Extraction of DNA from orange juice, and detection of bacterium Candidatus Liberibacter asiaticus by real-time PCR.

Orange juice processed from Huanglongbing (HLB) affected fruit is often associated with bitter taste and/or off-flavor. HLB disease in Florida is associated with Candidatus Liberibacter asiaticus (CLas), a phloem-limited bacterium. The current standard to confirm CLas for citrus trees is to take samples from midribs of leaves, which are rich in phloem tissues, and use a quantitative real-time polymerase chain reaction (qPCR) test to detect the 16S rDNA gene of CLas.

G-protein-coupled alpha2A-adrenoreceptor agonists differentially alter citrus leaf and fruit abscission by affecting expression of ACC synthase and ACC oxidase.

Temporal and spatial expression patterns of genes encoding 1-aminocyclopropane-1-carboxylate (ACC) synthase (ACS1 and ACS2) and ACC oxidase (ACO), ACC concentration, and ethylene production in leaves and fruit of 'Valencia' orange (Citrus sinensis [L.] Osbeck) were examined in relation to differential abscission after treatment with 2-chloroethylphosphonic acid (ethephon) alone or in combination with guanfacine or clonidine, two G-protein-coupled alpha(2A)-adrenoreceptor selective agonists. Guanfacine and clonidine markedly reduced ethephon-enhanced leaf abscission, but had little effect on ethephon-enhanced fruit loosening.

Phenylalanine ammonia lyase gene expression during abscission in citrus.

Phenylalanine ammonia lyase (PAL) gene expression was examined in fruit and leaf abscission zones of Valencia orange for periods up to 72 h after induction of abscission with Ethrel(R) (CEPA) or the citrus mature fruit-specific abscission material 5-chloro-3-methyl-4-nitro-1H-pyrazole (CMN-P). PAL gene expression was detected in mature fruit abscission zones beginning 6 and 24 h after CEPA and CMN-P application, respectively, and continued up to 72 h. PAL gene expression was detected in leaf abscission zones 6 h after CEPA application and continued throughout the remainder of the study.

A cytochrome P450 gene is differentially expressed in compatible and incompatible interactions between pepper (Capsicum annuum) and the anthracnose fungus, Colletotrichum gloeosporioides.

The anthracnose fungus, Colletotrichum gloeosporioides, was previously shown to have an incompatible interaction with ripe-red fruit of pepper (Capsicum annuum). However, the fungus had a compatible interaction with unripe-mature-green fruit. Using mRNA differential display, we isolated and characterized a PepCYP gene expressed in the incompatible interaction.

Coexpression of a defensin gene and a thionin-like via different signal transduction pathways in pepper and Colletotrichum gloeosporioides interactions.

The anthracnose fungus, Colletotrichum gloeosporioides, interacts incompatibly with the ripe fruit of pepper (Capsicum annuum). It interacts compatibly with the unripe-mature fruit. We isolated a defensin gene, jl-l, and a thionin-like gene, PepThi, expressed in the incompatible interaction by using an mRNA differential display method.