The Submedium São Francisco Valley is renowned for its particular conditions for cultivating grapes for different uses. The production of grapes for juice is relatively recent, and thus, knowledge is still limited on components of the production system. The aim of this study was to characterize the quality and antioxidant activity of ‘BRS Magna’ grapes in irrigated crops of the Submedium São Francisco River Valley under the influence of training systems and rootstocks, in production cycles of the first half of the year. The experiment was conducted in the Experimental Field of Bebedouro/Embrapa Semiárido, in Petrolina, Pernambuco, Brazil. The following were studied: overhead trellis, lyre, and vertical shoot positioning (VSP) systems and rootstocks ‘IAC 572’ and ‘IAC 766’, in the production cycles corresponding to the first halves of 2017 and 2018. Experimental design was in randomized blocks, with sub-subplots through time and four replicates. Overall, responses depended on training systems, rootstocks, and production cycles, which determined specific traits of the grapes. Production in the first half of 2018 was characterized by high anthocyanin contents, high total extractable polyphenols, and higher antioxidant activity, and responses were differentiated according to training system and rootstock. Plants trained to overhead trellis and grafted on ‘IAC 572’ had higher accumulation of total extractable polyphenols and antioxidant activity in berries. Plants trained to VSP had increased sugar, yellow flavonoid, and anthocyanin contents in berries while lyre training system led to higher bunch mass.

Seedless table grapes cultivars have been studied in the Sub-middle region of São Francisco Valley at northeast Brazil. For that region, it is important to identify cultivars with productive potential, better quality and efficiency, minimizing the expenses in terms of inputs and workforce, when compared to traditional cultivars. Specifically, the objective of this study was to determine the influence of different rootstocks on the quality and on the antioxidant potential of BRS Clara and Arizul table grapes cultivars of two production cycles. The experimental area belongs to the Experimental Field of Bebedouro/Embrapa Semiárido, located in the sub-middle region of São Francisco Valley, in Petrolina - PE, northeast Brazil. Both BRS Clara and Arizul cultivars were analyzed individually using IAC 313, IAC 572, IAC 766, SO4, Paulsen 1103 and Harmony rootstocks, during production cycles from October/2016 to February/2017 and from March/2007 to June/2017. The experimental design was planned in randomized blocks, in a 2 (production cycle) x 6 (rootstock) factorial, with three replications each. More favorable conditions to quality for ‘BRS Clara’ grapes, as evidenced by higher berry mass, lower soluble solids (SS)/titratable acidity (TA) ratio and higher antioxidant activity, were observed after the March-June, 2017 harvest, especially from scions grafted onto IAC 572, SO4 and Harmony. The Arizul cultivar was characterized by better quality after the March-July, 2017 harvest, showing higher berry mass, lower acidity and lower SS/TA ratio and a better color mainly in SO4 and Harmony rootstocks. Therefore, an appropriate rootstock enhances the quality of the grapes.

