Mapping of quantitative trait loci for carotenoid pigmentation in flower tepals of Asiatic hybrid lily

Flower pigmentation is one of the most important traits for ornamental plants. To clarify the genetic basis for carotenoid pigmentation in flower tepals of Asiatic hybrid lily (Lilium sp.), we evaluated the segregation of a tepal-carotenoid content among F₁ plants derived from a cross between ‘Montreux’ (having a small amount of carotenoids) and ‘Connecticut King’ (having a large amount of carotenoids), and mapped genetic loci for the carotenoid pigmentation onto the molecular linkage maps of ‘Montreux’ and ‘Connecticut King’ that we constructed previously. The tepal-carotenoid content among the F₁ plants showed continuous segregation, indicating that several genes are associated with this trait. Quantitative trait loci (QTL) analysis identified one QTL, qCARmon6, on the sixth linkage group of the ‘Montreux’ map. qCARmon6 explained 58.2% of the total phenotypic variation, that is, this locus had a large effect on the carotenoid accumulation. The result that qCARmon6 was mapped on the linkage group of ‘Montreux’ which has a small amount of carotenoid pigments in tepals indicates that this locus has a dominant negative effect on carotenoid pigmentation.     

甜瓜侧枝相关性状的QTL定位

以甜瓜长侧枝自交系‘TopMark’和短侧枝自交系‘PI353814’为亲本,构建了F_2群体和F_2:3家系。利用92个F_2单株构建了一张包含12个连锁群,353个SSR标记的遗传连锁图谱,覆盖基因组长度为1 565.88 cM,连锁群长度在86.98～186.68 cM,标记间的平均距离为4.44 cM。利用该连锁图谱结合F_2:3家系表型鉴定数据,对甜瓜侧枝相关性状进行定位,共检测到6个QTL,分布在连锁群LGⅠ、LGⅢ和LGⅦ上,LOD值介于2.5067～12.5524之间,可解释9.9242%～48.2348%的表型变异率。其中侧枝总长主效QTLlbtl7.1和侧枝均长主效QTLlbal7.1均位于连锁群LGVⅡ的SSR标记CmSSR17145和CmSSR17293之间,贡献率分别为38.5923%和48.2348%。进一步利用186个F_2:3家系和新开发标记对主效QTL进行了验证,发现侧枝总长主效QTL lbtl7.1定位在SSR标记CmSSR17251和CmSSR17253之间,与两标记的遗传距离分别为2.5和0.5 cM,可解释41.2742%的表型变异,侧枝均长主效QTL lbal7.1被定位在SSR标记CmSSR17238和CmSSR17251之间,距离两标记分别为1.5和0.5cM,可解释55.1739%的表型变异。     

梨AFLP标记遗传图谱构建及果实相关性状的QTL定位

以‘八月红’ב砀山酥梨’的97株F1群体为试材,利用AFLP技术构建梨（2n=34）的分子遗传连锁图谱,共获得17个连锁群,包含209个标记位点,覆盖基因组1506.3cM,平均图距为7.21cM;用区间作图法进行梨果实可溶性固形物、单果质量、果实纵径、果实横径和纵横径比等5个性状的QTL定位,其中在LG1连锁群上定...     

黄瓜遗传图谱构建及株高相关性状的QTL定位

 为利用分子标记辅助选择黄瓜矮生性状, 以矮生黄瓜D8 ×蔓生黄瓜J IN5的188株F^₂单株作为 作图群体, 应用ISSR和SRAP分子标记技术进行多态性筛选, 构建了含65个标记位点的遗传连锁图谱。整个图谱覆盖7个连锁群, 全长831.6 cM。标记平均间距为12.7 cM, 标记间最小遗传距离为4.8 cM, 最大遗传距离为22.3 cM。采用复合区间定位分析, 检测到控制黄瓜株高性状的QTL位点2个, 均位于第4连锁群上, 贡献率分别为13.2%和13.0%; 控制节间距的QTL位点1个, 也位于第4连锁群上; 控制第一雌花开花期的QTL位点7个, 分别位于第1、2、3、5、7连锁群上, 各QTL的贡献率在6.5%～12.5%之间。     

A new set of microsatellite markers for Fragaria species and their application in linkage analysis

