Characterization of Citrus tristeza virus isolates from grapefruit (Citrus paradisi Macf.) accessions of Citrus Active Germplasm Bank

Citrus tristeza virus (CTV) isolates from 35 grapefruit accessions belonging to Citrus Active Germplasm Bank of the "Instituto Agronômico de Campinas" located at the "Centro APTA Citros Sylvio Moreira", Cordeirópolis, São Paulo state, Brazil, were characterized and evaluated through symptoms in the trees, biological indexing, immunological diagnosis with different monoclonal antibodies and SSCP analysis (single-strand conformation polymorphism) of the coat protein gene. Symptomatology indicated that, in general, the group of plants with smaller canopy volume and severe stem pitting differed significantly from the group that presented greater vegetative development and mild to moderate stem pitting. However, the isolates from most of the accessions induced mild reaction on Mexican lime. The serological evaluation through the DAS-ELISA using monoclonal antibodies did not reveal any association between virus titer in the plant tissue and symptoms. The reaction with different monoclonal antibodies and the distinct electrophoresis patterns obtained through SSCP showed that there is a high degree of diversity among the isolates that infect these grapefruit accessions. High complexity within the same isolate was also observed in the SSCP profiles. This finding indicates that the CTV isolates from these plants are a complex mixture of CTV haplotypes. Similar SSCP banding patterns were observed among some plants with strong stem pitting symptoms, and among some plants with weak or moderate stem pitting symptoms.

Citrus asymmetric somatic hybrids produced via fusion of gamma-irradiated and iodoacetamide-treated protoplasts

The objective of this study was to produce citrus somatic asymmetric hybrids by fusing gamma-irradiated protoplasts with iodoacetamide-treated protoplasts. Protoplasts were isolated from embryogenic suspension cells of grapefruit (Citrus paradisi Macfad.) cultivars Ruby Red and Flame, sweet oranges (C. sinensis Osbeck) 'Itaboraí', 'Natal', Valencia', and 'Succari', from 'Satsuma' (C. unshiu Marcow.) and 'Changsha' mandarin (C. reticulata Blanco) and 'Murcott' tangor (C. reticulata x C. sinensis). Donor protoplasts were exposed to gamma rays and receptor protoplasts were treated with 3 mmol L-1 iodoacetamide (IOA), and then they were fused for asymmetric hybridization. Asymmetric embryos were germinated, and the resulting shoots were either grafted onto sour orange, rough lemon or 'Swingle' (C. paradisi x Poncirus trifoliata) x 'Sunki' mandarin rootstock seedlings, or rooted after dipping their bases in indol-butyric acid (IBA) solution. The products were later acclimatized to greenhouse conditions. Ploidy was analyzed by flow cytometry, and hybridity was confirmed by amplified fragment length polymorphism (AFLP) analysis of plantlet DNAsamples. The best treatment was the donor-recipient fusion combination of 80 Gy-irradiated 'Ruby Red' protoplasts with 20 min IOA-treated 'Succari' protoplasts. Tetraploid and aneuploid plants were produced. Rooting recalcitrance was solved by dipping shoots' stems in 3,000 mg L-1 IBA solution for 10 min.

Fusion of protoplasts with irradiated microprotoplasts as a tool for radiation hybrid panel in citrus

The objective of this work was to combine asymmetric somatic hybridization (donor-recipient fusion or gamma fusion) to microprotoplast-mediated chromosome transfer, as a tool to be used for chromosome mapping in Citrus. Swinglea glutinosa microprotoplasts were irradiated either with 50, 70, 100 or 200 gamma rays and fused to cv. Ruby Red grapefruit or Murcott tangor protoplasts. Cell colonies were successfully formed and AFLP analyses confirmed presence of S. glutinosa in both 'Murcott' tangor and 'Ruby Red' grapefruit genomes.

Comportamento de seis variedades de pomelo (Citrus paradisi Macfad.) cultivadas sob irrigação na região semi-árida de Pernambuco

O uso da irrigação nas regiões semi-áridas do Nordeste brasileiro tem viabilizado o cultivo comercial de inúmeras fruteiras, tais como a uva, a manga, a goiaba, o coco e a banana. Outras espécies, como o pomelo, ou grapefruit, vêm sendo ainda objeto de estudos e avaliações. Uma coleção formada de 06 variedades de pomelos (Citrus paradisi), de polpas com coloração rosa-avermelhada ('Marsh Foster', 'Star Ruby', 'Rio Red' e 'Red Blush') e amarelada ('Triumph' e 'Marsh Foster Nucelar'), foi implantada em 1993 na Estação Experimental de Ibimirim, localizada no município de Ibimirim, no Vale do Rio Moxotó - região semi-árida de Pernambuco. Contando com cinco plantas por parcela, a coleção foi conduzida sob irrigação localizada e as avaliações realizadas durante três anos (2000 a 2002). Os resultados demostraram alta variabilidade na produção de frutos, tendo a variedade 'Marsh Foster Nucelar' alcançado a produção média de 135,0 kg/planta, enquanto a 'Star Ruby' atingiu apenas 31,0 kg/planta. O peso médio dos frutos variou de 285,5g ('Red Blush') até um máximo de 401,6g na variedade 'Triumph'. O volume de suco extraído, os sólidos solúveis totais (SST), a acidez total titulável (ATT) e a relação SSS/ATT também apresentaram mudanças entre as variedades estudadas.

Quality of Canned mandarin as affected by preservation liquid

This study is integrated within a research line dedicated to evaluate different options to introduce mandarin in Spanish agro-food industries and in both national and international markets. The effects of different preservation liquids (sucrose solution, sucrose and ascorbic acid solution, grape, and grapefruit juices), soluble solids (10, 12, 14 ºBrix), and thermal processing (30 seconds at 98 ºC) on vitamin C, color, carotenoids and sensory quality of canned Satsuma mandarin segments were studied. The liquid preservation that presented the best results was grapefruit juice, which provided the highest vitamin C (323 mg.L-1) and total carotenoids (16.4 mg.L-1) contents (the main carotenoid found was β-cryptoxanthin), intense orange color, high thermal stability, and very good sensory quality (e.g. intense floral and fresh-mandarin aromas and low levels of off-flavors).