Regulation of propylene-induced ripening and ethylene biosynthesis by oxygen in ‘Hayward’ kiwifruit

Kiwifruit, cv Hayward, were treated with 130 μl/l propylene under 1, 5, 10, 13, 16, and 21% O₂ concentrations in a continuous flow-through system at 20 °C. Control kiwifruit were kept in air (21%O₂). Flesh firmness, soluble solids content, internal ethylene concentration, l-aminocyclopropane-l-carboxylic acid concentration (ACC), malonyl-l-aminocyclopropane-l-carboxylic acid concentration (MACC), and EFE capacity were measured during the experiment. Ethylene biosynthesis and fruit ripening were stimulated when kiwifruit were exposed to a mixture of propylene in 21% O₂. Reduction of oxygen concentration (< 10%) inhibited the effectiveness of propylene on autocatalytic ethylene production possibly through a reduction in ACC concentration in the tissue. Exposure of kiwifruit to low oxygen concentrations (< 5%) delayed propylene-induced fruit ripening.     

Mode of action of nitric oxide in inhibiting ethylene biosynthesis and fruit softening during ripening and cool storage of ‘Kensington Pride’ mango

The mode of action of nitric oxide (NO) in inhibiting ethylene biosynthesis and fruit softening during ripening and cool storage of mango fruit was investigated. Hard mature green mango (Mangifera indica L. cv. ‘Kensington Pride’) fruit were fumigated with 20 μL L⁻¹ NO for 2 h at 21 °C and allowed to ripen at 21 ± 1 °C for 10 d, or stored at 13 ± 1 °C for 21 d. During ripening and cool storage, ethylene production and respiration rate from whole fruit were determined daily. The 1-aminocyclopropane-1-carboxylic acid (ACC) content, activities of ACC synthase (ACS), ACC oxidase (ACO), and fruit softening enzymes such as pectin esterase (PE), endo-1,4-β-d-glucanase (EGase), exo- and endo-polygalacturonase (exo-PG, endo-PG) as well as firmness and rheological properties of pulp were determined at two- and seven-day intervals during ripening and cool storage, respectively. NO fumigation inhibited ethylene biosynthesis and respiration rate, and maintained higher pulp firmness, springiness, cohesiveness, chewiness, adhesiveness, and stiffness. NO-fumigated fruit during cool storage and ripening had lower ACC contents through inhibiting the activities of both ACS and ACO in the fruit pulp. NO-fumigated fruit showed decreased activities of exo-PG, endo-PG, EGase, but maintained higher PE activity in pulp tissues during ripening and cool storage. In conclusion, NO fumigation inhibited ethylene biosynthesis through inhibition of ACS and ACO activities leading to reduced ACC content in the fruit pulp which consequently, reduced the activities of fruit softening enzymes during ripening and cool storage.     

Description of a new trans-generic <Emphasis Type="Italic">S</Emphasis>kb-RNase allele in apple

Polish apple cvs: ‘Ligol’, ‘Odra’ and ‘Primula’ served for studies of self-incompatibility. Basing on available sequence data, a new set of primers upstream and downstream of the hypervariable (HV) region of apple S-RNases were designed. Using the RT-PCR method, cDNA was amplified on RNA isolated from styles. PCR products were cloned and sequenced. A new trans-generic S-RNase allele, designated as Skb (GenBank accession no. EU443101), was discovered in cvs ‘Odra’ and ‘Primula’. Nucleotide sequence alignment revealed that Skb-RNase shows 98% identity to SaucS19-RNase from Sorbus aucuparia and 97% identity to CmonS17-RNase from Crataegus monogyna. The occurrence of extensive intergeneric hybridization among extant Pyrinae is considered since the deduced amino acid sequence of Skb-RNase from M. × domestica showed higher similarity to CmonS17 from C. monogyna, SaucS19-RNase from S. aucuparia, St from Malus transitoria, S5-RNase and S3-RNase from Pyrus pyrifolia, and S40-RNase from P. ussuriensis than to S-alleles from Malus × domestica and all of them are grouped in the same cluster of phylogenetic tree. In respect to extremely high similarities between aforementioned S-RNases it could be possible that these alleles existed before the separation of Malus, Pyrus, Sorbus and Crataegus genera. Within Malus, the Skb-RNase from M. × domestica and St-RNase from M. transitoria show 100% identity of the HV region at the deduced amino acid level, suggesting that these S-RNases diverged more recently than the other Malus S-RNases. In ‘Ligol’, the agronomically most important cultivar in Poland, the S2 and S9 were identified.     