Summary

This study reports the development of 68 new microsatellite markers. Of these, 45 were obtained, together with 20 others already published, from an AC-enriched genomic library of the wild strawberry Fragaria vesca. The 68 markers were tested for transportability to the cultivated strawberry F. ananassa ‘Miss’ and 83% gave positive amplifications. Twenty pairs of primers were selected and tested for their transportability to 16 Fragaria taxa and eight species of Rosaceae (peach, almond, apricot, European and Sino-Japanese plums, sweet and sour cherry, apple). The average proportion of primers amplifying loci in Fragaria was 69%, while the transportability to Rosaceae was very low and resulted in null amplification for 80% of the primer pairs. In addition, 23 microsatellite markers were developed from F. ananassa ‘expressed sequence tags’ databases. A total of 141 primer pairs from these and published primers, were tested for polymorphism in the two parents (91.333.2 and ‘Snovit’; both belonging to F. vesca) of a full sib population of 46 individuals. Fifty-eight percent of the primers were discarded because they were monomorphic, or were difficult to interpret, or their allelic conformation was not useful for mapping. The segregation of 73 primers was tested in the progeny and a partial map of the female parent was constructed, based on the segregation of 66 useful markers that were ordered into eight linkage groups of which four had from seven to 14 markers.     

大白菜抗TuMV-C_4的QTL分析

采用高抗芜菁花叶病毒C4株系(TuMV-C4)的大白菜高代自交系A52-2为父本、感病自交系高IV-5为母本杂交后获得的F2代263个单株作为作图群体,利用SRAP分子标记技术进行遗传分析,构建了1张包含10个连锁群,由152个 SRAP标记组成的大白菜分子遗传图谱。该图谱覆盖长度为1066.3cM,平均图距7.06cM。利用Windows QTL Cartographer V2.0软件和复合区间作图法进行分析,共检测到5个与抗TuMV-C4株系相关的QTLs。     

Lettuce (Lactuca sativa): a species with a high capacity for cadmium (Cd) accumulation and growth stimulation in the presence of low Cd concentrations

Summary

Cadmium (Cd) is a metal pollutant that accumulates in cultivated soils and has detrimental consequences in terms of food safety. Lettuce (Lactuca sativa) can be characterised as having a high capacity to accumulate Cd in its tissues. An analysis of Cd tolerance and Cd accumulation was carried out using two varieties of lettuce (‘Divina’ and ‘Melina’). A wide range of CdCl₂ concentrations was used (0.0, 0.1, 0.6, 3.0, and 15.0 µM CdCl₂). The lowest concentration (0.1 µM CdCl₂) stimulated growth, while the two highest concentrations resulted in a reduction in biomass. Cadmium concentrations were found to be twice as high in roots as in shoots. ‘Divina’ displayed lower concentrations of Cd than ‘Melina’ in nearly all treatments. A strong negative correlation was observed between Cd concentration and Cd tolerance in the roots and shoots (R² > 0.87) of both ‘Melina’ and ‘Divina’. Lettuce grown in the presence of 15.0 µM CdCl₂ had leaf Cd concentrations that were 100-fold higher than the legal maximum level for vegetable products marketed for human consumption, but showed no symptoms of dehydration, chlorosis, or necrosis. This result represents an important alert for lettuce consumers and growers.     

Abscisic acid content of Citrus flavedo in relation to colour development

Summary

The relationship between endogenous abscisic acid concentrations and the development of colour was examined in six cultivars of Citrus sinensis. Abscisic acid content increased throughout the course of colour development and reached a maximum at time of colour break. Late-maturing cultivars accumulated substantially more abscisic acid and development of colour occurred visibly later than in ‘Navel’ selections. A decline in abscisic acid concentration occurred concomitantly with full expression of colour. Analysis of the pigment composition of flavedo from Citrus sinensis cv. Midknight revealed that development of orange colour was associated with a decline in levels of β,β-carotenoids, an increase in violaxanthin monoesters and formation of xanthophyll acyl esters.     

西瓜糖含量相关性状的QTL分析

以高糖西瓜品系花园母本为母本、低糖西瓜品系LSW-177为父本配制杂交组合,构建含有125个单株的F2S7重组自交系群体(RILs),利用CAPS分子标记构建了1张包含245个CAPS标记、11个连锁群的遗传连锁图谱,该图谱覆盖基因组长度2423.9c M,标记间的平均距离9.9c M。采用复合区间作图法对西瓜糖含量相关性状进行QTL分析,定位到与可溶性固形物相关的QTL4个,表型贡献率分别为14.80%、11.50%、32.10%、8.60%;与果糖相关的QTL3个,表型贡献率分别为8.80%、20.50%、9.50%;与蔗糖和葡萄糖相关的QTL各1个,表型贡献率分别为11.34%、24.10%。这9个QTL均表现为对糖含量的正加性效应,表明系高糖西瓜品系花园母本提供了对糖含量的贡献。     

