Tomato Fruit Development and Ripening Are Altered by the Silencing of LeEIN2 Gene

Loss-of-function ethylene insensitive 2 （EIN2） mutations showed ethylene insensitivity in Arabidopsis, which indicated an essential role of EIN2 in ethylene signaling. However, the function of EIN2 in fruit ripening has not been investigated. To gain a better understanding of EIN2, the temporal regulation of LeEIN2 expres- sion during tomato fruit development was analyzed. The expression of LeEIN2 was constant at different stages of fruit development, and was not regulated by ethylene. Moreover, LeEIN2-silenced tomato fruits were developed using a virus-induced gene silencing fruit system to study the role of LeEIN2 in tomato fruit ripening. Silenced fruits had a delay in fruit development and ripening, related to greatly descended expression of ethylene-related and ripening-related genes in comparison with those of control fruits. These results suggested LeEIN2 positively mediated ethylene signals during tomato development. In addition, there were fewer seeds and Iocules in the silenced fruit than those in the control fruit, like the phenotype of parthenocarpic tomato fruit. The content of auxin and the expression of auxin-regulated gene were declined in silenced fruit, which indicated that EIN2 might be important for crosstalk between ethylene and auxin hormones.     

Elevation-related variation in the population characteristics of distylous Primula nivalis affects female fitness and inbreeding depression

The population characteristics of distylous species are highly sensitive to stochastic natural selection pressure.Therefore,populations growing under different environmental conditions may vary in floral morph ratios,potentially affecting female fitness and leading to inbreeding depression.However,the variation in offspring quality among populations as a result of inbreeding depression is poorly understood in distylous species.This study investigates variations in plant density,seed mass,seed viabilityfemale fitness,and post-dispersal inbreeding depression in both sexual morphs(long-styled and shortstyled plants)of the distylous Primula nivalis that were subjected to different pollination treatments along an elevational gradient from 1657 to 2704 m a.s.l.Population characteristics(morph plant density and ratio)and fruit set were significantly affected by sexual morph and elevation.Plant density and fruitset frequencies were lower for short-styled than for long-styled plants at 2704 m a.s.l.The seeds from the cross-pollinated flowers of both morphs were higher in quality than those of self-pollinated flowers.The female fitness of seeds from cross-pollinated flowers of both morphs was higher than that of seeds from open-pollinated and self-pollinated flowers.The female fitness of seeds from long-styled flowers was higher than that of seeds from short-styled flowers at all elevations.Inbreeding depression increased with elevation among plants with short-styled flowers but not among those with long-styled flowers.Variation in the elevation-dependent mating system might influence female fitness and affect inbreeding depression in both floral morphs.In conclusion,the low quality of seeds from short-styled flowers at high elevations might decrease short-styled flower frequency,affecting population characteristics.     

Deletional analysis of functional regions of complementary sense promoter from cotton leaf curl virus

Complementary sense promoter from cotton leaf curl virus (CLCuV) is a novel plant promoter for genetic engineering that could drive high-level foreign gene expression in plant. To determine the optimal promoter sequence for gene expression, CLCuV promoter was deleted from its 5' end to form promoter fragments with five different lengths, and chimeric gus genes were constructed using the promoterdeletion. These vectors were delivered into Agrobacterium and tobacco (Nicotiana tabacum L cv. Xanthi) plants which were transformed by leaf discs method. GUS activity of transgenic plants was measured. The results showed that GUS activities with the promoter deleted to -287 and -271 from the translation initiation site were respectively about five and three times that of full-length promoter. There exists a c/s-element which is important for the expressing activity in phloem from -271 to -176. Deletion from -176 to -141 resulted in a 20-30-fold reduction in GUS activity in leaves with weak activity in leaves and     

Magnitude of modulation of gene expression in aneuploid maize depends on the extent of genomic imbalance

