Biotechnology provides plant breeders an additional tool to improve various traits desired by growers and consumers of horticultural crops. It also provides genetic solutions to major problems affecting horticultural crops and can be a means for rapid improvement of a cultivar. With the availability of a number of horticultural genome sequences, it has become relatively easier to utilize these resources to identify DNA sequences for both basic and applied research. Promoters play a key role in plant gene expression and the regulation of gene expression. In recent years, rapid progress has been made on the isolation and evaluation of plant-derived promoters and their use in horticultural crops, as more and more species become amenable to genetic transformation. Our understanding of the tools and techniques of horticultural plant biotechnology has now evolved from a discovery phase to an implementation phase. The availability of a large number of promoters derived from horticultural plants opens up the field for utilization of native sequences and improving crops using precision breeding. In this review, we look at the temporal and spatial control of gene expression in horticultural crops and the usage of a variety of promoters either isolated from horticultural crops or used in horticultural crop improvement.

Edited by F. Peter Guengerich Energy partitioning and plant growth are mediated in part by a type I H ؉-pumping pyrophosphatase (H ؉-PPase). A canonical role for this transporter has been demonstrated at the tonoplast where it serves a job-sharing role with V-ATPase in vacuolar acidification. Here, we investigated whether the plant H ؉-PPase from Arabidopsis also functions in "reverse mode" to synthesize PP i using the transmembrane H ؉ gradient. Using patch-clamp recordings on Arabidopsis vacuoles, we observed inward currents upon P i application on the cytosolic side. These currents were strongly reduced in vacuoles from two independent H ؉-PPase mutant lines (vhp1-1 and fugu5-1) lacking the classical PP i-induced outward currents related to H ؉ pumping, whereas they were significantly larger in vacuoles with engineered heightened expression of the H ؉-PPase. Current amplitudes related to reverse-mode H ؉ transport depended on the membrane potential, cytosolic P i concentration, and magnitude of the pH gradient across the tonoplast. Of note, experiments on vacuolar membrane-enriched vesicles isolated from yeast expressing the Arabidopsis H ؉-PPase (AVP1) demonstrated P i-dependent PP i synthase activity in the presence of a pH gradient. Our work establishes that a plant H ؉-PPase can operate as a PP i synthase beyond its canonical role in vacuolar acidification and cytosolic PP i scavenging. We propose that the PP i synthase activity of H ؉-PPase contributes to a cascade of events that energize plant growth.

Stimuli-induced fluctuations in intracellular free calcium (Ca 2?) serve as secondary messenger signals that regulate diverse biochemical processes in eukaryotic cells, such as developmental transitions and responses to biotic and abiotic stresses. Stimuli-specific Ca 2? signals are manifested as spatially and temporally defined differential Ca 2? signatures that are sensed, decoded, and transduced to elicit distal responses via an array of Ca 2? binding proteins (CBPs) that function as intracellular Ca 2? sensors. Calmodulin (CaM), the most important eukaryotic CBP, senses and responds to fluctuations in intracellular Ca 2? levels by binding to this ubiquitous second messenger, and transducing given Ca 2? signatures that differentially activate distal effector (target) proteins regulating a broad range of biochemical responses. Ca 2? /CaM targets include an increasing number of proteins whose functions continue to be elucidated. Hundreds of reports have highlighted the importance of CaM, and other CBPs, in the transduction of Ca 2?-mediated signals involved in transcriptional regulation, protein phosphorylation/dephosphorylation, and metabolic shifts. Other Ca 2?-binding proteins are known to play significant functional roles in plant cells as well. This review is primarily focused on the role of CaM in some key plant processes, and discusses recent advances in understanding the pivotal role of CaM in an ever-increasing number of plant cell functions and biochemical responses. We also discuss recent work highlighting the emerging importance of CaM in nuclear and organellar signaling. Keywords Calcium Á Calmodulin Á Intracellular signaling Á Plant defense Á Secondary messenger Endorsed by Sadanand Dhekney.

Napier grass (Pennisetum purpureum Schum.) is a well-established perennial fodder crop of African origin which recently has also drawn attention for its potential as biofuel feedstock. The absence of genome information in Napier grass limits the development of sequence-specific markers which often involves a high developmental cost. This study aimed to determine cross-species transferability of microsatellite markers between pearl millet (Pennisetum glaucum L.) and Napier grass and to assess the genetic diversity of Napier grass accessions. A total of 107 pearl millet microsatellite markers were tested of which 71 markers (66 %) showed successful cross-amplification. Only 29 markers were selected to study the genetic diversity of Napier grass accessions maintained at the US Department of Agriculture-Agriculture Research Service (USDA-ARS) Tifton, GA. A total of 108 alleles were identified among 99 accessions, a pearl millet line, and a sugarcane hybrid. The average polymorphic information content (PIC) value was 0.212 per marker, while Dice coefficient of similarity ranged from 0.50 to 1.0, indicating high genetic variability among accessions. The accessions with the lowest Dice coefficient of similarity values could be useful in breeding programs. The similarity coefficient of accessions equal to 1.00 is likely an indication of a single genotype being represented by two accessions with different names. This study provides an expanded set of microsatellite markers transferable from pearl millet to Napier grass that can be used to evaluate genetic diversity in Napier grass accessions.

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