The production and consumption of nuts are increasing in the world due to strong economic returns and the nutritional value of their products. With the increasing role and importance given to nuts (i.e., walnuts, hazelnut, pistachio, pecan, almond) in a balanced and healthy diet and their benefits to human health, breeding of the nuts species has also been stepped up. Most recent fruit breeding programs have focused on scion genetic improvement. However, the use of locally adapted grafted rootstocks also enhanced the productivity and quality of tree fruit crops. Grafting is an ancient horticultural practice used in nut crops to manipulate scion phenotype and productivity and overcome biotic and abiotic stresses. There are complex rootstock breeding objectives and physiological and molecular aspects of rootstock–scion interactions in nut crops. In this review, we provide an overview of these, considering the mechanisms involved in nutrient and water uptake, regulation of phytohormones, and rootstock influences on the scion molecular processes, including long-distance gene silencing and trans-grafting. Understanding the mechanisms resulting from rootstock × scion × environmental interactions will contribute to developing new rootstocks with resilience in the face of climate change, but also of the multitude of diseases and pests.

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Pecan is native to the United States. The US is the world’s largest pecan producer with an average yearly production of 250 to 300 million pounds; 80 percent of the world’s supply. Georgia, New Mexico, Texas, Arizona, Oklahoma, California, Louisiana, and Florida are the major US pecan producing states. Pecan trees frequently suffer from spring freeze at bud break and bloom as the buds are quite sensitive to freeze damage. This leads to poor flower and nut production. This review focuses on the impact of spring freeze during bud differentiation and flower development. Spring freeze kills the primary terminal buds, the pecan tree has a second chance for growth and flowering through secondary buds. Unfortunately, secondary buds have less bloom potential than primary buds and nut yield is reduced. Spring freeze damage depends on severity of the freeze, bud growth stage, cultivar type and tree age, tree height and tree vigor. This review discusses the impact of temperature on structure and function of male and female reproductive organs. It also summarizes carbohydrate relations as another factor that may play an important role in spring growth and transition of primary and secondary buds to flowers.

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mThe conformation structure of the tetrapeptide Ac-Lys-Ala-Leu-Ala-OMe, the repeat unit of a 30 residue peptide YAA(KALA)6LAA, and also its analog containing an unusual amino acid, (Aib): Ac-Lys-Aib-Leu-Aib-OMe, has been investigated by the PCILO method. The global/low-energy minima for all the residues lies at 4 = -30" and I ++ = 120". In this conformation, the potential hydrogen-bonding sites are free, i.e., capable of intermolecular hydrogen bonding. As the angles lie closer to the collagen helical region and potential hydrogen-bonding sites are free, this structure is named the collagen-type helix. In aqueous solution, this structure is stabilized by solvation of the peptide bond. The local-energy minimum in all maps corm ond to the right-handed one lateral hydrophobic side and the other hydrophilic side. The pore thus formed is cation-selective and accounts for the leakage of contents from vesicles. On the basis of the length of the helix and placement of the side chains of lysine and leucine, a model has been proposed for the aggregation and fusion of the vesicles. The amphipathic basic residues interact with the head groups of the acidic liposomes by extending toward the polar face of the helix to insert their charged moieties by overcoming the electrostatic repulsive forces between the opposing vesicles. 0 1995 John Wiley & Sons, Inc.helical region. The helix thus formed generates a pore of 3 R along the helix axis, with