Aneuploidy has profound effects on an organism,typically more so than polyploidy,and the basis of this contrast is not fully understood.A dosage series of the maize long arm of chromosome 1(1L)was used to compa re relative global gene expression in diffe rent types and degrees of aneuploidy to gain insights into how the magnitude of genomic imbalance as well as hypoploidy affects global gene expression.While previously available methods require a selective examination of specific genes,RNA sequencing provides a whole-genome view of gene expression in aneuploids.Most studies of global aneuploidy effects have concentrated on individual types of aneuploids because multiple dose aneuploidies of the same genomic region are difficult to produce in most model genetic organisms.The genetic toolkit of maize allows the examination of multiple ploidies and 1-4 doses of chromosome arms.Thus,a detailed examination of expression changes both on the varied chromosome arms and elsewhere in the genome is possible,in both hypoploids and hyperploids,compared with euploid controls.Previous studies observed the inverse trans effect,in which genes not varied in DNA dosage were expressed in a negative relationship to the varied chromosomal region.This response was also the major type of changes found globally in this study.Many genes varied in dosage showed proportional expression changes,though some were seen to be partly or fully dosage compensated.It was also found that the effects of aneuploidy were progressive,with more severe aneuploids producing effects of greater magnitude.     

Computational and Structural Investigation of Deleterious Functional SNPs in Breast Cancer BRCA2 Gene

In this work, we have analyzed the genetic variation that can alter the expression and the function in BRCA2 gene using computational methods. Out of the total 534 SNPs, 101 were found to be non synonymous (nsSNPs). Among the 7 SNPs in the untranslated region, 3 SNPs were found in 5′ and 4 SNPs were found in 3′ un-translated regions (UTR). Of the nsSNPs 20.7% were found to be damaging by both SIFT and PolyPhen server among the 101 nsSNPs investigated. UTR resource tool suggested that 2 SNPs in the 5′ UTR region and 4 SNPs in the 3′ UTR regions might change the protein expression levels. The mutation from asparagine to isoleucine at the position 3124 of the native protein of BRCA2 gene was most deleterious by both SIFT and PolyPhen servers. A structural analysis of this mutated protein and the native protein was made which had an RMSD value of 0.301 nm. Based on this work, we proposed that this most deleterious nsSNP with an SNPid rs28897759 is an important candidate for the cause of breast cancer by BRCA2 gene.     

Pollen and Resource Limitation in Veratrum nigrum L. （Liliaceae）, an Andromonoecious Herb

Pollen limitation and resource limitation were invoked to account for the pattern that flowering plants produce more flowers and ovules than fruits and seeds. This study aimed to determine their relative importance in Veratrum nigrum, a self-compatible, perennial, andromonoecious herb. In order to determine whether female production was limited by pollen grains on stigmas or by available resources, we performed supplemental hand pollination in three populations, male-flower-bud removal in three other populations, and emasculation of hermaphroditic flowers in still another population, resulting in a total of seven populations experimentally manipulated. Across the three populations, supplemental hand pollination did not significantly increase fruit set, seed number per fruit, and total seed production per individual, nor did emasculation of hermaphroditic flowers. Taken together, our results suggest that pollen grains deposited on stigmas were abundant enough to fertilize all the ovules. Male-flower-bud removal significantly increased the mean size of hermaphroditic flowers in all three populations. Female reproductive success was increased in one population, but not in the other two populations possibly due to heavy flower/seed predation. We concluded that the female reproductive success of V. nigrum was not limited by pollen grains but by available resources, which is consistent with Bateman＇s principle. Furthermore, the female reproduction increase of male-flower-bud removal individuals might suggest a trade-off between male and female sexual functions.     

