The determination of chromosomes involved in controlling epicuticular wax,water statues and stomatal characteristics using selected wheat substitution lines under water-stress conditions

Some selected chromosomal substitution lines were used to determine the role of their relevant chromosomes in affecting variation of epicuticular wax, water statues and stomatal characteristics under water-deficit conditions. Recipient and donor parents of the substitution lines were Chinese spring (CS) and Timstein, respectively. Analyses of variance revealed highly significant variations among the candidate substitution lines for leaf relative water content (LRWC), excised leaf water lost and grain weight. However, no significant variation was found for epicuticular wax (ECW). In the case of stomatal characteristics, analyses of variance indicated significant variation for stomatal frequency only and no significant variation was found for other stomatal characteristics. Comparison between the substitution lines and their recipient parent (CS) revealed that none of the substitution lines was significantly different with the recipient parent (CS) for ECW, thus indicating none of the candidate chromosomes involved in controlling this character. However, the results indicated the effects of chromosomes 1A, 3D and 7D from donor parent (Tim) in controlling LRWC. Chromosomes 7D of Timstein also had a significant effect in enhancing LRWC when substituted into CS background. In addition, it was observed that none of the characters correlated with grain yield in water-stressed experiments.     

Quantitative trait locus analysis of drought tolerance and yield in Maize in China

Drought accounts for significant yield losses in crops. Maize (Zea mays L.) is particularly sensitive to water stress at reproductive stages, and breeding to improve drought tolerance has been a challenge. By use of a linkage map with 121 single sequence repeat (SSR) markers, quantitative trait loci (QTLs) for grain yield and yield components were characterized in the population of the cross X178×B73 under water-stressed and well-watered conditions. Under the well-watered regime, 2, 4, 4, 1, 2, 2, and 3 QTLs were identified for grain yield, 100-kernel weight, kernel number per ear, cob weight per ear, kernel weight per ear, ear weight, and ear number per plant, respectively, whereas under the water-stressed conditions, 1, 5, 2, 6, 1, 3, and 2 QTLs, respectively, were found. The significant phenotypic correlations among yield and yield components to some extent were observed under both water conditions, and some overlaps between the corresponding QTLs were also found. QTLs for grain yield and kernel weight per ear under well-watered conditions and ear weight under both well-watered and water-stressed conditions over-lapped, and all were located on chromosome 1.03 near marker bnlg176. Two other noticeable QTL regions were on chromosome 9.05 and 9.07 near markers umc1657 and bnlg1525; the first corresponded to grain yield, kernel weight per ear, and ear weight under well-watered conditions and kernel number per ear under both water conditions, and the second to grain yield and cob weight per ear under water-stressed conditions and ear number per plant under both water conditions. A comparative analysis of the QTLs herein identified with those described in previous studies for yield and yield components in different maize populations revealed a number of QTLs in common. These QTLs have potential use in molecular marker-assisted selection.     

Correlation and Quantitative Trait Loci Analyses of Total Chlorophyll Content and Photosynthetic Rate of Rice (Oryza sativa) under Water Stress and Well-watered Conditions

In order to explore the relevant molecular genetic mechanisms of photosynthetic rate (PR) and chlorophyll content (CC) in rice ( Oryza sativa L.), we conducted a series of related experiments using a population of recombinant inbred lines (Zhenshan97B × IRAT109). We found a significant correlation between CC and PR ( R = 0.19**) in well-watered conditions, but no significant correlation during water stress ( r = 0.08). We detected 13 main quantitative trait loci (QTLs) located on chromosomes 1, 2, 3, 4, 5, 6, and 10, which were associated with CC, including six QTLs located on chromosomes 1, 2, 3, 4, and 5 during water stress, and seven QTLs located on chromosomes 2, 3, 4, 6, and 10 in well-watered conditions. These QTLs explained 47.39% of phenotypic variation during water stress and 56.19% in well-watered conditions. We detected four main QTLs associated with PR; three of them ( qPR2 , qPR10 , qPR11 ) were located on chromosomes 2, 10, and 11 during water stress, and one ( qPR10 ) was located on chromosome 10 in well-watered conditions. These QTLs explained 34.37% and 18.41% of the phenotypic variation in water stress and well-watered conditions, respectively. In total, CC was largely controlled by main QTLs, and PR was mainly controlled by epistatic QTL pairs.     

