<i>Hevea</i>
            Rubber Breeding and Genetics

Clément-Demange, André; Priyadarshan, P. M.; Hoa, Tran Thi Thuy; Venkatachalam, P.

doi:10.1002/9780470168035.ch4

Cited by 54 publications

(47 citation statements)

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“…appearance of dry zones (without latex dripping out) along the tapping cut, was also observed on many trees and could be very extensive in severe cases. According to Clément-Demange et al (2007), there is uncertainty about the relationships between the two forms. Indeed, some researchers assume that TPD is directly linked to over-exploitation (excessive tapping and intense ethylene stimulation), and that there is a progressive evolution from tapping cut dryness (reversible TPD) to brown bast (irreversible TPD), whereas others think that they are two distinct diseases differing in their origin.…”

Section: Introductionmentioning

confidence: 99%

Histo- and cytopathology of trunk phloem necrosis, a form of rubber tree (Hevea brasiliensis Müll. Arg.) tapping panel dryness

Faÿ¹

2011

Aust. J. Bot.

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Abstract. Trunk phloem necrosis (TPN) is a physiological disease of rubber tree (Hevea brasiliensis Müll. Arg.) discovered in the 1980s. It has been distinguished from rubber tree tapping panel dryness (TPD) by its macroscopic symptoms and presumed origin. But little attention has been paid to its microscopic features, and there is now some evidence that both syndromes could be linked to an impaired cyanide metabolism. In order to characterise TPN and compare it with TPD microscopically, the inner phloem of tapping panels was investigated by light and transmission electron microscopy in healthy trees and TPN-affected trees. TPN-affected phloem presented numerous and varied structural and ultrastructural features. There were signs of cellular deterioration in a great number of specialised cells, i.e. laticifers and sieve tubes, and not very specialised cells, i.e. parenchyma cells and companion cells. There were also signs of cellular dedifferentiation in other parenchymatous cells, e.g. in tylosoids and hyperplasic cells. These cells were derived from parenchyma cells that ensheath laticifers in which the latex coagulated. Numerous structural features of TPN are common to TPD, notably tylosoids associated with in situ coagulated latex, which are also known to be early structural markers of TPD and cyanide-induced. It is therefore concluded that TPN is identical to or a variant of TPD, and is a degenerative disease of rubber tree trunk phloem resembling plant stress response, programmed cell death and plant tumourigenesis in some aspects.

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Section: Introductionmentioning

confidence: 99%

Histo- and cytopathology of trunk phloem necrosis, a form of rubber tree (Hevea brasiliensis Müll. Arg.) tapping panel dryness

Faÿ¹

2011

Aust. J. Bot.

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“…Whatever that may be, the immediate cause of TPD remains still unknown. Moreover, according to some researchers (Clément-Demange et al, 2007), the term TPD covers two syndromes: "tapping cut dryness" and "brown bast" (irreversible TPD).…”

Section: Introductionmentioning

confidence: 99%

Cyanogenesis and the onset of tapping panel dryness in rubber tree

Faÿ

Moraes

Moraes³

2010

Pesq. agropec. bras.

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-The objective of this work was to study the influence of cyanogenesis on the onset of irreversible tapping panel dryness (TPD) and the physiological and histological aspects of secondary phloem in the trunk (tapping panel) of rubber trees (Hevea spp.). Two cyanogenic compounds, linamarin and KCN, were applied separately on the trunk bark of healthy mature trees belonging to two Brazilian clones (Fx 4098 and Fx 3899). Changes in histology, latex pressure potential (Ψ P ) and cyanogenic potential (HCNp) were followed in the trunk inner barks. In addition, the HCNp levels were determined in TPD-affected plants of both clones. The applications of linamarin or KCN in healthy plants decreased latex Ψ P , and formed tylosoids associated with in situ coagulation of latex. The clone Fx 4098 had the higher HCNp and showed the quicker and stronger responses to the cyanogenic compounds. Plants with TPD syntoms had a higher HCNp than the untreated healthy ones. Since histological changes are also structural markers of early TPD, it can be inferred that excessive release of cyanide can induce it in sensitive rubber clones.Index terms: Hevea, clonal sensitivity, cyanogenic potential, latex pressure potential, linamarin, secondary phloem. Cianogênese e estabelecimento do secamento de painel de sangria em seringueiraResumo -O objetivo deste trabalho foi estudar a influência da cianogênese no estabelecimento do secamento do painel de sangria (TPD) e os aspectos fisiológicos e histológicos do floema secundário do tronco (painel de sangria) em seringueira (Hevea spp.

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“…Meanwhile, conventional rubber breeding has been stagnating in the introduction of high-yield cultivars. The reasons include a narrow genetic basis for exploiting breeding potential and difficulty in introducing wild germplasms because of the genetic burden in removing unfavourable alleles 6 . The incorporation of marker-assisted selection and transgenic techniques offers promise to improve breeding efficiency for latex yield, and sequencing of the Hevea genome would uncover even more avenues leading to this end.…”

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confidence: 99%

The rubber tree genome reveals new insights into rubber production and species adaptation

et al. 2016

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The Para rubber tree (Hevea brasiliensis) is an economically important tropical tree species that produces natural rubber, an essential industrial raw material. Here we present a high-quality genome assembly of this species (1.37 Gb, scaffold N50 = 1.28 Mb) that covers 93.8% of the genome (1.47 Gb) and harbours 43,792 predicted protein-coding genes. A striking expansion of the REF/SRPP (rubber elongation factor/small rubber particle protein) gene family and its divergence into several laticifer-specific isoforms seem crucial for rubber biosynthesis. The REF/SRPP family has isoforms with sizes similar to or larger than SRPP1 (204 amino acids) in 17 other plants examined, but no isoforms with similar sizes to REF1 (138 amino acids), the predominant molecular variant. A pivotal point in Hevea evolution was the emergence of REF1, which is located on the surface of large rubber particles that account for 93% of rubber in the latex (despite constituting only 6% of total rubber particles, large and small). The stringent control of ethylene synthesis under active ethylene signalling and response in laticifers resolves a longstanding mystery of ethylene stimulation in rubber production. Our study, which includes the re-sequencing of five other Hevea cultivars and extensive RNA-seq data, provides a valuable resource for functional genomics and tools for breeding elite Hevea cultivars.

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Hevea Rubber Breeding and Genetics

Cited by 54 publications

References 0 publications

Histo- and cytopathology of trunk phloem necrosis, a form of rubber tree (Hevea brasiliensis Müll. Arg.) tapping panel dryness

Histo- and cytopathology of trunk phloem necrosis, a form of rubber tree (Hevea brasiliensis Müll. Arg.) tapping panel dryness

Cyanogenesis and the onset of tapping panel dryness in rubber tree

The rubber tree genome reveals new insights into rubber production and species adaptation

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