番茄果实成熟软化过程中细胞壁作用机制研究进展

番茄是研究果实成熟的重要模式作物,细胞壁结构和成分的改变是造成果实成熟变软的重要因素,综述了果实成熟过程中细胞壁各种相关基因、酶和转录因子的功能和研究进展,旨在构建番茄果实成熟软化中的细胞壁作用机制相关调控网络,为增强果实耐贮性方面的相关研究提供参考.     

果实成熟软化机理分子生物学的研究进展

果实成熟软化是一个复杂的发育调控过程,其间经历了一系列生理生化变化,同时概述了果实成熟软化过程中相关酶及乙烯等因素分子生物学方面的研究进展.     

微藻油脂合成与调控的生化及基因工程研究进展

微藻可作为一种新型的生物柴油原料。对微藻油脂积累和代谢调控的了解有助于利用微藻生产生物柴油。本研究综述了生化工程及基因工程对微藻油脂合成与调控的研究进展,包括营养控制、光照、温度等对微藻油脂积累的影响;脂肪酸、三酰甘油合成过程中一些关键酶基因及转录因子的遗传操作在微藻油脂合成和积累过程中的作用等。氮营养缺乏是生化工程中最有效的提高微藻含油量的方法;参与脂肪酸、三酰甘油合成过程中的关键酶,如乙酰辅酶A羧化酶、甘油-3-磷酸脱氢酶、二脂酰甘油酰基转移酶一些关键酶基因及转录因子Dof4、bHLH的遗传操作都能大幅提高微藻油脂含量。对微藻油脂代谢的研究前景做了进一步的展望。     

果实成熟及品质调控遗传研究进展

果实的成熟涉及许多生物化学变化过程,主要包括香气、糖的产生以及果实软化等,这与果实在成熟过程中所发生的一系列代谢路径密不可分。因此,研究并了解果实成熟过程及品质调控遗传学机理,对于果实品质改良具有重大意义。本综述将结合近年来国内外果实成熟及品质改良遗传研究现状,对果实成熟变化遗传分析研究中的代谢路径、果实品质改良遗传规律、品质QTL等进行综述,旨在为果树品质育种研究提供技术参考。     

华中农业大学在番茄红素生物合成代谢研究上取得突破

<正>番茄红素是植物中所含的一种天然色素,主要存在于番茄等成熟果实中,具有极强的抗氧化功能,可清除人体内自由基。早在上世纪60年代,研究人员就针对番茄果实中番茄红素的合成代谢展开了系统而深入的研究,鉴定出番茄果实中番茄红素的生物合成和代谢途径及其限速酶,但对番茄红素生物合成和代谢的调控机制的研究一直都没有重大进展,提升番茄果实番茄红素含量的研究进展也十分缓慢。     

转录因子对果实发育成熟及品质形成调控研究进展

水果在人们日常饮食中占有十分重要的地位。果实的发育、成熟及品质形成一直是研究的热点。果实的发育、成熟及品质形成是众多转录因子综合调控的结果。转录因子对果实发育、成熟及品质形成的调控的综述有利于全面了解果实品质形成及调控的基本规律,为果实品质遗传改良提供一定的理论依据。     

哺乳动物卵母细胞成熟及调节机制

哺乳动物卵母细胞的成熟是一个复杂的生理生化过程,包括核成熟和胞质成熟。对卵母细胞研究发现,卵母细胞成熟后表现出一些特征性变化,可作为判断卵母细胞成熟的标志。进一步研究表明,卵母细胞的成熟过程受许多生化因子的调节。     

SPL调控因子在植物生长调控的研究进展

SPL(SQUAMOSA promoter-binding protein-like)是植物特有的转录因子,它参与了植物叶、花、果实的发育、发育阶段转变、花青素的合成以及胁迫应答等调控过程。SPL转录因子家族成员均含有高度保守的SBP结构域,可以特异性结合所调控基因启动子的顺式作用元件,还可与其它调控蛋白相互作用,共同调控相关基因的表达。另外,SPL在转录后水平还受miRNA156/miRNA157的负调控。本研究从SPL调控因子在植物形态建成、次生代谢、生理胁迫中的表达调控研究进展方面进行综述。     

外源硒对植物抗盐性的影响研究进展

硒作为营养元素,能够参与调控植物抗盐的生理生化代谢过程。本文就硒对植物生长发育的影响、吸收转运及提高植物抗盐性的作用机制3个方面作了总结,并对下一步的研究和应用进行了展望,以期为硒调控植物抗盐的生理生化代谢过程提供理论依据。     

温度对植物花青素苷合成影响研究进展

为了探明温度对植物花色呈色的影响,归纳了温度在植物花青素苷合成过程中的重要作用,总结了温度通过多种途径影响花青素苷的合成,分析了温度对植物花青素苷生理代谢、稳定性及关键色素酶活性的影响。认为温度在花青素苷的合成途径中以对关键色素酶活性的影响最大,指出花青素苷合成过程受多重因子影响,要探明植物呈色机制还应综合大量单因子及多因子的研究。     

A note on the origin of Kalanchoë x vadensis Boom & Zeilinga (Crassulaceae)

Summary K x vadensis is a hybrid of K. blossfeldiana and K. marmorata obtained after doubling the number of chromosomes.     