Physiological Effects of 1-Methylcyclopropene on Well-Watered and Water-Stressed Cotton Plants

The current study investigated the effect of 1-methylcyclopropene (1-MCP), an ethylene inhibiting compound, in alleviating the detrimental effect of drought on cotton plants. The experiment was conducted in a growth chamber in 2006 and 2007. Treatments consisted of (T1) an untreated control well-watered, (T2) 1-MCP at 10 g ai/ha well-watered, (T3) an untreated control water-stressed, and (T4) 1-MCP at 10 g ai/ha water-stressed. Water-stress treatment consisted of withholding water from the pots until stomatal closure. The water-stress regime and the 1-MCP treatments were imposed at the pinhead-square stage, approximately 4 weeks after planting. Water-stressed plants treated with 1-MCP had a higher stomatal resistance, less negative water potential, higher activity of antioxidant enzymes, and better maintenance of membrane integrity. The greatest effects on stomatal resistance were observed at 5 days after treatment initiation, in which water-stressed 1-MCP-treated plants exhibited stomatal resistance of 0.079 m² s mmol⁻¹, whereas water-stressed untreated plants exhibited only 0.047 m² s mmol⁻¹. There was no significant effect of 1-MCP on water-use efficiency, transpiration, and dry matter production. These results indicated that application of 1-MCP to water-stressed cotton may have the potential to lower levels of stress in treated plants.     

The effects of water,nutrient availability and their interaction on the growth,morphology and physiology of two poplar species

We exposed cuttings of two poplar species, Populus cathayana Rehder and Populus przewalskii Maximowicz, from Sect. Tacamahaca Spach to two watering regimes (well-watered and water-stressed conditions) and to two nutrient regimes (with or without fertilization) in a greenhouse to determine how fertilization affects the growth, morphology and physiology of poplars under different water conditions. Under stress conditions, changes in early growth and dry matter allocation, and decrease in gas exchange and the related functions are usually observed. Moreover, the measurement of carbon isotope composition (δ¹³C) provides an integrated measurement of water use efficiency. And abscisic acid (ABA) is a phytohormone which plays a prominent role in various physiological and biochemical processes related to environmental stresses. So we determine these characteristics and related parameters, and our results showed the following: (1) Fertilization promoted the growth of poplars under well-watered conditions, while under water-stressed conditions its effect on growth was negative. (2) Fertilization increased δ¹³C, total N concentration, chlorophyll a/b and intrinsic efficiency of photosystem II (Fv/Fm) but decreased relative water content of leaves, stomatal conductance, transpiration rate and C/N ratio under both well-watered and water-stressed conditions. (3) Fertilization appeared to increase net photosynthesis rate and decrease ABA content under well-watered conditions, while it decreased net photosynthesis rate and increased ABA content under water-stressed conditions. Moreover, compared to P. cathayana, collected from a lower altitude region, P. przewalskii, collected from a high-altitude region, has a slower growth rate and stronger adaptability to drought stress, which perhaps resulted from its chronic adaptability to the low water availability of high-altitude region; but to the nutrient stress, there was no difference between the two species.     

Reciprocal substitutions analysis of embryo induction and plant regeneration from anther culture in wheat (Triticum aestivum L.).

