Biochemical and molecular identification of Enterococcus spp. from red pitaya

Red pitaya is a popular fruit worldwide due to its unique appearance and high nutrient contents. Many studies about the nutritional content and the physico-chemical characteristics of red pitaya have been performed but microorganisms that occurred naturally in the fruit remained unknown. Therefore, this study was conducted to characterize the enterococci present in red pitaya. Enterococci were isolated from red pitaya fruit and characterized with biochemical tests, randomly amplified polymorphic DNA (RAPD) and restriction fragment length polymorphism (RFLP) of the 16S rDNA region. A total of 30 bacteria were isolated from red pitaya, of which 20 isolates were confirmed as enterococci, genus Enterococcus. 13 isolates were further confirmed as Enterococcus casseliflavus and 7 were identified as Enterococcus gallinarum.     

火龙果愈伤组织诱导与植株再生

为了建立火龙果愈伤组织诱导与植株再生体系,以火龙果茎段、幼苗和子叶为外植体进行离体培养试验。结果表明：茎段诱导愈伤组织的最优培养基为1／2MS＋2,4-D2．0mg·L^-1＋6-BAO．5mg·L^-1,诱导子叶愈伤组织的最适培养基是1／2MS＋2,4-D2．0mg·L^-1＋6-BA1．0mg·L^-1,诱导愈伤组织分化的最优培养基为1／2MS＋6-BA4．0mg·L^-1＋NAA0．5mg·L^-1,最佳生根培养基为1／2MS＋6．BA1mg·L^-1＋NAA0-3mg·L^-1。     

外源ABA对低温胁迫下火龙果苗活性氧代谢的影响

为了探讨外源ABA对火龙果苗活性氧(ROS)代谢的调控作用,阐明ABA提高火龙果耐寒性的机理,以‘台湾6号’红心火龙果扦插苗为材料,用150mg/L的ABA预处理后,进行10d的低温胁迫(8℃/0℃,12h/12h),测定火龙果苗相关生理指标。结果表明,(1)低温胁迫后,火龙果苗出现水渍状斑点及萎焉黄化等寒害症状,寒害指数达0.52,而外源ABA处理使寒害指数降低至0.20。(2)低温胁迫使火龙果苗O_(2)^(·)产生速率和H_(2)O_(2)含量显著增加,丙二醛(MDA)含量及相对电导率(REC)也显著升高;外源ABA显著降低了H_(2)O_(2)含量、MDA含量和REC。(3)火龙果苗SOD、POD、CAT活性在低温胁迫下显著增强,外源ABA使这些酶活性进一步增强。(4)低温胁迫使火龙果苗APX、DHAR、GR及MDHAR活性显著增加,As A、GSH、DHA、GSSG含量也显著提升,但As A/DHA和GSH/GSSG比值下降;外源ABA可显著提高APX、GR及MDHAR活性,增加As A、GSH含量,并提高As A/DHA、GSH/GSSG比值。可见,外源ABA处理能增加火龙果苗抗氧化酶活性和As A-GSH循环的代谢活性,增强ROS的清除能力,减轻膜脂过氧化程度和电解质外渗,有效缓解火龙果苗受到的寒害。     

补光对大棚火龙果冬季促花的影响

为探讨夜间补充光照对大棚火龙果冬季植株促花的效应,以2年生‘短芯’红肉(心)火龙果植株为试材,每天夜间补光6 h,以不补光为对照,观测火龙果枝条抽蕾状况。结果显示,在平均光强500 lx、每天补充光照6 h、连续补光45 d条件下,第一批次植株抽生花蕾率达83.3%,老枝(枝龄≥12个月)抽生花蕾率为15.2%,青枝(枝龄＜12个月)抽生花蕾率为28.0%,抽生花蕾枝条占植株总枝条数的21.4%;枝条花蕾数占枝条上芽点数的比率,老枝为2.7%、青枝为2.9%。而对照植株没有抽生花蕾,抽蕾率为0。表明夜间补充光照可有效地促进大棚火龙果冬季植株抽花。     

火龙果茎基因组DNA提取方法改良

火龙果(Hylocereus undulatus)是近年发展起来的一种新兴热带水果, 其茎富含多糖、多酚及其它次生代谢物, 黏性极大, 很难从中提取高质量的DNA。特别是一年生以上的老茎, 目前尚未有较好的DNA提取方法。为了解决这一难题, 该研究对CTAB+Tris-HCl洗涤法进行了3种方式的改良。结果表明, “改进三”方法可不受取样时期和取样部位的限制, 从一年生以上火龙果茎中提取的DNA质量最好且不含黏性物质, 可用于酶切与分子标记等生化和分子生物学实验。该研究探索了一条较为理想的火龙果茎DNA提取方法, 值得推广应用。     

火龙果溃疡病防治药剂的筛选

火龙果溃疡病是火龙果生产中常见的病害之一,对火龙果产量和品质的影响较大,近年来火龙果溃疡病的发生频率逐年增加.本研究通过菌丝生长抑制法测定9种杀菌剂对火龙果溃疡病病菌的杀菌活性.结果表明,戊唑·咪鲜胺、肟菌·戊唑醇、吡唑·毒氟磷有较强的抑菌作用,EC50分别为0.0209,0.0762,2.0358mg/L,本研究为生产上防治火龙果溃疡病药剂的筛选提供了参考.     