Maturity assessment at harvest and prediction of softening in a late maturing nectarine cultivar after cold storage

The absorption coefficient μ_a measured at 670 nm in fruit pulp at harvest by time-resolved reflectance spectroscopy (TRS) has been shown to be a good maturity index for early nectarine cultivars. By including individual fruit maturity as a biological shift factor (BSF) into a kinetic model for softening it is possible to select fruit with different shelf-life potential. The BSF approach combined with TRS measurement and kinetic modeling of firmness was applied to a late maturing nectarine cultivar (‘Morsiani 90’), ripened at 20 °C after harvest or after storage at 0 °C and 4 °C, the latter conditions inducing chilling injury. At harvest the absorption coefficient μ_a had low values and low variability, indicating advanced maturity, while firmness was similar to that of early cultivars. The softening model took into account these differences, showing parameters similar to those of the early cultivars with the exception of the softening rate which was 2-6 times lower, indicating a slower softening in ‘Morsiani 90’ fruit. Decay of μ_a at 20 °C was also slower. Softening continued during storage at 4 °C, but not at 0 °C. After storage at 0 °C softening was resumed similarly to non-stored fruit, but with much variability. Fruit stored at 4 °C, which showed chilling injury, had a softening rate at 20 °C significantly higher than that of 0 °C fruit. It is suggested that the same changes in cell wall metabolism which induce the appearance of chilling injury also affect firmness and increase softening rate.     

Cytoplasmic relatedness of apple landraces and cultivars: a molecular analysis

Summary Mitochondrial DNA (mtDNA) diversity has been determined in apple landraces and cultivars, based upon restriction fragment length polymorphisms (RFLPs) for several mitochondrial genes. Our analysis includes three cultivars, Golden Delicious, McIntosh and Delicious, which represent the various patterns of mtDNA polymorphisms previously described (Ishikawa et al., 1992). A total of five RFLPs were detected, allowing classification of the apple genotypes into four cytoplasmic groups: GroupI, Golden Delicious-type; GroupII, McIntosh-type; GroupIII, Delicious-type; and Group IV, Dolgo Crab-type. European landraces and cultivars were assigned to Groups I, II, and III, while chinese crab apples were placed in either Group III or IV.     

Restrictions of the efficiency of haploid plant production in apple cultivar Idared,through parthenogenesisin situ

Summary For haploid plant production in Idared apple, parthenogenesisin situ was induced by irradiated pollen. The most important restrictions were seed set, embryo germination and green plant recovery from germinated embryos. The efficiency of green plant production was strongly influenced by irradiation dose, picking time and quality of the irradiated pollen. 250 Gy pollen was more efficient for green plant production than 500 Gy pollen. Using 250 Gy pollen with reduced germination capacity resulted in a five-fold lower green plant yield. Delaying picking of the fruits (140 instead of 70 days after pollination) had a significant positive effect. Up to 20 plants per 1000 pollinated flowers, showing no expression of a marker gene present in the pollen parent, were obtained in some treatments. Induction efficiency was high when seed weight was high. This offers the possibility of selecting seeds with the best chances for haploid plant production. Heavy seeds generally contained visual normal developed embryos, which germinated better than those from lighter seeds and gave normal plant development. Delayed picking increased the proportion of large seeds, suggesting that pollination with irradiated pollen retards embryo development. From treatments with irradiated pollen of poor quality more small seeds were harvested.     

津田芜菁BrSIZ1基因克隆、定位及表达

SIZ1是植物细胞蛋白质翻译后修饰SUMO化的E3连接酶,参与植物蛋白相互作用、定位和抗逆反应等。为研究BrSIZ1在津田芜菁中的表达特性,本研究克隆了津田芜菁SIZ1基因全长cDNA序列,命名为BrSIZ1 (GenBank登录号为KY441465),该基因全长2754 bp,其ORF全长2571 bp,编码856个氨基酸残基的多肽。构建了BrSIZ1-GFP表达载体进行亚细胞定位研究,结果显示BrSIZ1-GFP定位于细胞核内,可能在细胞核中发挥其功能。利用荧光定量PCR检测表明,该基因表达量在叶子中最高,幼苗和红色根皮中次之,表达具有组织特异性。而且BrSIZ1在芜菁根皮中的表达受长波紫外线(UV-A)诱导,在4°C、37°C胁迫的幼苗中,表达量增加。     

