation; and (4) WSC used for respiration and remobilization during the mid-grain filling. Association and favorable allele analyses of 209 genome-wide SSR markers and the four types of WSC were conducted using a mixed linear model. Seven novel favorable WSC alleles exhibited positive individual contributions to TGW, which were verified under 16 environments. Dosage effects of pyramided favorable WSC alleles and significantly linear correlations between the number of favorable WSC alleles and TGW were observed. Our results suggested that pyramiding more favorable WSC alleles was effective for improving both WSC and grain weight in future wheat breeding programs.     

Grain Size and Seedling Growth of Wheat at Different Ploidy Levels

A study was made of the influence of grain size variation withinand between diploid, tetraploid and hexaploid wheat, on a numberof seedling growth characters. Differences in grain size within the three ploidy levels appearedto be related to total photosynthetic area and dry weight accretionin the seedling. In the diploids there was a positive correlationbetween seed size and total photosynthetic area (r = +0·99,P < 0·01) and total dry weight (r = +0·84,P < 0·05) of the seedling at 10 weeks after emergence.In the tetraploid and hexaploids, seed size was negatively correlatedwith both total photosynthetic area (r = –0·69,P < 0·05 and r = –0·33, P < 0·05for the tetraploids and hexaploids respectively) and total dryweight (r = –0·69, P < 0·05 and r = –0·59,P < 0·05 for the tetraploids and hexaploids respectively),of the seedlings 10 weeks after emergence. The main physiological distinction between the tetraploids andhexaploids appeared to be the superiority of the hexaploidsin rate of leaf appearance and the lower ratio of expanded tounexpanded leaves in the seedling 10 weeks after emergence.The tetraploids, in turn, appeared to be superior to the diploidsin these two characters. Triticum spp., wheat, polyploidy, grain size, photosynthetic area, net assimilation rate, tiller number     

Effect of Temperature During Various Growth Stages on Grain Development and Yield of Pennisetum americanum

In controlled temperature glasshouses plant morphology, gramdevelopment and yield of pearl millet (Pennisetum americanum)were markedly affected by temperature during three stages ofplant growth: vegetative, stem elongation, and grain development.High temperature (to 33/28 °C day/night) during all threegrowth stages lowered grain yields by reducing basal tillering,numbers of grains per inflorescence, and single grain weight.Low temperature (21/16 °C) during the vegetative stage increasedbasal tillering and, as a result, total grain yield per plant.However, low temperature during the stem elongation stage reducedspikelet fertility and influorescence length, and thereby reducedthe potential main shoot grain yield. Low temperature duringgrain development increased the grain filling period and grainyield. The rate of grain filling did not vary over the rangeof 21/16 to 33/28 °C. Although plant morphology and grainyield were markedly affected by pre-anthesis thermal environment,grain development was not. At all temperatures ethanol-solublecarbohydrates stored in the stem were depleted during earlygrain development.     

Effects of Radiation and Temperature on Tiller Survival, Grain Number and Grain Yield in Winter Wheat

Effects of the environment on shoot survival were studied inwinter wheat cv. Avalon grown in microplots at a density of247 plants m^–2. The incident radiation and mean temperaturewere altered during one of three periods of between 14 and 29d duration, the first (P1) starting at the end of tiller productionand the last (P3) finishing near the end of the tiller deathphase, about three weeks before anthesis. Plants were giventemperature and radiation treatments in growth rooms in twoexperiments and extra light outdoors in a third experiment:they were at other times grown outdoors. Increasing radiation by between 60 and 100 per cent during P1had negligible effects on shoot number; during P2 it alwaysdelayed tiller death but increased final ear number in onlyone experiment; during P3 it consistently increased ear numberby up to 100 m^–2. Increased radiation always increasedcrop dry weight immediately after treatment but only sometimesdid this increase persist to maturity. Grain dry weight wasincreased by treatment during P3 of one experiment. Increasingthe temperature by 4 C decreased shoot number, usually onlytemporarily, by hastening death of some tillers. Warmer temperaturesdecreased crop growth after, but not during, treatment and decreasedgrain dry weight. Radiation and temperature rarely interacted. Variation in grain yield within and between experiments relatedwell to variation in number of grains m^–2, which in turnrelated to variation in ear dry weight at anthesis. Triticum aestivum L., wheat, radiation, temperature, tillers, grain yield, grain number     