发育期火龙果内参基因的筛选和验证

[目的]筛选火龙果果实发育期稳定表达的内参基因。[方法]以火龙果不同发育时期的果实为材料,利用qRT-PCR技术检测17个看家基因的表达水平,借助ge Norm和Norm Finder筛选出果实发育期理想的内参基因。[结果]Ge Norm评估YLS8和ACT并列排名第一,表达稳定值均为0. 221,配对差异值V_2/3为0. 105; Norm Finder排名前两名为TBP2和YLS8,表达稳定值为0. 160和0. 191。使用内参基因YLS8和TBP2分析火龙果甜菜色素合成途径关键基因HpCytP450-like1的表达水平,与基因Hp Cyt P450-like1在火龙果果实发育期表达趋势一致。[结论]从17个候选基因中筛选出2个理想的的内参基因YLS8和TBP2,可作为火龙果果实发育期相关基因的表达调控研究。     

Genetic relationships among Hylocereus and Selenicereus vine cacti (Cactaceae): evidence from hybridization and cytological studies

BACKGROUND AND AIMS: Hylocereus and Selenicereus are native to tropical and sub-tropical America. Based on its taxonomic status and crossability relations it was postulated that H. megalanthus (syn. S. megalanthus) is an allotetraploid (2n = 4x = 44) derived from natural hybridization between two closely related diploid taxa. The present work aimed at elucidating the genetic relationships between species of the two genera. METHODS: Crosses were performed and the putative hybrids were analysed by chromosome counts and morphological traits. The ploidy level of hybrids was confirmed by fluorescent in situ hybridization (FISH) of rDNA sites. Genomic in situ hybridization (GISH) was used in an attempt to identify the putative diploid genome donors of H. megalanthus and an artificial interploid hybrid. KEY RESULTS: Reciprocal crosses among four diploid Hylocereus species (H. costaricensis, H. monacanthus (syn. H. polyrhizus), H. undatus and Hylocereus sp.) yielded viable diploid hybrids, with regular chromosome pairing. Reciprocal crosses between these Hylocereus spp. and H. megalanthus yielded viable triploid, pentaploid, hexaploid and aneuploid hybrids. Morphological and phenological traits confirm the hybrid origin. In situ detection of rDNA sites was in accord with the ploidy status of the species and hybrid studied. GISH results indicated that overall sequence composition of H. megalanthus is similar to that of H. ocamponis and S. grandiflorus. High sequence similarity was also found between the parental genomes of H. monacanthus and H. megalanthus in one triploid hybrid. CONCLUSIONS: The ease of obtaining partially fertile F1 hybrids and the relative sequence similarity (in GISH study) suggest close genetic relationships among the taxa analysed.     

基于转录组的不同火龙果品种抗性差异分析

不同的品种抗性不同,为进一步探究不同火龙果品种之间的抗性差异,为后续火龙果抗性育种提供参考,该研究利用Illumina HiSeq 2000测序平台对'普通白肉'(BR)和'厄瓜多尔黄龙'(EY)两个品种进行转录组测序分析,并参考GO Ontology、KEGG等公共数据库对差异表达基因进行功能分类与富集分析.结果表明...     

Seed hydration memory in Sonoran Desert cacti and its ecological implication

Cactus seeds on the soil surface in the desert are subjected to periods of drought that last for up to a few months, and thus they are typically under discontinuous hydration (or discontinuous dehydration). Apparently, they can tolerate long periods of dehydration after single or multiple hydration events and subsequently germinate in accordance with the previous hydration experience. This was verified in three cactus species from the Sonoran Desert. Seeds of Stenocereus thurberi hydrated for 72 or 80 h followed by a dehydration period lasting for 4, 14, 70, 120 or 181 d germinated 2–3 d earlier and had 1.4–2 times shorter mean germination time (MGT) than untreated seeds. Seeds given shorter hydration periods also began to germinate sooner than the controls. MGT was shorter only when the hydration period was 48 h or longer. Final germination percentages were not affected by these treatments, only the MGT. Except for differences in germination percentages, similar results were found for Pachycereus pecten-aboriginum and Ferocactus peninsulae. When the cycle of 24 h hydration followed by 4 d dehydration was repeated one or two times, the effect was cumulative: MGT was equal to 48 and 72 h hydration, respectively. These results suggest a phenomenon of “seed hydration memory,” the ability of seeds to retain during dehydration periods those physiological changes that result from seed hydration. Thus, treated seeds subsequently germinated earlier then untreated seeds, regardless of the duration of dehydration period. This led to a greater biomass accumulation and thus to higher survival in seedlings from treated than from untreated seeds.