玉米BEL1-like基因家族的鉴定、表达和调控分析

BEL1-like(BELL)家族蛋白是植物中普遍存在的一类具有同源异型结构域的转录因子。拟南芥中BELL家族蛋白能与KNOTTED1-like蛋白互作形成异源二聚体,并结合到特异顺式作用元件来调控基因的表达,从而影响植物生长发育进程。本文采用隐马可夫(HMM)模型,在玉米基因组中鉴定到15个BELL家族基因(Zm BELL),分布于7条玉米染色体。通过与拟南芥BELL基因的序列比较将这些基因分为两大类。在玉米8种组织中Zm BELL有不同的表达模式,具有明显的组织表达特异性。基于基因共表达分析及BELL-like蛋白特异结合的顺式元件分析,预测到86个可能受Zm BELL调控的下游靶标基因。这86个基因和12个Zm BELL表达模式相同,并且在基因启动子区存在与BEL1-like蛋白结合的顺式元件。这些结果为进一步解析玉米BELL家族基因的功能和作用机制积累了有价值的资料。     

芥菜型油菜黄籽性状的遗传、基因定位和起源探讨

油菜种皮颜色既是一个形态指示性状, 又与种子休眠和品质有关。以芥菜型油菜种皮颜色分离的2个BC₆F₂群体为作图群体,用微卫星(SSR)等标记进行连锁定位, 并用定位标记对22份材料进行关联分析, 通过反转录-聚合酶链反应(RT-PCR)分析12份材料种皮中4-二氢黄酮醇还原酶(DFR)、花色素合酶(ANS)和花色素还原酶(ANR)基因的表达, 对6份黄籽材料的种皮颜色基因等位性进行测定, 结果将芥菜型油菜控制种皮颜色的2个基因位点分别定位到A9和B3连锁群, 并找到其两侧紧密连锁标记, 发现黄籽材料种皮颜色基因位点附近0.9 cM和1.5 cM区域高度保守, 所有黑色种皮中DFR、ANS和ANR基因均表达, 所有黄色种皮中DFR和ANS均不表达,但ANR基因表达或不表达,黄籽材料的种皮颜色基因等位。根据这些结果结合前人研究, 认为芥菜型油菜种皮颜色基因是调控基因,黄籽为单一起源。     

水稻Ef7基因的一个新等位基因Ef7-l的遗传效应及表达分析

水稻Ef7基因控制抽穗期。本研究从我国籼稻品种龙特甫中克隆了Ef7的等位基因Ef7-l;序列比对表明,Ef7-l编码序列与日本晴Ef7相比存在5个氨基酸的差异。利用两个等位基因的序列差异,以日本晴为受体构建了含有Ef7-l的近等基因系CL63。CL63在长日照条件下比轮回亲本日本晴延迟抽穗约6 d,但在短日照条件下两者抽穗期无显著差异。田间性状分析显示Ef7-l等位基因在长日照条件下能够使植株茎秆变粗、粒重显著增加,这可能是通过上调OsPHYB的表达水平而延迟水稻抽穗期实现的。     

Molecular and genealogical analysis of grain dormancy in Japanese wheat varieties,with specific focus on MOTHER OF FT AND TFL1 on chromosome 3A

In the wheat (Triticum aestivum L.) cultivar ‘Zenkoujikomugi’, a single nucleotide polymorphism (SNP) in the promoter of MOTHER OF FT AND TFL1 on chromosome 3A (MFT-3A) causes an increase in the level of gene expression, resulting in strong grain dormancy. We used a DNA marker to detect the ‘Zenkoujikomugi’-type (Zen-type) SNP and examined the genotype of MFT-3A in Japanese wheat varieties, and we found that 169 of 324 varieties carry the Zen-type SNP. In Japanese commercial varieties, the frequency of the Zen-type SNP was remarkably high in the southern part of Japan, but low in the northern part. To examine the relationship between MFT-3A genotype and grain dormancy, we performed a germination assay in three wheat-growing seasons. On average, the varieties carrying the Zen-type SNP showed stronger grain dormancy than the varieties carrying the non-Zen-type SNP. Among commercial cultivars, ‘Iwainodaichi’ (Kyushu), ‘Junreikomugi’ (Kinki-Chugoku-Shikoku), ‘Kinuhime’ (Kanto-Tokai), ‘Nebarigoshi’ (Tohoku-Hokuriku), and ‘Kitamoe’ (Hokkaido) showed the strongest grain dormancy in each geographical group, and all these varieties, except for ‘Kitamoe’, were found to carry the Zen-type SNP. In recent years, the number of varieties carrying the Zen-type SNP has increased in the Tohoku-Hokuriku region, but not in the Hokkaido region.     

