Cell Wall Pectin and its Methyl-esterification in Transition Zone Determine Al Resistance in Cultivars of Pea (Pisum sativum)

Abstract

The initial response of plants to aluminum (Al) is the inhibition of root elongation, while the transition zone is the most Al sensitive zone in the root apex, which may sense the presence of Al and regulate the responses of root to Al toxicity. In the present study, the effect of Al treatment (30 μM, 24 h) on root growth, Al accumulation, and properties of cell wall of two pea (Pisum sativum L.) cultivars, cv Onward (Al-resistant) and cv Sima (Al-sensitive), were studied to disclose whether the response of root transition zone to Al toxicity determines Al resistance in pea cultivars. The lower relative root elongation (RRE) and higher Al content were founded in cv Sima compared with cv Onward, which were related to Al-induced the increase of pectin in root segments of both cultivars. The increase of pectin is more prominent in Al-sensitive cultivar than in Al-resistant cultivar. Aluminum toxicity also induced the increase of pectin methylesterases (PME), which is 2.2 times in root transition zone in Al-sensitive cv Sima to that of Al resistant cv Onward, thus led to higher demethylesterified pectin content in root transition zone of Al-sensitive cv Sima. The higher demethylesterified pectin content in root transition zone resulted in more Al accumulation in the cell wall and cytosol in Al-sensitive cv Sima. Our results provide evidence that the increase of pectin content and PME activity under Al toxicity cooperates to determine Al sensitivity in root transition zone that confers Al resistance in cultivars of pea (Pisum sativum).

Plant Cell Walls Tackling Climate Change: Biotechnological Strategies to Improve Crop Adaptations and Photosynthesis in Response to Global Warming

“…Pectins are involved in the formation of the pollen grain walls, as seen in Quercus suber L. and Citrus clementina [28]. Changes in pectin methylesterification occur in tomato, apple, and strawberry fruits during ripening; pectin methylesterification is also critical for proper seed development and germination [29,30], or root development [31,32]. The most abundant polysaccharides of the secondary CW are mannans, which play a key role for proper gynoecium, i.e., fruit transition [33,34].…”

The Role of the Plasma Membrane H+-ATPase in Plant Responses to Aluminum Toxicity

“…Tolerant plants, such as buckwheat ( Ma et al, 1998 ), hydrangea ( Ma et al, 1997 ), melastoma ( Watanabe et al, 1998 ), and tea ( Morita et al, 2008 ) allow Al accumulation in plant tissues, using Al sequestration in the vacuole and/or Al detoxification via Al binding to organic acid anions or proteins as the tolerance mechanisms. In contrast, plants with the avoidance mechanisms decrease Al accumulation in roots via cell wall polysaccharide modifications ( Schmohl et al, 2000 ; Yang et al, 2008 , 2011a , 2016 ; Li et al, 2016 ) or exudation of organic acid anions from root tips ( Ma, 2000 ; Chen and Liao, 2016 ).…”

Putrescine alleviates aluminum toxicity in rice (Oryza sativa) by reducing cell wall Al contents in an ethylene‐dependent manner

“…Most of the Al in plants is deposited in the cell wall, for example approximately 70–99% of total Al is found in the cell wall in Hordeum vulgare (barley; Clarkson ), in the giant alga Chara corallina (Rengel and Reid ) and in Triticum aestivum (wheat; Ma et al ). Pectin and hemicellulose are the main components that carry the negative charges that can bind Al 3+ in the cell wall, and modifications of their chemical structures or changes in their quantities significantly affect plant Al tolerance (Yang et al , Li et al ). In addition, a variety of factors, such as NH 4 + , H 2 S and boron (B), are involved in excluding Al from the cell wall via reducing pectin and hemicellulose content in Oryza sativa (rice) and Pisum sativum (pea) or decreasing the content of negatively charged particles via repressing pectin methylesterase (PME) activity in rice (Yang et al , Yu et al , Wang et al , Zhu et al ).…”