甜瓜结实花初花节位QTL分析

 以WI998为母本（纯雌株、厚皮网纹甜瓜品系）,TopMark为父本（雄全同株纯合品系）,配置杂交组合,利用单粒传得到171个株系的重组自交系（F₂S₄）群体构建甜瓜SSR分子标记遗传连锁图谱。该连锁图谱包含19个连锁群,覆盖基因组长度为1 414.2 cM,标记间平均距离为10.2 cM。对结实花初花节位开展QTL分析,共检测到9个QTL,分别分布在第1、9、10、11连锁群上,各QTL的LOD值在2.89 ~ 9.42之间,4个QTL贡献率超过10%。位于第9连锁群的QTL Fp9.4贡献率最大,为18.57%（2010秋季LOD = 9.17）;位于第9连锁群的Fp9.3（2010春季8.64%,LOD = 6.44;2010秋季17.99%,LOD = 9.42）,位于第10连锁群的Fp10.1（2010春季3.59%,LOD = 2.89;2010秋季6.20%,LOD = 3.43）在两季的位置都很稳定。获得与结实花初花节位紧密连锁（< 10 cM）的8个特异标记（SSR01737、MU141991、TJ105、GCM206、SSR04910、MU173563、NR52、MU146331）,为进一步开展QTL精细定位提供参考。     

盐胁迫下两个苹果品种光合性能研究

研究不同浓度(0、0.2%、0.4%)NaCl盐分胁迫处理对"寒富"、"华红"2个苹果品种1a生嫁接苗叶片中光合作用和光合色素含量的影响。结果表明:盐胁迫改变了苹果叶片光合日变化曲线,使其光合性能整体下降;2个苹果品种的光合色素含量均随着盐浓度的增加而降低。综合分析发现,2个品种在盐胁迫下的光合能力为:"华红""寒富"。     

茄子果形的QTL 定位

 以圆茄高代自交系106和长茄高代自交系113为亲本,利用其F₂群体构建了一张包括23个SSR标记和85个AFLP标记,共15个连锁群的复合遗传图谱。该图谱覆盖基因组长度1 007.9 cM,平均图距9.3 cM,长度和密度符合定位标准。采用MapQTL4.0软件并结合MQM作图法对果形QTL进行定位分析,定位到与果形指数相关的两个QTL,位于第1和第12连锁群上,表型贡献率分别为20.8%和41.5%;与果长相关的5个QTL,位于第1、8、11、12、14连锁群上,表型贡献率分别为16.5%、36.8%、9.8%、45.0%和41.9%;与果径相关的两个QTL,位于第1和第5连锁群上,表型贡献率分别为16.2%和15.8%。果形指数、果长和果径QTL同时定位在第1连锁群上,且与AFLP标记M23E21B距离3.5 cM,表明果形性状与该标记紧密连锁。     

Comparison of cell membrane thermostability and chlorophyll fluorescence parameters for the determination of heat tolerance in ten cabbage lines

Summary

Cell membrane thermostability (CMT) and chlorophyll fluorescence (CF) were determined for ten lines of cabbage in order to select heat-tolerant varieties, to provide an improved method to screen for heat tolerance, and to determine whether there is a relationship between CMT and CF. Chlorophyll fluorescence parameters, especially variable fluorescence (Fv) and the ratio between Fv and maximum fluorescence (Fm), were found to be better than CMT for screening cabbage lines for heat tolerance. Fv values and the Fv/Fm ratio of stressed plants corresponded to high heat damage for the varieties ‘HRI 002605’, ‘HRI 003202’, and ‘HRI 007827’; and to low heat damage for the varieties ‘HRI 013011’, ‘HRI 005237’, and ‘HRI 006556’. The latter group may therefore be more tolerant of high temperature stress in the tropics. There were significant relationships (P < 0.05) between relative injury (RI), an index of CMT, and two of the CF parameters [miniumum florescence (Fo) and Fv/Fm] under stress conditions (35° – 40°C). This suggests that parameters measured under stress temperatures are more reliable than those measured under non-stressed conditions when determining heat tolerance.     