The Number and Sizes of Starch Granules in the Wheat Endosperm, and their Association with Grain Weight

The number and size of starch granules was measured in developingand mature endosperms of two wheat varieties, Chinese Springand Spica. Chromosomal effects on particular aspects of starchgranule size and number were detected in the analysis of disomicgenotypes derived from reciprocal monosomic hybrids betweenthe two parental varieties. Among these genotypes, a greaterweight per endosperm cell was associated with a greater volumeper A-type starch granule. It is suggested that the number percell and volume of these large starch granules are the majordeterminants of endosperm cell weight, and there exists separategenetic control of these parameters. It should therefore bepossible genetically to combine these attributes to achievedirected increases in mature grain weight. Triticum aestivum, grain weight, starch granules     

小麦辐射突变体及原始品种不同发育期酯酶、过氧化物酶同工酶分析

采用不同发育时期的小麦辐射突变体及原始品种材料对其酯酶（EST）、过氧化物酶（POD）酶谱进行了比较研究,并对一些农艺性状之间的相关性进行了测定。结果表明,第一套材料（南大2419、鄂麦6号、81-61562、82-2291）的株高和粒重分别与过氧化物酶和酯酶的活性在一定时期呈相反的变化趋势,第二套材料（St-2422／464、62027、80-15678）则无明显规律性关系。不同时期起主要作用的谱带不同。     

1-甲基环丙烯对低温贮藏的香蕉果实后熟的影响

香蕉果实先在6℃下贮藏不同时间后转入常温用1-甲基环丙烯(1-MCP)处理或先以1-MCP处理后转入6℃下贮藏不同时间,然后在常温下用乙烯利处理,结果表明, 经1-MCP处理过的果实对乙烯不敏感,后熟过程受抑;而未经1-MCP处理的果实能够后熟,并有明显的呼吸及乙烯峰出现.     

Expression Dynamics of Genes and microRNAs at Different Growth Stages and Heat Treatments in Contrasting High Temperature Responsive Rice Genotypes

The global warming-driven climate change is becoming a major challenge for rice cultivation in Asia and Africa. High-temperature stress impairs the physiology and growth of rice plant, and ultimately results in reduced grain yield. This study was aimed to decipher the physiological and molecular changes occurring during different growth stages of heat-tolerant (N22) and -susceptible (Vandana) rice cultivars under three different heat treatments. Chlorophyll content, membrane integrity, gas exchange parameters and expression of genes and miRNAs were analyzed in N22 and Vandana at seedling, vegetative, and reproductive growth stages after exposing to short and long duration of high temperature stress, and recovery. A number of genes and miRNAs showed dynamic changes in their expression patterns at different growth stages and heat treatments, highlighting the necessity to understand gene regulation before employing the genes for modification through transgenic or gene editing approaches. Predominantly N22 showed distinct and unique capability to reprogram its physiological and molecular machinery during prolonged heat stress at reproductive stage, suggesting that the dynamics in gene regulation is crucial to determine its heat tolerant ability. The study has larger implications in deploying genes for the development of heat tolerant rice cultivars through breeding, transgenic, and genome editing approaches.

     

不同施肥灌水处理对不同小麦品种产量和品质的影响

在小麦生育期间降水47.9 mm的条件下,以3个小麦品种为试验材料,采用四因素三水平正交设计,研究了不同灌水和施肥处理对不同小麦品种子粒产量、蛋白质含量和沉降值的影响。结果表明,全生育期施氮量300 kg/hm2和225 kg/hm2的处理子粒产量和蛋白质含量差异不显著,但均显著高于150kg/hm2的处理。在中产条件下氮肥底施和追施比例以7∶3时产量最高。春季灌4水产量显著高于灌2水的处理,但与灌3水差异不显著,子粒蛋白质含量以灌2水时最高。供试品种中以京冬8号的产量、千粒重、容重最高,CA0206和核优1的蛋白质含量差异不显著,但均显著高于京冬8号。CA0206的沉降值显著高于另两个品种。以产量、品质和经济效益综合考虑,在本试验条件下,以春季灌3水、施氮量225 kg/hm2、底施和追施比例为7∶3的处理为宜,与超高产条件下氮素底施和追施比例5∶5的结果有明显的差异。