The genus Ulocladium is thought to be strictly asexual. Mating-type (MAT) loci regulate sexual reproduction in fungi and their study may help to explain the apparent lack of sexual reproduction in Ulocladium. We sequenced the full length of two MAT genes in 26 Ulocladium species and characterized the entire MAT idiomorphs plus flanking regions of Ulocladium botrytis. The MAT1-1 ORF encodes a protein with an alpha-box motif by the MAT1-1-1 gene and the MAT1-2 ORF encodes a protein with an HMG box motif by the MAT1-2-1 gene. Both MAT1-1-1 and MAT1-2-1 genes were detected in a single strain of every species. Moreover, the results of RT-PCR revealed that both MAT genes are expressed in all 26 Ulocladium species. This demonstrates that MAT genes of Ulocladium species might be functional and that they have the potential for sexual reproduction. Phylogenies based on MAT genes were compared with GAPDH and Alt a 1 phylograms in Ulocladium using maximum parsimony (MP) and Bayesian analysis. The MAT genealogies and the non-MAT trees displayed different topologies, indicating that MAT genes are unsuitable phylogenetic markers at the species level in Ulocladium. Furthermore, the conflicting topologies between MAT1-1-1 and MAT1-2-1 phylogeny indicate separate evolutionary events for the two MAT genes. However, the intergeneric phylogeny of four closely allied genera (Ulocladium, Alternaria, Cochliobolus, Stemphylium) based on MAT alignments demonstrated that MAT genes are suitable for phylogenetic analysis among allied genera.
The floral coloration of tulip flowers is one of the most prominent traits contributing to its high ornamental value. The molecular mechanisms of petal coloration remain elusive in tulip species. In this study, we performed comparative metabolome and transcriptome analyses using four tulip cultivars with distinguished petal colors. Four types of anthocyanins were identified, including cyanidin derivatives and pelargonidin derivatives. Comparative transcriptome analysis identified 22,303 differential expressed genes (DEGs) from the four cultivars, and 2589 DEGs were commonly regulated in three comparison groups (colored vs. white cultivar), including anthocyanins biosynthesis-related genes and regulatory transcription factors. Two basic helixloop-helix (bHLH) transcription factors, TgbHLH42-1 and TgbHLH42-2, with differential expression levels among cultivars and petal developmental stages, have high homology to TRANSPARENT TESTA 8 (AtTT8) of Arabidopsis. The anthocyanins accumulation in TgbHLH42-1 overexpressing (OE) seedlings was markedly greater than that in wild-type seedlings in the presence of methyl jasmonate (MeJA), but not for TgbHLH42-2 OE seedlings. Both TgbHLH42-1 and TgbHLH42-2 restored pigmentation defects in tt8 mutant seeds after complementation assay. TgbHLH42-1 could interact with MYB protein AtPAP1 to synergistically activate the transcription of AtDFR, whereas TgbHLH42-2 failed to. Silencing TgbHLH42-1 or TgbHLH42-2 individually could not, but simultaneously silencing both TgbHLH42 could reduce the anthocyanin in tulip petals. These results indicate that TgbHLH42-1 and TgbHLH42-2 function partially redundantly to positively regulate anthocyanin biosynthesis during tulip petal coloration.
| INTRODUCTIONTulip (Tulipa gesneriana L.) is a bulbous plant belonging to the genus Tulipa in the Liliaceae family. It is distributed throughout the Mediterranean, Central and East Asia, Europe and Northern Africa and is widely grown around the world (Eker et al., 2014). Floral coloration is an important trait of tulips that determines their commercial value. Detailed color composition analyses in tulip have been performed since the 1950s, and the results indicated that tulip petal pigmentation is mainly due to the accumulation of carotenoids and anthocyanins. Carotenoids impart yellow color, while anthocyanins help produce various flower colors ranging from red, orange, pink, and purple (Nieuwhof et al., 1990).Eleven anthocyanin compounds have been identified in tulips, including pelargonidin, cyanidin, delphinidin and derivatives (Nakayama
When 3 % (v/v) liquid paraffin was added to the medium, β-carotene production increased from 397 to 715 mg l(-1) in mated cultures of Blakeslea trispora. Liquid paraffin also enhanced the oxygen concentration and induce high oxidative stress, as observed by the increase in activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD). After 84 h of cultivation in the presence of liquid paraffin, the activities of SOD, CAT and POD in B. trispora increased 77, 52.5 and 76.6 %, respectively.
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