莲子产量相关性状的QTL定位

以中国长江流域圆柱形莲子资源‘中间湖野莲’为母本,泰国圆球形莲子资源‘清迈野莲’为父本,构建了含86个单株的F2遗传群体。2017和2018年对亲本及群体黑子期莲子长、莲子宽、单粒质量、开花数、心皮数、饱粒数等6个莲子产量相关性状进行了表型鉴定,利用197个SSR标记对亲本及F2单株进行基因分型,结合表型和基因型数据对相关性状进行了QTL定位和分析。结果表明:莲子产量相关性状在F2群体中均呈近正态连续分布,表明均为多基因控制的数量性状。6个莲子产量相关性状共检测到28个QTL位点,分布在7条连锁群上,LOD值变幅为2.55～12.34,可解释5.5%～27.4%表型变异率。贡献率≥10的QTL位点有25个,占QTL总数的89.29%。黑子期莲子长(bsl1),莲子宽(bsw6)、开花数(fn4.1,fn5)可在两年被稳定检测到,贡献率变幅为7.33%～17.6%。     

Detached Cane Assay of Resistance to Botryosphaeria Cane Canker (Botryosphaeria dothidea) in Eastern U.S. Blackberry Genotypes

Abstract

Resistance to Botryosphaeria cane canker in blackberry (Rubus subgenus Rubus Watson) was studied in eleven cultivars (‘Apache’, ‘Arapaho’, ‘Chester Thornless’, ‘Chickasaw’, ‘Illini Hardy’, ‘Kiowa’, ‘Navaho’, ‘Ouachita’, ‘Prime-Jim?’, ‘Shawnee’ and ‘Triple Crown’) using a detached cane assay. Ends of stem segments were sealed with wax and wound-inoculated using squares of media with mycelium. Segments were kept in humid containers on a lab bench and reaction was evaluated ten days after inoculation by measuring the area of the resulting lesion. ‘Chicaksaw’ was found to be the most susceptible by this assay, while ‘Arapaho’ and ‘Triple Crown’ were found to be the most resistant.     

Control of black spot disease caused by Alternaria alternata on jujube (Ziziphus jujuba Mill. cv. Dongzao) using HarpinXoo protein

Summary

Currently, no adequate control measures exist for the fungal disease, black spot (Alternaria alternata (Fr.) Keissler) on ‘Dongzao’ jujube (Ziziphus jujuba Mill. cv. Dongzao). Black spot is an important factor limiting jujube fruit yield under certain conditions. In this study, three concentrations (10, 20, or 30 µg ml^–1) of the Harpin_Xoo protein, or water (negative control), were sprayed onto ‘Dongzao’ jujube trees to control black spot disease. Following Harpin_Xoo protein treatment, its effects on the control of black spot disease were determined, and the levels of a defence-related substance [i.e., salicylic acid (SA)], and the activities of peroxidase (POD), polyphenol oxidase (PPO), and phenylalanine ammonia lyase (PAL) were measured. The incidence of black spot disease was significantly decreased, compared with water-treated control, fruit by ≤ 88.4%. After 2 d, SA levels, and POD, PPO, and PAL activities in Harpin_Xoo-treated fruit were clearly higher than those in control fruit. After fruit had been stored for 45 d at 0ºC, SA levels, and POD and PPO activities showed no differences between the Harpin_Xoo treatments and the controls, but PAL activities in Harpin_Xoo-treated fruit were lower than those in the controls. The most appropriate concentration of Harpin_Xoo protein to control black spot disease was 20 µg a.i. ml^–1. These results suggest that the Harpin_Xoo protein induced systemic acquired resistance in ‘Dongzao’ jujube trees and may offer a worthwhile strategy for disease control.     

Comparison of cell wall components between Fragaria × ananassa and Fragaria chiloensis grown in Chile

Summary

Fruit firmness and cell wall composition were compared among five cultivars of F. × ananassa (‘Chandler’, ‘Seascape’, ‘Tudla’, ‘Hokowase’ and ‘Reiko’) and two land races of F. chiloensis (‘94BAU-1A’ and ‘97PUR-1A’) grown in central Chile. Fruits of F. chiloensis were smaller than those of F. × ananassa. Firmness of epidermal tissue did not differ significantly between F. × ananassa and F. chiloensis. Firmness of cortical tissue, however, was significantly lower in F. chiloensis than in F.× ananassa and as a result, difference in the firmness between epidermal and cortical tissues was significantly greater in F. chiloensis than in F. × ananassa. Calcium concentration was low in ‘Reiko’ and ‘Hokowase’ while high in the other varieties of F. × ananassa. F. chiloensis showed intermediate values between these two groups. Higher levels of total uronic acid and neutral sugars in cell wall fractions of F. chiloensis as compared with F. × ananassa were mainly due to its high concentration in the water soluble fraction. Total uronic acid in cell wall fraction was significantly higher in F. chiloensis than in F. × ananassa, mainly due to significantly higher concentrations in the water-soluble fraction. Non-cellulosic neutral sugars, especially arabinose in the water, CDTA, and Na₂CO₃-soluble fractions were significantly higher in F. chiloensis than in F. × ananassa. On the other hand, galactose in the CDTA-, Na₂CO₃-, and KOH-soluble fractions was significantly lower in F. chiloensis than in F. × ananassa. Moreover, cellulose concentration of F. chiloensis was also significantly lower than that of F. × ananassa. Results obtained from cell wall analysis suggest that softer cortex in F. chiloensis might be due to either lower cellulose content, higher solubilization rate of pectic substances, and/or compositional differences in the branching of neutral sugars.     

