Efficient Agrobacterium tumefaciens-mediated transformation of Malus zumi (Matsumura) Rehd using leaf explant regeneration system

Malus zumi is known as an excellent dwarfing apple rootstock occurring in natural or arid/semiarid soil or salina. Gene manipulation of M. zumi through transgenic technology can modify plant feature for further improvement fruit tree production by grafting the scion on a transgenic rootstock. Here, we report the establishment of an efficient, in vitro, shoot regeneration system and Agrobacterium tumefaciens- mediated transformation from the leaf explants for Malus zumi (Matsumura) Rehd. Leaf explants were infected with Agrobacterium strains containing nptII and gus gene. The highest frequency of shoot regeneration was obtained on MS medium containing 500 mg l-1 Lactalbumin hydrolysate, 30 g l-1 fructose, supplemented with 3.0 mg l-1 BA, 0.2 mg l-1 NAA.Using fructose instead of sucrose significantly increases the shoot regeneration and decreases vitrification. This regeneration procedure was incorporated into an Agrobacterium-mediated transformation procedure in M. zumi. Kanamycin was an efficient selective agent for selection. Pre-selection (5 days after co-cultivation) improved the transformation efficiency. The emergence of expected bands by PCR analysis and Southern blot in transgenic plantlets confirmed the transformation of foreign DNA into plant genome.

Differences in FMO2*1 allelic frequency between Hispanics of Puerto Rican and Mexican descent.

A polymorphism for the phase I drug-metabolizing enzyme, flavin-containing monooxygenase isoform 2 (FMO2), encoding either truncated inactive protein, FMO2X472 (FMO2.2A), or full-length active enzyme, FMO2Q472 (FMO2.1), is known and exhibits significant interethnic differences in allelic frequency. FMO2 is the major or sole FMO isoform expressed in the lung of most mammals, including nonhuman primates. To date, FMO2.1 has been found only in African-American and Hispanic populations, rendering individuals with this allele subject to drug metabolism that is potentially different from that of the general population. Approximately 26% of African-Americans (n = 180) possess the FMO2*1 allele. In preliminary studies, we initially estimated that 5% of Hispanics (n = 40) have the FMO2*1 allele, but access to large cohorts of individuals of defined national origin has allowed us to determine the occurrence among Mexican-American and Puerto Rican-American groups. We used allele-specific genotyping to detect FMO2*1 from 632 Hispanic individuals, including 280 individuals of Mexican origin and 327 individuals of Puerto Rican origin. Statistical analysis indicated that results from Mexican (five sample sources) and Puerto Rican (three sample sources) samples were consistent with the hypothesis of homogeneity within each group from different sources. Data were subsequently pooled across sources to test for evidence of a difference in occurrence of FMO2*1 between ethnic groups. There was strong evidence (p = 0.0066) that FMO2*1 is more common among Puerto Ricans (7%) than among individuals of Mexican descent (2%). The overall occurrence of FMO2*1 among Hispanics of all origins is estimated to be between 2 and 7%.