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YT521-homology (YTH) domain-containing RNA-binding proteins (YTPs) are a small gene family involved in post-transcriptional regulation. We identified 26 putative YTP gene models in the apple genome. Although plant YTPs have been classified into three groups, those in multi-cellular organisms belong only to Groups A and B. The apple genome contains 22 YTP gene models in Group A and four in Group B. Duplication analysis showed that tandem and segmental duplications contributed only partially to an expansion in apple YTP numbers. YTH was the only recognizable domain in apple YTPs; its three-dimensional structure implied possible motifs for RNA-binding. After the assembly of expressed sequence tags (ESTs) and gene-cloning, we were able to identify 14 apple YTPs that were expressed in various tissues, especially senescing leaves. Expression analysis showed that these YTPs also responded to several abiotic stresses. Taken together, our genome-wide evaluation provides new insight for further research on the effects of those stresses., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The objectives of this study were to test the effects of exogenous melatonin on apple (Malus domestica Borkh. cv. Golden Delicious) leaves and investigate its possible physiological role in delaying leaf senescence. Detached leaves treated with 10 mm melatonin solutions clearly showed a slowing in their process of dark-induced senescence, as evidenced by both biochemical and molecular parameters. Melatonin delayed the normal reduction in chlorophyll content and maximum potential photosystem II efficiency (F(v) /F(m) ). It also suppressed the transcript levels of a key chlorophyll degradation gene, pheide a oxygenase (PAO), and the senescence-associated gene 12 (SAG12). This outcome was thought to be because of the enhanced antioxidant capabilities of melatonin. Indeed, H(2) O(2) accumulation was inhibited by exogenous melatonin, which might have resulted from direct reactive oxygen species scavenging by melatonin and a great enhancement of ascorbate peroxidase (APX; EC 1.11.1.11), which acted on both mRNA and protein activity levels. Melatonin treatment led to the maintenance of higher contents of ascorbic acid (AsA) and glutathione (GSH) but less dehydroascorbate (DHA) and oxidized glutathione (GSSG) compared with the control, possibly through its regulation of the AsA-GSH cycle., (© 2011 John Wiley & Sons A/S.)

Strigolactones have multiple roles for plants, including repression of the development of lateral buds and lateral roots, and improvement of stress tolerance, while the knowledge about the regulation of strigolactone synthesis is rare. The Malus genus is important resource of apple’s rootstocks, thus study on strigolactone synthesis in Malus is helpful to realize the signal communication between apple scion and rootstock. Here, we detected the strigolactone contents of seven Malus species and confirmed the synthesis of strigolactones widely existed in Malus . Then the putative strigolactone synthesis gene, carotenoid cleavage dioxygenase 7 ( CCD7 ), and its promoter sequence were cloned. The sequences were quite conserved and some stress responsive cis -acting elements were predicted in the promoters. The CCD7’s expressions and its promoter's activity decreased under drought, waterlogging or methyl jasmonate (MeJA) treated conditions. By yeast one-hybrid screening, it was found that one transcriptional factor (TF) basic pentacysteine 1 ( BPC1 ) had the ability of binding to CCD7’s promoter. Transient overexpression of BPC1 repressed the activity of CCD7 promoter. The expressions of BPC1 were increased when Malus suffered from the stresses, and it was believed that BPC1 was one of the potential regulator of CCD7’s expression and strigolactone synthesis. [ABSTRACT FROM AUTHOR]

Highlights: [•] We isolate and characterize MdATG18a from Malus domestica. [•] MdATG18a protein has WD40 repeats and two putative PI3P binding sites. [•] MdATG18a–GFP fusion protein localizes in the nucleus and cell membrane in onion epidermal cells. [•] Promoter region of MdATG18a contains some cis-regulatory elements related to abiotic stress. [•] The expression of MdATG18a is responsive to leaf senescence and abiotic stress. [Copyright &y& Elsevier]