Protoplast Culture and Its Application in Fruit Breeding

The progress in protoplast technology and its application in fruit breeding were summarized,and the existing problems and application prospect were also discussed.

Mitochondrial Dysfunction and Alzheimer’s Disease

Alzheimer’s disease (AD) is a neurodegenerative disorder that is characterized by progressive loss of basal forebrain cholinergic neurons, leading to reduction in transmission through cholinergic fibers involved in processes of attention, learning, and memory. Mitochondria provide and regulate cellular energy and are crucial for proper neuronal activity and survival. Mitochondrial dysfunction is evident in early stages of AD and is involved in AD pathogenesis. This review focuses on the evidence supporting a clear association between amyloid-β toxicity, mitochondrial dysfunction, oxidative stress and neuronal damage/death in Alzheimer’s disease. To date, the beta amyloid (Aβ) cascade hypothesis still remains the main pathogenetic model of Alzheimer’s disease (AD), but its role in the majority of sporadic AD cases is uncertain. Furthermore, the “mitochondrial cascade hypothesis” could explain many of the biochemical, genetic, and pathological features of sporadic AD. This hypothesis promotes mutations in mitochondrial DNA (mtDNA) as the basis for Alzheimer’s disease. The mutations could lead to energy failure, increased oxidative stress, and accumulation of Aβ, which in a vicious cycle reinforces the mtDNA damage and oxidative stress.

Mitochondrial Genome of Callus Protoplast Has a Role in Mesophyll Protoplast Regeneration in Citrus: Evidence From Transgenic GFP Somatic Homo-Fusion

Protoplast fusion has great potential in citrus improvement. Although citrus mesophyll protoplasts usually cannot divide and regenerate,symmetric protoplast fusion of embryogenic callus protoplast + mesophyll protoplast sometimes results in the regeneration of mesophyllparent-type cybrids. It suggested that mitochondrial DNA(mt DNA) from protoplasts of embryogenic callus parent plays an important role in stimulating division and regeneration of mesophyll protoplasts. Herein, somatic fusion was conducted via electrofusion between callus protoplasts isolated from Valencia orange [Citrus sinensis(L.) Osbeck] cell suspension cultures and transgenic GFP-tagged mesophyll protoplasts from the same genotype, i.e. transgenic Valencia orange plants containing the green fluorescent protein(GFP) gene, in an effort to elucidate whether mt DNA of callus line could stimulate the division and regeneration of mesophyll protoplasts from the same genotype. Two embryoids and one plantlet with GFP expression were successfully obtained and subsequent ploidy analysis by flow cytometry indicated that they were all diploids. The regenerated diploid embryoids and plantlet with GFP expression could be considered as ‘cybrids' with mt DNA from the callus protoplasts of Valencia orange. The result indicated that citrus mesophyll-parent-type cybrid regeneration needed the stimulation of mt DNA from protoplasts of embryogenic callus parent regardless of their origin either from another genotype or the same genotype as the mesophyll parent.