Influence de la température d'endurcissement sur la tolérance au gel de la luzerne et sa teneur en sucres, amidon et proline

1991 ◽  
Vol 71 (3) ◽  
pp. 737-747 ◽  
Author(s):  
Annick Bertrand ◽  
Roger Paquin
Keyword(s):  
Medicago Sativa ◽  
Cold Tolerance ◽  
Sugar Content ◽  
Frost Tolerance ◽  
Proline Content ◽  
Starch Degradation ◽  
Limiting Factor ◽  
Total Sugar Content ◽  
Medicago Sativa L

The increased sugar and starch in crowns and roots during hardening is considered a limiting factor for the acquisition of cold tolerance in alfalfa (Medicago sativa L.). We wanted to determine the effect of a decrease in carbohydrate on cold tolerance. Alfalfa plants (Medicago sativa L.) were hardened at 1 °C or −2 °C during the day and at 10 °C or 15 °C during the dark while control plants were kept continuously at 1 °C or −2 °C. Hardening alfalfa at 10 °C and 15 °C during darkness decreased the total sugar content while it increased at 1 °C and −2 °C. However, frost tolerance and growth of the plants were not changed by raising the night temperature to 10 and 15 °C. The sugar increase corresponded in general to a starch degradation, mainly in the crowns. In plants hardened at −2 °C the proline content was higher in the leaves and lower in crowns. The opposite was observed in plants hardened at 10 and 15 °C during darkness. However, during hardening at −2 °C, we observed the desiccation of leaves and an increase in the proline content. We discuss the role of sugars as promoting agents for the acquisition of frost tolerance. Key words: Alfalfa, frost tolerance, sugars, starch, proline, hardening

scholarly journals Starch branching enzymes as putative determinants of postharvest quality in horticultural crops

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Jingwei Yu ◽  
Keyun Wang ◽  
Diane M. Beckles
Keyword(s):  
Sugar Content ◽  
Postharvest Quality ◽  
Starch Accumulation ◽  
Starch Degradation ◽  
Published Data ◽  
Horticultural Crops ◽  
Starch Branching Enzymes ◽  
Branching Enzymes ◽  
End Use

AbstractStarch branching enzymes (SBEs) are key determinants of the structure and amount of the starch in plant organs, and as such, they have the capacity to influence plant growth, developmental, and fitness processes, and in addition, the industrial end-use of starch. However, little is known about the role of SBEs in determining starch structure-function relations in economically important horticultural crops such as fruit and leafy greens, many of which accumulate starch transiently. Further, a full understanding of the biological function of these types of starches is lacking. Because of this gap in knowledge, this minireview aims to provide an overview of SBEs in horticultural crops, to investigate the potential role of starch in determining postharvest quality. A systematic examination of SBE sequences in 43 diverse horticultural species, identified SBE1, 2 and 3 isoforms in all species examined except apple, olive, and Brassicaceae, which lacked SBE1, but had a duplicated SBE2. Among our findings after a comprehensive and critical review of published data, was that as apple, banana, and tomato fruits ripens, the ratio of the highly digestible amylopectin component of starch increases relative to the more digestion-resistant amylose fraction, with parallel increases in SBE2 transcription, fruit sugar content, and decreases in starch. It is tempting to speculate that during the ripening of these fruit when starch degradation occurs, there are rearrangements made to the structure of starch possibly via branching enzymes to increase starch digestibility to sugars. We propose that based on the known action of SBEs, and these observations, SBEs may affect produce quality, and shelf-life directly through starch accumulation, and indirectly, by altering sugar availability. Further studies where SBE activity is fine-tuned in these crops, can enrich our understanding of the role of starch across species and may improve horticulture postharvest quality.

An overview of the role of lucerne (Medicago sativa L.) in pastoral agriculture

2012 ◽  
Vol 63 (9) ◽  
pp. 734 ◽  
Author(s):  
J. H. Bouton
Keyword(s):  
Medicago Sativa ◽  
Complex Traits ◽  
Production Systems ◽  
Bioenergy Feedstock ◽  
Continue Development ◽  
Breeding Programs ◽  
Grazing Tolerance ◽  
History Of ◽  
Medicago Sativa L

Pastoral agriculture is unique among the world’s agricultural production systems. Lucerne (also known as alfalfa), Medicago sativa L. subsp. sativa, has a long history of playing a very important role in pastoral agriculture. That role is expanding outside traditional hay and grazing production systems into sprouts for salads, nutritional supplements, and bioenergy feedstock. It is also the forage legume of choice for delivery of new traits via biotechnologies. The use of biotechnologies in lucerne improvement will cause re-examination of research methods and will require unique collaborations that are both interdisciplinary and even cross-institutional. The Consortium for Alfalfa Improvement (CAI) is discussed as a model for this type of collaboration. Breeding programs will continue development of cultivars with the proper fall (autumn) dormancy, a broad genetic base for pest resistance, increased local adaptation, persistence, and yield, while also adding new complex traits to these base traits. Increasing nutritional quality via down-regulation of lignin genes and increasing persistence via grazing tolerance, drought tolerance, and tolerance to acid, aluminium-toxic soils are discussed as examples of the potential impacts and challenges surrounding incorporation of complex traits. However, it is the potential for lucerne to become a major part of tropical or subtropical production systems or even an important adjunct to overcome deficiencies in the widely used perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) temperate systems that begs further attention.

