e-journal

Evidence for land plant cell wall biosynthetic mechanisms in charophyte green algae

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† Background and Aims:
The charophyte green algae (CGA) are thought to be the closest living relatives to the land plants, and ancestral CGA were unique in giving rise to the land plant lineage. The cell wall has been suggested to be a
defining structure that enabled the green algal ancestor to colonize land. These cell walls provide support and protection, are a source of signalling molecules, and provide developmental cues for cell differentiation and elongation. The cell wall of land plants is a highly complex fibre composite, characterized by cellulose cross-linked by non-cellulosic polysaccharides, such as xyloglucan, embedded in a matrix of pectic polysaccharides. How the land plant cell wall evolved is currently unknown: early-divergent chlorophyte and prasinophyte algae genomes contain a low number of glycosyl transferases (GTs), while land plants contain hundreds. The number of GTs in CGA is currently unknown, as no genomes are available, so this study sought to give insight into the evolution of the biosyntheticmachinery of CGA through an analysis of available transcriptomes.

† Methods:
Available CGA transcriptomes were mined for cell wall biosynthesis GTs and compared with GTs characterized in land plants. In addition, gene cloning was employed in two cases to answer important evolutionary questions.

† KeyResults:
Genetic evidencewas obtained indicating that many of the most important core cell wall polysaccharides have their evolutionary origins in theCGA,including cellulose, mannan, xyloglucan, xylan and pectin, aswell as
arabino-galactan protein. Moreover, two putative cellulose synthase-like D family genes (CSLDs) from the CGA
species Coleochaete orbicularis and a fragment of a putative CSLA/K-like sequence from a CGA Spirogyra
species were cloned, providing the first evidence that all the cellulose synthase/-like genes present in early-divergent land plants were already present in CGA.

†Conclusions:
The results provide new insights into the evolution of cell walls and support the notion that the CGA
were pre-adapted to life on land by virtue of the their cell wall biosynthetic capacity. These findings are highly significant for understanding plant cell wall evolution as they imply that some features of land plant cell walls evolved prior to the transition to land, rather than having evolved as a result of selection pressures inherent in this transition.

Key words: Plant cell wall, charophyte green algae, polysaccharides, glycosyl transferases, transcriptomes,
evolution, CAZy, cellulose synthase-like, CSLA, CSLK, CSLD, Coleochaete orbicularis, Spirogyra.

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Informasi Detail

Judul Seri

Annals of Botany

No. Panggil

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Penerbit

Oxford : Oxford University Press on behalf of the Annals of Botany Company., 2014

Deskripsi Fisik

Annals of Botany 114: 1217–1236, 2014

Bahasa

English

ISBN/ISSN

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Klasifikasi

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Tipe Isi

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Tipe Media

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Tipe Pembawa

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Edisi

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Subjek

EKOFISIOLOGI TANAMAN

Info Detail Spesifik

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Pernyataan Tanggungjawab

agus

Versi lain/terkait

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