Mechanisms and diversity of resistance to sorghum shoot fly,Atherigona soccata

Sorghum shoot fly, Atherigona soccata, is one of the important pests of postrainy season sorghums. Of the 90 sorghum genotypes evaluated for resistance to this pest, RHRB 12, ICSV 713, 25026, 93046 and 25027, IS 33844‐5, Giddi Maldandi and RVRT 3 exhibited resistance in postrainy season, while ICSB 463, Phule Anuradha, RHRB 19, Parbhani Moti, ICSV 705, PS 35805, IS 5480, 5622, 17726, 18368 and 34722, RVRT 1, ICSR 93031 and Dagidi Solapur showed resistance in rainy season, suggesting season‐specific expression of resistance to A. soccata. ICSB 461, ICSB 463, Phule Yasodha, M 35‐1, ICSV 700, 711, 25010, 25019 and 93089, IS 18662, Phule Vasudha, IS 18551 and 33844‐5 and Barsizoot had fewer deadhearts than plants with eggs across seasons, suggesting antibiosis as one of the resistance mechanism. Five genotypes exhibited resistance with high grain yield across seasons. Correlation, path and stepwise regression analyses indicated that leaf glossiness, seedling vigour, trichome density, oviposition and leaf sheath pigmentation were associated with the expression of resistance/susceptibility to shoot fly, and these can be used as marker traits to select and develop shoot fly‐resistant sorghums.     

Reaction of tritordeum to Fusarium culmorum and Septoria nodorum

Summary Hordeum chilense is a wild barley extensively used in wide crosses in the Triticeae. It could be a valuable source of resistance to Fusarium culmorum and Septoria nodorum. Some H. chilense x Triticum spp. amphiploids, named tritordeums, were more resistant than the parental wheat line to these diseases, others were not. Average contents of ergosterol and deoxynivalenol (DON) suggested that resistance to colonization by Fusarium was the highest for Hordeum chilense, followed by tritordeum and wheat in decreasing order. In particular, the H. chilense genotypes H7 and H17 enhanced the wheat resistance to F. culmorum in its tritordeum offsprings. Resistance to S. nodorum in tritordeum was not associated with tall plant height. There is sufficient genetic variation for resistance to F. culmorum and S. nodorum among tritordeum to allow the breeding of lines combining short straw and resistance to both diseases.     

Avoidance of leaf rust fungi in wild relatives of cultivated cereals

Summary Avoidance of rust fungi that was based on poor appressorium induction was previously found in Hordeum chilense. In the present study 95 accessions of Triticeae were screened for avoidance of Puccinia hordei. The percentage of appressorium formation per germinated spore ranged from 6 to 90%. On none of the 41 accessions of Aegilops, Agropyron, Elymus, Secale, Thinopyrum or Triticum studied was the rate of appressorium formation lower than 25%. Lower rates of appressorium formation were, however, found on accessions of wild barley species Hordeum brachyantherum, H. marinum, H. parodii and H. secalinum. Its implications in cereal breeding are discussed.     

Disease resistance in protected crops and mushrooms

Summary Cultivars of tomatoes, cucumbers, lettuce and peppers have been bred for resistance to one or more pathogens. Some tomato and cucumber cultivars have resistance to a wide range of diseases. Resistance has been transient in many cases and a succession of cultivars with new genes or new combinations of resistance genes has been necessary to maintain control. There has been a number of notable exceptions and these have included durable resistance to such pathogens asFulvia fulva and tomato mosaic virus. With lettuce the resistance situation is complicated by the occurrence of fungicide resistant pathotypes. There are no strains ofAgaricus bisporus purposely bred for disease resistance.In protected flower crops only resistance to Fusarium wilt in carnations has been purposely bred but differences in disease resistance are apparent in cultivars of many ornamental crops. This is particularly so in chrysanthemums where there are cultivars with resistance to many of the major pathogens. Similar situations occur with other flower crops and pot plants. Cultivars of some species have not been systematically investigated for resistance.The need for genetic resistance will increase with the further reduction, in the limits on pesticide use and an increasing public awareness and importance of pesticide pollution.ADAS is an executive agency of the Ministry of Agiculture, Fisheries and Food and the Welsh Office.     