Factors affecting shoot development in apically dominant Acer cultivars in vitro.

Summary

Axillary shoot cultures of both Acer saccharinum L. ‘Pyramidale’ and A. platanoides L. ‘Crimson King’ displayed strong apical dominance and prolific basal callus in vitro, which was not conducive to rapid multiplication and rooting. Basal callus was reduced in ‘Pyramidale’ by replacing 6-benzylaminopurine (BAP-5μM) with zeatin (5μM), but this also reduced axillary shoot growth. The addition of 2,3,5-triiodobenzoic acid (1-20 μM) altered callus development and promoted a concentration-dependent increase in axillary shoot growth. Supplementing medium with thidiazuron (0.005 and 0.05 μM) in addition to BAP (1 μM) enhanced shoot growth, especially with nodal shoot sections, and increased subsequent rooting. Although thidiazuron also increased basal callus, this correlated with better shoot growth in ‘Crimson King’. Selection of apical buds from ‘Crimsom King’ stockplants was essential for the establishment of sustainable cultures; axillary bud-derived expiants quickly died. Once shoots of ‘Pyramidale’ and ‘Crimson King’ had elongated, they could be readily rooted in vitro, and plantlets were successfully weaned under high humidity ‘dry fog’.     

Jasmonic acid effects on gibberellic acid-induced seedlessness in ‘Neo Muscat’ table grapes

Summary

The effect of jasmonic acid (JA), applied alone or in combination with gibberellin A3 (GA₃), on the induction of seedlessness in ‘Neo Muscat’ (Vitis vinifera) was investigated. Endogenous JA levels in the florets of ‘Neo Muscat’ and ‘Delaware’ (Vitis vinifera x Vitis labrusca) were also studied. The proportion of seedless berries induced by application of GA₃ alone 12 d before full bloom (DBB) was 17.0%, and at 6 DBB it was 62.7%. The proportion of seedless berries induced by GA₃ + JA applied 6 DBB increased significantly with increasing JA concentration, while pollen germination decreased quadratically with increasing JA concentration. JA did not affect seed number per berry or the seed’s fresh weight. Treatment with JA alone also induced seedlessness effectively. Although the fresh weight of the seedless berries induced by the application of GA₃ + JA 12 DBB decreased quadratically with increasing JA concentration, there were no significant differences between the treatments at 6 DBB. Fruit soluble solids and titratable acidity were not affected by JA. There were no obvious differences in the amounts of JA in the florets of ‘Delaware’ and ‘Neo Muscat’.     

Effect of short-term exposure to high-temperature on total gene expression in the leaves of four raspberry (Rubus idaeus L.) cultivars

Summary

The effect of high temperature stress (27ºC or 37ºC for 24 h) on total gene expression profiles in the annual-fruiting raspberry (Rubus idaeus L.) cultivars ‘Autumn Bliss’, ‘Autumn Treasure’, ‘Erika’, and ‘Polka’ were evaluated at the floral initiation stage using a customised Rubus microarray. Significantly affected genes were obtained by pairwise t-tests using ‘volcano plots’ for each cultivar × treatment. A 10ºC elevation in temperature altered levels of expression, in at least one cultivar, of 644 differentially expressed genes in total, with ‘Erika’ and ‘Autumn Treasure’ showing elevated expression of 38 genes compared to ‘Autumn Bliss’ and ‘Polka’. We identified 12 common candidate genes that were modulated differentially in ‘Autumn Bliss’ and ‘Erika’ at 37ºC compared to 27ºC. In addition, two aquaporin genes (PIP1 and TIP2) were down-regulated in ‘Autumn Bliss’, but up-regulated in ‘Autumn Treasure’, ‘Polka’, and ‘Erika’ at 37ºC. Other down-regulated genes from the list of 38 genes included those encoding major latex-like proteins, plasma membrane proteins, cysteine rich proteins, and other stress-related proteins. Validation by real-time quantitative RT-PCR (RT-qPCR) indicated subtle changes in differential gene expression, suggesting a mild response to heat stress. This study used molecular tools to increase our understanding of, and to identify candidate genes involved in, the heat stress response of four annual-fruiting raspberry cultivars.