Reciprocal substitutions for all chromosomes between the hard red winter wheat cultivars Wichita and Cheyenne were used to investigate the effects of individual chromosomes, as well as their interactions with the genetic background, on androgenesis. Duplicate lines for each chromosome were included to check background homogeneity. Six experiments, two for each genome, were performed. In each experiment, 14 substitution lines, their 14 duplicate lines, and the two parental genotypes ('Cheyenne' and 'Wichita') were studied. The experimental design was a randomized block with three replications. 'Wichita' and 'Cheyenne' differed significantly in embryo yield and green plant regeneration (except green plant regeneration for the B-genome tests) and were equal for albino and total plant regeneration. Embryogenesis was influenced by some chromosomes of the A, B, and D genomes; green plant production was influenced by all chromosomes of the A and D genomes except 5D; albino and total plant regeneration were affected by some chromosomes of the B and D genomes. Reciprocal effects were obtained with chromosomes 1A, 7A, 1B, 5B, 1D, and 2D for embryogenesis, chromosomes 2D and 7D for green plant regeneration, and chromosome 2D for total plant regeneration. Reciprocal substitution lines revealed reciprocal effects of homologous chromosomes, as well as interactions between substituted chromosomes and their specific genetic background.     

Interactions between biochar and mycorrhizal fungi in a water-stressed agricultural soil

Biochar may alleviate plant water stress in association with arbuscular mycorrhizal (AM) fungi but research has not been conclusive. Therefore, a glasshouse experiment was conducted to understand how interactions between AM fungi and plants respond to biochar application under water-stressed conditions. A twin chamber pot system was used to determine whether a woody biochar increased root colonisation by a natural AM fungal population in a pasture soil (‘field’ chamber) and whether this was associated with increased growth of extraradical AM fungal hyphae detected by plants growing in an adjacent (‘bait’) chamber containing irradiated soil. The two chambers were separated by a mesh that excluded roots. Subterranean clover was grown with and without water stress and harvested after 35, 49 and 63 days from each chamber. When biochar was applied to the field chamber under water-stressed conditions, shoot mass increased in parallel with mycorrhizal colonisation, extraradical hyphal length and shoot phosphorus concentration. AM fungal colonisation of roots in the bait chamber indicated an increase in extraradical mycorrhizal hyphae in the field chamber. Biochar had little effect on AM fungi or plant growth under well-watered conditions. The biochar-induced increase in mycorrhizal colonisation was associated with increased growth of extraradical AM fungal hyphae in the pasture soil under water-stressed conditions.     

Growth,photosynthetic performance and antioxidative response of ‘Hass’ and ‘Fuerte’ avocado (<Emphasis Type="Italic">Persea americana</Emphasis> Mill.) plants grown under high soil moisture

‘Hass’ and ‘Fuerte’ avocado plants were grown under well-watered or waterlogged conditions. Results indicated significant effects on the majority of the allometric parameters in waterlogged plants, with ‘Fuerte’ displaying a more pronounced growth inhibition. Waterlogged conditions caused a progressive and simultaneous decline in net photosynthetic rate and stomatal conductance, earlier in ‘Fuerte’ than in ‘Hass’. Maximal potential quantum yield of PSII was unaffected by the soil water regime and/or variety and leaf water potential values in waterlogged plants were not more negative compared with control plants. ‘Fuerte’ waterlogged plants exhibited increased contents of thiobarbituric acid reactive substances, whereas oxidative injury was not detected in ‘Hass’. Finally, none of the two cultivars displayed valuable antioxidant potential, as evidenced by the decreased activities of the antioxidant enzymes superoxide dismutase, guaiacol peroxidase, glutathione peroxidase, and ascorbate peroxidase.     

QTL mapping for germination of seeds obtained from previous wheat generation under drought

