Isolation and characterization of genes associated with shade-induced apple abscission

Abstract

Apple trees generally produce excessive number of flowers and young fruitlets, which negatively affects commercial value. Thus, thinning is an important practice by which excessive flowers and fruitlets abort. Fruit abscission is difficult to predict or control, as many factors including shading can cause fruitlets to abort. In order to understand the molecular basis of shade-induced fruit abscission, two cDNA libraries were constructed using the suppression-subtractive hybridization (SSH) method and 347 expressed sequence tags (ESTs) were obtained. 168 ESTs represent transcripts that are preferentially expressed after 24 h of shading, and the other 179 are derived from RNAs of small apple fruits that were shaded for 72 h. Sequence analyses revealed that these clones represent 68 (24 h) and 44 (72 h) unique genes; these genes belong in eight functional categories. The largest set of genes is related to carbohydrate metabolism including the sorbitol 6-phosphate dehydrogenase (S6PDH) gene that was generally believed not to be expressed in young fruits, while the second largest group contains unclassified or unknown genes. RNA gel blot analysis confirmed that at least 26 genes are up-regulated after shade treatment. Some of these known genes may serve as molecular markers for apple monitoring the induction of fruitlet abscission. Improved genetic understanding is critical to the development of targeted abscission agents to better control apple crop loads and optimize apple production.

Fruitlet abscission: A cDNA-AFLP approach to study genes differentially expressed during shedding of immature fruits reveals the involvement of a putative auxin hydrogen symporter in apple (Malus domestica L. Borkh)

“…patens) was reported. The results were related to each of the reference species because of three main reasons: annotation may be different depending on accession, apple seems to have some specific genes not encountered in other species, and orthologs may be encountered in annual but not in perennial plants and vice versa (Zhou et al, 2008). The first three species were chosen because the majority of the euchromatin of their genome has been sequenced.…”

MADS Box Transcript Amount is Affected by Ethylene during Abscission

“…Fruitlet abscission in apple (Malus × domestica L. Borkh) occurs in a period of competition between reproductive and vegetative parts and among fruitlets [7]. This competition is due to several factors [8,10,11]. Hormones play a central role in modulating abscission as can be proven by the fact that bioregulators are widely used to thin excess fruitlet load [5].…”

Molecular cloning and characterization of a chitinase gene up-regulated in longan buds during flowering reversion

“…Coupe et al (1997) screened two chitinases, Chia1 and Chia4, which were up-regulated in the leaflet abscission zone of Sambucus nigra. Four different chitinase transcripts were also identified during abscission of citrus leaves and apple fruits (Agusti et al, 2008;Zhou et al, 2008). Two chitinase genes were up-regulated in the abscission zone at 2 h after flower removal and remained highly expressed during 14 h, while in the non-abscission zone, their observed increase of expression was only transient and peaked at 2 h after flower removal and the class II chitinase was suggested as abscission zone specific gene (Meir et al, 2010).…”