Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Doctorat → États-Unis → 1989 → Physiology of drought stress in Pinus ponderosa (Dougl. ex Laws.) and the influence of low irradiance

Oregon State University (1989)

Physiology of drought stress in Pinus ponderosa (Dougl. ex Laws.) and the influence of low irradiance

Vance, Nan C.

Titre : Physiology of drought stress in Pinus ponderosa (Dougl. ex Laws.) and the influence of low irradiance

Auteur : Vance, Nan C.

Université de soutenance : Oregon State University

Grade : Doctor of Philosophy (Ph. D.) in Forest Science 1989

The physiology of progressively drought-stressed ponderosa pine (Pinus ponderosa Dougl. Laws.) var. scopulorum and var. ponderosa was characterized in seedlings unwatered for about a month. Additional seedlings of var. scopulorum were shaded to 10% full light and compared to unshaded seedlings to determine the influence of light starvation on drought-stress tolerance. Pressure-volume and carbohydrate analyses indicated that needles of light starved seedlings had significantly lower symplastic osmotic concentrations, cell-wall capacitance, apoplastic water content, cellulose content, and higher cell volume-to mass ratios. The light-starved seedlings demonstrated reduced drought stress tolerance by low recovery rates and loss of structural integrity at relative water contents below 60%. A method was developed for the analysis of free amino acids extracted from the needles using derivatization with dansyl chloride and high performance liquid chromatography. Concentrations of most amino acids increased in light-starved seedlings. Arginine and proline accumulated to highest concentrations in all drought-stressed seedlings ; in unstressed, light-starved seedlings arginine and glutamine accumulated most, indicating the sequestering and storage of free annuonia is important under stress conditions. Characterization of protein synthesis was by in vivo labeling with [3H]leucine, one and two dimensional electrophoresis and fluorography. Drought stress induced or enhanced the synthesis of specific low Mr proteins. Western blots were used to identify putative 70-80 kDa heat shock proteins. Antibody against a 26 kDa osmotic stress-induced protein cross-reacted to antigen in salt stressed, but not in drought-stressed seedlings. Metabolic changes induced by severe drought stress, including synthesis of new proteins and increases in arginine and proline, were altered by light starvation which also reduced drought tolerance. Unshaded seedlings of both varieties demonstrated their drought tolerance in surviving water potentials as negative as -4.0 MPa and RWC below 65%. Physiological differences between the two varieties may have been due to differences in needle type, ie. the early development of secondary needles in var. scopulorum.

Mots clés : Ponderosa pine — Drought tolerance — Ponderosa pine — Physiology


Version intégrale (1,21 Mb)

Page publiée le 17 octobre 2013, mise à jour le 7 mars 2019