为了解白肉火龙果'玉龙1号'新品种的成花结果节律与果实品质形成变化规律,以4年生结果树为研究对象,对全年成花结果物候期进行观测,并对果实品质进行分析分级.结果显示'玉龙1号'每年自然开花结果9个批次,花蕾发育期需17～22d,果实发育期需38～42d,果实转红第10～14天时可溶性固形物含量(TSS)达到峰值.全年果心TSS含量峰值从高到低排序依次是:11月批＞9月批＞8月次＞10月批＞7月批＞翌年1月批;果实中心TSS含量相近(平均17.5％)的3个品种中果糖含量相比,'大红'(37.7g·kg-1)＞'玉龙1号'(37.3g·kg-1)＞'越南白肉'(26.3g·kg-1);甜度口感是'玉龙1号'及'大红'优于'越南白肉'.综合果心TSS、相对甜度等级和品质,初步制定'玉龙1号'指标评价标准,以期为生产高品质果品提供参考依据.

Pitaya (genus Hylocereus ) is a popular fruit. To develop pitaya fruit with greater marketability and high nutritional value, it is important to elucidate the roles of candidate genes and key metabolites that contribute to the coloration of the pitaya pulp and peel. By combining transcriptome and biochemical analyses, we compared and analyzed the dynamic changes in the peel and pulp of H. undatus (white pulp) and H. polyrhizus (red pulp) fruits at four key time points during ripening. Differential expression analysis and temporal analysis revealed the difference regulation in pathways of plant hormone signal transduction, phenylpropanoid biosynthesis, and betalain biosynthesis. Our results suggest that color formation of purple-red peel and pulp of pitaya is influenced by betalains. Increased tyrosine content and fluctuation in acylated betalain content may be responsible for pulp color formation, while some of the key genes in this network showed differential expression patterns during ripening between white pulp and red pulp fruits. The data and analysis results of this study provide theoretical basis for the red color formation mechanism of pitaya, which will facilitate future work to improve pitaya fruit physical appearance and marketability.

Aroma is one of the major inherent quality characteristics in fruits. Understanding the composition of aroma volatiles and their biosynthesis mechanism is crucial to improving fruit quality. However, the biosynthesis mechanism of aroma volatiles has not been characterized yet in white-fleshed pitaya (Hylocereus undatus). This study was performed to investigate aroma volatiles and related gene expression patterns in the pulp of "mild grassy" and "strong grassy" aroma cultivars. Analysis of volatile composition and concentration showed that aldehydes, alcohols, esters, and alkenes were predominant in both cultivars. However, comparative analysis revealed a significant difference in the concentration of several metabolites, particularly hexanal and 1-hexanol. The results of the comparative transcriptome identified a large number of aroma-related differentially expressed genes. The majority of these genes were enriched in fatty acid and isoleucine degradation pathways. According to integrative analyses, changes in the expression of lipoxygenase pathway genes, specifically FAD, LOXs, HPLs, and ADHs, probably lead to the difference in strength of "grassy" aroma between both cultivars. The qRT-PCR of 18 aroma-related genes was performed to validate the transcriptome analysis. Our results identified key genes and pathways connected with the biosynthesis of aroma volatiles in white-fleshed pitaya. These results will be useful to dissect the genetic mechanism of fruit aroma in white-fleshed pitaya.

Background: Pitaya is an important economic fruit worldwide due to its numerous health benefits. A systematic understanding of the mechanism underlying flower development is essential to obtain higher fruit yield and quality. However, the genetic mechanism of flower development is not yet investigated in pitaya. Herein, a transcriptome analysis was performed to determine the transcriptional changes during flower development in red-flesh pitaya by utilizing nine different stages of flower development. Result: A total of 95,412 unigenes were generated with a mean length of 913 nt, and N50 value of 1878 nt. Comparative transcriptomic analysis showed many differentially expressed genes (DEGs) among the flower growth stages. Furthermore, an array of key DEGs were enriched in hormone signaling, transcription, carbohydrate transport, and energy production pathways. In particular, indole-3-acetic acid, abscisic acid, ethylene-responsive transcription factor, constans-like, teosinte branched 1/cycloidea/proliferating cell nuclear antigen factor, apetala1-like, agamous-like MADS-box protein, sepallata, growth-regulating factor, putative axial regulator yabby, leafy/floricaula homolog, and MYB gene-associated transcription factors displayed altered expression, suggesting their critical roles in floral organ development of pitaya. Besides, genes related to sugar synthesis, transportation, and utilization mediate flower growth regulation in pitaya. Eleven genes were selected to perform qRT-PCR analysis to verify the results of the RNA sequencing. Conclusions: Our results provide important insights into the transcriptional regulation of pitaya flower development. These data resources will be a cornerstone for future research that aims at exploring the genetic control of flower development in pitaya. How to cite: Wu Z, Huang L, Huang F, et al. Temporal transcriptome analysis provides molecular insights into flower development in red-flesh pitaya. Electron J Biotechnol 2022;58 https://doi.org/10.1016/j.ejbt. (c) 2022 Pontificia Universidad Catolica de Valparaiso. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