scholarly journals Role of Potassium in Carbon Dioxide Assimilation in Medicago sativa L

1979 ◽  
Vol 63 (5) ◽  
pp. 878-881 ◽  
Author(s):  
Timothy R. Peoples ◽  
David W. Koch
Keyword(s):  
Carbon Dioxide ◽  
Medicago Sativa ◽  
Carbon Dioxide Assimilation ◽  
Medicago Sativa L

scholarly journals The rôle of the young lucerne plant in determining the infection of the root by the nodule-forming bacteria

1929 ◽  
Vol 104 (732) ◽  
pp. 481-492 ◽  
Keyword(s):  
Medicago Sativa ◽  
Culture Solution ◽  
Nodule Bacteria ◽  
True Leaf ◽  
Plant Culture ◽  
Medicago Sativa L ◽  
The Relationship

Observations have been made at Rothamsted over a period of about five years upon the development of nodules on young seedlings of lucerne (Medicago sativa, L.). Some thousands of seedlings have been examined in various experiments and it was found to be the rule that the first appearance of nodules coincided with that of the expansion of the first true leaf. When lucerne is sown under summer glasshouse conditions, in pots of soil or sand, the seedlings are up in from 3 to 5 days, and in 8 to 12 days the first true leak becomes visible. This is at first closed, but in 8 to 12 days from the date of sowing it opens out (fig. 1). The following experiment illustrates the relationship between the opening of the List leak and the appearance of nodules. Lucerne seed, inoculated with nodule bacteria was sown in 12 pots, each containing about 8 pounds of sand, and these were watered with a plant-culture solution free from nitrogen.* Five days after sowing the seedlings were up, and in another 4 the first true leak, still closed, could be seen on most of them. The appearance of nodules and the opening of the first true leaves is shown in fig. 2, where each point represents observations made upon 20 seedlings, 10 from each of duplicate pots. The general agreement in the time of appearance of nodules and in the opening of the first true leaves is evident.

scholarly journals The Role of Different Daily Irradiations on Shoot Growth and Root/Shoot Ratio in Lucerne (Medicago sativa L.)

1991 ◽  
Vol 68 (4) ◽  
pp. 329-335 ◽  
Author(s):  
S. PHILIPPOT ◽  
J. M. ALLIRAND ◽  
M. CHARTIER ◽  
G. GOSSE
Keyword(s):  
Medicago Sativa ◽  
Shoot Growth ◽  
Shoot Ratio ◽  
Root Shoot Ratio ◽  
Medicago Sativa L

Phytotoxicity and genotoxicity as a new approach to assess heavy metals effect on Medicago sativa L.: Role of metallo-resistant rhizobacteria

2021 ◽  
pp. 101833
Author(s):  
Anas Raklami ◽  
Mohamed Oubane ◽  
Abdelilah Meddich ◽  
Mohamed Hafidi ◽  
Bernd Marschner ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Medicago Sativa ◽  
New Approach ◽  
Medicago Sativa L

Studies on the nutritional role of selenium. I. The distribution of radioactive selenium in mice

1963 ◽  
Vol 14 (5) ◽  
pp. 716 ◽  
Author(s):  
GB Jones ◽  
KO Godwin
Keyword(s):  
Medicago Sativa ◽  
Stomach Wall ◽  
Relative Importance ◽  
Cell Nuclei ◽  
High Concentration ◽  
Liver And Kidney ◽  
Wet Weight ◽  
Medicago Sativa L ◽  
Young Mice

Lucerne (Medicago sativa L.) in which the proteins were labelled with radioactive selenium was fed to mice. The distribution of 75Se among the various organs was studied. On the basis of 75Se activity per unit wet weight, the importance of the liver and kidney as metabolic sites is confirmed, and attention is directed to the pancreas, endocrines, and the stomach wall as additional sites where selenium is present in comparable concentrations. The relative importance of the above organs is supported by the results of autoradiography; in addition, this demonstrates the high concentration of 75Se in the cell nuclei, where selenium may play a fundamental role. Radioactive selenium from labelled lucerne was found in the milk of a lactating mouse within 4 hr of it being fed. Within 24 hr approximately 20% of the selenium absorbed by the dam had been transferred to the young mice through the milk.

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