The QTLs controlling germination and early seedling growth were mapped using seeds acquired from mapping population and parental lines of Chinese Spring and SQ1 grown under water-limited conditions, severe drought (SDr) and well-watered plants (C). Germination ability was determined by performing a standard germination test based on the quantification of the germination percentage (GP24) of seeds incubated for 24 h at 25°C in the dark. Early seedling growth was evaluated on the basis of the length of the root and leaf at the 6th day of the experiment. QTLs were identified by composite interval mapping method using Windows QTLCartographer 2.5 software. For the traits studied, a total of thirty eight additive QTLs were identified. Seventeen QTLs were mapped in C on chromosomes: 1A, 2A, 7A, 1B, 2B, 3B, 4B, 5B, 6B, 7B, 2D, 3D, 4D and 6D, while twenty one QTLs were identified in SDr on chromosomes: 1A, 2A, 5A, 2B, 3B, 4B, 5B, 6B, 7B, 3D, 5D and 6D. Most of the QTLs for GP and early leaf growth parameters were clustered on chromosome 4B (associated with the Rht-B1 marker) both in C and SDr plants. The results indicate the complex and polygenic nature of germination.     

Two consensus quantitative trait loci clusters controlling anthesis–silking interval, ear setting and grain yield might be related with drought tolerance in maize

Unravelling the molecular basis of drought tolerance will provide novel opportunities for improving crop yield under water-limited conditions. The present study was conducted to identify quantitative trait loci (QTLs) controlling anthesis–silking interval (ASI), ear setting percentage (ESP) and grain yield (GY). The mapping population included 234 F₂ plants derived from the cross X178 (drought tolerant) × B73 (drought susceptible). The corresponding F_2:3 progenies, along with their parents, were evaluated for the above-mentioned traits under both well-watered and water-stressed field conditions in three different trials carried out in central and southern China. Interval mapping and composite interval mapping identified 45 and 65 QTLs for the investigated traits, respectively. Two QTL clusters influencing ASI and ESP on chromosomes 1 (bin 1.03) and 9 (bins 9.03–9.05) were identified in more than two environments, showing sizeable additive effects and contribution to phenotypic variance; these two QTL clusters influenced GY only in one environment. No significant interaction was detected between the two genomic regions. A comparative analysis of these two QTL clusters with the QTLs controlling maize drought tolerance previously described in three mapping populations confirmed and extended their relevance for marker-assisted breeding to improve maize production under water-limited conditions.     

Detection of Quantitative Trait Loci for Yield and Drought Tolerance Traits in Soybean Using a Recombinant Inbred Line Population

To investigate the genetic basis of drought tolerance in soybean ( Glycine max L. Merr.) a recombinant inbred population with 184 F_2:7:11 lines developed from a cross between Kefeng1 (drought tolerant) and Nannong1138-2 (drought sensitive) were tested under water-stressed and well-watered conditions in field and greenhouse trials. Traits measured included leaf wilting coefficient, excised leaf water loss and relative water content as indicators of plant water status and seed yield. A total of 40 quantitative trait loci (QTLs) were identified: 17 for leaf water status traits under drought stress and 23 for seed yield under well-watered and drought-stressed conditions in both field and greenhouse trials. Two seed yield QTLs were detected under both well-watered and drought-stressed conditions in the field on molecular linkage group H and D1b, while two seed yield QTLs on molecular linkage group C2 were found under greenhouse conditions. Several QTLs for traits associated with plant water status were identified in both field and greenhouse trials, including two leaf wilting coefficient QTLs on molecular linkage group A2 and one excised leaf water loss QTL on molecular linkage group H. Phenotypic correlations of traits suggested several QTLs had pleiotropic or location-linked associations. These results will help to elucidate the genetic basis of drought tolerance in soybean, and could be incorporated into a marker-assisted selection breeding program to develop high-yielding soybean cultivars with improved tolerance to drought stress.     

Effect of individual Sumai 3 chromosomes on resistance to scab spread within spikes and deoxynivalenol accumulation within kernels in wheat