本文对农业农村部南宁火龙果种质资源圃从我国广西、广东、海南、福建、上海、云南、贵州、台湾等省(区)以及越南和以色列等地收集引进的359份资源进行鉴定分析,将相关资源数据通过建立数据库形式进行共享应用.火龙果种质资源数据库基于B/S三层网络架构,采用ASP.NET和SQL Server2008数据库技术和领域驱动模式进行开发.系统录入各火龙果种质资源相关数据,包括基本信息、植物学性状、农艺性状、果实品质等,系统具有数据可视化管理、检索、图片管理等功能.数据库的构建与应用,旨在实现火龙果种质资源信息化、规范化、标准化管理,提升火龙果种质资源信息共享利用率,为火龙果育种和产业发展提供助力.

'美龙1号'是由哥斯达黎加火龙果原生种(Hylocereus costaricensis)和越南白肉品种'白玉龙'(Hylocereus undatus)杂交后代中选出的红肉火龙果新品种.果实长椭圆形,鳞片绿色,果皮鲜红色,果肉大红色;平均单果质量525 g,中心可溶性固形物含量20.1％,可食率76％,肉质脆爽、清甜多汁、微香,品质优.果实生育期为30～50d,末批次果成熟时间为12月下旬.植株成花能力强,自花亲和性好,丰产稳产,适合广西桂南以及生态条件相似地区栽培.

Pitaya (Hylocereus undatus) is one of the most economic fleshy fruit tree crops. This study aimed at producing a high-density linkage genetic map of pitaya based on the whole genome resequencing (WGrS) approach. For this purpose, a bi-parental F1 population of 198 individuals was generated and genotyped by WGrS. High-quality polymorphic 6434 single polymorphism nucleotide (SNP) markers were extracted and used to construct a high-density linkage map. A total of 11 linkage groups were resolved as expected in accordance with the chromosome number. The map length was 14,128.7 cM with an average SNP interval of 2.2 cM. Homology with the sequenced reference genome was described, and the physical and genetic maps were compared with collinearity analysis. This linkage map in addition to the available genomic resources will help for quantitative trait mapping, evolutionary studies and marker-assisted selection in the important Hylocereus species.

火龙果为仙人掌科量天尺属和蛇鞭柱属植物,不同类型火龙果种质的染色体倍性尚不明确.为明确所收集的种质资源以及创制的新材料的染色体倍性,利用流式细胞技术对29份火龙果材料进行了倍性鉴定.结果显示,供试的18份种质资源中共鉴定出二倍体火龙果14份,四倍体4份,无三倍体材料.通过不同倍性亲本杂交和秋水仙素诱变所创制的8份后代材料经鉴定发现有二倍体材料1份,三倍体材料3份,四倍体材料4份,这表明火龙果属间杂交和化学诱变可获得多倍体材料.研究结果对火龙果资源的遗传学评价以及开展倍性杂交育种提供重要的参考依据.

以"紫龙"与"武鸣-4"火龙果及其杂交后代为试材,测定亲本及其杂交后代果实的主要性状,并对其遗传倾向进行分析.结果表明:单果质量、果形指数、皮厚、可食率和可溶性固形物含量呈连续变异,属数量性状遗传.单果质量遗传传递力低,变异系数大,整体呈趋小回归.果形指数、皮厚、可食率和可溶性固形物含量表现较高的遗传传递力.果形指数呈超高亲遗传趋势.可溶性固形物含量表现一定的杂交优势.杂交后代果肉颜色分离出紫红色、白色、红白双色及粉色4种类型,分别占41.63％、30.62％、15.79％和11.96％.果肉风味分离为甜、清甜、淡味或稍甜、蜜甜及甜带微酸,分别占39.23％、33.97％、10.53％、9.09％,7.18％.

对火龙果种质资源花表型性状的多样性及其与结果性状的相关性进行观察分析.结果表明:火龙果种质资源花盛开时的柱头与花药相对位置、柱头打开程度、花粉量、花的香气4个描述性状的Simpson指数为0.224～0.604,花朵长度、花冠直径、柱头与花药高度差、柱头裂条长度4个数量性状的遗传变异系数在0.08～0.96之间,存在着极为丰富的遗传多样性;火龙果自然坐果率、果实大小、商品果率与花盛开时的表型性状呈显著相关性,花盛开时柱头与花药相对位置和高度差、柱头裂条长度、花粉量等性状与自然坐果率和果实大小有密切相关性,是选育种中需要考量的重要指标.

