The characterization of aroma of the 14 main apricot (Prunus armeniaca L.) cultivars in Xinjiang was evaluated using high-performance solid-phase microextraction (HP-SPME) with gas chromatography-mass spectroscopy (GC-MS). A total of 208 volatiles that include 80 esters, 25 aldehydes, 15 terpenes, 21 ketones, 39 alcohols, 27 olefins, and 1 acid were identified from these cultivars. The compounds propyl acetate, 3-methyl-1-butanol acetate, (Z)-3-hexen-1-ol acetate, d-limonene, β-linalool, hexanal, hexyl acetate, butyl acetate, β-myrcene, ethyl butanoate, and β-cis-ocimene were the major compounds responsible for aroma in these cultivars. GC-MS results showed that Kuchexiaobaixing, Guoxiyuluke, and seven other cultivars were characterized by a high level of esters and were considered to be fruity apricot aroma. ‘Luotuohuang’ and ‘Heiyexing’ accumulate high levels of terpenes and exhibited an outstanding floral aroma. Higher levels of alcohols and aldehydes were observed in ‘Danxing’, ‘Sumaiti’, and ‘Kumaiti’. The latter are considered green aroma cultivars. These three types of cultivars with different aroma characteristics can be significantly differentiated by using the principal component analysis (PCA) method. The contributions of volatiles to the apricot aroma were assessed by using the partial least squares regression (PLSR) model. Esters, terpenes, and C6 components were shown to be responsible for the fruity, floral, and green character of fresh apricots, respectively.
Jian-rong Feng, Wan-peng Xi, Wen-hui Li, Hai-nan Liu, Xiao-fang Liu and Xiao-yan Lu
Hai-nan Liu, Jian-rong Feng, Xiao-fang Liu, Wen-hui Li, Wen-juan Lv and Ming Luo
Three kinds of expression vectors of a pollen-S determinant were constructed to provide a reference for molecular breeding of self-compatible (SC) Prunus species. An S-haplotype-specific F-box (SFB) protein gene from the ‘Xiaobaixing’ apricot (Prunus armeniaca) was cloned by reverse transcription polymerase chain reaction (RT-PCR) and 3′-rapid-amplification of cDNA ends (3′-RACE). A 1136-bp sequence complementary to the 3′-end of the cDNA (GenBank accession number KP938528.2) with a 912-bp complete open reading frame (ORF) was obtained. The deduced amino acid sequence contained an F-box domain, two variable regions, and two hypervariable regions with structural characteristics similar to SFB in other Rosaceae plants. Sense, antisense, and RNA interference (RNAi) vectors for SFB were constructed by enzyme restriction. The target fragment was restricted using the corresponding restriction enzyme and then directionally inserted between the 35S cauliflower mosaic virus promoter and the nopaline synthase terminator (NOS-ter) of the expression vector pCAMBIA-35S-MCS-NOS-NPTII. The intron-containing hairpin RNA (ihpRNA) was obtained by fusion PCR. The constructed vectors were transferred into Agrobacterium tumefaciens strain LBA4404 by freezing/thawing. The RNAi vector of SFB was also transformed in tobacco (Nicotiana tabacum). The successful construction of these three expression vectors provides a basis for transforming ‘Xiaobaixing’ apricot and the breeding of SC Prunus cultivars.
Yanbin Su, Yumei Liu, Huolin Shen, Xingguo Xiao, Zhansheng Li, Zhiyuan Fang, Limei Yang, Mu Zhuang and Yangyong Zhang
Head splitting resistance (HSR) in cabbage is an important trait closely related to appearance, yield, storability, and mechanical harvestability. In this study, a doubled haploid (DH) population derived from a cross between head splitting-susceptible inbred cabbage line 79-156 and resistant line 96-100 was used to analyze inheritance and detect quantitative trait loci (QTLs) for HSR during 2011–12 in Beijing, China. The analysis was performed using a mixed major gene/polygene inheritance method and QTL mapping. This approach, which uncovered no cytoplasmic effect, indicated that HSR can be attributed to additive-epistatic effects of three major gene pairs combined with those of polygenes. Major gene and polygene heritabilities were estimated to be 88.03% to 88.22% and 5.65% to 7.60%, respectively. Using the DH population, a genetic map was constructed with simple sequence repeat (SSR) markers anchored on nine linkage groups spanning 906.62 cM. Eight QTLs for HSR were located on chromosomes C4, C5, C7, and C9 based on 2 years of phenotypic data using both multiple-QTL mapping and inclusive composite interval mapping. The identified QTLs collectively explained 37.6% to 46.7% of phenotypic variation. Three or four major QTLs (Hsr 4.2, 7.2, 9.3, and/or 9.1) showing a relatively larger effect were robustly detected in different years or with different mapping methods. The HSR trait was shown to have a complex genetic basis. Results from QTL mapping and classical genetic analysis were consistent. Our results provide a foundation for further research on HSR genetic regulation and molecular marker-assisted selection (MAS) for HSR in cabbage.