Two sets of substitution lines were developed by crossing individual monosomic lines of Chinese Spring (recipient) with scab (Fusarium graminearum) resistant cultivar Sumai 3 (donor) and then using the monosomics as the recurrent male parent for four backcrosses (without selfing after each backcross). The disomic substitution lines were separated from selfed BC4F2 plants. Chromosome specific SSR markers were analyzed for polymorphism between Sumai 3 and Chinese Spring. Polymorphic markers were used to identify substitution lines for specific chromosomes. Based on the specific SSR markers, chromosome substitutions occurred in thirty-six lines, and six lines segregated alleles from the two parents or were homozygous for the allele from Chinese Spring. These substitution lines were used to evaluate Type II (spread within the head) and Type V (deoxynivalenol accumulation within kernels) scab resistance. The objective was to use the substitution lines to evaluate the effect of individual chromosomes of Sumai 3 on Type 11 and Type V scab resistance in the greenhouse. Significant differences in Type II scab resistance and deoxynivalenol (DON) levels among different Chinese Spring (Sumai 3) substitution lines were detected. Positive chromosome substitution effects on Type II scab resistance were found on chromosomes 2B, 3B. 6B, and 7A from Sumai 3. Chromosomes 3B and 7A also reduced DON accumulation within the kernels, while chromosomes IB, 2D, and 4D from Sumai 3 increased DON concentration. Chromosome 7A from Sumai 3 had the largest effect on resistance to scab spread and DON accumulation. Additional research is in progress on the scab resistance conferred by chromosome 7A.     

玉米雌雄开花间隔天数、结穗率与产量的数量性状位点(QTL)分析

采用SSR标记连锁图谱和复合区间作图法在山西灌溉和干旱胁迫条件下,对玉米(Zea mays L.)自交系黄早四×掖107组合的F3群体雌雄开花间隔天数(ASI)、结穗率和籽粒产量进行了数量性状位点(QTL)定位及基因效应分析.结果表明,在两种水分处理下,ASI、结穗率与籽粒产量的相关性均达到显著水平(P＜0.05).在灌溉和干旱胁迫下,分别检测到3个和2个控制ASI的QTL,位于第1、2、3和第2、5染色体上.在灌溉条件下,在第3和第6染色体上各检测到1个控制结穗率的QTL,基因作用方式呈加性或部分显性,可解释19.9%的表型变异;在干旱条件下,在第3、 7、10染色体上共检测到4个控制结穗率的QTL,基因作用方式为显性或部分显性,可解释60.4%的表型变异.在灌溉和干旱胁迫下,控制产量的QTL分别定位在第3、6、7和第1、2、4、8染色体上,基因作用方式均以加性或部分显性为主,可解释的表型变异为7.3%～22.0%.在干旱条件下,借助连锁分子标记和基因效应分析,可构建包含ASI、结穗率和产量QTL的选择指数,用于分子标记辅助育种.     

In vitro androgenesis response of durum wheat disomic substitution

The variety 'Langdon' and its substitution series were used to evaluate the effect of each substituted chromosome of the A and B genomes on the in vitro androgenetic potential. This study showed the implication of chromosomes 1B and 5B in repressing embryogenesis. Genes located on these chromosomes seem to have an inhibitor effect. The substitution of these chromosomes by their homeologous ones from the D genome increased the number of embryos while with the presence of the original genes the number of embryos was less than in the control. Chromosome 5B is also especially involved in the regeneration of green plants. The genetic control is inhibitory; this explains the difficulty of obtaining good levels of in vitro androgenesis in durum wheat. In this study no effect of the D genome on the androgenetic response of the substitution lines was observed.     

Leaf dehydroascorbate reductase and catalase activity is associated with soil drought tolerance in bread wheat

A number of morphological, physiological and phenological traits have been suggested as significant markers of adaptation to drought in bread wheat (Triticum aestivum L.). This study was aimed at the identification of a relationship between dehydroascorbate reductase (DHAR, EC 1.8.5.1) and catalase (CAT, EC 1.11.1.6) activities in leaves of wheat plants and stability of yield components under water deficit. The single chromosome substitution lines of cv. Chinese Spring carrying separate chromosomes from the donor Synthetic 6x, an artificial hexaploid combining the genomes of the two wild species, Triticum dicoccoides (AABB) and Aegilops tauschii (DD), were the objects of the investigations. The activities of the DHAR and CAT were correlated with flag leaf relative water content and two indexes of stability of grain yield components under drought across the set substitution lines. The lines carrying a synthetic hexaploid homologous pair of chromosomes 1B, 1D, 2D, 3D or 4D all expressed a low constitutive level of DHAR and the lines carrying chromosomes 3B, 1D, 2D and 3D a low constitutive level of CAT. All were able to increase this level (by fourfold for DHAR and by 1.5-fold for CAT) in response to stress caused by water deficit. When challenged by drought stress, these lines tended to be the most effective in retaining the water status of the leaves and preventing the grain yield components from being compromised. The discovered genetic variability for enzymes activity in leaves of wheat might be a useful selection criterion for drought tolerance.     

