Diversification of ergot alkaloids and heritable fungal symbionts in morning glories

Heritable microorganisms play critical roles in life cycles of many macro-organisms but their prevalence and functional roles are unknown for most plants. Bioactive ergot alkaloids produced by heritable Periglandula fungi occur in some morning glories (Convolvulaceae), similar to ergot alkaloids in grasses infected with related fungi. Ergot alkaloids have been of longstanding interest given their toxic effects, psychoactive properties, and medical applications. Here we show that ergot alkaloids are concentrated in four morning glory clades exhibiting differences in alkaloid profiles and are more prevalent in species with larger seeds than those with smaller seeds. Further, we found a phylogenetically-independent, positive correlation between seed mass and alkaloid concentrations in symbiotic species. Our findings suggest that heritable symbiosis has diversified among particular clades by vertical transmission through seeds combined with host speciation, and that ergot alkaloids are particularly beneficial to species with larger seeds. Our results are consistent with the defensive symbiosis hypothesis where bioactive ergot alkaloids from Periglandula symbionts protect seeds and seedlings from natural enemies, and provide a framework for exploring microbial chemistry in other plant-microbe interactions.

Diversification of ergot alkaloids and heritable fungal symbionts in morning glories

Heritable microorganisms play critical roles in life cycles of many macro-organisms but their prevalence and functional roles are unknown for most plants. Bioactive ergot alkaloids produced by heritable Periglandula fungi occur in some morning glories (Convolvulaceae), similar to ergot alkaloids in grasses infected with related fungi. Ergot alkaloids have been of longstanding interest given their toxic effects, psychoactive properties, and medical applications. Here we show that ergot alkaloids are concentrated in four morning glory clades exhibiting differences in alkaloid profiles and are more prevalent in species with larger seeds than those with smaller seeds. Further, we found a phylogenetically-independent, positive correlation between seed mass and alkaloid concentrations in symbiotic species. Our findings suggest that heritable symbiosis has diversified among particular clades by vertical transmission through seeds combined with host speciation, and that ergot alkaloids are particularly beneficial to species with larger seeds. Our results are consistent with the defensive symbiosis hypothesis where bioactive ergot alkaloids from Periglandula symbionts protect seeds and seedlings from natural enemies, and provide a framework for exploring microbial chemistry in other plant-microbe interactions.

Susceptibility of four Ipomoea genus weed species to the herbicides saflufenacil or flumioxazin

Among weeds commonly found in Brazil that directly interfere on agriculture, those classified in Convolvulaceae Family may be highlighted, particularly Ipomoea L. genus, popularly known as morning glories. Flumioxazin and saflufenacil are herbicide molecules registered to control these weeds. In this context, this work was developed with the objective of evaluating the susceptibility of four Ipomoea genus weed species to the herbicides flumioxazin and saflufenacil. Two similar and independent experiments were performed in 2017, adopting completely randomized blocks and four replicates. Treatments were organized according to an 8x4 factorial scheme, which eight were the rates of each herbicide and four were the weed species of Ipomoea genus (I. hederifolia, I. nil, I. quamoclit and I. triloba). The following rates were adopted to saflufenacil (g ha-1): 0, 1.5, 3.0, 6.1, 12.3, 24.5, 49.0 and 98.0. The rates adopted to flumioxazin were (g ha-1): 0, 3.75, 7.5, 15.0, 30.0, 60.0, 120.0 and 480.0. Ipomoea genus weed species were completely controlled by the herbicides saflufenacil and flumioxazin, which may be considered excellent alternatives to control morning glories. I. triloba and I. nil were identified as the least sensible species to flumioxazin at the rate of 3.75 g ha-1; lower control of I. triloba was also identified with 7.5 g ha-1 of flumioxazin; rates equal to or higher than 15.0 g ha-1 promoted total control of weeds.

Generation of Yellow Flowers of the Japanese Morning Glory by Engineering Its Flavonoid Biosynthetic Pathway toward Aurones

Wild-type plants of the Japanese morning glory (Ipomoea nil) produce blue flowers that accumulate anthocyanin pigments, whereas its mutant cultivars show wide range flower color such as red, magenta and white. However, I. nil lacks yellow color varieties even though yellow flowers were curiously described in words and woodblocks printed in the 19th century. Such yellow flowers have been regarded as ‘phantom morning glories’, and their production has not been achieved despite efforts by breeders of I. nil. The chalcone isomerase (CHI) mutants (including line 54Y) bloom very pale yellow or cream-colored flowers conferred by the accumulation of 2′, 4′, 6′, 4-tetrahydoroxychalcone (THC) 2′-O-glucoside. To produce yellow phantom morning glories, we introduced two snapdragon (Antirrhinum majus) genes to the 54Y line by encoding aureusidin synthase (AmAS1) and chalcone 4′-O-glucosyltransferase (Am4′CGT), which are necessary for the accumulation of aureusidin 6-O-glucoside and yellow coloration in A. majus. The transgenic plants expressing both genes exhibit yellow flowers, a character sought for many years. The flower petals of the transgenic plants contained aureusidin 6-O-glucoside, as well as a reduced amount of THC 2′-O-glucoside. In addition, we identified a novel aurone compound, aureusidin 6-O-(6″-O-malonyl)-glucoside, in the yellow petals. A combination of the coexpression of AmAS1 and Am4′CGT and suppression of CHI is an effective strategy for generating yellow varieties in horticultural plants.