Begomovirus constitui o maior gênero da família Geminiviridae, uma das maiores famílias de vírus de plantas, cujas espécies infectam diversas monocotiledôneas e dicotiledôneas cultiváveis e representam severa limitações à produtividade agrícola mundialmente. Esse amplo espectro de gama de hospedeiros resulta de estratégias sofisticadas desenvolvidas por geminivírus para superar o arsenal de defesas antivirais em espécies de plantas tão diversas. Portanto, torna-se necessário o desenvolvimento de estratégias moleculares para obtenção de resistência a begomovírus. Nesta investigação, foram exploradas tanto estratégias para manipulação de resistência dominante quanto silenciamento de genes de resistência recessiva na planta modelo Arabidopsis thaliana. Para garantir resistência dominante, foi utilizado o gene NIK1 [Nuclear shuttle protein (NSP)-interacting kinase 1] que protege plantas contra begomovírus em interações incompatíveis, mas cuja resistência é superada pela proteína de geminivírus NSP em hospedeiros suscetíveis. Plantas Columbia (Col-0) e nocaute nik1-1 foram transformadas com o mutante simples NIK1-T469A e duplo NIK1-T474D/T469A sob o controle do promotor 35S. As plantas transformadas foram confirmadas por PCR, obtendo-se cinco linhagens expressando o duplo mutante e duas linhagens, o mutante simples. Com inserção única do gene e em homozigose, as plantas Col-0 transformadas exibiram alta expressão dos transgenes, e os mutantes complementados com o duplo mutante, exibiram baixa expressão do transgene. Foi observado que a expressão dos mutantes NIK1-T469A e NIK1-T474D/T469A reprimiram acentuadamente a expressão dos genes marcadores da via de imunidade antiviral mediada por NIK1, RPL28, S25, PSII e FD1. Consistente com esses resultados, as plantas superexpressando NIK1-T469A e NIK1-T474D/T469A apresentam menor comprimento da raiz. Todas as plantas mutantes demonstraram baixo acúmulo viral, e baixos sintomas da infecção por CabLCV, comparados com as plantas Col-0, nik-1 e NIK1-8 (uma linhagem complementando o gene NIK1 intacto). Estes resultados indicam que os mutantes NIK1-T469A e NIK1-T469A/T474D são constitutivamente ativados e conferem resistência contra geminívírus em Arabidopsis. No caso de resistência recessiva, inicialmente foi confirmado o carater recessivo do gene NIG. Para isso, foi demonstrado que plantas nig-1 submetidos à infecção por begomovírus acumularam menor carga viral e exibiram sintomas atenuados quando comparadas com Col-0. Além disso, foi examinado o efeito do silenciamento dos genes de suscetibilidade NIG e NISP no desenvolvimento de Arabidopsis. Inativação de NIG ou NISP não causou efeitos adversos no desenvolvimento e crescimento das linhagens silenciadas nig-1 ou nisp-1 comparados com Col-0. Para obter resistência recessiva mais eficaz, foi utilizado a tecnologia CRISPR/Cas para o duplo silenciamento dos genes NIG e NISP. Foi inicialmente construído o cassete contendo os RNAs guias de NISP e então inserido no vetor de transformação de plantas contendo o gene Cas pela técnica de Golden Gate. As plantas nocautes nig-1 foram transformadas com o vetor do CRISPR/Cas nisp-pHEE-401E, e as plantas selecionadas fora confirmadas por PCR. Foi possível confirmar plantas editadas em apenas um alelo do gene de NISP, demonstrando a funcionabilidade dessa técnica. Experimentos estão em progresso para selecionar os mutantes duplos nisp/nig em homozigose e avaliar o efeito do silenciamento duplo dos genes recessivos na resistência contra begomovírus. Palavras-chave: Geminiviridae. Begomovirus. NIK1. Resistencia dominante. NIG. NISP. Resistência recessiva. Arabidopsis. CRISPR/CAS. Duplo mutante. Duplo nocaute.

Production system and environmental factors might cause changes in grapevine physiology, affecting grape yield, quality, phenolic composition, and antioxidant potential. The aim of this study was to characterize the quality and antioxidant potential of 'Isabel Precoce' grapes on different training systems and rootstocks in warmer seasons, in tropical conditions. Experimental design was in randomized blocks, in sub-subplots through time and four replicates. Three training systems (overhead trellis, lyre and vertical shoot positioning - VSP) and two rootstocks (‘IAC 572’ and ‘IAC 766’) were studied in the production cycles from July to October, 2017 and from July to October, 2018 in the Submedium of São Francisco Valley. Berry weight; cluster weight; color attributes; berry resistance to compression (COMP); titratable acidity; soluble solids; total soluble sugars (TSS); yellow flavonoids; total anthocyanins; total extractable polyphenols and antioxidant activity by ABTS●+ and DPPH● free radical capture methods were analyzed. Lyre and VSP resulted on increases of 6% and 17% in berry weight and COMP, respectively. Moreover, differences between production cycles were more intense for both variables. In production cycle from July to October 2017, lyre and VSP systems provided increases of 2 g 100 g-1 of TSS and higher anthocyanin and yellow flavonoid contents, while grapes trained in VSP had higher antioxidant activity. Mean values of anthocyanins reached 529.34 mg 100 g-1 in grapes harvested in October 2017. Some grape quality and chemical components showed high variation in warmer seasons of sucessive years, according to training system or rootstock and their combinations