Analysis on virus resistance and fruit quality for T4 generation of transgenic papaya

Molecular biological characterization,fruit characters,and nutrients were analyzed for T4 generation of transgenic papaya.All transgenic papaya plants with the mutated replicase (RP) gene from papaya ringspot virus (PRSV) showed high resistance or immunity against PRSV in the field.The RP transgene can be steadily inherited to,and expressed at RNA level,the progenies.The growth characteristics of transgenic papaya were much better than nontransgenic papaya in the field.The non-transgenic papaya seedlings began to show typical symptoms caused by PRSV after being inoculated with PRSV.They died quickly and never grew to produce fruit.The adult trees developed yellow leaves and produced smaller fruits and were doomed to a slow death after some time,while most oftransgenic papaya plants (about 91.8%) did not show any symptoms caused by PRSV,and produced more,bigger,and high quality fruits.Compared with non-transgenic plants,the fresh fruit length of T4 generation of transgenic papaya increased 2.6%-5%,and the diameter decreased 0.6%-1.5%.The flesh thickness of fresh fruit increased 12%-15%,which made it fitter for eating.Although the fresh fruit quality changed,there was no significant difference between transgenic and non-transgenic papaya.The quality characteristics of dry fruit including the contents of water,lipid,N,protein,reduced sugar,vitamin A,vitamin C,and carotene in the T4 generation of transgenic papaya were all the same as their non-transgenic parents.This means that transgenic plants and non-transgenic plants are substantially equivalent,and the transgene has no effect on dry fruit quality.In this study,we found that vitamin A and vitamin C in red-fleshed papaya were 1.4-1.8 and 1.78-2.07 times more than the yellow-fleshed ones,respectively,while N and protein were only 84.2%-92.1% and 82.1%-98.9% of the yellow-fleshed ones.     

Analysis on virus resistance and fruit quality for T4 generation of transgenic papaya

Molecular biological characterization, fruit characters, and nutrients were analyzed for T4 generation of transgenic papaya. All transgenic papaya plants with the mutated replicase (RP) gene from papaya ringspot virus (PRSV) showed high resistance or immunity against PRSV in the field. The RP transgene can be steadily inherited to, and expressed at RNA level, the progenies. The growth characteristics of transgenic papaya were much better than non-transgenic papaya in the field. The non-transgenic papaya seedlings began to show typical symptoms caused by PRSV after being inoculated with PRSV. They died quickly and never grew to produce fruit. The adult trees developed yellow leaves and produced smaller fruits and were doomed to a slow death after some time, while most of transgenic papaya plants (about 91.8%) did not show any symptoms caused by PRSV, and produced more, bigger, and high quality fruits. Compared with non-transgenic plants, the fresh fruit length of T4 generation of transgenic papaya increased 2.6%–5%, and the diameter decreased 0.6%–1.5%. The flesh thickness of fresh fruit increased 12%–15%, which made it fitter for eating. Although the fresh fruit quality changed, there was no significant difference between transgenic and non-transgenic papaya. The quality characteristics of dry fruit including the contents of water, lipid, N, protein, reduced sugar, vitamin A, vitamin C, and carotene in the T4 generation of transgenic papaya were all the same as their non-transgenic parents. This means that transgenic plants and non-transgenic plants are substantially equivalent, and the transgene has no effect on dry fruit quality. In this study, we found that vitamin A and vitamin C in red-fleshed papaya were 1.4–1.8 and 1.78–2.07 times more than the yellow-fleshed ones, respectively, while N and protein were only 84.2%–92.1% and 82.1%–98.9% of the yellow-fleshed ones. Translated from Acta Ecologica Sinica, 2005, 25(12): 3301–3306 [译自: 生态学报]     

Genetic diversity of genes involved in the carotenoid pathway of <Emphasis Type="Italic">Carica papaya</Emphasis> L. and their expression during fruit ripening

