The VvSUPERMAN-like Gene Is Differentially Expressed between Bicarpellate and Tricarpellate Florets of Vitis vinifera L. Cv. ‘Xiangfei’ and Its Heterologous Expression Reduces Carpel Number in Tomato

Multicarpellate fruits are larger and produce more seeds than mono- or bicarpellate fruits, enhancing the reproductive capacity of the plant. To identify the phenotypic and molecular differences among florets of different carpel types, we studied carpel formation and fusion in the grapevine (Vitis vinifera) cultivar ‘Xiangfei’, which produces a high proportion of multicarpellate fruit. We also determined the function of VvSUPERMAN-like (VvSUP-like) and explored its relationship with VvWUS (VvWUSCHEL) and VvAG1 (VvAGAMOUS), which is related to the formation of carpel primordia. We showed that carpel formation and fusion were largely consistent between bicarpellate and tricarpellate ovaries, which both involve congenital fusion; rather, the differences between these ovary types arose from variation in carpel primordia number and location. Transgenic tomato (Solanum lycopersicum) plants expressing VvSUP-like produced significantly fewer carpels and other floral organs than the wild type. Moreover, transcriptome sequencing results indicate that VvSUP-like was more highly expressed in bicarpellate than in tricarpellate ‘Xiangfei’ florets. Luciferase reporter assays indicated that VvSUP-like inhibits the expression of VvAG1 and VvWUS by directly binding to their promoters, and VvWUS promotes VvAG1 expression by directly binding to its promoter. VvSUP-like inhibits the feedback signaling between VvWUS and VvAG1. Together, these results suggest that VvSUP-like negatively regulates the number of carpels that develop by inhibiting VvAG1 and VvWUS expression.

General Comments

Viticulture is the art and science of vine-growing and grape-harvesting. In general, the portions of our planet lying between 20° and 50° latitude on either side of the equator (Figure 1.1) are considered suitable for the vines. In these temperate climates, the tilt of the earth’s axis in relation to the sun results in temperatures in the Northern hemisphere in March (and the Southern hemisphere in September) that rarely fall below about 50° Fahrenheit (F) (10° Celsius [C]). As analytical chemistry and possibilities for genomic and epigenomic analysis have evolved, it has become possible to begin to monitor and understand, in detail, how climate affects wine production. For example, a recent Italian study investigated the changes, over a three-year period, in phenotype of a Vitis vinifera cultivar by looking at the transcriptome. They found that most responses they could follow could be attributed to local early spring weather patterns. While a complete analysis was not reported, it was concluded that weather patterns in the previous year were correlated with current year growth. Much of the biology for raising grapes has been discussed, and while 80% of the world’s grape crop is used for production of wine there have been and remain formidable technical difficulties in breeding grapevines. Part of the breeding problem derives from the fact that grapevines are highly heterozygous outcrossers, and so they do not breed true from seed. But they are good cultivars and are polygenic (poly = many; genic = genes). Their inheritance appears to be controlled by large numbers of genes of minor effect. As a consequence, traditional cultivars, grown in their accustomed places, appear to possess subtle combinations of genes whose totality can be preserved by grafting techniques but not in other ways. That is why it appears that the wines produced by such longstanding and traditional cultivars in the hands of vintners accustomed to their nature have unique characteristics of style and quality. Indeed, it seems that it is largely to encourage and maintain such subtle differences that grapevines are seldom propagated from seedlings (but see below) unless a “new” variety is sought by breeders.

Iron content in the fruits of the grapevines and peach trees growing near the mining and smelting complex Bor, east Serbia

The samples of fruits of the grapevine (Vitis vinifera, cultivar Tamjanika) and the peach tree (Prunus persica L. Batech) from the Bor region were analyzed using an ICP-OES to determine the content of iron (Fe). This was done in order to assess possible health risks related to this essential element; the region of Bor?s municipality is known as one of the most polluted areas in Serbia. The content of Fe in unwashed grapes seems not to be affected by the mining/metallurgical activities, as it was either in the normal concentration range or was at even lower than critical deficiency concentration in plants (21.8-98 mg/kg). The level of Fe in the samples of peaches ranged from 62.4 to 1418 mg/kg, which is much higher than that in grape samples and in one case, even higher than the phytotoxic threshold. The values of the enrichment factor (EF) were lower than 2 in the case of grape samples, while for peach samples, these values ranged from rather low (0.99) to extremely high (22.66). Based on the herein obtained results, in the region of Bor, it seems that the cultivation of grapevine should be favored over the cultivation of peach trees.