兼抗型成株抗性小麦品系的培育、鉴定与分子检测

小麦条锈病、叶锈病和白粉病是我国小麦的重要真菌病害,培育兼抗型成株抗性品种是控制病害最为经济有效和持久安全的方法。本研究选用由成株抗性育种方法培育的21份冬小麦高代品系和96份春小麦高代品系,在多个环境下进行这3种病害的成株期抗性鉴定,并利用紧密连锁的分子标记检测了兼抗型基因Lr34/Yr18/Pm38、Lr46/Yr29/Pm39和Sr2/Yr30的分布。田间鉴定表明,21份冬小麦品系中有17份兼抗3种病害,占80.9%;96份春小麦品系中有85份兼抗3种病害,占88.5%。分子标记检测发现,21份冬小麦品系均含QPm.caas-4DL,其中7份还含QPm.caas-2BS,9份还含QPm.caas-2BL;96份春小麦品系中,18份含Lr34/Yr18/Pm38,37份含Lr46/Yr29/Pm39,29份含Sr2/Yr30。以上结果表明,分子标记与常规育种相结合,可有效培育兼抗型成株抗性品种,为我国小麦抗病育种提供了新思路。     

Effects on flowering and seed yield of dominant alleles at maturity loci E2 and E3 in a Japanese cultivar,Enrei

‘Enrei’ is the second leading variety of soybean (Glycine max (L.) Merr.) in Japan. Its cultivation area is mainly restricted to the Hokuriku region. In order to expand the adaptability of ‘Enrei’, we developed two near-isogenic lines (NILs) of ‘Enrei’ for the dominant alleles controlling late flowering at the maturity loci, E2 and E3, by backcrossing with marker-assisted selection. The resultant NILs and the original variety were evaluated for flowering, maturity, seed productivity and other agronomic traits in five different locations. Expectedly, NILs with E2 or E3 alleles flowered later than the original variety in most locations. These NILs produced comparatively larger plants in all locations. Seed yields were improved by E2 and E3 in the southern location or in late-sowing conditions, whereas the NIL for E2 exhibited almost the same or lower productivity in the northern locations due to higher degrees of lodging. Seed quality-related traits, such as 100-seed weight and protein content, were not significantly different between the original variety and its NILs. These results suggest that the modification of genotypes at maturity loci provides new varieties that are adaptive to environments of different latitudes while retaining almost the same seed quality as that of the original.     

Molecular diversity and genome-wide linkage disequilibrium patterns in a worldwide collection of <Emphasis Type="Italic">Oryza sativa</Emphasis> and its wild relatives

Genetic diversity analysis within a species is vital for understanding evolutionary processes at the population and genomic levels. We report a detailed study of molecular diversity, polymorphism and linkage disequilibrium in three groups of rice (Oryza) germplasm accessions based on 176 SSR markers. The first group included 65 rice (O. sativa L.) accessions introduced from seven countries, including five regions of China. The second group included 58 US rice varieties released in the past 25 years. The third group consisted of 54 accessions of rice wild relatives represented by ten different species. The number of alleles per SSR marker ranged from 4 to 32 with a mean of 16 alleles and the polymorphism information content values ranged from 0.43 to 0.91 with a mean of 0.70. The variation in SSR alleles was a significant contribution to the genetic discrimination of the 177 accessions within the three Oryza groups. Analysis of molecular variance identified deviation from Hardy–Weinberg equilibrium. Principal coordinates analysis clearly separated the accessions into their respective three groups. Neighbor-joining phylogenetic cluster reflects the ordination of each accession. Linkage disequilibrium (D′) averaged 0.75 in wild Oryza spp., and about 0.5 in both US and international O. sativa accessions. Our results showed that LD among adjacent loci in both O. sativa and Oryza spp. accessions is strong enough to be detecting marker-trait association via genome-wide scans.