Genetic constitution and diversity in four narrow endemic redwoods from the family Cupressaceae

The genetic constitution and diversity of four relictual redwoods are discussed in this review. These include monotypic genera of the family Cupressaceae: coast redwood (Sequoia sempervirens), giant sequoia (Sequoiadendron giganteum), dawn redwood (Metasequoia glyptostroboides), and alerce (Fitzroya cupressoides). All four species are narrow endemics, share a number of common phenotypic traits, including red wood, and are threatened species. Fossil history suggests that the ancestors of redwoods probably originated during the Cretaceous and Tertiary periods and flourished thereafter for millions of years. Towards the end of the Tertiary period began their decline and struggle for existence that continued during the subsequent geologic upheavals and climate changes, until the survival of the present-day redwoods in the current restricted locations in the world (USA, China, and South America). Although two species, Sequoiadendron and Metasequoia, are diploids (2n = 22), and the other two are polyploids: Fitzroya a tetraploid (2n = 4x = 44), and Sequoia a hexaploid (2n = 6x = 66); they all share the same basic chromosome number x = 11. The genome size in the hexaploid Sequoia is one of the largest (31,500 MB) in the conifers, while the genome sizes of diploid Metasequoia and Sequoiadendron are about one-third (~10,000 MB) of Sequoia. Genetic diversity in the redwoods is lower than most other gymnosperms, except in Sequoia, which seems to rank near the upper quarter of the coniferous forest trees. Genomic research is sparse in the redwoods, and should be pursued for a better understanding of their genome structure, function, and adaptive genetic diversity.     

Distribution,ecology and reproductive biology of wild tomatoes and related nightshades from the Atacama Desert region of northern Chile

Over the past 20 years, several expeditions were made to northern Chile to collect populations of wild tomatoes (Solanum chilense, S. peruvianum) and allied nightshades (S. lycopersicoides, S. sitiens), and obtain information about their geographic distribution, ecology and reproductive biology. Restricted mainly to drainages of the Andean and the coastal cordillera, populations are geographically fragmented. The two nightshade species are rare and threatened by human activities. Adaptation to extreme aridity and soil salinity are evident in S. chilense and S. sitiens (the latter exhibits several xerophytic traits not seen in the tomatoes) and to low temperatures in S. lycopersicoides and S. chilense. All tested accessions are self-incompatible, with the exception of one S. peruvianum population collected at the southern limit of its distribution. Several distinguishing reproductive traits—anther color, attachment, and dehiscence, pollen size, and flower scent—suggest S. sitiens and S. lycopersicoides attract different pollinators than S. chilense and S. peruvianum. The four Solanum spp. native or endemic to Chile provide a variety of novel traits which, through hybridization and introgression with cultivated tomato, could facilitate development of improved varieties, as well as research on a variety of basic topics, including plant-pollinator interactions, abiotic stress responses, and evolution of reproductive barriers.     

The induction in vitro of adventitious shoots in Rosa

Summary Adventitious shoots were formed on excised leaves, roots and callus of Rosa persica x xanthina and on excised leaves of R. laevigata and R. wichuraiana on culture media that included BAP and NAA as growth regulators. Shoots formed freely on freshly cultured callus of R. persica x xanthina but their production declined in successive cultures and ceased after twelve weeks. Transplantation to soil was improved by rooting plantlets in cellulose plugs in vitro and transferring plantlets to soil while still in the plugs.     

The exploration of genetic resources of Portuguese cabbage and kale for resistance to several Brassica diseases

Summary Twenty three accessions of nine Portuguese cabbage and kale land races from different geographic origins were tested at the seedling stage for resistance to several important brassica diseases. Resistance to downy mildew (Peronospora parasitica), expressed as necrosis of the cotyledon mesophyll, was found in all the accessions. Type A resistance to cabbage yellows (Fusarium oxysporum f. sp. conglutinans race 1) was present in most of the landraces. Resistance to clubroot (Plasmodiophora brassicae race 6) was found in one accession of the Portuguese tree kale. High resistance to blackleg (Leptosphaeria maculans) and white rust (Albuco candida) was not detected, although several accessions showed 20 to 30% of plants with intermediate expression of resistance. All Portuguese cole accessions were susceptible to blackrot (Xanthomonas campestris pv. campestris).     

Production and characterization of intergeneric diploid cybrids derived from symmetric fusion between Microcitrus papuana Swingle and sour orange (Citrus aurantium)

Plants were regenerated from intergeneric somatic hybridization between embryogenic protoplasts of Microcitrus papuana Swingle and leaf-derived protoplasts of sour orange (Citrus aurantium L.) via electrofusion. The regenerated plants were morphologically similar to the leaf parent in growth vigor, leaf and branch structure. FCM analysis showed that they were diploids. Simple-sequence-repeat (SSR) and cleaved-amplified-polymorphic-sequence(CAPS) were employed for hybridity characterization. SSR banding patterns of the regenerated plants were identical to the leaf parent, sour orange, indicating that they possessed nuclear component derived from sour orange. DNA amplification with chloroplast and mitochondrial universal primers, followed by restriction endonuclease digestion, revealed polymorphism between the fusion parents. Therefore, this method was used to determine the cytoplasmic compositions of the regenerated plants. Banding patterns for all the polymorphic primer/enzyme combinations of the regenerated plants were similar to those of the embryogenic parent, M. papuana, suggesting that only the cytoplasmic components derived from the embryogenic parent were present in the regenerated plants. FCM, SSR and CAPS demonstrated that intergeneric diploid cybrids have been successfully obtained by symmetric fusion. Related results concerning nuclear and cytoplasmic composition of previous diploid somatic hybrids and potential mechanism for regeneration of such kind of plants are discussed herein. This revised version was published online in July 2006 with corrections to the Cover Date.