Component traits of plant water use are modulated by vapour pressure deficit in pearl millet (Pennisetum glaucum (L.) R.Br.)

Traits influencing plant water use eventually define the fitness of genotypes for specific rainfall environments. We assessed the response of several water use traits to vapour pressure deficit (VPD) in pearl millet (Pennisetum glaucum (L.) R.Br.) genotypes known to differ in drought adaptation mechanisms: PRLT 2/89–33 (terminal drought-adapted parent), H 77/833–2 (terminal drought-sensitive parent) and four near-isogenic lines introgressed with a terminal drought tolerance quantitative trait locus (QTL) from PRLT 2/89–33 (ICMR01029, ICMR01031, ICMR02042, and ICMR02044). Plant water use traits at various levels of plant organisation were evaluated in seven experiments in plants exposed either transiently or over the long term to different VPD regimes: biomass components, transpiration (water usage per time unit) and transpiration rate (TR) upon transient VPD increase (g H2O cm–2 h–1)), transpiration efficiency (g dry biomass per kg H2O transpired), leaf expansion rate (cm per thermal time unit) and root anatomy (endodermis dimensions)). High VPD decreased biomass accumulation by reducing tillering, the leaf expansion rate and the duration of leaf expansion; decreased root endodermis cell size; and increased TR and the rate of TR increase upon gradual short-term VPD increases. Such changes may allow plants to increase their water transport capacity in a high VPD environment and are genotype-specific. Some variation in water use components was associated with terminal drought adaptation QTL. Knowledge of water use traits’ plasticity in growth environments that varied in evaporative demand, and on their genetic determinacy, is necessary to develop trait-based breeding approaches to complex constraints

Nastal čas prodloužit dobu expirace kryoprezervovaných alograftů srdečních chlopní

V současné době existuje velké množství umělých komerčních náhrad chlopní. Přesto jsou stále žádané a úspěšně transplantované kryoprezervované semilunární alografty srdečních chlopní (C-AHV). U těchto náhrad zatím není přesně definována doba expirace.Většina tkáňových bank používá pět let. Z fyziologického, funkčního a operačního pohledu představuje morfologie a mechanické vlastnosti aortálních a pulmonárních kořenů hlavní limitaci doby expirace C-AHV. Cílem této práce je podat přehled metod strukturní a mechanické analýzy tkání AHV, které jsou vhodné pro stanovení doby expirace. alograftů. Pro stanovení mikrostruktury je vhodná kvantitativní morfologie za použití stereologické testovací mřížky. Touto metodou lze snadno, efektivně a opakovatelně stanovit možství buněk a mezibuněčných komponent. Pro stanovení mechanických parametrů, jako Youngův modul pružnosti, mezní napětí a deformace, lze využít tahovou zkoušku. C-AHV jsou v různých tkáňových laboratořích připravovány podle různých protokolů. Je tedy nutné, aby každá laboratoř stanovila dobu expirace samostatně.Despite the wide choice of commercial heart valve prostheses, cryopreserved semilunar allograft heart valves (C-AHV) are required, and successfully transplanted in selected groups of patients. The expiration limit (EL) criteria have not been defined yet. Most Tissue Establishments (TE) use the EL of 5 years. From physiological, functional, and surgical point of view, the morphology and mechanical properties of aortic and pulmonary roots represent basic features limiting the EL of C-AHV. The aim of this work was to review methods of AHV tissue structural analysis and mechanical testing from the perspective of suitability for EL validation studies. Microscopic structure analysis of great arterial wall and semilunar leaflets tissue should clearly demonstrate cells as well as the extracellular matrix components by highly reproducible and specific histological staining procedures. Quantitative morphometry using stereological grids has proved to be effective, as the exact statistics was feasible. From mechanical testing methods, tensile test was the most suitable. Young’s moduli of elasticity, ultimate stress and strain were shown to represent most important AHV tissue mechanical characteristics, suitable for exact statistical analysis. C-AHV are prepared by many different protocols, so as each TE has to work out own EL for C-AHV