Hypernodulating soybean mutant line nod4 lacking 'Autoregulation of Nodulation' (AON) has limited root-to-shoot water transport capacity
| Autor: | Katherine Ruas Fraga, Fábio Afonso Mazzei Moura de Assis Figueiredo, Peter M. Gresshoff, José Altino Machado Filho, Weverton Pereira Rodrigues, Emile Caroline Silva Lopes, Mara de Menezes de Assis-Gomes, Eliemar Campostrini, Jefferson Rangel da Silva |
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| Rok vydání: | 2018 |
| Předmět: |
0106 biological sciences
0301 basic medicine Stomatal conductance Root nodule Water flow Vapour Pressure Deficit Plant Science Biology 01 natural sciences 03 medical and health sciences chemistry.chemical_compound Homeostasis Photosynthesis Transpiration Water transport Chlorophyll A fungi food and beverages Water Plant Transpiration Original Articles Plant Leaves Horticulture 030104 developmental biology chemistry Chlorophyll Shoot Soybeans 010606 plant biology & botany |
| Zdroj: | Ann Bot |
| ISSN: | 1095-8290 |
| Popis: | Background and AimsAlthough hypernodulating phenotype mutants of legumes, such as soybean, possess a high leaf N content, the large number of root nodules decreases carbohydrate availability for plant growth and seed yield. In addition, under conditions of high air vapour pressure deficit (VPD), hypernodulating plants show a limited capacity to replace water losses through transpiration, resulting in stomatal closure, and therefore decreased net photosynthetic rates. Here, we used hypernodulating (nod4) (282.33 ± 28.56 nodules per plant) and non-nodulating (nod139) (0 nodules per plant) soybean mutant lines to determine explicitly whether a large number of nodules reduces root hydraulic capacity, resulting in decreased stomatal conductance and net photosynthetic rates under high air VPD conditions.MethodsPlants were either inoculated or not inoculated with Bradyrhizobium diazoefficiens (strain BR 85, SEMIA 5080) to induce nitrogen-fixing root nodules (where possible). Absolute root conductance and root conductivity, plant growth, leaf water potential, gas exchange, chlorophyll a fluorescence, leaf ‘greenness’ [Soil Plant Analysis Development (SPAD) reading] and nitrogen content were measured 37 days after sowing.Key ResultsBesides the reduced growth of hypernodulating soybean mutant nod4, such plants showed decreased root capacity to supply leaf water demand as a consequence of their reduced root dry mass and root volume, which resulted in limited absolute root conductance and root conductivity normalized by leaf area. Thereby, reduced leaf water potential at 1300 h was observed, which contributed to depression of photosynthesis at midday associated with both stomatal and non-stomatal limitations.ConclusionsHypernodulated plants were more vulnerable to VPD increases due to their limited root-to-shoot water transport capacity. However, greater CO2 uptake caused by the high N content can be partly compensated by the stomatal limitation imposed by increased VPD conditions. |
| Databáze: | OpenAIRE |
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