Stomatal and nonstomatal limitations to net photosynthesis in seedlings of woody angiosperms

Comparative responses of net photosynthesis (A) to water stress in woody species from a variety of habitats were studied to assess the relationship between photosynthetic attributes and drought tolerance. Stomatal and nonstomatal limitations to A were compared in three-month-old white oak (Quercus alba L.), post oak (Quercus stellata Wangenh.), sugar maple (Acer saccharum Marsh.), and black walnut (Juglans nigra L.) seedlings during a drying cycle. Relative stomatal limitation of photosynthesis (I) was less than 50% in all species except for Q. stellata seedlings subjected to severe water stress. No significant changes in I were observed in Q. alba and J. nigra before, during, and after drought. In A. saccharum, I was generally low and decreased significantly under water stress. Under well-watered conditions, A was highest in Q. stellata, intermediate in Q. alba, and lower in A. saccharum and J. nigra. High A in well-watered Q. stellata was associated with high stomatal conductance and carboxylation efficiency, whereas low A was associated with low stomatal conductance and carboxylation efficiency in A. saccharum and low stomatal conductance, low carboxylation efficiency, and high CO₂ compensation point in J. nigra. Under severe water stress, A, carboxylation efficiency, and stomatal conductance decreased substantially in all species; however, Q. stellata had the highest carboxylation efficiency and lowest CO₂ compensation point under these conditions. After 5 days at high soil moisture after drought, stomatal and mesophyll components of A in A. saccharum and J. nigra had not recovered to predrought levels, whereas they had completely recovered in Q. stellata and Q. alba. The photosynthetic apparatus, especially mesophyll components, of drought-tolerant Quercus species showed either less inhibition under water stress, superior recovery to predrought capacity, or both. Exposure of the leaves to ¹⁴CO₂ indicated apparent asymmetric stomatal closure for mildly water-stressed seedlings, but not for leaves of well-watered, severely stressed, or rehydrated plants. These results suggest that patchy stomatal closure under mild water stress might be important for water stress-induced inhibition of photosynthesis, but not under the more severe water stress imposed in this study.     

Uniconazole-induced tolerance of soybean to water deficit stress in relation to changes in photosynthesis, hormones and antioxidant system

This study investigated whether uniconazole confers drought tolerance to soybean and if such tolerance is correlated with changes in photosynthesis, hormones and antioxidant system of leaves. Soybean plants were foliar treated with uniconazole at 50 mg L-1 at the beginning of bloom and then exposed to water deficit stress at pod initiation for 7 d. Uniconazole promoted biomass accumulation and seed yield under both water conditions. Plants treated with uniconazole showed higher leaf water potential only in water-stressed condition. Water stress decreased the chlorophyll content and photosynthetic rate, but those of uniconazole-treated plants were higher than the stressed control. Uniconazole increased the maximum quantum yield of photosystemand ribulose-1,5-bisphosphate carboxylase/oxygenase activity of water-stressed plants. Water stress decreased partitioning of assimilated 14C from labeled leaf to the other parts of the plant. In contrast, uniconazole enhanced translocation of assimilated 14C from labeled leaves to the other parts, except stems, regardless of water treatment. Uniconazole-treated plants contained less GA3, GA4 and ABA under well-watered condition than untreated plants, while the IAA and zeatin levels were increased substantially under both water conditions, and ABA concentration was also increased under water stressed condition. Under water-stressed conditions, uniconazole increased the content of proline and soluble sugars, and the activities of superoxide dismutase and peroxidase in soybean leaves but not the malondialdehyde content or electrical conductivity. These results suggest that uniconazole-induced tolerance to water deficit stress in soybean was related to the changes of photosynthesis, hormones and antioxidant system of leaves.     

