Biology of over-wintering of perennial root nodules and seed development in beach pea (Lathyrus maritimus L.)

• Main Author: Chinnasamy, Gurusamy
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 2000
• Subjects: Canada; Salmon Cove; Sandy Beach; Newfoundland
• Online Access: https://research.library.mun.ca/1436/; https://research.library.mun.ca/1436/1/Chinnasamy_Gurusamy.pdf; https://research.library.mun.ca/1436/3/Chinnasamy_Gurusamy.pdf

Beach pea (Lathyrus maritimus L.) is a potential cold-climate circumpolar legume crop that naturally grows along the shorelines of Newfoundland, Canada. The present study was undertaken to determine the over-wintering (winter survival) strategies of perennial root nodules of beach pea on the sandy beach of Salmon Cove, Newfoundland, with emphasis on oleosomes (lipid bodies). Seasonal changes in other biochemical constituents of nodules such as carbohydrates, proteins and elements were also studied. In addition, attempts were made to screen the suitable rhizobial inoculum for beach pea and also to trace the patterns of seed development, maturation and abortion in beach pea. -- The native rhizobial strain (ACCCRC) isolated from beach pea nodules was found to be the most effective inoculum. It was superior in nitrogen-fixing traits compared to other bacterial strains. Studies on seasonal changes in nodule structure revealed that perennial nodules undergo winter dormancy when the aerial parts of the plant dry out. With the advent of spring, the nodule meristem is activated to regenerate effective nodule tissues that perform normal functions of the nodule in the following summer. A higher number of oleosomes was seen in histological preparations of winter nodules compared to summer nodules. As winter approached, nodules stored higher amounts of lipids, which decreased gradually throughout winter and spring. The degradation of oleosomes could be localized at the electron microscopic level. -- Phospholipids and monoglycerides were identified as the major oleosomic lipids in perennial root nodules. C16:0, C18:0 and C18:1 were the dominant fatty acids. The fatty acid composition and double bond index differed among lipid classes depending upon the season. Overall, the level of many unsaturated fatty acids increased and many saturated fatty acids decreased in oleosomes of winter nodules. Nodules selectively utilized fatty acids depending upon the season to overcome environmental influence. -- Microscopical studies showed ...