Modulating plant growth-metabolism coordination for sustainable agriculture.

Enhancing global food security by increasing the productivity of green revolution varieties of cereals risks increasing the collateral environmental damage produced by inorganic nitrogen fertilizers. Improvements in the efficiency of nitrogen use of crops are therefore essential; however, they require an in-depth understanding of the co-regulatory mechanisms that integrate growth, nitrogen assimilation and carbon fixation. Here we show that the balanced opposing activities and physical interactions of the rice GROWTH-REGULATING FACTOR 4 (GRF4) transcription factor and the growth inhibitor DELLA confer homeostatic co-regulation of growth and the metabolism of carbon and nitrogen. GRF4 promotes and integrates nitrogen assimilation, carbon fixation and growth, whereas DELLA inhibits these processes. As a consequence, the accumulation of DELLA that is characteristic of green revolution varieties confers not only yield-enhancing dwarfism, but also reduces the efficiency of nitrogen use. However, the nitrogen-use efficiency of green revolution varieties and grain yield are increased by tipping the GRF4-DELLA balance towards increased GRF4 abundance. Modulation of plant growth and metabolic co-regulation thus enables novel breeding strategies for future sustainable food security and a new green revolution.

Tracking celiac disease-triggering peptides and whole wheat flour quality as function of germination kinetics.

Germination is already a well-accepted process by consumers with many products made from sprouted seeds or containing limited amounts of flour form sprouted grains. The present work aimed assessing the usefulness of germination in reducing gluten peptides associated with celiac disease, at the same time evaluating some technological features of the obtained germinated wheat. In the first part of the work, celiac disease (CD)-triggering peptides were tracked as a function of germination kinetics (from day 1 to day 6). Using simulated gastrointestinal digestion and liquid chromatography coupled to mass spectrometry, ten celiac disease triggering peptides were identified: seven peptides presumably involved in the adaptive immune response (TI) and three peptides mainly involved in the innate immune response (TT). All the identified peptides belonged to gliadins. TI track pattern showed three phases: the first two days displayed a significant degradation, a stability phase was observed from day 3 to day 5, and finally a drastic reduction occurred on the 6th day. For TT peptides, important degradation was exclusively observed at the 6th day. In the second part, some techno-functional features of germinated whole wheat flour were assessed to estimate its potential as an alternative to conventional flour. Functionality comparison of the non-germinated versus germinated flours revealed that germination significantly influenced solvents retention capacities as well as swelling and solubility. Thus, with a reduced amount of celiac disease triggering peptides, but also with different technological behavior compared to traditional wheat flour.

Exploring high hydrostatic pressure-mediated germination to enhance functionality and quality attributes of wholegrain brown rice.

This investigation aims to evaluate the effects of high hydrostatic pressure (HHP) applied prior to germination on functionality and quality of wholegrain-germinated brown rice (GBR). Wholegrain brown rice (WBR) were firstly stressed by HHP treatments (50-350 MPa/20 min), and then incubated at 37 °C to obtain GBR grains after a 2-day soaking period. Gama-aminobutyric acid contents significantly depended on the pressure applied, showing 25% increment in 50 MPa-stressed grains compared to the control. HHP shock led to significantly improved in vitro starch digestibility, which was related to the transformation of crystalline starch granules into amorphous form as consistently revealed by scanning electron microscope imaging and Fourier-transform infrared spectroscopy. HHP-pretreated samples achieved markedly enhanced storability by influencing kinetic curves of lipid hydrolysis and oxidation. These results suggested that metabolic response to HHP during germination could significantly improve functional and quality characteristics of WBR products.

Overexpression of rice serotonin N-acetyltransferase 1 in transgenic rice plants confers resistance to cadmium and senescence and increases grain yield.

While ectopic overexpression of serotonin N-acetyltransferase (SNAT) in plants has been accomplished using animal SNAT genes, ectopic overexpression of plant SNAT genes in plants has not been investigated. Because the plant SNAT protein differs from that of animals in its subcellular localization and enzyme kinetics, its ectopic overexpression in plants would be expected to give outcomes distinct from those observed from overexpression of animal SNAT genes in transgenic plants. Consistent with our expectations, we found that transgenic rice plants overexpressing rice (Oryza sativa) SNAT1 (OsSNAT1) did not show enhanced seedling growth like that observed in ovine SNAT-overexpressing transgenic rice plants, although both types of plants exhibited increased melatonin levels. OsSNAT1-overexpressing rice plants did show significant resistance to cadmium and senescence stresses relative to wild-type controls. In contrast to tomato, melatonin synthesis in rice seedlings was not induced by selenium and OsSNAT1 transgenic rice plants did not show tolerance to selenium. T2 homozygous OsSNAT1 transgenic rice plants exhibited increased grain yield due to increased panicle number per plant under paddy field conditions. These benefits conferred by ectopic overexpression of OsSNAT1 had not been observed in transgenic rice plants overexpressing ovine SNAT, suggesting that plant SNAT functions differently from animal SNAT in plants.

Phenolic compounds in grains, sprouts and wheatgrass of hulled and non-hulled wheat species.

BACKGROUND: The use of sprouts and young plantlets in human nutrition is increasing because they often contain phytochemicals and other high value nutrients. This is also the case for wheat, although there is no literature for hulled wheat species. Thus we determined total polyphenols, phenolic acids (PAs), fibre and minerals in grains, 5-day-old sprouts and 12-day-old wheatgrass of einkorn (cv. Monlis), emmer (cvs Augeo, Rosso Rubino, Zefiro), spelt (cvs Pietro, Giuseppe), durum wheat (cv. Creso) and soft wheat (cv. Orso). RESULTS: Grains of einkorn and emmer contained twice bound PAs as compared to soft and durum wheat and spelt, with p-coumaric acid accounting for about 50% of total bound PAs. In wheatgrass, differences between species for bound PAs decreased due to a decrease in einkorn and emmer and an increase in soft and durum wheat. In all species, total phenols and free PAs increased passing from grains to sprouts and wheatgrass. Neutral and acid detergent fibre content increased with sprouting only in einkorn and emmer. CONCLUSION: Our evidence suggests that the grains of einkorn and emmer and the sprouts and wheatgrass of all Triticum species might potentially be valuable for the development of functional foods.