为明确火龙果种质资源的遗传多样性水平和亲缘关系,以69份火龙果核心种质为研究对象,采用ISSR分子标记进行火龙果遗传分析.结果表明:13条ISSR引物共检测到247个位点,其中多态性位点数为232个,多态性条带百分比(PPB)为93.93％,平均多态性信息含量(PIC)为0.9189;平均观测等位基因数(Na)为1.9084,有效等位基因数(Ne)为1.4606,期望杂合度(He)为0.2750,Nei氏基因多样性(H)为0.2616,香农信息指数(I)为0.4190.火龙果种质资源的遗传距离为0.0707?0.6741.基于遗传距离聚类分析结果,火龙果种质资源分为6大类群,第Ⅰ类群为红皮白肉类型,包括25份种质;第Ⅱ类群有19份种质,全部为红肉或紫红肉类型,包括红皮、青皮、橘黄皮类型;第Ⅲ类群包含类型较杂,包括粉肉、双色类型和水晶系列品种;第Ⅳ大类为黄皮白肉类型;第V类和第Ⅵ类群均仅有一个种质,单独自聚一类.研究结果为火龙果种质资源的分类、保存与利用、遗传进化等研究及杂交组合选配提供理论指导和技术支持.

为探寻火龙果种子最佳的贮藏温度及贮藏期,以低温恒湿种质库为平台,以贮藏温度为环境因素,探究8、4、-1、-10℃低温冷藏和室温(25～30℃)贮藏下3个火龙果品种的种子萌发及幼苗生长特性随贮藏时间延长的变化规律.结果 表明,随着贮藏时间延长,3个火龙果品种的种子发芽率、发芽指数、健康幼苗率、苗高和10苗鲜重变化趋势基本一致,均呈现下降趋势.火龙果种子冷藏367 d后,发芽率由100％降低至92.33％～98.00％,室温处理降为54.00％～86.33％;冷藏种子健康幼苗率由96.33％～98.00％降低至77.33％～97.33％,室温处理降为12.00～68.33％.各低温贮藏的3个火龙果品种的发芽率、发芽指数、健康幼苗率和苗高在储藏367 d内基本明显高于室温.8℃贮藏的3个品种的发芽率与其他低温之间差异均不显著,而在贮藏367 d时发芽指数明显低于其他低温处理.说明-10～8℃低温贮藏均可显著延长火龙果种子活力及贮藏时间.综合考虑成本等因素,采用4℃下干燥贮藏火龙果种子为佳,贮藏1年种子发芽率均可保持在90％以上,健康幼苗率在85％以上.

为了解不同量天尺(火龙果)品种根部内生真菌菌群组成及多样性,采集GHL-1、GHL-2、GHL-3、ML-1和DL5个量天尺品种健康根部样品,进行内生真菌分离,采用形态观察和ITS序列分析相结合的方法进行鉴定、归类.共分离得到内生真菌菌株117株,总体分离率为25.71％,分别隶属于13个属,其中Trichoderma、Fusarium、Chaetomium和Phoma为量天尺内生真菌的优势种群,分别占总菌株数的24.79％、35.04％、10.26％和10.26％;不同量天尺品种内生真菌的结构和组成存在一定差异,GHL-2、GHL-3和DL 3个品种中分离频率最高的内生真菌类群为Fusarium,GHL-1和ML-1分离频率最高的类群为Trichoderma;多样性分析结果反映出不同量天尺品种内生真菌菌群的多样性指数、丰富度指数和均匀度指数水平存在差异,其中GHL-2的3项指数均为最高.表明品种差异对内生真菌的组成和多样性均有影响.

为探究碳离子束辐照对火龙果种子的损伤效应并且确定适宜的诱变辐照剂量,以红肉火龙果种子为试材,采用5个不同剂量(0、15、30、45、60 Gy)的碳离子束12C6+进行辐照处理,观察其对火龙果种子萌发、存活率及幼苗生长的影响.结果表明,12C6+离子束在辐照剂量0～60 Gy内大多数种子均能正常萌发,对发芽率的影响不大,而对发芽势和发芽指数存在一定的抑制作用;对幼苗苗高具有显著的促进作用,而对根长、子叶长和宽均呈现不同程度的抑制作用.碳离子束辐照对火龙果幼苗存活率的影响具有极显著的剂量效应,随剂量升高而极显著下降.火龙果种子碳离子束辐照的半致死剂量(LD50)为24 Gy,建议适宜辐照剂量范围为15～30 Gy.

