Effect of different rootstocks on the leaf metabolite profile of 'Sugar Belle' mandarin hybrid.

Currently, citrus greening is threatening the citrus industry worldwide. So far, there is no effective cure for this destructive disease and management mainly depends on the control of Diaphorina citri vector using insecticides. Although the use of different rootstocks could increase citrus scions' tolerance to biotic and abiotic stresses, little work has been conducted to investigate the effect of rootstocks on citrus tolerance to citrus greening pathogen. In this study, we investigated the effect of rootstock on the metabolite profile of 'Sugar Belle' mandarin hybrid using gas-chromatography mass spectrometry (GC-MS). The principle component analysis showed that the metabolite profiles of the 'Sugar Belle' mandarin hybrid on the three selected rootstocks were different from each other. These results indicated that rootstocks could affect the primary and secondary metabolites of citrus scions, and consequently could affect scion tolerance to pathogens.

Metabolically speaking: Possible reasons behind the tolerance of 'Sugar Belle' mandarin hybrid to huanglongbing.

Huanglongbing (HLB) is currently considered the most destructive disease of citrus. Since its spread to the Americas, HLB has killed millions of trees and caused a sharp decline in production in many citrus growing regions. With the continuous spread of HLB disease in Florida and worldwide, there is an urgent need for the development of commercial citrus cultivars with a strong tolerance to HLB. Interestingly, field observations showed that some of the recently released mandarin hybrids such as 'Sugar Belle' were tolerant to HLB. In this study, we investigated the volatile and non-volatile metabolites of greenhouse-grown 'Sugar Belle' mandarin and four of its ancestors in order to understand why 'Sugar Belle' mandarin is relatively tolerant to HLB. Leaf volatiles were directly extracted with hexane and analyzed using gas chromatography-mass spectrometry (GC-MS). Leaf polar metabolites were extracted with a mixture of methanol:water (1:1, v/v), derivatized to their trimethylsilyl ethers, and analyzed using GC-MS. Forty-seven volatile compounds and forty-two polar metabolites were detected in 'Sugar Belle' mandarin leaves and its ancestors. 'Sugar Belle' was high in several volatiles such as α-thujene, para-cymene, γ-terpinene, thymol, ß-elemene, and (E)-ß-caryophyllene. Some of these volatiles, especially thymol, ß-elemene, and (E)-ß-caryophyllene are known for their anti-microbial activity. In addition, 'Sugar Belle' mandarin was the highest in synephrine, benzoic acid, ferulic acid, caffeic acid, chiro-inositol, fructose, glucose, threonic acid, saccharic acid, and galactaric acid, and the second in threonine, malic acid, and myo-inositol compared to the ancestors. Phenolic compounds such as benzoic, ferulic, and caffeic acids may act as antibacterial agents, whereas others like sugar alcohols may protect 'Sugar Belle' mandarin from stress during pathogen attack. The tolerance of 'Sugar Belle' and other newly released mandarin hybrids should be further evaluated using greenhouse controlled studies. If tolerance of these hybrids is confirmed, they could be used to replace the traditionally susceptible cultivars.

Occurrence of free fatty acids in the phloem sap of different citrus varieties.

Candidatus Liberibacter asiaticus is a phloem restricted bacterium that causes citrus greening disease or huanglongbing (HLB), a major treat to commercial citrus production in Florida. It is transmitted by the Asian citrus psyllid, a phloem sap-feeding insect. Studies conducted on the composition of citrus phloem sap revealed the presence amino acids, organic acids and sugars and of low amounts of free fatty acids. In the present study, the phloem sap of 12 citrus varieties with different degrees of tolerance to HLB were extracted with ethyl acetate and analyzed by GC-MS after derivatization with boron trifluoride, a fatty acid-specific reagent. Nine free fatty acids were detected in all varieties. Of the 9 fatty acids detected, only capric acid was significantly different among varieties.

Efeito da extrusao termoplástica no teor de lisina disponível da farinha desengordurada de grao-de-bico (Cicer arietinum, L) / Effect of thermoplastic extrusión on lysine availability of chickpea (Cicer arietinum, L) flour

Amostras de farinha desengordurada de grao-de-bico (Cicer arietinum, L) contendo diferentes teores de umidade inicial (13 por ciento, 18 por ciento e 27 por ciento) foram submetidas ao processo de extrusao termoplástica e, em seguida, foi realizada a avaliaçao de seus teores de lisina disponível. Foi verificado que o processo de extrusao provocou perda de 58 por ciento e 55 por ciento na lisina disponível nas farinhas com teores de umidade de 13 por ciento e 18 por ciento, respectivamente. Na farinha de grao-de-bico com 27 por ciento de umidade inicial, a perda de lisina disponível foi de 71 por ciento, após o processo de extrusao

Avaliaçäo da composiçäo química dos tubérculos e do amido de diferentes cultivares de batata-doce (Ipomoea batatas L. Lam) / Sweet potato (Ipomoea batatas L. Lam) starch: chemical composition evaluation of the tubers and extraction, purification of starch from different varieties

O objetivo deste trabalho foi avaliar a composiçäo química dos tubérculos e do amido obtido de diferentes cultivares de batata-doce (Ipomoea batatas L.Lam). Os resultados obtidos demonstraram que os tubérculos estudados possuem 4,24 por cento de proteína (Nx 6,25), base seca, e baixas concentraçöes de gordura (extrato etéreo), cinzas, fibra bruta. O teor de amido no tubérculo é de 77,6 por cento, base seca, e o rendimento médio obtido, na extraçäo de amido, foi de 42,32 por cento. O amido obtido mostrou baixas concentraçöes de gordura e proteína e o teor médio de fósforo é de 25,88 por cento µg/por cento. O teor médio de vitamina C na polpa e casca é, respectivamente, 10,2 por cento e 5,12 mg/por cento, base úmida