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This breeding project, initiated at the United States Potato Genebank (USPG) in collaboration with Peruvian partners Instituto Nacional de Innovacion Agraria (INIA), International Potato Center, Peru (CIP), and local farmers, sought to enhance cold hardiness and frost tolerance in native potato cultivars in Peru. The Andes and Altiplano are often affected by frost, which causes significant reduction in yield; creating varieties with superior resilience is a critical undertaking. The goal was to transfer outstanding non-acclimated cold tolerance and acclimation capacity found in wild potato species Solanum commersonii (cmm). Breeding families segregating for cold hardiness were created using (a) a somatic hybrid cmm + haploid Solanum tuberosum (tbr) (cv. Superior, US variety from Wisconsin) as male and (b) seven cultivars native to Peru of the species S. tuberosum sbsp. andigenum (adg) as females. All plant materials were part of the USPG germplasm collection. Sexual seeds of each family were sent to Peru for evaluations under the natural conditions of the Andean highlands and Altiplano. The plants were assessed for their response to frost, and genotypes showing exceptional tolerance were selected. Plants were also evaluated for good tuber traits and yield. Initial planting involving ~2,500 seedlings in five locations resulted in selecting 58 genotypes with exceptional frost tolerance, good recovery capacity after frost, and good tuber traits. Over the years, evaluations continued and were expanded to replicated field trials in the harsher conditions of the Altiplano (Puno). All trials confirmed consistency of frost tolerance over time and location, tuber quality, and yield. After 8 years, two advanced clones were considered for cultivar release because of their exceptional frost tolerance and superior field productivity that outyielded many of the established cultivars in the region. In November 2018, a new native cultivar named Wiñay, a Quechua word meaning “to grow” was released in Peru. In 2022, a second cultivar followed with the name Llapanchispaq (meaning “for all of us”). This project evidenced that a multinational and all-encompassing approach to deploy valuable genetic diversity can work and deliver effective results. This is even more significant when outcomes can promote food security and sustainability in very vulnerable regions of the world.

Maize grain hardness influences storage pest resistance, a key characteristic valued by smallholder farmers. The structural changes in the endosperm determine grain hardness and are influenced by agronomic practices. The purpose of this study was to establish whether supply of calcium and magnesium based fertilizers can alter physicochemical properties of local and hybrid maize varieties and reduce the infestation by larger grain borer (Prostephanus truncatus (Coleoptera: Bostrichidae)) during storage. Two local and one hybrid maize varieties commonly grown by smallholder farmers in Malawi were cultivated under three fertilizer treatments (NPK (nitrogen, phosphorous, potassium), NPK plus gypsum, and NPK plus dolomite). After harvest, the grains were classified into flint and dent types, followed by P. truncatus infestation and determination of their physicochemical properties. The addition of gypsum and dolomite fertilizers led to higher levels of amylose, total zein and β-14 zein, traits associated with kernel hardness, compared to the application of NPK fertilizer. Moreover, local maize varieties showed higher resistance to P. truncatus infestation, hardness and biochemical properties associated with hardness (total zein, α-19 and β-14 zein, starch lysophosphatidylcholine, and non-starch free fatty acid) compared to hybrid variety. Our study suggests the potential for utilizing Ca and Mg nutrition in maize to improve kernel hardness, thus adoption of gypsum and dolomite by smallholder farmers may be beneficial against P. truncatus during storage.

Consistent with reports on other plants we recently reported that a potato transgenic line (AT010901) overexpressing sCAX1 show classic symptoms of calcium deficiency shoot tip injury, leaf curling, leaf margin necrosis and tuber internal defects such as hollow heart and brown spots. The present study was undertaken to quantify calcium in various fraction of leaf and tuber tissues of this transgenic and wild type potato clones to understand the development of these deficiency symptoms at normal calcium nutrition (1mM) and its mitigation at higher calcium nutrition (10mM). Plants were grown in controlled environment growth chamber and watered with balanced nutrient solution containing either 1 or 10 mM calcium. The plants overexpressing sCAX1 showed calcium deficiency symptoms while sequestering calcium in the vacuole as calcium oxalate crystals. Various fractions of calcium were qualified in the young and mature leaves as well as tuber tissue. A reduced concentration of water soluble fraction of calcium was most important factor related to the development of calcium deficiency symptoms in the line overexpressing sCAX1. Furthermore, an increase in this fraction appear to explain the alleviation of the deficiency symptoms in these transgenic plants.Ours is the first study to document the significance of water-soluble calcium in the development of calcium-deficiency symptoms in the potato transgenic lines overexpressing sCAX1. Furthermore, our result demonstrates that an increase in this fraction plays a significant role in the alleviation of calcium deficiency symptoms when calcium concentration in the nutrient media is increased. These results provide important insight on the role of sCAX1 in the calcium homeostasis.

Although the importance of phospholipase D (PLD) in signal transduction in mammalian cells is well documented, the negative regulation of PLD is poorly understood. This is primarily due to a lack of known specific inhibitors of PLD. We herein report that the activity of partially purified rat brain PLD is inhibited by certain lysophospholipids, such as lysophosphatidylinositol, lysophosphatidylglycerol, and lysophosphatidylserine in a highly specific manner. Inhibition of PLD by lysophospholipids was dose-dependent: the concentration of lysophosphatidylinositol required for half-maximal inhibition was about 3 μm. An analysis of the enzyme-kinetics suggested that lysophospholipids act as non-competitive inhibitors of PLD activity. As expected, PLD activity was stimulated by ADP-ribosylation factor (Arf) and phosphatidylinositol 4,5-bisphosphate (PIP2). The inhibition of PLD by lysophospholipids, however, was not affected by the presence or absence of Arf or by an increase in PIP2 concentration. A protein-binding assay suggested that lysophospholipids bind directly to PLD. These results indicate that the observed inhibition of PLD by lysophospholipids is due to their direct interaction rather than to an interaction between lysophospholipids and either Arf or PIP2.The present study suggests that certain lysophospholipids are specific inhibitors of rat brain PLD in a cell-free system and may provide the new opportunities to investigate mechanisms by which PLD is regulated by lysophospholipids, presumably liberated by phospholipase A2 activation, in mammalian cells.