为探讨适用于高温高湿地区的火龙果果袋,以红皮红肉型'桂红龙2号'火龙果为材料,测定5种不同类型果袋套袋后袋内温湿度日变化及对火龙果果实品质、果实病害以及采后果实失水率等的影响.结果表明,套袋后袋内温度升高速度更快,白天袋内温度均显著高于对照;套袋使果皮变薄,增加可食率,促进了果皮鳞片转红,以牛皮纸袋为最高;套袋显著增加了果皮与果肉的色素含量;显著增加了果实可溶性固形物含量,不同程度的提高了葡萄糖和果糖的含量;但套袋也提高了果实苹果酸及柠檬酸的含量.套袋总体上降低了采后水分散失的程度,白色纸袋和无纺布袋有利于降低采后病害发生率,延长货架期.除黑色尼龙网袋以外,套袋均提高了果实煤烟病的发病率.综上,在广西南宁周边高温高湿地区,可使用黑色尼龙网袋,有利于防止鸟啄和虫害,或使用白色纸袋和无纺布袋,有利于延长货架寿命,但采收后要注意煤烟斑的清洗.

以“大红”红肉火龙果结果树为观测研究对象,对全年现蕾盛花成熟批次进行命名,通过周年生长动态观测,明确了各批次花和果实的抽生发育时间节点.为方便栽培管理,将结果树的年生长周期划分为相对休眠期、新梢生长期、第一茬花果发育期、第二茬花果发育期、第三茬花果发育期共5个发育阶段;单茬花果发育期又分为“恢复—现蕾—开花—成熟”4个发育小阶段.在试验基础上,结合多年栽培管理经验,集成总结出以“补光延长光照与持续去蕾疏花”为关键调控措施的红肉火龙果一年三茬(熟)栽培周年栽培技术.该技术的应用可缓解不同火龙果产区自然成熟上市日期和产量同步性高,鲜果上市高峰期与市场需求匹配度较低的问题,具有较高的推广应用价值.

以145份火龙果种质资源为研究对象,基于从200对EST-SSR引物中筛选出的20对核心引物,通过荧光毛细管电泳技术检测分析扩增产物片段大小,应用基因型编码方法构建火龙果种质资源的分子身份证.结果 表明,20对SSR引物共检测到等位基因数(Na) 117个和带型(基因型)231个,平均每个引物扩增等位基因数(Na) 5.9个,扩增基因型为11.6个,平均有效等位基因数(Ne)为4.03个,平均多态性信息含量(PIC)为0.688.采用个位数字和小写英文字母对不同带型进行编码,成功构建了145份火龙果种质资源的分子身份证,实现不同种质的有效区分.

对农业部南宁火龙果种质资源圃内不同来源地的218份火龙果种质的果实形状、果皮果肉颜色、果实大小、可溶性固形物、可食率、果肉质地和风味等8个果实品质性状进行了鉴定评价和分析.结果 表明,供试种质果实形状从扁圆形到长椭圆形,果皮颜色从玫红色到暗紫红色,果肉颜色从白色到深紫红色,果肉质地从软绵到较粗、从细滑到较紧实,果肉风味从较淡到蜜甜、从甜酸到微酸,单果质量89.62～554.83 g,果肉中心部位可溶性固形物含量10.7％～22.5％,果实可食率50.97％～81.54％,果实品质评价等级从较差到优良均有分布.果实的单果质量、果肉中心部位可溶性固形物、果实可食率3个数量性状的变异系数和多样性指数(H')分别为36.89％、9.21％、8.23％和2.039 1、2.039 7、1.979 7,火龙果种质资源之间果实品质性状表现出不同变异和多样性.

在执行农业部项目的过程中,根据火龙果种质的特征特性和田间调查实际情况,对植物学、生物学和农艺等性状记载和描述规范开展了研究.初步确定记载和描述的主要内容由植株、茎蔓、花、果实的60个形态特征、18个农艺性状、26个果实品质性状和6个抗性性状组成,初步建立火龙果种质资源性状记载和描述评价体系,可为火龙果种质资源调查收集、保存和利用提供参考.

针对传统的火龙果杂交育种模式存在的育种周期长、优选单株不易保持健康性、育种占地多管理不便以及成本高见效慢等缺陷,本文介绍一种可移动箱式标准化保存火龙果种质及实生苗的新模式,包括设施设备要求、结构参数、外界环境及关键栽培技术措施等.该模式配合人工气候室催花、高位嫁接缩短童期快速鉴定杂交后代等技术的应用,可缩短从种质资源至杂交配种所需时间并方便管理操作,还能加速杂交后代实生苗脱离童期阶段,使火龙果的传统育种杂交周期世代由原来的24～36个月缩短至8个月左右,并可保持优选实生苗单株的健康性.