Compensating effect of fulvic acid and super-absorbent polymer on leaf gas exchange and water use efficiency of maize under moderate water deficit conditions

A field-based pot experiment with maize plants was conducted to examine the effect of combined fulvic acid (FA) and super-absorbent polymer (SAP) on leaf gas exchange, water use efficiency, and grain yield under soil water deficit. SAP (45 kg hm^?2) was applied to the topsoil at sowing. Plants were well-watered (80% field capacity), but subjected to water deficit (50% field capacity) from tassel stage to grain-fill. FA solution (2 g L^?1) was sprayed onto plant leaves at 2 and 9 days after imposing water deficit. Under water deficit, SAP and FA application did not affect evapotranspiration, but increased leaf abscisic acid and decreased leaf transpiration rate with a little change in photosynthesis, thus improving instantaneous water use efficiency. Applying SAP and FA under water deficit also increased grain yield by 19% and grain water use efficiency by 24%, largely attributed to an increase in kernel number. In contrast, under well-watered condition the two chemicals increased stomatal conductance, leaf transpiration, photosynthesis and chlorophyll content, but did not change kernel number and were relatively less effective in respect to water use efficiency compared to water-stressed condition. This study showed that application of foliar FA and soil SAP had little effect on evapotranspiration but maintained high photosynthesis and kernel number, and improved water use efficiency under soil water deficit.     

普通小麦基因组中耐低磷胁迫特性的染色体控制

以普通小麦中国春的一套缺四体为材料,对其耐低磷胁迫特性进行鉴定和遗传分析。结果表明：（１）第１,４,７部分同源群与低磷胁迫特性关系最密切,且第１,７部分同源群内各染色体间在该性状的遗传互补性良好。第４部分同源群则不同,４Ａ可以有效补偿４Ｂ与４Ｄ的缺失,反之则不能。（２）第２,３,５６部分同源群与低磷胁迫特性关系不密切,且这些同源群内某一染以体的缺失大多不能被其他染色体有效地补偿,尤其是第３与第６部     

Chromosome mapping of low-temperature induced Wcs120 family genes and regulation of cold-tolerance expression in wheat

 Low-temperature (LT) induced genes of the Wcs120 family in wheat (Triticum aestivum) were mapped to specific chromosome arms using Western and Southern blot analysis on the ditelocentric series in the cultivar Chinese Spring (CS). Identified genes were located on the long arms of the homoeologous group 6 chromosomes of all 3 genomes (A, B, and D) of hexaploid wheat. Related species carrying either the A, D, or AB genomes were also examined using Southern and Western analysis with the Wcs120 probe and the WCS120 antibody. All closely related species carrying one or more of the genomes of hexaploid wheat produced a 50 kDa protein that was identified by the antibody, and a Wcs120 homoeologue was detected by Southern analysis in all species. In the absence of chromosome arm 6DL in hexaploid CS wheat no 50 kDa protein was produced and the high-intensity Wcs120 band was missing, indicating 6DL as the location of Wcs120 but suggesting silencing of the Wcs120 homoeologue in the A genome. Levels of proteins that cross-reacted with the Wcs120 antibody and degrees of cold tolerance were also investigated in the Chinese Spring/Cheyenne (CS/CNN) chromosome substitution series. CNN chromosome 5A increased the cold tolerance of CS wheat. Densitometry scanning of Western blots to determine protein levels showed that the group 5 chromosome 5A had a regulatory effect on the expression of the Wcs120 gene family located on the group 6 chromosomes of all three hexaploid wheat genomes. Received: 10 July 1996 / Accepted: 30 September 1996