The genetic variation of seven genes in the carotenoid biosynthetic pathway was investigated in thirteen papaya cultivars. DNA analysis revealed a total of 46 polymorphisms; 42 SNPs (29 positions in introns and 13 positions in exons) and four insertions/deletions. Six SNPs were transversions resulting in amino acid changes. Most variations were found in cpLCYE (21), followed by cpVDE (10). In cpLCYB and cpNCED3, only one polymorphism was found in each gene. Expression studies indicated the differential expression of caroteogenic genes in red, orange and yellow-fleshed papaya during ripening. At ripe stage, the expression level of cpZEP, cpLYCE, cpVDE, cpLCYB and cpNCED3 was higher in red-fleshed than in orange- and yellow-fleshed papaya. The expression level of cpBCH in ripe red-fleshed papaya was significantly lower than that of both orange and yellow-fleshed papaya. Yellow-fleshed papaya cv. Krung Yellow had highest level of beta-carotene at 1428 ± 32 µg/g FW. Lycopene content of red-fleshed papaya cv. Mexico was 1830 ± 208 µg/g FW was highest among the three cultivars. This study revealed DNA polymorphisms in cartenogenic genes among papaya cultivars and their differential expressions in red, orange and yellow-fleshed papaya correlated with carotenoid content and flesh colour.     

番木瓜果实扩展蛋白Cp-EXP1基因表达的荧光定量PCR分析

目的：对番木瓜果实扩展蛋白Cp-EXP1的基因进行荧光定量PCR分析,以便对其功能做进一步研究。方法：以不同成熟阶段的番木瓜果实总RNA为模板,设计引物进行荧光定量PCR。结果：Cp-EXP1基因在不同成熟阶段的番木瓜果实中的表达是有差异的,其表达水平受乙烯调控。结论：Cp-EXP1基因的表达与番木瓜的成熟软化密切相关,其表达分析为研究番木瓜的生长发育及其品种改良打下了良好的基础。     

Genetic engineering of parthenocarpic fruit development in tomato

Parthenocarpy was engineered in two genotypes of Lycopersicon esculentum Mill. by using the DefH9-iaaM chimeric gene. The parthenocarpic trait consists of fruit set and growth in the absence of fertilization. Seedless parthenocarpic fruits were obtained from emasculated flowers, and fruits with seeds from pollinated flowers. All parthenocarpic tomato plants analysed expressed the DefH9-iaaM gene during flower development. The fruit set percentage of emasculated transgenic flowers was similar to that of control plants. In 7 out of 8 independent transgenic plants, the fresh weight of fruits derived from pollinated or emasculated flowers did not significantly differ from that of fruits obtained by pollination of the control plants. The pH of the parthenocarpic fruit was generally unaffected and the soluble solid concentration was either unchanged or increased. Thus, the DefH9-iaaM gene is a genetic tool that might be used to improve tomato productivity.     

Cloning,expression and immunolocalization pattern of a cinnamyl alcohol dehydrogenase gene from strawberry (Fragaria x ananassa cv. Chandler)

Cinnamyl alcohol dehydrogenase (CAD; EC 1.1.1.195) catalyses the conversion of p-hydroxy-cinnamaldehydes to the corresponding alcohols and is considered a key enzyme in lignin biosynthesis. By a differential screening of a strawberry (Fragariax ananassa cv. Chandler) fruit specific subtractive cDNA library, a full-length clone corresponding to a cad gene was isolated (Fxacad1). Northern blot and quantitative real time PCR studies indicated that the strawberry Fxacad1 gene is expressed in fruits, runners, leaves, and flowers but not in roots. In addition, the gene presented a differential expression in fruits along the ripening process. Moreover, by screening of a strawberry genomic library a cad gene was isolated (Fxacad2). Similar to that found in other cad genes from higher plants, this strawberry cad gene is structured in five exons and four introns. Southern blot analyses suggest that, probably, a small cad gene family exists in strawberry. RT-PCR studies indicated that only the Fxacad1 gene was expressed in all the fruit ripening stages and vegetative tissues analysed. The Fxacad1 cDNA was expressed in E. coli cells and the corresponding protein was used to raise antibodies against the strawberry CAD polypeptide. The antibodies obtained were used for immunolocalization studies. The results showed that the CAD polypeptide was localized in lignifying cells of all the tissues examined (achenes, fruit receptacles, runners, leaves, pedicels, and flowers). Additionally, the cDNA was also expressed in yeast (Pichia pastoris) as an extracellular protein. The recombinant protein showed activity with the characteristic substrates of CAD enzymes from angiosperms, indicating that the gene cloned corresponds to a CAD protein.