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Rootstocks play a vital role in regulating the environmental adaptability and controlling the growth and development of apple trees. M9T337, an excellent apple rootstock widely used in commercial orchards, could confer dwarf tree architectures, early fruiting and suitability for high-density planting. However, the rooting ability of M9T3337 is low when it is vegetatively propagated, and researchers have not yet established an efficient micropropagation system. The present study systematically evaluated the multiplication in adventitious shoots and the in vitro formation of adventitious roots to determine the effects of the culture media and plant growth regulators of M9T337 and a rapid micropropagation system was developed. For the shoot multiplication, the highest multiplication index of 3.93 was obtained on Murashige and Skoog (MS) media supplemented with 2.0 mg/L 6-BA, 0.1 mg/L NAA and 0.3 mg/L GA3 from 12 combinations of 6-BA and NAA. Stronger and taller adventitious shoots were grown on MS supplemented with 1.8 mg/L 6-BA and 0.5 mg/L NAA. The optimal media with 100% rooting was obtained using 1/2 MS supplemented with 0.3 mg/L IBA or MS supplemented with 0.6 mg/L IBA for the rooting induction, resulting in mean rooting numbers of 13.00 and 11.33, respectively. Additionally, the effect on rooting of adding 0.3 mg/L IBA or not on the 1/2 MS and MS media was compared; the results suggested that an appropriate IBA concentration was the key to successful rooting. The rooted plantlets were acclimatised in a shaded greenhouse with an 84% survival rate. The established micropropagation system could be used for the rapid propagation of M9T337 for commercial production. [ABSTRACT FROM AUTHOR]

Background. Heat shock factors (HSFs) play important roles during normal plant growth and development and when plants respond to diverse stressors. Although most studies have focused on the involvement of HSFs in the response to abiotic stresses, especially in model plants, there is little research on their participation in plant growth and development or on the HSF (PpHSF) gene family in peach (Prunus persica). Methods. DBD (PF00447), the HSF characteristic domain, was used to search the peach genome and identify PpHSFs. Phylogenetic, multiple alignment and motif analyses were conducted using MEGA 6.0, ClustalW and MEME, respectively. The function of PpHSF5 was confirmed by overexpression of PpHSF5 into Arabidopsis. Results. Eighteen PpHSF genes were identified within the peach genome. The PpHSF genes were nonuniformly distributed on the peach chromosomes. Seventeen of the PpHSFs (94.4%) contained one or two introns, except PpHSF18, which contained three introns. The in silico-translated PpHSFs were classified into three classes (PpHSFA, PpHSFB and PpHSFC) based on multiple alignment, motif analysis and phylogenetic comparison with HSFs from Arabidopsis thaliana and Oryza sativa. Dispersed gene duplication (DSD at 67%) mainly contributed to HSF gene family expansion in peach. Promoter analysis showed that the most common cis-elements were the MYB (abiotic stress response), ABRE (ABA-responsive) and MYC (dehydration-responsive) elements. Transcript profiling of 18 PpHSFs showed that the expression trend of PpHSF5 was consistent with shoot length changes in the cultivar 'Zhongyoutao 14'. Further analysis of the PpHSF5 was conducted in 5-year-old peach trees, Nicotiana benthamiana and Arabidopsis thaliana, respectively. Tissue-specific expression analysis showed that PpHSF5 was expressed predominantly in young vegetative organs (leaf and apex). Subcellular localization revealed that PpHSF5 was located in the nucleus in N. benthamiana cells. Two transgenic Arabidopsis lines were obtained that overexpressed PpHSF5. The root length and the number of lateral roots in the transgenic seedlings were significantly less than in WT seedlings and after cultivation for three weeks. The transgenic rosettes were smaller than those of the WT at 2-3 weeks. The two transgenic lines exhibited a dwarf phenotype three weeks after transplanting, although there was no significant difference in the number of internodes. Moreover, the PpHSF5-OE lines exhibited enhanced thermotolerance. These results indicated that PpHSF5 might be act as a suppresser of growth and development of root and aerial organs. [ABSTRACT FROM AUTHOR]

Resveratrol contributes to a plant's tolerance of various abiotic and biotic stresses and is highly beneficial to human health. A search for elite alleles affecting resveratrol production was undertaken to find useful grapevine germplasm resources. Resveratrol levels in both berry skins and leaves were determined in 95 grapevine accessions (including 50 wild Chinese grapevine accessions and 45 cultivars) during two consecutive years. Resveratrol contents were higher in berry skins than in leaves and in wild Chinese grapevines than in grapevine cultivars. Using genotyping data, 79 simple sequence repeat (SSR) markers linked to 44 stilbene synthase (STS) genes were detected in the 95 accessions, identifying 40 SSR markers with higher polymorphisms. Eight SSR marker loci, encompassing 19 alleles, were significantly associated with resveratrol content on (P < 0.001), and 5 SSR loci showed repeated associations. Locus Sh5 had four associations: three positive for allele 232 (including leaves in the 2 years) and one negative for allele 236 in four environments. Loci Sh9 and Sh56 for a total of 7 alleles exhibited positive effects in berry skins in the 2 years. In berry skins, locus Sh56 with positive effects was closely linked to VvSTS27, and locus Sh77 with negative effects to VvSTS17, importantly, the two candidate genes both were located on Chromosome 16. The SSR marker loci and candidate genes identified in this study will provide a useful basis for future molecular breeding for increased production of natural resveratrol and its derivatives. [ABSTRACT FROM AUTHOR]