TY - JOUR

T1 - Aquatic adventitious roots of the wetland plant Meionectes brownii can photosynthesize

T2 - implications for root function during flooding

AU - Rich, Sarah Meghan

AU - Ludwig, Martha

AU - Pedersen, Ole

AU - Colmer, Timothy David

N1 - © 2010 The Authors. New Phytologist © 2010 New Phytologist Trust.

PY - 2011

Y1 - 2011

N2 - • Many wetland plants produce aquatic adventitious roots from submerged stems. Aquatic roots can form chloroplasts, potentially producing endogenous carbon and oxygen. Here, aquatic root photosynthesis was evaluated in the wetland plant Meionectes brownii, which grows extensive stem-borne aquatic roots during submergence. • Underwater photosynthetic light and CO(2) response curves were determined for aquatic-adapted leaves, stems and aquatic roots of M. brownii. Oxygen microelectrode and (14)CO(2)-uptake experiments determined shoot inputs of O(2) and photosynthate into aquatic roots. • Aquatic adventitious roots contain a complete photosynthetic pathway. Underwater photosynthetic rates are similar to those of stems, with a maximum net photosynthetic rate (P(max)) of 0.38 µmol O(2) m(-2) s(-1); however, this is c. 30-fold lower than that of aquatic-adapted leaves. Under saturating light with 300 mmol m(-3) dissolved CO(2), aquatic roots fix carbon at 0.016 µmol CO(2) g(-1) DM s(-1). Illuminated aquatic roots do not rely on exogenous inputs of O(2). • The photosynthetic ability of aquatic roots presumably offers an advantage to submerged M. brownii as aquatic roots, unlike sediment roots, need little O(2) and carbohydrate inputs from the shoot when illuminated.

AB - • Many wetland plants produce aquatic adventitious roots from submerged stems. Aquatic roots can form chloroplasts, potentially producing endogenous carbon and oxygen. Here, aquatic root photosynthesis was evaluated in the wetland plant Meionectes brownii, which grows extensive stem-borne aquatic roots during submergence. • Underwater photosynthetic light and CO(2) response curves were determined for aquatic-adapted leaves, stems and aquatic roots of M. brownii. Oxygen microelectrode and (14)CO(2)-uptake experiments determined shoot inputs of O(2) and photosynthate into aquatic roots. • Aquatic adventitious roots contain a complete photosynthetic pathway. Underwater photosynthetic rates are similar to those of stems, with a maximum net photosynthetic rate (P(max)) of 0.38 µmol O(2) m(-2) s(-1); however, this is c. 30-fold lower than that of aquatic-adapted leaves. Under saturating light with 300 mmol m(-3) dissolved CO(2), aquatic roots fix carbon at 0.016 µmol CO(2) g(-1) DM s(-1). Illuminated aquatic roots do not rely on exogenous inputs of O(2). • The photosynthetic ability of aquatic roots presumably offers an advantage to submerged M. brownii as aquatic roots, unlike sediment roots, need little O(2) and carbohydrate inputs from the shoot when illuminated.

KW - Aquatic Organisms

KW - Biomass

KW - Chlorophyll

KW - Floods

KW - Light

KW - Organ Specificity

KW - Oxygen

KW - Partial Pressure

KW - Photosynthesis

KW - Plant Roots

KW - Saxifragaceae

KW - Wetlands

U2 - 10.1111/j.1469-8137.2010.03524.x

DO - 10.1111/j.1469-8137.2010.03524.x

M3 - Journal article

C2 - 21062289

VL - 190

SP - 311

EP - 319

JO - New Phytologist

JF - New Phytologist

SN - 0028-646X

IS - 2

ER -