International Society for Plant Anaerobiosis

International Society for Plant Anaerobiosis - flooded Rumex crispus (c) Ole Pedersen

   

CONFERENCES - International Society for Plant Anaerobiosis (ISPA)

 

Adaptation to flooding and submergence: surviving energy deficits

 

Brian Atwell

 

Macquarie University, NSW, Australia

 

Plants tolerate flooding and indeed, total submergence, to varying degrees depending upon where they have evolved. This allows flowering plants to populate much of the planet which would otherwise be too hostile: lakes, rivers, ponds, paddies and shallow seabeds alike. The limiting factors to plant growth in these extreme environments are diverse and while they can be highly specific (e.g. micronutrient toxicities) there are some general features that restrict metabolism. These include: deficiencies of oxygen, leading to impaired oxidative ATP production; restricted carbon dioxide diffusion, leading to restricted photosynthetic capacity and phytotoxic effects through carbon dioxide buildup; low light penetration and restricted photosynthesis. Oxygen/carbon dioxide cycling are features of well adapted, fully submerged plants. This talk will describe two cases of energy saving in oxygen deficient environments. First, I describe the role of pyrophosphatases on the tonoplast which transport protons into the vacuole with modest energy costs. Overexpression of the key V-PPase in rice confers a degree of flood tolerance as demonstrated by membrane polarisation and ion fluxes. Second, we describe the energy budgets of rice tissues by quantitative analysis and make the argument that rice selectively conserves ATP for the most critical anabolic reactions.